2. SHS Chemistry and Technology


O-2-01: Usage of Filtrational Combustion for Accelerated Synthesis

of Active Charcoals

V.A.Borodulya1, L.M.Vinogradov1, S.A.Zhdanok1, V.S.Komarov2,

A.V.Krauklis1, N.K.Lunyova2, A.M.Safonova2

1HMTI named after A.V.Lykov of National Academy of Sciences of Belarus, Belarus

2IONCh of National Academy of Sciences of Belarus, E-mail: bor@dsl.itmo.by

Traditional method to obtain active charcoals is a two-stage one and differs in power consumption and duration. In includes carbonization of initial timber and subsequent activation of raw coal.

Based on results of studies performed by the authors, specific one-stage technique of obtaining carbon adsorbents from timber wastes is proposed. It is based on thermocemical pyrolysis of raw material in the steam-gas flow from gas radiation porous burners. Under such conditions

cellulose containing materials are exposed simultaneously to intensive heat radiation and interaction with gaseous products of combustion. During contact heating high active radicals H, OH, HO2 which are formed during gas filtrational combustion initiate destruction of bonds in polymeric chains with forming liquid and gaseous products and char residue. Combining pyrolysis and steam-gas activation under speedy heating (40 to 50 degrees per min) with short-term endurance at final processing temperature (near 600 - 7000C) leads to carbonization of impregnated timber and formation of porous absorbent's structure. Impregnating additives contain catalysts of charring and pore-forming substances. Again char residue yield increases 2 to 2.5 times and iongenic functional groups are introduced at the same time. Chars obtained in such a manner possess high consumption characteristics. They can absorb both organic compounds and ions of heavy metals and are comparatively cheap in the production. The process is characterized by high degree of ecological safety and is the basis to develop compact mobile devices to produce carbon adsorbents from timber wastes and other vegetation raw materials.

O-2-02: Kinetic Study of Synthesis of SiC Powders and Whiskers

in a Presence of KClO3 or Teflon

J. A. Puszynski, Shuxia Miao

Chemistry and Chemical Engineering Department South Dakota School of Mines and Technology , Rapid City, SD 57701 USA

Tel: 605-394-1230, Fax: 605-394-1232, E-mail: pusz@silicone.che.sdsmt.edu

It has been demonstrated that an addition of certain chemicals, such as Teflon and KClO3, makes the reaction between silicon and carbon self-sustaining without any additional energy input. Nanosize SiC powders with an average particle size of about 200 nm have been successfully synthesized using that approach.

The effect of KClO3 and Teflon on maximum combustion temperature, reaction heating rate, and the combustion front velocity have been studied in detail. With increasing concentrations of KClO3 (5 ~ 20 wt%) and Teflon (8 ~ 20 wt%), the maximum combustion temperature increases from 1400oC to approximately 2000oC. However, the combustion front velocity in the case of KClO3 varies from 0.5 cm/sec to 2 cm/sec, and it is ten times faster than that when Teflon is used as the additive.

It has been found that the gas pressure has a very significant effect on the combustion characteristics. When the concentration of additives is greater than the minimum concentration, three different combustion regimes might exist. If the gas pressure is lower than minimum pressure, no propagation can be achieved. However, when the gas pressure is higher, low-temperature and high-temperature combustion waves might be generated. The propagation regime depends on the absolute value of the gas pressure.

The activation energy of SiC formation in the presence of KClO3 and Teflon were estimated using non-isothermal technique and they were found to be 380 kJ/mole and 520 kJ/mole respectively.

It has also been demonstrated that SiC whiskers can be formed in the presence of above discussed additives and other growth promoters, such as Fe, Co and Ni. Mechanism of whisker growth and their morphology will be presented in detail.

O-2-03: Magnesium Thermite Method for Preparing Hydrides of Alkali Metals

V. V. Zakharov, A. P. Alekseev, G. P. Bugaeva, V. V. Kedrov, N. Nechiporenko

Institute of Chemical Physics Researches RAS, 142432,Chernogolovka, Russia

Hydrides of alkali metals are widely used as reagents or reducing agents in organic and inorganic chemistry as well as in compositions generating hydrogen.

The most known method for preparing hydrides of alkali metals is hydrogenation of molten alkali metals with molecular hydrogen at temperatures up to 700oC during long time and that is the principal disadvantage of such methods. Besides, in order to prepare some hydrides it is necessary to use stirring means. In some cases hydrogenation is performed in inert organic solvents and that makes the process significantly more complex.

The proposed magnesium thermite method for preparing hydrides of alkali metals consists in reduction of hydroxides of alkali metals with magnesium that is perfomed in the combustion regime after ignition of a mixture and further hydrogenation of a formed in an active form alkali metal with evolved hydrogen at cooling the combustion products. In fact, both reactions proceed as a unique process.

MeOH + Mg = Me + MgO + 1/2H2 (1)

Me + 1/2 H2 = MeH (2)

MeOH + Mg = MeH + MgO (3)

The effect of various technological parameters (ratio of components, their dispersity, the relation between free volume and a mass mixture, etc.) on the yield and chemical activity of a hydride was studied. It was established that hydrides of alkali metals may be prepared by the proposed method with high yields (up to 90-95% LiH, 70-80% NaH and KH) at rather low hydrogen pressures

(5-10 ata) growing as a result of the reaction (1).

It was experimentally shown that inseparable mixtures of hydrides of alkali metals with magnesium oxide possess higher chemical activity than crystalline hydrides of alkali metals, which were prepared by direct hydrogenation of alkali metals. in particular, in exchange reactions with aluminium chloride at reduction of organic compounds and particularly upon using solvents or gases as drying agents.

O-2-04: The Reaction Rechanism Of Aln and Growth Mechanisms of Aln Whiskers by Combustion Synthesis Method

Jiang Guojian, Zhuang Hanrui, Li Wenlan, Wu Fengying, Zhang Baolin

Department of High Temperature Structural Ceramics, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi road, Shanghai 200050, China,

Tel:+86-21-625-129-90-6275,Fax: 86-21-62513903, Telex: 33309 ASSIC CN

E-mail: hrzhuang@sunm.shcnc.ac.cn)

Aluminum nitride is well known for high thermal conductivity. AlN fibres or whiskers have been used to optimize the thermal properties of electronic-packing application.

Under high pressure nitrogen, AlN containing higher nitrogen content (33.5wt%) has been prepared by SHS method. The combustion reaction characteristics in the nitridation of Al was investigated by measuring nitrogen content. Based on calculating the free energy ((rGm() of reactions, the reaction mechanism of combustion synthesis of AlN is possibly the reactions between N2 and Al vapor and/or liquid Al. Based on experiments, the reaction mechanism of combustion synthesis of AlN is proposed. The primary structure of the combustion wave in the nitridation of Al is proposed. the reaction is divided into four zones, i.e. preheat zone, reaction zone (which, in turn, is divided into kinetics control stage, thermal explosion stage, transition stage and diffusion stage), after-burn zone and cold zone. The Activation Energy of the Kinetic Reaction Process is 6 KJ/mol.

SEM morphology of combustion products and its production mechanism have also been studied simply.

To apply AlN whisker commercially, it is necessary to produce it by an economic means. The AlN whiskers used in this investigation have been produced by SHS technique. Here, the morphology, chemistry, and growth mechanism of AlN whiskers have been investigated using high-resolution electron microscopy, and X-ray diffraction techniques. Emphasis has been placed on the crystallographic aspect of the mechanism of growth of the whiskers. The growth mechanisms of AlN whiskers are VLS and VS mechanism.

O-2-05: About Possibility of Use of SHS Nitrided Alloys for Production of


L.N. Chuhlomina, M.Kh. Ziatdinov, Yu.M. Maksimov

Tomsk Branch of the Institute of Structural Macrokinetics and Materials Science Russian Academy of Sciences,Tomsk, 634021, pr. Academicheskii, 10/3, Russia.

E-mail: maks@fisman.tomsk.su

The method of nitrides extraction from nitrided ferroalloys, obtained in special furnaces in nitrogen is known. The alloy formed is subjected to treatment by mineral acids with production of metal nitrides and water soluble iron salts. The most important condition for the use of this method is the production of composite iron - nitride alloy, in this case nitride component must be one-phase one. In conventional furnace method it is achieved through long many-staged nitriding. In this work SH synthesis of iron-nitrides of chromium, niobium, titanium, vanadium alloys was investigated. The effect of synthesis conditions upon the character of nitriding process and products' composition was studied. Changing the parameters of SHS we obtained two-phase iron-mononitrides alloys of the corresponding metals.

To extract the nitride phases through the acid enrichment, the solutions by hydrochloric and sulphuric acids in a wide concentration range (5-25%) were used. The kinetic curves of accumulation of iron, chromium, niobium, vanadium, titanium in the solutions of various concentrations are presented. Owing to the results of the acid enrichment investigation, treatment conditions of SHS nitrided ferroalloys were chosen; under these conditions the content of iron in metal nitrides and the losses of the latter are minimal.

Physical and chemical properties of the nitrides, being extracted, were investigated. Phase and elementary composition of obtained niobium, chromium, vanadium, titanium nitrides was determined with X-ray-phase and chemical analysis. The oxidation nitrides in air up to 1000oC was investigated with the help of complex thermal analysis. The specific surface of the nitrides obtained was determined.

Thus, the nitrides of chromium, niobium, vanadium and titanium were produced through acid enrichment of SHS nitrided ferroalloys. Some of their physical and chemical properties were investigated.

O-2-06: Combustion Synthesis of Ternary Carbides TixSc-xCy Scandium

Hydride, Ti and C

A.G. Aleksanyan, S.K. Dolukhanyan

Institute of Chemical Physics of National Academy of Sciences of Republic of Armenia, 5/2, Paruir Sevak Str., Yerevan 375014, Republic of Armenia.Phone:(374 2)28-17-80,

28-16-41; Fax:(8 3742)28-17-42; E-mail:chph@chemphys.iiap.sci.am

The complicated carbides on the base of Ti-Sc possessed high hardness close that of diamond. The diagram of states of the TiC-ScC systems is poorly studied yet. However, some information about the mutual dissolvation of these carbides is available at present.

The investigation of the combustion systems xTi + (1-x)ScH2-z(Sc) + yC in hydrogen and argon atmosphere were carried out in wide ranges of Ti/ScH2-z and Ti/Sc ratios at various carbon content (z<1; 0.4 < y < 1) .

Preliminary, the combustion process in Sc-H system was studied. The hydride of Sc (fcc structure, a = 4.76A, H-content - 2.0 %) was synthesized.

The thermal dissociation of ScH2-z was studied using Derivatograph Q-1500. It was established that the dissociation began at 600oC. The complete dissociation occured at 1000oC. The powder of Sc of hcp structure (a=3.308; c=5.268) was obtained.

In this work ScH2-z and Sc were used as initial reagents.The obtained experimental data prove that the combustion process in the above mentioned system is a two-stage process. In the first, high temperature stage, Ti + xC reaction takes place (when x > 5 and Ti/Sc > 0.5). Because of high temperature arised in the reaction zone, the dissociation of scandium hydride and its interaction with carbon begin. As a result, the scandium carbide is formed. Then depending on combustion temperture, full or partial dissolvation of ScC in TiC takes place. It has been found that the full dissolvation of this carbides is possible at Ti/ScH2-z < 4. On the solubility of these carbides, the content of carbon in the initial mixture also influences.

This work was supported by ISTC. Grant A-192.

O-2-07: Hydriding Shs of Mg2Nih4

T. Akiyama 1 , Liquan Li 2, J. Yagi 3
1 Institute for advanced materials processing, Tohoku University 1-1, Katahira,

Sendai, 980-8577, Japan

2 Research Institute of Electric Light Source Material, 5 Jinchuanmenwai, Nanjing 210015, P. R. China

3 Miyagi National College of Technology 48, Natori, Miyagi Prefecture, 981-1239, Japan
Hydriding and dehydriding behaviors of the product in hydriding combustion synthesis of Mg2NiH4 were investigated by TG-DTA. During seven cycles of heating (dehydriding) and cooling (hydriding) under a rate of 0.1 K / sec, the TG-DTA curves of the combustion synthesis product were measured in 1.0 MPa pressure of hydrogen atmosphere. Some behaviors like activation within the early four cycles of hydriding and dehydriding were observed. The hydriding and dehydriding reactions were gradually getting rapid from 1st cycle to 4th cycle, then, they were in constant almost after 4th cycle. This behavior is likely an activation process. It is much easier in present hydriding combustion synthesis than that in a conventional ingot process. The splitting and the overlapping of the peaks from the dehydriding reaction in DTA curves give some information on the existence of

two pairs of the modifications of Mg2NiH4.

O-2-08: Transition Metal Nitrides Prepared by HP-SHS

M. Ferretti1, A. Martinelli1, V.Buscaglia2

1INFM and Dip.to di Chimica e Chimica Industriale, via Dodecaneso 31,

I-16146 Genoa, Italy,E-mail:amartin@chimica.unige.it

2Istituto di Chimica Fisica Applicata dei Materiali,CNR,via De Marini 6,1-16149 Genoa,Italy

Various carbides and nitrides of the group IV B, V B and VI B transition metals exist in fields of rather extended homogeneity. These materials are non-stoichiometric and their properties (thermodynamic, mechanical, electrical, magnetic, superconducting) depend strongly on the presence of structural defects, in particular on vacancy concentration on the metal and nonmetal sublattices1.2.3.4 thus carbon/metal and nitrogen/metal ratios play an important role. Materials prepared with various techniques are characterised by different structural defects and therefore also by different properties. Researches conducted in the field of high pressure and high temperature could carry to the synthesis of phases of stoichiometric composition with low vacancy concentration. By a high pressure autoclave (up to 1000 bar N2) they were studied some systems where phase equilibria and nitrides composition depend strongly on nitrogen pressure, as the Cr-N5,6, Mo-N5, Nb-N7,8 and V-N9 systems. For example, applying the chemical oven technique to the Nb-N system, it was observed10 the growth in few seconds of thick nitride layers of (50 (m (for comparison a (100 (m nitride layer was obtained by isothermal nitridation after 10 hours in 15 kPa N2 at 1900-C11). Moreover the value of the superconductive transition temperature of (-NbN1-x it was found to depend on the nitrogen pressure applied during combustion. The maximum value of Tc=17.2(0.2 K was measured on a sample nitrided at 200 bar and it is in good agreement with the highest Tc values reported in literature (Tc=17.3 K)12,13.


1. L.E. Toth,Transition Metal Carbides and Nitrides, Academic Press, 1971.

2. K. Schwarz, N. Rysch, J. Phys. C: Solid State Phys., 9 (1976) L433.

3. G. Ries, H. Winter, J. Phys. F: Metal Phys., 10 (1980) 1-7.

4. V.N. Lipatnikov, W. Lengauer, P. Ettmayer, E. Keil, G. Groboth, E. Kny, J. Alloys Comp., 261 (1997) 192-197.

5. K. Frisk, CALPHAD, 15 (1991) 79-106.

6. W. Mayr, W. Lengauer, P. Ettmayer, D. Rafaja, J. Bauer, M. Bohn, Def. Diff. For., 143-147 (1997) 569-574.

7. W. Huang, Metall. Trans. A, 27A (1996) 3591-3600.

8. M. Joguet, W. Lengauer, M. Bohn, J. Bauer, J. Alloys Comp., 269 (1998) 233-237.

9. Y. Du, R. Schmid-Fetzer, H. Ohtani, Z. Metallkd., 88 (1997) 545-556.

10.V. Buscaglia, F. Caracciolo, M. Ferretti, M. Minguzzi, R. Musenich, J. Alloys Comp., 266 (1998) 201-206.

11. R. Musenich, P. Fabbricatore, G. Gemme, R. Parodi, M. Viviani, B. Zhang, V. Buscaglia, C. Bottino, J. Alloys Comp., 209 (1994) 319-328.

12. M.W. Williams, K.M. Ralls, M.r. Pickus, J. Phys. Chem. Solids, 28 (1967) 333.

13. K.S. Keskar, T. Yamashita, Y. Onodera, Jap. J. Appl. Phys., 10 (1971) 370.

O-2-09: Peculiarities of SHS Fine-Dispersive Complex Titanium-

Chromium Carbide in Complex System

S.S. Mamyan, D. Belov, I.P. Borovinskaya

Institute of Structural Macrocinetics and Materials Science,

Russian Academy of Sciences, Chernogolovka, 142432, Russia

Regularity of the fine-grained complex carbide TiC - Cr3C2 - Ni synthesis have been studied.

Thermodynamic researches have shown the possibility of the formation of that complex compound at the combustion of Ti - Cr - C - TiO2 - NiO system. The experimental researches have shown that we can regulate the particle size, replace elementary Ni by its oxide and replace approximately to 20-30% elementary Ti by TiO2 at SHS of this system.

The effect of the initial synthesis parameters on the product quality (particles morphology, size and distribution components, chemical composition, etc.) has also been shown.

O-2-10: Formation of Metal Sulfides in Combustion of Metal Nitrates Complex

Compounds with Sulfur-Containing Organic Ligands

R.K. Tukhtaev, V.V. Boldyrev, A.I. Gavrilov, S.V. Larionov, Z.A. Saveljeva,L.I. Myachina Institute of Solid State Chemistry and Mechanochemistry SO-RAN, Russia

Complex compounds of metal nitrates with hydrazine and its derivatives are knows as energy-rich substances able to undergo self-sustaining combustion [1, 2]. The presence of metal atoms in the complexes leads to the formation of solid products during combustion, along with gas-phase ones. This allows to consider these complexes as initial substances to obtain definite target products during combustion.

It was shown earlier that the combustion of complex compounds of nickel and copper nitrates with some hydrazine derivatives, e.g. semicarbazide, aminoguanidine, and oxalyl dihydrazide, leads to the formation of metal nickel and copper with porous, carcass structure [3-5].

In the present work we demonstrate the possibility to obtain sulfides of different metals during the combustion of such complexes. The formation of sulfides occurs if a sulfur-containing hydrazine derivative, thiosemicarbazide, is used as a ligand. Nickel, cobalt, copper, zinc and cadmium sulfides were obtained by this method. We also found that complexes of some metal nitrates with thiocarbamide (which are not so rich in energy) are also able to burn. Their combustion is also accompanied by the formation of the sulfides of corresponding metals.

It is important that the morphology and dispersity of the combustion products can be governed. This can be done by changing the conditions of their formation in the combustion wave by varying some parameters, e.g. external pressure, temperature and combustion rate. This effect is especially vivid in obtaining sublimable sulfides with rather high vapour pressure at the temperature of complex combustion.


  1. Shidlovsky A.A., Gorbunov V.V., Shmagin L.F. Izv.VUZov. Ser. Khim. i Khim. Tekhnolog.,1978, v.21, N 9, p.1249 (in Russian).
  2. Sinditsky V.P., Fogelzang A.E. Rossiyski Khimicheskii Zhurnal, 1997,N 4, p.74 (in Russian).
  3. Gavrilov A.I., Tukhtaev R.K., Larionov S.V., Lavrenova L.G., Saveljeva Z.A., Boldyrev V.V. Dokl.RAN, 1996, v 348, N 2, p.201.
  4. Tukhtaev R.K., Gavrilov A.I., Larionov S.V., Saveljeva Z.A., Lavrenova L.G., Boldyrev V.V. Journal of Materials Synthesis and Processing, 1997, v.5, N 5, p.371.
  5. Boldyrev V.V., Tukhtaev R.K., Gavrilov A.I., Larionov S.V., Saveljeva Z.A.,Lavrenova L.G. Russian Journal of Inorganic Chemistry, 1998, v.43, N 3, p.302.

O-2-11: SHS of Metal Carbides; Reactions of Calcium Carbide with Anhydrous

Metal Halides I. P. Parkin1, A. T. Nartowski, A. Craven2, M. Mackeenzie2

1 Department of Chemistry, University College London,20 Gordon Street, London WC1H OAJ, UK

2 The Department of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ,
Transition metal carbides are widely utilised in industry as components of hard coatings and wear resistance parts. They are conventionally synthesised from the elements at extreme temperatures

(> 2,000°C) under controlled atmospheres for prolonged time periods. We have developed two new routes to a wide range of transition metal carbides (TiC, ZrC, HfC, V8C7, NbC, TaC, Cr3C2, Mo2C, WC, Fe3C) from the self propagating reactions of aluminium carbide or calcium carbide with anhydrous metal chlorides (Eqn.1, Eqn.2). In the calcium carbide reactions crystalline metal carbides such as TaC can be made in less than ten seconds and the reaction promoted in air. The solid state metathesis reactions have been extended to the synthesis of solid solutions of mixed metal carbides and metal carbonitrides. Microstructure of the metal carbides has been investigated in detail by TEM and ELNES studies.

CaC2 + TaCl5 --------> TaC + CaCl2 + C Eqn.1

Al4C3 + 3WCl4 --------> 3WC + 4AlCl3 Eqn.2

O-2-12: Silicon Nitride Synthesis by SHS. Ammonium Salts Role in the Final Product Characteristics

I. G. Cano, S. Purez, M. A. Rodriguez, S. de Aza

Instituto de Cerámica y Vidrio (CSIC), Arganda del Rey (Madrid), Spain

Silicon Nitride is one of the most interesting ceramic materials due to their good mechanical behavior at high temperature. There are a lot of applications for this material, but they can increase their possibilities decreasing the cost of the raw materials. This is the reason because SHS is a good candidate in order to reduce the cost of the Si3N4 powders.Due to the high temperatures involved in SHS process, almost of the Si3N4 synthesized is b phase. In order to obtain a powder fully a -Si3N4, with high productivity, ammonium salts are added to the raw materials mixture.

In the present work, the effect of the amount and chemical composition of the ammonium salt used, on the physic-chemical characteristics of the final products are studied.

Compositions using different amounts of Ammonium Chloride, Ammonium Fluoride and mixes of them are added to the raw materials to improve the Synthesis. Final products are characterized by SEM and XRD.

O-2-13: Chemistry and Technology of Combustion Synthesis of Complex


M. D. Nersesyan1, D. Luss2 1 Institute of Structural Macrokinetics and Materials Science, Russia Academy of Science, Chernogolovka, 142 432 Russia

2 University of Houston, Dept of Chemical Engineering, Houston, TX, USA

We review the various combustion methods that can be used to produce complex oxide materials (ferroelectrics, high-Tc supperconductors, La-based perovskites, NZP-compositions, etc). We discuss the unique features of each process, their advantages and shortcomings. The reviewed combustion processes include: GNP (glycine-nitrate process), nitrate- tetraformal trisazine method, metal salts (nitrate, phosphate) -urea mixture synthesis, solid - state metathesis process, and SHS.

O-2-14: Synthesis of Perovskites (ABO3) by Combustion Process

G.L. Morelli, M.R. Morelli Federal University of São Carlos, Department of Materials,Via Washington Luiz, km 235,

CEP 13565-905, São Carlos, Spain – Brazil, E-mail:morelli@power.ufscar.br

The development of ceramic materials with characteristic of laser properties, electrical conductivity, electro-optical and piezoelectric behaviour is a quite attractive subject of fundamental and technological research of the last years, due the properties highly peculiar that has been observed in these classes of materials. The work searches through the synthesis by combustion reaction the preparation of ABO3 perovskite-type compounds, namely, LaAlO3, LaCoO3, LaCrO3, LaNiO3, LiNbO3 powders, with adapted characteristics of high crystallinity and phase stability. The main objective is to evaluate the combustion technique for powder preparation as an alternative method to the sophisticated and complex processes, which involve high costs, besides the acquaintance conventional mixing of oxides that produces powders of low reactivity and/or with the presence of undesired secondary phases. Powder’s characteristics prepared by combustion reaction are presented and discussed. The purpose of this work is to attempt to bring together the information obtained from this study and to evaluate the combustion process as an alternative rote for preparing new perovskite compounds with new and improved properties.

The authors are thankful to FAPESP - State of São Paulo Research Support Foundation - Brazil.

O-2-15: Self-Propagating High-Temperature Synthesis of Complex Chromium-

Containing Alkaline and Alkaline-Earth Metals Oxides

M.V. Kuznetsov, Yu.G. Morozov

Institute of Structural Macrokinetics and Materials Science RAS,

Chernogolovka, 142432 Russia

Complex chromium-containing oxides of alkaline and alkaline-earth metals with general formula MexCryOz (Me = Li, Na, K, Ba, Sr, Ca, Mg; x = 1-2; y = 1-2; z = 2-4) were synthesized by Self-Propagating High-Temperature Synthesis (SHS), a combustion process involving reactions of appropriate alkaline or alkaline-earth metals peroxides or superoxides like sources of oxygen and chromium oxides (III) or (VI). Preliminary thermodynamic calculations indicated the possibility of combustion process producing in all the above systems without metal powder using like source of fuel. Change of Gibbs free energy and enthalpy of reactions shows that all the reactions from binary oxides are thermodynamically allowed. X-ray diffraction characterization of the products of mechanochemically promoted reactions of appropriate peroxides with the chromium oxides give us the evidence about beginning of the mixturing metal oxide formation during the mechanical activation on the stage of the green mixture preparation. SHS reaction was carried out as in non-pressed powder mixtures as in pressing pellets. Temperature and velocity of combustion was 0.2-1.0 mm/s and 500-8000C accordingly in dependence from the reaction scheme and starting reagents. X-ray diffraction of the final combustion products showed the single phase samples formation during SHS and was in good agreement with the literature data. In combustion of the studied systems in absence of measuring current, the emergence of potential difference were observed when the steady-state combustion front passed though green mixture. The concepts of ionization chemistry of combustion are known to be based on the reaction of chemi-ionization developed for combustion in flames. Some ionization of reagents, which is probably taking place during an SHS reaction, promotes the formation of negatively and positively charged particles of intermediate product. The mechanism of elementary chemical reactions that occur in the combustion wave can be characterized by degree of ionization, ion changes and temperatures, and also their spatial distribution and density. Electric field influence on the combustion wave propagation were also studied. When the negative electric field was applied along the combustion front propagation, the combustion parameters exhibited their maximum at the same field strength. It should be noted that the field effect on the combustion velocity was stronger as compared to that on the combustion temperature.

Synthesizing SHS products can be used in pigment mixtures; in the tunnery industry; like dry electrolytes; corrosion inhibitors etc.

O-2-16: Synthesis of Lattice Matched Cd-In-Ga Oxides for Gan Thin Film


Sy-Chyi Lin1 , R. Wilkins1 , M. D. Nersesyan2 , D. Luss3

1 NASA Center of Applied Radiation Research, Prairie View A&M University

Prairie View, TX 77446. E-mail: sclin@uh.edu

1 Institute of Structural Macrokinetics and Materials Science,

Russia Academy of Science, Chernogolovka, 142 432 Russia

3 Chemical Engineering Department, University of Houston,Houston, TX 77204, USA

Gallium nitride and associated III-N materials have various potential electro-optical applications. The lack of cost-effective latticed-matched substrates for growing these nitride films is a recognized problem. CdIn2-dGadO4, with lattice constants from 8.39 Å (d =2) to 9.17 Å (d =0) may be suitable substrates for growing various nitride thin films. For examples, CdIn1.673Ga0.327O4, having a lattice constant of 9.04 Å (2x cubic GaN), and CdIn0.952Ga1.048O4, having a lattice constant of 8.76 Å (2x AlN), may be substrates for growth of GaN and AlN thin films, respectively. The sointering/calcination processes to produce Cd-In-Ga oxides are time consuming and expensive. We studied the use of Self-propagating High-temperature Synthesis (SHS) to fabricate Cd-In-Ga oxides to circumvent these synthesis problems. We studied the impact of the standard SHS variables on the product quality at normal pressures using various precursor powders, pellet diameters and densities, oxygen flow rates, and additives. A high-pressure reactor was used to investigate the impact of oxygen pressure on product quality. The crystal structure and local stoichiometry of the product were determined by XRD and EMPA. The thermal behavior of the reactants at high temperatures was determined by TG/DTA. The reaction network and kinetics for the reaction were deduced from the temperature history during the combustion.

O-2-17: Disilicides Elaboration by Combustion Synthesis: Interest

of Using a Mechanical Activation Step

Ch.Gras1,2, E.Gaffet1, F. Bernard2, D. Vrel3, J.C. Niepce2

1 “Far from equilibrium phase transition” group UPR CNRS AO423 IPSé F-90010 Belfort

2 “ fine grained materials ” group LRRS UMR 5613 CNRS-University of Burgundy

BP 47870 –F 21078 Dijon Cédex, France

3 LIMHP CNRS av. J-B. Clément F 93430 Villetaneuse, France

Mechanical high-energy ball milling of X+2Si (X=Mo or Fe) elemental powders mixture was firstly used to activate self sustaining combustion reaction or so-called SHS (Self-propagating High-temperature Synthesis) in the case of MoSi2 formation and, secondly, in the case of FeSi2 . In the case of Fe-Si system, the thermodynamic criterion is not favorable to a direct synthesis via SHS process (Tad < 1800 K).

The mechanically activated SHS process is able to produce via a very fast combustion front (> 20 mms-1) a pure “ bulk ” a-MoSi2 with a nanometric structure (66nm). In addition, the nanostructure of the starting powder mixture (Mo+2Si) influences the propagation of the combustion front and modifies the values of thermal parameters during the process. In the case of Fe-Si system, mechanical activation allows to initiate a self-sustaining reaction after heating up to 400°C a cylindrical sample.

Thermal and structural informations describing the combustion front initiated in Fe-Si or in Mo-Si green samples were clearly determined using a Time-Resolved X-ray Diffraction (TRXRD) experiment coupled to an infrared camera. Mo+2Si-> MoSi2 appears to be the only reaction, which is monitored with a temporal resolution of 30 ms inside the combustion front during SHS process. The existence of a combustion wave in Fe-Si system was assumed to be linked to the formation of FeSi compounds during gasless reaction.

O-2-18: The Effect of Mechanical Treatment on the Rate and Combustion

Limits of Shs Processes

M.A. Korchagin, T.F. Grigorieva, A.P. Barinova, N.Z. Lyakhov

630128 Novosibirsk, Kutateladze 16, Russia, e-mail: root@solid.nsk.su

The influence of preliminary treatment of reaction mixtures in high-energy ball mill AGO-2 on the rate and concentration limits of combustion in the systems Ni-Al, Ni-Si, Ni-Ge, Ni-Ga, Ni-Ti, Co-Al has been studied. In order to prevent oxidation, mechanical activation and SHS were performed in argon. It has been established that with increasing time of mechanical treatment (MT) in all the systems at first the rate of combustion increases, then decreases. This decrease is connected with the fact that primary (intermediate) intermetallides begin to form in mixtures as a result of mechanical alloying. Practically all the investigated systems exhibit broadening of the concentration limits within which SHS processes occur. For example, it is known that in the Ni-Al system, the compositions containint less than 13,5 mass.% Al do not burn. MT of the initial mixture for 30 - 40 s allows to perform SHS with the compositions containing only 7 mass% Al. The products are Ni2Al3, NiAl and Ni. The composition Ni-Ti burns without additional heating after MT for 1,5 min. We succeeded in performing SHS in somewhat exotic system Ni-Ga after MT.

It is known that it is difficult (or even impossible) to obtain a single-phase product by means of SHS in many intermetallic systems. MT of SHS products allows to carry out phase homogenisation. For example, the mixture of Ni2Al3 with NiAl after MT for 3 min is transformed into a single-phase product composed only of NiAl with the size of coherent scattering domains 8-10 nm. Electron microscopic studies of the changes in the morphology of particles in the reaction mixture during MT have been conducted.

O-2-19: Effect of High-Energy Milling Reactant on the Combustion Synthesis of


R. Tomasi1, Z.A. Munir2

1Department of Materials Engineering, Federal University of Sao Carlos, Sao Carlos, 13565-905, Brazil. E-mail:tomasi@power.ufscar.br

2 Department of Chemical Engineering and Materials Science, Facility for Advanced Combustion synthesis,University of California,Davis,CA 95616,USA.


The Ti3SiC2 is one interesting material due its high thermal and chemical resistance and good machinability and ductility at elevated temperatures. Most of the solid-state synthesis of Ti3SiC2, including the combustion synthesis, has resulted in the presence of TiC, TiSi2 or SiC as second phase. Although the reported good stability of the Ti3SiC2 up to 1600oC, the formation of a second phase during solid phase synthesis has explained by decomposition of the ternary phase at the temperature range of the synthesis process. In the combustion synthesis the velocity and the stability of combustion wave propagation can be significantly improved by decreasing reactant particle size. High-energy milling can also mechanically activate the reactivity in solid state process. In this work, it was studied the effect of high-energy milling the mixture of Ti, Si and graphite on the combustion synthesis of Ti3SiC2. Reactant mixtures were milled at different time and ball to powder mass ratio and the transformations during milling were characterized by X-ray diffraction. The combustion synthesis experiments were performed in cylindrical pressed pellets. It was observed the significant effect of milling on propagation velocity, probably due both the reactant particle size and the partial transformations, by mechanically induced reaction, during milling. The correspondent effect was also observed for final microstructure.


O-2-20: Shs Synthesis of the Oxide Systems Based on the "Mechanochemical"

Quartz Modified by Organometallic Compounds

G.I. Ksandopulo, N.N. Mofa, T.A. Keteguenov, O.V. Chervyakova, O.A. Tyumentseva

Combustion Problems Institute, Almaty, Kazakhstan, e-mail icp@kaznet.kz

The preliminary mechanochemical activation of the powder systems is one of the most efficient methods of material energetic state modification and further effects on the solid phase reactions in the synthesis of new compounds notable for their required properties complex. The relaxation of metastable state of the material obtained by mechanical processing promotes the running of divers chemical processes that makes possible the efficient decrease of the synthesis temperature and speeds-up the interactions of such system components.

The use of divers alcohols and other organic additives in the mechanical quartz processing as a surface active substances makes possible the formation of polymer compound particles on the surfaces. During further heating of the particles having their modificated surfaces there are occurred organic compound decomposition and high-active radicals formation which participate in the redox processes and effect on the starting and kinetics of such processes running out.

In this paper the evaluation analysis of energy saturation of the quartz particles resulted of the mechanochemical processing in the centrifuge-planetary mills is carried out. This investigation showed that the variations of mechanical action conditions and its time duration (5-100 minutes) result in the observed stage-by-stage modification of the processed material structure and state. The quartz activation during 15 minutes results in the most pronounced effects, the synthesis starting temperature being decreased and making possible the most complete reaction running out at minimum charge content of aluminum (up to 6%). The energy saturation of the quartz processed individually or in the mixture with other oxides substantially depends on the used organic additions. The buthanol as a modifying additive is the most efficient to speed up the reactions between quartz and aluminum.

It is shown that the kinetic combustion characteristics, phase composition, structure and properties of the end synthesis products of the analyzed materials based on the SiO2 + Al system depend on the organic and organometallic compound types formed on the surfaces of the quartz particles during preliminary mechanochemical processing and that the most pronounced effects on the SH-synthesis are attributed to the action of aluminum and organic compounds.

O-2-21: Mechanically Stimulated Self-Propagating Syntheses of

Coordination Compounds

V.D.Makhaev, A.P.Borisov, V.V.Aleshin, L.A.Petrova Institute of New Chemical Problems RAS Chernogolovka, 142432, Russia

In the course of systematic investigations we have shown wide possibilities of solid-state mechanochemical methods in the synthetic chemistry of coordination compounds such as metallocenes, b -diketonates, carboxylates, metallocarboranes etc. Physico-chemical (IR, XRD, TGA, DTA etc.) and preparative investigations of the reaction mixtures consisting of solid metal chlorides and salts of organic ligands allowed us to draw a corollary that all systems studied can be divided into three main groups depending on their response to mechanical loading.

The first group includes ordinary mechanochemical reactions, formation of products in which takes place directly in the course of mechanical loading, as, for example, formation of ferrocene in the system “FeCl3 — TlC5H5”. The second group consists of the systems, mechanical loading of which leads initially to the formation and accumulation of activated mixture without formation of the final products. Formation and relative quantity of activated mixture can be detected by the appearance of a new exothermic event on DTA curves of mechanically loaded reaction mixtures. Prolongation of mechanical treatment after accumulation of the activated mixture in the systems leads to “explosive mechanochemical synthesis” - a sudden initiation of a fast exchange reaction leading to a vigorous self-heating and formation of final products. Bulk heating of the activated reaction mixtures leads to the exothermic interaction of reactants with formation of final products which can occur in the form of heat explosion. Exothermic interaction of reactants in such systems can be organized in the self-propagating mode: the action of a local thermal impulse on an end face of the specimen formed from the activated mixture causes the appearance of reaction zone which propagates along the specimen up to a full exhaustion of a material with formation of final products. “CrCl3 — NaC5H7O2” is an example of such systems.

The majority of the systems investigated takes an intermediate position between these extreme cases. That is, formation of final products and intermediate activated mixture occurs in the course of mechanical loading. Further transformation of mechanically activated mixtures to the products can be organized in various modes, including self-propagating, depending on conditions of the mechanical loading, organization of the process and chemical identity of reactants.

Characteristic features of self-propagating syntheses of coordination compounds are discussed.

We acknowledge support from RFBR (grants No 99-03-32253; 99-03-32900).

O-2-22: Mechanism of Interaction and Combustion Limits for Niobium and

Carbon under Conditions of Chemical Activation

A.V. Kostanyan, H.H. Nersisyan, S.L. Kharatyan

Nalbandyans Institute of Chemical Physics NAS RA Yerevan, 375044,

Republic of Armenia. E-mail: Suren@ichph.sci.am

According to literary data the process of combustion in Nb-C system can be realized on two various manners: a). with mechanical compression of initial samples before ignition; b). by introduction of chemical activators in an initial mixture. In the first case the process proceeds unstable and at the rather small particle size of niobium (m Nb³ 15mm) there is failure of combustion. In the second case the upper limit of combustion on Nb particle size is much wider (m Nb£ 80 mm).

The purpose of presented work is to study the interaction mechanism and expansion of combustion limits of Nb-C system on various parameters in conditions of activation.

Combustion limits of Nb-C system on following parameters are experimentally investigated: the size of metal particles, ratio of initial reagents, tablet diameter, amount of inert additive. Various activators of combustion with the purpose of activation both metal, and carbon were tested.

It was shown, that at introduction in an initial mixture Nb with C a few (less than 1%) chemical activator successfully selected for the given system - polytetrafluoroethylene, steady-state combustion in a wide range of values of various parameters takes place: the size of niobium particles (m Nb£ 80 mm), initial tablet diameter (d³ 10 mm), ratio of initial reagents (0,3£ a £ 1,0), amount of the inert additive in a mixture (up to 50 % mass.) etc.

It was shown, that the observable expansion of combustion limits is result of intensification of gas-transport transfer of niobium to carbon particles, by means of niobium fluorides. The similar studies on activation of carbon using various gas-generating additives, including of oxalates of metals, appreciable results have not brought.

It was established by X-ray and SEM analyses, that it’s possible to synthesize single-phase carbide NbC in the form of half-perfect crystallites by the sizes 5 ¸15 microns at rather wide range of process parameters.

Complete distributions of temperature on combustion zones for Nb - aC mixtures in conditions of activation are received. Leading stages of process are established, sizes of reaction zones are estimated.

O-2-23: Shs in Fabrication of Composites

Z.Y. Fu,W.M. Wang, H. Wang, Q.J. Zhang, R.Z. Yuan

State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology, Wuhan 430070,China

Self-propagating High-temperature Synthesis (SHS) is a promising method for fabrication of composites. However, the products obtained directly from the SHS process are generally porous. SHS plus dynamic mechanical pressing, which combines synthesis and densification in one step was proposed and was named SHS/QP. In this paper, fabrication of cermets and multiphase ceramics by SHS/QP was reported and compared. The optimum conditions of SHS/QP for cermets and multiphase were different. The densification mechanisms both for cermets and multiphase ceramics were analyzed.

O-2-24: SHS of Composite Materials in Thin Multilayer Systems

G. Ksandopoulo, A.Baydeldinova, N. Korobova, E. Kruglova , M. Kanackidi

Combustion Problems Institute, 172 Bagenbay Bat., Almaty, Kazakstan, 480012

E-mail: icp@kaznet.kz

SHS study of regularities and the development of ways of control over the product synthesis present the most important problems of SHS. High velocities of combustion wave and the temperatures in the center of interaction create non-equilibrium conditions for formation of structure phase and products of SHS method. These physical features are the main idea in the creation of SHS gradient materials. Now it was found that SHS is not a chaotiic burning of something, but controlled process with strict external regularities. Profound knowledge of regularities and mechanisms of structure evolution in the combustion wave is needed to manage the control over the structure formation on all structural levels: macrostructure, microstructure, and crystal atomic structure. Similarity of the mechanisms of the structure formation in the SHS systems with intensive melting of reagents results in the similarity of the microstructures of the final product. As a rule the methastable condition of substance is connected with its high chemical and diffusion activity. We use interactions of heavily and opposite directed processes. It ensures high possibilities of synthesis management and creation of diverse materials ( from single-phase up to heterogeneous with variable structure and complicated microstructure). In the given work the degree of process nonuniformity has been achieved by transition to long-sized and flat objects, which ensure a large heat irradiation and gradient of temperatures. The main influence to a combustion regime render a ratio between mass of an initial reactant mixture and geometric sizes of distribution it in a lay. Small modification of combustion quantitative characteristics has carried out by the set of parameters, which include chemical and phase structures of a charge, intensity and duration of mechanical-chemical activation, press pressure, temperature of furnace heating. The interaction of two and more combustion waves is the main factor for producing new composite materials. Theoretical and practical problems of the SHS are interpreted in the paper. General regularities and mechanisms of burning, structure formation of synthesis products are considered. The dynamics of phase formation in the synthesis of compositional materials in the combustion regime has been studied. The data on structure and properties of SHS ferro-alloys are presented, and the field of SHS-processes annd products application in th modern technique and industry is introduced as well.

O-2-25: Reactive-Casting of NiAl-Base Intermetallic Compounds

Kiyotaka Matsuura, Hiroshi Jinmon, Tatsuya Ohmi, Masayuki Kudoh

Division of Materials Science and Engineering Graduate School of Engineering

Hokkaido University Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan

E-mail: matsuura@eng.hokudai.ac.jp

Molten aluminum and a molten nickel-iron alloy are stepwise cast into a cylindrical bar. The pouring temperatures of the two liquids are 1023 K and 1773 K, respectively. The two liquids exothermically react to produce an NiAl-Fe intermetallic alloy, and the temperature of the liquid mixture instantly reaches approximately 2900 K, which is approximately 1000 K higher than the melting temperature of NiAl. This novel method based on an exothermic reaction between the molten metals may be useful for casting of high-melting-temperature intermetallic alloys. The oxidation resistance, corrosion resistance and wear resistance of the produced NiAl-Fe alloys have been evaluated from a weight gain during exposure in air at 1623 K, a weight loss during immersion in an aqueous solution of hydrochloric acid of 36 mass% and a volume loss during sliding on a gray cast iron, respectively. Those results are all significantly excellent compared with those of stainless steels. As the iron content of the NiAl-Fe intermetallic alloy increases from 0 to 25 at.%, the density, Vickers hardness, and bending strength of the alloy increase from 5.9 to 6.3 Mg/m3, 260 to 380, and 400 to 600 MPa, respectively.

O-2-26: Processing of in-situ Nitride Reinforced Aluminum Matrix


H.J. Brinkman, J.Duszczyk, L. Katgerman

Laboratory of Materials Science, Delft University of Technology

Rotterdamseweg 137, 2628 AL Delft, The Netherlands

A new method is described for the production of aluminum matrix composites in-situ reinforced with AlN and/or TiN. The process consists of a two step reactive process. In the first step an intermediate, solid structure is made by controlled solid-solid exothermic reactions between powders. This structure is of an intermetallic type of material and has an open porosity. In the second step of the process the porous structure is infiltrated with Nitrogen bearing gas and heated up to a point were the porous intermediate structure melts and collapses. This melting causes collapsing of the solid structure and entraps the Nitrogen bearing gas. The Nithogen reacts wit either Ti and / or Al to form in-situ AlN and/or TiN. In the paper the new method will be described in more detail and examples will be given for demonstration.

O-2-27: Hybrid SHS Technologies Based for Production of

Composite Materials and Coatings

E.A. Levashov1, B.V. Spitsyn2

1Center of SHS of the Moscow Steel and Alloys Institute

and the Institute of Structural Macrokinetics and Materials Science

2Institute of Physical Chemistry of RAS, Moscow 117915, Russia

The 30-year history of the SHS development revealed the opportunities of manufacturing inorganic and organic compounds, composite materials and coatings of various destinations. The success of the fixture progress of the SHS technologies is determined by two trends:

- the development of new materials and chemical products using known technological types of the SHS processes;

- the development of novel technological versions and hybrid SHS-based technologies which in combination with other methods allows achieving super effects.

Let's take as super effect the creation of unique materials with a new, earlier inaccessible, level of properties and also a considerable growth of the technological process efficiency with a heightened product quality. Taking this point of view the method ofthermoreactive electrospark surface strengthening (TRESS) developed at the SHS- Center of the Moscow Steel and Alloys Institute can be classified with the hybrid technologies. The production of gradient ceramic and metal ceramic substrates for the subsequent precipitation of highly adhesive thick film coatings on them is another way of the effective SHS application. The report presents the results of the research connected with the synthesis of diamond containing graded materials with a thick diamond film. According to the force SHS- pressing technology poreless plates are produced with a variable through the thickness concentration of diamond grains from 0 to 60 vol. ^o in the cramic binder based on TiB2, TiC etc. Then polycrystalline diamond films more then 30 u,m in thickness were precipitated on the plate surface by the CVD technology (in an arc discharge). A high adhesion of a coating to the substrate is an advantage of such composites. In contrast to the other technologies (powder metallurgy, HIP, HTHP) SHS allows to "seal up" a diamond grain into various ceramic binders, in particular into a highly heat conductive binder of titanium diboride. The composite's structure and properties were studied in the paper.

O-2-28: Multilayer Component Prepared by Combining Tape

Casting and SHS Process

J.P. Bonnet, S. Desiles, A.L. Dumont, T. Chartier, D.S. Smith

GEMH- ENSCI., (1) SPCTS-CNRS, 47 avenue Albert Thomas, 87065 Limoges, France

E-mail : jp.bonnet@ensci.fr

The combination of tape casting and SHS process can be used for the preparation of functionally graded components. This work is an attempt to evaluate the potential of such a processing route.

MoSi2-Al2O3 based composites can be prepared by S.H.S. reactions between MoO3, Al and Si or SiO2. Addition of Al2O3 or MoSi2 to the reactants allows to the relative amount of each phase in the final product to be controlled. It is then possible to obtain either electrically conducting (addition of MoSi2) or insulating composites (addition of Al2O3).

The addition of additives, which contribute to a decrease in the maximum temperature reached during the process, allows the amount of transient liquid to be altered. Therefore this parameter can be used as a processing variable.

Tapes of about 250 m m thickness of both MoSi2-rich and Al2O3-rich compositions are prepared by tape casting. Ten layers of each composition are then stacked alternately. After debinding, the S.H.S. reaction is initiated in the self-propagating mode and densification is achieved by the application of a small mechanical load.

The quality of the multilayer structure, as well as the efficiency of the densification step, are strongly dependent on the amount of transient liquid formed during the S.H.S. process. After optimisation of this parameter, dense multilayer plates were obtained. The final layers thickness is about 120 m m. Local electrical measurements confirmed the presence of alternating conducting

(0.1 W ) and insulating (10 MW ) layers.

O-2-29: Preparation of Carbide Fiber-Reinforced Composites

by High Pressure Combustion Sintering

Jondo Yun, Hwancheol Bang, Cheolho Go, Tae-Hyeon Choi, and Bongseob Kim

Department of Inorganic Materials Engineering, Kyungnam University,

449 Weolyeong-dong, Masan, 631-701, Korea, E-mail:jdyun@hanma.kyungnam.ac.kr

Alumina ceramic or titanium metal composites reinforced with short fibers of titanium carbides were fabricated by high pressure combustion sintering method. The dense body of titanium matrix composites were produced by the self-propagating high temperature synthetic reaction between carbon fibers, and excessive titanium powders, under the conditions of high pressure and electrothermal heating. It was found that the fiber shape was well maintained after the reaction, and the fibers were aligned due to the pressure. The fibers were either of carbon with carbide shell, or all carbide, depending on the reaction time and temperature. Alumina ceramic matrix composites with carbide fibers were also fabricated in the same way from aluminum, titania powders and carbon fibers. The EDS analysis showed that the thin layers of aluminum oxycarbide were formed between the carbon core and carbide shell in case of C-TiC-Al2O3 composites. Mechanical properties, such as a strength, fracture toughness, and hardness were investigated and discussed in terms of the microstructure and compositional variation along the interface between the fibers and matrix.

O-2-30: Characterization of Li-Cu Ferrite Powders Prepared by Self-

propagating High Temperature Synthesis

Yong Choi1, Y. D. Hahn2

1 Department of Metallurgical and Materials Engineering, Sunmoon University, #100 Kalsan-Ri, Tangjeoung-Myun, Asan, Chung Nam, 336-840 Korea

2 Korea Institute of Metal and Machinery, Changwon, Kyung Nam, (641-110),Korea

Characterization of (Li, Cu)Fe2O4 powders prepared through self-propagating high temperature synthesis reaction was carried out to study the effects of initial oxide powder size on the magnetic properties of the final combustion products. The ferrite powders were combustion synthesized with iron, iron oxide, nickel oxide, and lithium oxide and copper oxide powders under various oxygen pressures of 0.5áí10 atmosphere after blended in n-hexane solution for 5 minutes with a spex mill, followed by dried at 120 áã in vacuum for 24 hours. The maximum combustion temperature and propagating rate were about 1150 áã and 7.8 mm/sec under the tap density, which depended on the composition, oxide and oxygen pressure. The final product had porous microstructure with spinel peaks in X-ray spectra. Microstructure observation with TEM will be carried. Magnetic properties with VIM will be determined with various compositions of the final products.

O-2-31: Mathematical Model of SHS Welding

S.A. Bostandgiyan

Institute of Structural Macrokinetics and Materials Science RAS,

Chernogolovka, 142432, Russia

The physical analysis of SHS-welding process has been carried out On the base of estimations of characteristic times of different process stages the mathematical model of SHS-welding is developed.

The whole of SHS- welding process may be divided into two stages. The first stage is complited out with electrothermal explosion with forming a charge melt. The second one involved in charge melt squeezing with simultaneous cooling and solidifying. Itis supposed that there is no reaction before melting temperature of charge metallic component is reached and heating is realized by Joule heat. The electrothermal explosion takes place when this temperature is reached. A reaction is proceeded instantly and the melt or suspension of reaction products are formed. Two postprocesses are realized after the electrothermal explosion: a) squeezing of a part of SHS-products; b) cooling and solidifying.

Squeezing in one’s turn may be divided into two stages. Simultaneously with melt squeezing melt cooling is occured. The first stage involved a period up to reaching of solidifying temperature. In this stage the problem is two-layer (solid electrode – liquid charge melt). After reaching of solidification temperature the problem transforms inton three layer (solid electrode – solidified reaction product – charge melt) with mooving boundary at which there is phase change. The systems of differential equations discribing different stages of SHS-welding process are developed.

O-2-32: In-Situ Joining of Nickel monoaluminide to Ni-base Superalloys

by High Pressure Combustion Synthesis

C.Pascal, R.M. Marin-Ayral, N. Frety, J.C. Tedenac

Laboratoire de Physicochimie de la Matière Condensée,(L.P.M.C. UMR 5617) c.c.003

University Montpellier II, Pl. E. Bataillon, 34095 Montpellier Cedex France

Phone (04 67 14 33 55) Fax (04 67 14 42 90)

Aeronautics gives rise to very particular needs concerning welding technology. In effect, turbine blade are made of nickel and cobalt-base superalloys used for their good high temperature properties. In France, SNECMA develops the BDR (Brazing Diffusion Remetalling) process. This process is very expensive because it allows a limited number of repairs.

High gas pressure combustion synthesis is a new way for welding. In this process, a Ni-base braze is placed between a substrate of Ni-base superalloy and a compact made of 50at% Ni-50at% Al mixture. The heat released during the combustion synthesis of the Ni+Al compact gives rise to interdiffusion of the elements and consequently to a joining interface. The main advantage of this new process is an important decrease of welding temperature which allows to increase the number of repairs by turbine blade.

In this presentation, we will develop the results obtained for a Ni-base superalloy. In a first part, we will describe the main experimental conditions to optimise the joint’s quality. Then, using scanning electron microscope (SEM) and electron probe microanalyser, we have studied microstructures and concentration distributions across the joining interface. Finally, we will present first results of mechanical characterisation of the joining interface by distribution of hardness across the interface, three point bending test and shear test.

This work was supported by DGA (n°97-2527A/DSP/STTC) and by Sochata-SNECMA service (Chatellerault-France)

O-2-33: Influences of Mechanical Vibration on SHS Ceramic -Lined Pipes

J.J.Wang, Z.M.Zhao, M.H.Ye, X.K.Du, L.Zhang

Dept.of Mater.Sci.and Eng., Shi Jia Zhuang Machenical Engineering College

Shi Jia Zhuang, He Bei, P.R. China, 050003

Based on using gravitational separation SHS process to produce ceramic-lined pipes under that condition of mechanical vibration with amplitude 5mm and frequency 5Hz in form of up-down motion with one degree of freedom, the influences of mechanical vibration have been investigated on SHS thermit combustion, ceramic densification as well as structure and properties of pipes. It is found that mechanical vibration can effectively promote thermit combustion process by increasing combustion temperature and combustion rate, causing content of metastable FeO-Al2O3 spinel phases on lined ceramic layers to be reduced. By increasing temperature of liquid-liquid phase melts and fluid acceleration, mechanical vibration will accelerated Al2O3-Fe liquid-liquid phase gravitational separation and gas escape from melts, and also make Al2O3 dendrite crystal during solidification to be changed in size and growth orientation. Results show from mechanical property tests on samples that each mechanical property of pipes and surface quality of lined ceramic layers have been improved to a great extent following mechanical vibration treatment. It is proved from this experiment that mechanical vibration will effectively control structure, properties and surface quality of ceramic-lined pipes under controlling SHS thermit combustion

and ceramic solidification process.

O-2-34: SHS Process for Manufacturing Aluminum Master Alloys by Use

of Flux

A.G. Makarenko, E.G. Kandalova, V.I. Nikitin, V.A. Shugayev

Samara State Technical University, 141 Galaktionovskaya, 443010, Samara,Russia

Tel.: (8462) 42-22-68, 42-28-89; Fax: (8462) 42-22-68, 32-42-35

The work on manufacturing fine-crystalline Al-Ti, Al-Zr, Al-Ti-B and other master alloys with the use of self-propagating high-temperature is still in progress. It gives a number of important advantages in comparison with conventional ones. The method offers to reduce the production expenses, to increase the output and the grain refining performance of a master alloy. However, the use of a powder SHS-mixture at lower temperatures initiates non-metallic inclusions and mixture residue in a master alloy. To eliminate these disadvantages the Al-5%Ti master alloy melt was treated with K1-3AlF4-6 NOCOLOKTM and cryolite Na3AlF6 fluxes.

The influence of flux agents on the SHS process, technological and structural parameters of the master alloy has been studied. The flux function is based on the SHS process activation through the dissolution of oxide films from a surface of aluminum powder particles. It is determined that the increase in flux quantity leads to the rise of the SHS reaction temperature and reduction of its delay time. It makes possible to reduce the temperature of master alloy production by 100-2000C without the degradation of its quality, to increase the completeness of the running reaction. The quantity variation of the flux and aluminum powder in a SHS mixture provides a wide range of different morphologies of TiAl3 particles- from needle-like, mixed to blocky and globular ones with the size of 10...15 m m. The small difference in the use of the two kinds of fluxes has been revealed. The NOCOLOK flux gives higher temperature of the SHS reaction (by 15-200C), rises the melt fluidity, results in a finer structure of master alloy.

The optimal modes of the master alloy production with the cheaper Russian flux Na3AlF6. have been found. The flux application makes possible to control the SHS process in an aluminum melt and thereby effect on structural and technological parameters of a grain refiner.


NOCOLOKTM is a registered trademark of Alcan Aluminum Ltd, Canada

O-2-35: Reaction Characteristics of the Fillers for SHS Welding of SiC Ceramic

to Ni-Based Superalloy

Shujie Li, Huiping Duan, Shuhua Li, Shen Liu

Beijing University of Aeronautics and Astronautics, Department of Materials

Science and Engineering, Beijing 100083, People*s Republic of China

Self-Propagating High-Temperature Synthesis (SHS) welding is a promising process to join SiC ceramic to Ni-based superalloy. As a fundamental work, the study of the SHS reaction characteristics of the fillers is very important for the development of the process. The ignition temperatures of the explosive reactions of the fillers composed of Ti, C, Ni, Al and Si were determined, and the reaction products were examined. The fillers were divided into four series with various compositions. For most of them, the reaction is very intense. The reaction products are strongly related to the exothermicity of the reaction. Some non-equilibrium phases, which can be eliminated by proper heat treatment, exist in the reaction products. This reveals the necessarity of heat treatment in order to achieve stabilized properties of the SHS welded samples serving at elevated temperatures. The products of the explosive reactions are fine powders, indicating that the fillers can form densified materials with fine grain size during SHS welding with additional proper measures.


O-2-36: Influence of Plastic Deformation on Microstructure and Properties

of Shs-Materials

O.A. Kaibyshev1, N.G. Zaripov1, Yu.A. Gordopolov2 1Institute for Metals Superplasticity Problems of RAS, Khalturina 39, Ufa 450001, Russia

2Institute of Structural Macrokinetics of RAS, Chernogolovka, 142432, Russia

The formation of a microstructure and mechanical properties in the nonstoichiometric titanium carbide was investigated by using three various methods of processing (C/Ti ratio was equal to 0.47): 1) the samples were prepared by SHS-reaction with the subsequent force compacting at high strain rates; 2) the samples were received after hot deformation of billets prepared by the 1st method; 3) the samples were prepared by combining SHS-reaction and hot deformation under temperature-rate conditions of superplasticity of nonstoichiometric titanium carbide. The porosity of the samples processed by the given methods did not exceed 3%.

The processing of titanium carbide by the first method led to formation of an extremely non-equilibrium two-phase microstructure. The average size of carbide grains was 10-12 m m and the volume fraction of excess titanium phase amounted to 12%. The ductile-brittle transition (DBT) of such material was observed at the temperature 750° C.

The subsequent deformation of such material showed its microstructure is non-equilibrium. Concurrent development in titanium carbide of phase transformation TiC0,47 ® b -Ti and dynamic recrystallization resulted in formation of a "microduplex" type microstructure with the average grain sizes of carbide and titanium phase about 2 m m at deformation in conditions of the enhanced strain rate sensitivity of flow stress (T=950° C, e =10-3 s-1). At that the volume fraction of titanium phase increased up to 30 vol.%, and the DBT-temperature decreased up to 650° C. Such material showed a much lower flow stress level, than that flow stress of titanium carbide produced by the 1st method.

The processing of titanium carbide by the third method promoted the formation of an equilibrium microstructure with an average size of carbide grains of 10-12 m m. The DBT-temperature of such material was observed at 750° C. This material showed an essentially higher level of flow stress at high temperatures (900° C and higher). The chemical composition of titanium carbide did not change during the further deformation, and the microstructure retained its stability.

Thus, the comparison of three methods of preparation of nonstoichiometric titanium carbide using SHS-reaction and plastic deformation showed that the temperature-rate conditions of plastic deformation essentially influence the formation of microstructure during self-propagating high-temperature synthesis. The control of conditions of plastic deformation might allow us to influence the completeness of chemical reaction during SHS.

O-2-37: Densification of Condensed Systems During Combustion

L.S. Stelmakh, A.M. Stolin, Zh. A. Zinenko

1Institute of Structural Macrokinetics and Materials Science Russian Academy of Sciences

1Insitute of Chemical Physics Problems Russian Academy of Sciences

142432, Chernogolovka, Russia

The mathematical model of joint weep of processes of combustion and densification of a hot powder materials is offered. The mathematical model includes a heat conduction equation, continuity, motion and rheological condition of reaction products. The dependence of rheological properties on porosity and temperature, and also distinction of density of reaction products and initial reactants is taken into account. As against the widespread approach at the theoretical analysis of a problem the allowance about combustion as “ to an intermediate asymptotics ” is not entered, and the densification is esteemed as much non-steady process. In this case the main problem of theoretical consideration is the finding of a hyperthermal zone of the most intensive compacting of products of combustion and initial materials.

Is allowed, that the capacity of combustion products to compaction is controlled by process of viscous flow at the expense of formation of hyperthermal fluid phases. In a general problem on combustion and densification the problems on a place of compacting are esteemed: behind front, in front and before combustion front.

The dependencies of combustion rate and final porosity on pressing efforts, and also on different ratio of characteristic times of densification both chemical reaction and cooling of products are analyzed. Influencing the fusible component on compaction of a material is during combustion. The analysis of transformation in time of initial distribution of density allows to observe propagation of densification boundary at moving of combustion wave along pattern.

This work was supported by RFBR Grant ¹98-03-32110a.

O-2-38: Formability of SHS-Materials


Institute of Structural Macrokinetics and Materials Science Russian Academy of Sciences

142432, Chernogolovka, Russia

The relevant problem of development of know-how SHS consists in analysis of a capability of direct obtaining of articles true-to-shape of products of combustion. The greatest successes are obtained at applying a method of SHS-compaction realizing single-axis volumetric contraction of a material in a mould for compacting of combustion products up to nonporous state. The description of process of forming can be constructed on the analysis of a specific manufacturing processes, as it was made for process of SHS-extrusion. More relevant represent the approach based on analysis of a common features of formation process, not bound to a particular production equipment.

In the present activity the outcomes on usage of a method of free SHS-compaction for analysis of capacity to forming some widespread classes of SHS- materials are set up.

Are investigated of regularity of forming of some classes of SHS-systems with a different ratio of combustion temperature and melting of initial reactants. As the characteristic of capacity to forming it is offered to use parameter - degree of deformation having sense of relation final to the initial area of a sample. The analysis of relations of this testimonial from of quantity and structure of flow bundle is conducted.

This work was supported by RFBR Grant ¹98-03-32110a.

O-2-39: Production of Dense Molybdenum Disiliside Materials

by Self-Propagating High Temperature Synthesis

P.Lintula1, J.Maunu1, M. Sundberg2, A. Magnusson2
1VTT Manufacturing Technology, P.O. Box 17031, FIN-33101,Tampere, Finland

2Kanthal AB, P.O. Box 502, SE-73427 Hallstahammar, Sweden

Nearly fully dense (95 - 99 %) MoSi2 materials were produced by combustion synthesis (SHS mode) of the elemental powders. Formation reaction for MoSi2 has rather low adiabatic temperature (1627oC), which makes it more difficult to obtain full density. Both the manufacturing process and the material composition have been developed to get high density and good high temperature properties. Experiments to alloy MoSi2 by zirconium oxide, titanium carbide and silicon carbide were also carried out. The phase composition, impurity content and density of the materials were evaluated. Depending on the composition and process parameters, small amounts of Mo5Si3 phase were found in some samples but most samples had a single phase MoSi2 structure. The materials have homogeneous microstructure and fine grain size. The microstructure and mechanical properties are compared to those manufactured by conventional processes.

O-2-40: New Technical Decisions Improving SHS Pressing Method

A.F. Fedotov, A.P. Amosov

Technology University, Galaktionovskaya 141, 443010 Samara, Russia, Phone:(846-2)33-3473, E-mail: mvm. @ mc. sstu. samara. ru.

At SHS pressing with an free-flowing sand sheath a nonuniform temperature field is formed in a self-heated powder compact. The cause of the nonuniformity is a nonsynchronous heating and cooling at layer-by-layer combustion of the green compact and a different rate of cooling the compact elements: points, edges, faces. The presence of the hot and cold zones with different level of their strength together with an elastic tool (sand) produces a nonuniform deformation and distortion of the shape of an article, especially with prismatic articles.

New technical decisions are developed and patented to improve the dimension accuracy of the article. To reduce the nonuniformity of the thermal field the side edges of the green compact are chamfered with dimension of 2 to 3 mm. To increase the axis contact stiffness of the tool: 1) the sheath thickness is reducer up to 2-3 mm simultaneously with cladding the green compact by a layer of heat-generating substance or 2) the sheath of the compact is performed thin rigid steel sheets.

At SHS pressing two objects are deformed plastically: the article and the sheath. The pressing power is distributed proportionally with energy consumption for deformation of the SHS product and the ring sheath around the article. To reduce the stiffness of the ring sheath and increase the press efficiency: 1) the ring sheath is made of material with a low stiffness or 2) the height of the ring sheath is increased in comparison with the central zone to reduce the rate of the axis deformation and compaction of the zone.

O-2-41: Metal-Like SHS Catalysts as Analogues of Noble Metals

E.H. Grigoryan

Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432, Russia, E-mail: grig@ism.ac.ru
Pseudometal catalysts based on borides, carbides, nitrides and other compounds of transition metals show high catalytic efficiency in various chemical processes [1,2]. These compounds are considered as promising catalysts with excellent mechanical characteristic, having in addition high heat and corrosion resistance, a wide range of physical and chemical properties. Pseudometal catalysts are interesting due to the similarity of electronic structure and catalytic activity to metals. It will allow to substitute the catalysts based on expensive noble metals (Pt,Pd,Rh,Ru and others) for appropriate compounds of d2-d4 elements. A possibility of borides, carbides, nitrides, and other compounds preparation during SHS process opens up additional opportunities for regulation of their catalytic properties. At present the catalytic properties of SHS borides, carbides, nitrides of Ti, Nb, Mo,Co, Zr, Hf, Ta and other metals have been studied in the processes of oxidation and hydrogenation of various organic compounds [2,3]. The effect of transition metal nature, ligands and composition of some SHS materials on the catalytic properties are given in the report.


1. J.P. Bonelle, B. Delmon, E. Derouane, "Surface Properties and Catalysis by Non-metals", NATO ACI, ser. C, Mathematical and Physical Sci., N 105,

D. reidel Publ. Comp., The Netherlands, 1983.

2. Grigoryan E.H.," SHS Catalysts and Supports", Intern. J. of SHS, 1997,v.6, N 3, p. 307.

3. Grigoryan E.H., Borovinskaya I.P., Merzhanov A.G., " SHS Catalysts for Neutralization of Exhaust Gases from Internal Combustion Engines", Intern. J. of SHS, 1997, v.6, N 4, p. 439


O-2-42: Influence of Cooling Conditions on the Composition and Activity

of SHS Catalysts

G. Xanthopoulou, G. Vekinis

Institute of Materials Science, NCSR “Demokritos”, Athens, Greece


The conditions under which many SHS ceramic catalysts are cooled after combustion were found to significantly influence their composition, structure, properties and catalytic activity. SHS catalysts containing Cu-Cr, Co and Fe were synthesised and thereafter quenched under a range of conditions including air, water, brine and liquid nitrogen. In cobalt and iron containing catalysts, the relative proportion of the compounds in the final products as well as the catalytic activity depended on the colling conditions. In the first case, the metallic cobalt content increased 28 times after quenching the specimen in brine whereas the cobalt oxide content decreased by about 1.5 times thereby changing drastically the properties and activity. During catalytic pyrolysis (dehydrogenation) of petrol, specimens quenched in brine produced hydrogen yields of up to about 90% as compared to only 50% for the same catalyst cooled in the furnace. The reason for these changes in these materials is believed to lie in the changes in composition, concentration and nature of crystal lattice defects as well as changes in the microstructure of the catalysts.

The proportion of spinels to simple oxides in Cu-Cr-O catalysts did not appear to depend to a substantial extent on the quenching media used. But significant differences were observed for their catalytic activity in the processes of deep methane oxidation and carbon monoxide and hydrocarbon oxidation. Detailed investigations using Scanning Electron Miscroscopy, EDX analysis and XRD showed that the underlying reason for the activity variation is the significant changes that take place in the microstructure in the materials.

O-2-43: Chemistry Reaction Processing and Microstructure Formation

Mechanism in SHS for TiO22eB2O33eMg System

W.M.Wang, Z.Y.Fu, H.Wang, R.Z.Yuan

State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology ,Wuhan 430070,China

Self-Propagating High-temperature Synthesis with a Reducing Stage is a promising method for fabrication of ceramics powders and ceramics-composites powders, in this type of combustion processing, the major raw materials are various oxides which are easy to supply and very cheap, so this combustion processing can be used in ceramics industry .

In this paper, the TiO22 B2O33 Mg SHS reaction system was chose as research objective ,the chemistry reaction processing and microstructure formation mechanism of this SHS reaction system were studied by DTA-TG,X-ray diffraction ,SEM ,EDS and Combustion Front Quenching (CFQ) . It was found that the B2O3 was reduced to B at the first step, and TiO2 was reduced to Ti through following step: TiO22wTi3O55iTi2OOiTi . In this combustion processing ,the Mg content have a key role .The microstructure formation processing was studied in detail by SEM and EDS.

O-2-44: Nanocrystalline Ti (Zr) Hydrides Produced Combustion Synthesis

V.Sh. Shekhtman, S.K. Dolukhanyan, H.G. Hakobyan,G.E. Abrosimova, A.G. Aleksanyan, N.N. Aghajanyan

Institute of Chemical Physics of National Academy of Sciences of Republic of Armenia, 5/2, Paruir Sevak Str., Yerevan 375014, Republic of Armenia.Phone:(374 2)28-17-80,

28-16-41; Fax:(8 3742)28-17-42; E-mail:chph@chemphys.iiap.sci.am

Nanocrystalline hydrides represents a new perspective class of materials, for wide problems of hydrogen material science.

For obtaining the nanocrystalline hydrides the SHS is very advantageous in compare with the known methods i.e. reactive mechanical grinding or alloy under H2 gas pressure of 1 MPa. We were successfull in synthesizing SHS nanohydrides. Nanocrystallization of hydrides of metals and alloys directly at combustion of metals in H2 is an unusual phenomenon. Why does it take place, what is the SHS hydrogenation kinetic? These questions are discussed in the present work.

The results of analysis of materials by TEM, SEM and XRD methods are presented. It was established that for SHS technique the crystal grain of sizes smaller than 0.1 mkm are available. The complete mechanisms of event are not known yet, but these preliminary results can become the starting point of future experiments directed to explain the conditions of SHS process resulting in nanocrystalline hydride formation (hydrogen pressure, grain size, temperature and rate of combustion etc.) Nevertheless, now we are ready to say that apparently excellent peculiarities of SHS-hydrides are the results of instataneous rapid formation of nanocrystalls in combustion regime. From this point of view it will be useful and important to turn to the study of their physico-chemical properties (thermal, mechanical, magnetic, electrochemical, electrical resistance).

This work was supported by ISTC. Grant A-192.

O-2-45: SHS prepared BaSnO3; Comparison of SHS and Conventionally Prepared Materials as Sensors for CO2

M.D. Aguas, I.P. Parkin, L. J. Morris,D. E. Willams

Dept. of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ, UK

Barium stannates have dielectric properties that have been used in capacitors and ceramic boundary layers. These materials also show considerable promise as gas phase sensors for the detection of carbon monoxide and carbon dioxide. Three phases in the BaO-SnO2 phase diagram have been reported; BaSnO3, Ba2SnO4 and Ba3Sn2O7. The BaSnO3 phase is the most technologically important, however it is difficult to synthesise. Traditionally it is made at 1200°C by the solid state reaction of BaCO3 and SnO2. This procedure suffers from significant impurities and large irregular grain sizes. One of the main synthetic challenges is the removal of the phase Ba2SnO4. This can be particularly problematic as non stoichiometry is supported in the structure through the formation of alternating layers of the perovskite BaSnO3 and rock salt BaO along the c-direction. Alternative routes to BaSnO3 have employed hydrothermal techniques and precipitation synthesis. These methods are at lower temperature but are complicated by the co-formation of SnO2 which has proved difficult to remove. We have formed BaSnO3 by six separate SHS reactions. These solid state reactions are self energetic, proceeded by a solid flame (synthesis wave) and have rapid heating and cooling. This forms products with different morphologies and particle size distributions compared to traditional synthesis. The SHS prepared powders show excellent gas response to CO2 corresponding to an n-type conductor model.