The 1st Russian–Japanese Workshop on SHS was held on October 30–November 3, 1998 in Karlovy Vary, Czech Republic just after the International Symposium on Functionally Graded Materials (Dresden, Germany, October 25–30, 1998). The agreement to conduct a bilateral Russian–Japanese meeting was reached during the IV International Symposium on SHS in Toledo, Spain (6–9 October, 1997). As agreed, 10 Japanese and 11 Russian participants took part in this event. The topics covered were as follows:

• Comparative analysis of SHS products
• Progress in the theory of SHS
• Ecological aspects of SHS
• Effects of external influences

The workshop was organized by Academician A.G. Merzhanov (Russia) and Professor Emeritus M. Koizumi (Japan) and supported by the Institute of Structural Macrokinetics and Materials Science (Russia), High-Tech Research Center of Ryukoku University (Japan), Japanese Research Association of SHS, and ADATA Travel Agency (Czech Republic).

The workshop was carried in two working days and had a thickened scientific program (19 oral presentations).

Four presentations were made on comparative analysis of SHS products. In their presentation "Comparative Analysis of SHS Metallic Hydride", Prof. T. Akiyama (Miyagi National College of Technology) and Prof. J. Yagi (Tohoku University) compared the Mg₂NiH₄ hydrogen storage alloys that were produced by conventional technique and by SHS. The results convincingly show that the combustion-synthesized product exhibits higher potentialities as concerning its characteristics, as well as energy- and time-saving.

In his presentation "Characteristic Features of the Ceramic–Metal Materials Produced by SHS", Prof. A.S. Rogachev (Institute of Structural Macrokinetics and Materials Science) discussed some means for controlling the microstructure of end product during SHS in comparison with other production methods. By controlling the second stage of structure formation (grain growth), the mean grain size in end product can be diminished down to 1 m m. But further decrease in the grain size of SHS products will require new approaches that would affect the initial stage of structure formation, nucleation during reaction.

Live interest was displayed by the participants in the presentation "SHS of Intermetallics from Elemental Liquids and Simultaneous Joining to Structural Materials" by K. Matsuura, K. Ohsasa, T. Ohmi, H. Jinmon, and M. Kudoh (Hokkaido University). These workers demonstrated the possibility of obtaining graded materials and intermetallides by reaction between cast metals. Upon casting molten Al and Ni, molten NiAl was formed and simultaneously joined to a steel substrate (owing to iron dissolution in molten NiAl).

In his presentation under the title "Few Words about New SHS Materials" (SHS Research Center at Moscow Institute of Steel and Alloys and ISMAN), Dr. E.A. Levashov compared the parameters of such materials as STIM-5 alloys, TiC–TiB₂ alloys, diamond containing materials, and intermetallic composites based on NiAl.

Two presentations from each side were made in the Section "Progress in the theory of SHS".

In his survey "Construction of the Heterogeneous Theory for the Flame Propagation in the SHS Process (A Short Survey for the Formulation of the Heterogeneous Theory)", Prof. A. Makino (Shizuoka University) claimed that the need in this theory stems from a heterogeneous nature on the combustion wave during SHS. Prof. Makino pointed out that the existing theory for flame propagation during combustion of gas suspensions had been markedly developed with the highest consideration for limited potentialities of homogeneous analysis as applied to propagation of SHS waves.

In his presentation "Some Features of Inflammation in SHS Systems", Prof. V.V. Barzykin (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) reviewed the available data on inflammation in homogeneous and heterogeneous condensed systems with special emphasis on SHS systems. The following aspects of the problem were considered: specificity of SHS systems, methods and modes of their inflammation, thermal explosion in condensed systems, thermal explosion under conditions of scheduled heating, thermal explosion in porous hybrid systems, mathematical simulation of initiation, and instability of ignition. It was concluded that the simplest, strongly formalized kinetic functions used in theoretical analysis represent a main obstacle to explicit quantitative description of inflammation in SHS systems.

In their presentation entitled as "Influences of Process Parameters on Stable Propagation of SHS Combustion Wave", Prof. M. Kuwabara and Dr. M. Sano (Nagoya University) reported the data obtained in their study on SHS in the Mo–Si and Fe₂O₃–Al systems where they theoretically predicted the features of real experiments. It was found that the stability of wave propagation can be improved upon small preloading of a green mixture or by its preheating. These influences diminish the induction period and enhance the homogeneity of resultant product. The suggested theoretical model can be used to predict the technological parameters of the SHS process.

An interesting presentation entitled as "Post-Induction Modes of Thermal Explosion" (by A.G. Merzhanov, N.I. Ozerkovskaya, K.G. Shkadinskii), was made by Academician A.G. Merzhanov (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences). In the work, computer-aided modeling of thermal explosion was performed for extended period of time, until completion of reaction. Application of the original method of arrested (disrupted) heat conduction allowed determining the limiting cases of the layer-by-layer (large Biot numbers) and phase (low Biot numbers) propagation of the combustion wave. The obtained data are of current importance in view of ever-increasing interest in the SHS processes performed in the mode of thermal explosion.

For the first time in the practice of international meetings and conferences on SHS, a special session devoted to "Ecological Aspects of SHS" was included in the Workshop Program. This was dictated by the fact that the R & D work on utilization of industrial wastes by SHS is already being conducted in a number of countries.

The first presentation at this Section was made by Prof. I.P. Borovinskaya (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences). Ecological problems that can be solved by SHS should be treated keeping in mind the following. First, SHS processes themselves are largely ecologically safe, wasteless, and controllable. Second, some current ecological problems can be solved by SHS. Considered are such applications of SHS as processing of nuclear wastes and Zr chips. Another applications are production of catalysts and catalyst supports for incineration of exhaust gases and special filters for purification of water, oil, and organic liquids.

Prof. Y. Myamoto (Osaka University) talked about "Application of SHS to Ecological Problems—Recycle of Wastes in Si Wafer Production to Sialon Based Ceramics". It was demonstrated that industrial wastes can readily be used as raw materials for SHS. The wastes formed upon cutting, polishing, and washing of Si ingots in production of Si wafers were recycled by performing SHS of silalon-based ceramics at high nitrogen pressures. According to Prof. Myamoto, another candidate for recycling by nitriding combustion is Al dross produced in Al foundries.

In the presentation " Solution of Ecological Problems by SHS-Metallurgy Method", Prof. V.I. Yukhvid (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) reported on SHS recycling of metal (Fe, Al, Cr, W, Ni, etc.) scales into Cr and Mn carbides and Mn alloys. SHS metallurgy offers two approaches to solving ecological problems: (1) utilization of industrial wastes and (2) replacement of ecologically hazardous technologies by SHS.

In their work "Mathematical Model of Combustion Synthesis for Producing Intermetallic Compound, Mg₂Ni", Prof. J. Yagi (Tohoku University) and Prof. T. Akiyama (Miyagi National College) investigated the reaction kinetics during synthesis of Mg₂Ni in terms of a model based on the theory of transport phenomena, including momentum and heat/mass transfer during chemical reaction. A conventional arc-melting process for synthesis of this compound (used as a hydrogen storage alloy) was found to be more complicate and labor-consuming.

A special session was devoted to the effects of external influences on SHS.

In the presentation "Induction Field Activated SHS Compaction", M. Ohyanagi, T. Hiwatashi, M. Koizumi (Ryukoku University) and Z. Munir (University of California, Davis, USA) demonstrated the feasibility of simultaneous synthesis and compaction of the TiC–Ti and WC–Co composites by a new method termed SHS/Dynamic Pseudo Isostatic Compaction (SHS/DPIC). Sample compaction is performed in external induction field (inside a coil). The method is applicable to synthesis of compound with low enthalpy of formation. Presented data illustrate the effect of current passage time on the composition, microstructure, density, and mechanical properties of end products.

In the presentation "The Effect of Gravity on the Self-Propagating High-Temperature Synthesis", Prof. V.I. Yukhvid (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) demonstrated the effects of mass forces (in centrifugal machines) on SHS: expansion, compression, and phase separation. The field of gravity was also found to affect the convection-related processes, such as melt spreading, gravity-assisted convection, etc.

In their presentation "The Effects of External Fields on SHS-Processes", Prof. N.I. Kidin (Institute for Problems in Mechanics, Russian Academy of Sciences) and I.A. Filimonov (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) reviewed the available data published in last 15 years. The most of papers concern the possibility of controllable SHS upon additional Joule heating. Advantages and drawbacks of different field geometry were analyze. The effect of external electric field on spinning combustion was considered.

In the presentation entitled as "Effect of DC Magnetic Field on the SHS", Dr. Yu.G. Morozov (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) considered the effect of DC magnetic field on structure formation in SHS-produced ferrites. In an applied field, SHS was found to proceed at a higher rate and combustion temperature. The in-field-synthesized materials exhibit also better magnetic parameters (magnetization, Curie temperature, etc.) compared to conventional ones. The SHS process was also found to depend on the sample orientation with respect to field lines.

In their communication "Self-Propagating High-Temperature Synthesis in Microgravity", A.G. Merzhanov, A.S. Rogachev, and A.E. Sytschev (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) presented the results of experiments carried out aboard the Mir space station in 1997–1998. Under microgravity conditions and in the absence of convection, end products were found to exhibit a coarser structure. In the first SHS experiments with a cloud of particles in vacuum, SHS reaction was found to proceed in the mode of steady frontal propagation.

In his communication "Synthesis of Thin Films by Pulsed-Laser Deposition Using Target Materials Prepared by Self-Propagating High-Temperature Synthesis (SHS)", Dr. Y. Aoi (Ryukoku University) demonstrated the feasibility of preparing B–C–N thin films by pulsed-laser deposition. In this case, SHS-produced materials were used as a target. The deposited films turned out to be amorphous and exhibited the presence of the C–C, B–C, and C–N bonds, thus indicating that an atomic hybrid of the three elements was synthesized.

The presentation "Analysis of Diamond Gradually-Dispersed Materials by FEM" by T. Tsujikami, M. Ohyanagi, M. Koizumi (Ryukoku University), E.A. Levashov (Moscow Steel and Alloys Institute), and I.P. Borovinskaya (Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences) was devoted to computer modeling of functionally graded materials by using the Image Mesh Generation System. By finite element method, thermal stress at the interface was estimated along with microscopic analysis of the graded materials. The suggested method can be used to predict the parameters and properties of composite materials at the macroscopic level.

Each of four sessions was followed by general discussion where each participant could express its own point of view and put questions to the authors. The discussions were of great interest for both the sides. Numerous informal fruitful discussions took place during the Workshop. The participants were also involved in social events (sightseeing in Karlovy Vary and the environment and excursion to the worldwide-known Moser glass factory). The Japanese participants had also sightseeing in Prague.

In conclusion, the Final Memorandum was signed by Academician A.G. Merzhanov, from the Russian side, and by Emeritus M. Koizumi, from the Japanese side. The Memorandum assumes joint projects in the field of SHS and similar bilateral meetings on exchange by achievements and experience in the field.

A.E. Sytschev

Scientific Secretary