| Compiled by | A.G.Merzhanov |
| A.E.Sytschev |
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Short information for the beginners: Self-propagating high-temperature synthesis (SHS) means the synthesis of compounds (or materials) in a wave of chemical reaction (combustion) that propagates over starting reactive mixture owing to layer-by-layer heat transfer. (See
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Quick Table of Contents 1. Starting Systems
2. Process and its Characterization
3. Products
4. SHS Research
5. Fundamentals of SHS
6. SHS Production Methods
7. Applications
8. History and State-of-Art
9. Useful References (reviews and monographs)
10. Glossary
11.  Information Brochure about SHS (26.2Mb)
Full Table of Contents 1. Starting Systems
1.1. Starting Reagents and their Morphology 1.2. Chemical Classes of Reagents 2. Process and its Characterization
2.1. Combustion in SHS processes (also termed solid flame or solid-flame combustion) 2.2. Initiation 2.3. Modes of Front Propagation 2.4. Combustion Thermograms 2.5. Front, Wave, and Post-Processes 2.6. Process Parameters 2.7. Chemical Classes of SHS Reactions 3. Products
3.1. Morphology and Macroscopic Structure 3.2. Product Composition 3.3. Microstructure of Products 3.4. Chemical Classes of Products 4. SHS Research
4.1. Three levels of experimental diagnostics 4.1.1.Level I: Phenomenology 4.1.2.Level II: Zone structure of the combustion wave 4.1.3.Level III: Mechanism and dynamics of phase/structure transformations behind the combustion front 4.2. Means of Control 5. Fundamentals of SHS
5.1. Thermodynamics 5.2. Chemical Kinetics 5.3. Combustion Theory 5.4. Chemistry and Structural Macrokinetics 5.5. Physical Materials Science 6. SHS Production Methods
6.1 Technological Types of SHS 7. Applications
7.1. SHS Products 7.2. SHS-Based Production 7.3. Effectiveness 8. History and State-of-Art
8.1. Discovery 8.2. SHS in the Former Soviet Union 8.3. SHS in the CIS countries 8.4. SHS all over the world 8.5. Most Important Accomplishments 8.6. Some Important Directions of Research 8.7. Symposia, Workshops, Seminars 9. Useful References (reviews and monographs)
10. Glossary
10.1. General Aspects of Combustion
10.2. Processes
11. Information Brochure about SHS (26.2Mb)
1. Starting Systems1.1. Starting Reagents and their MorphologySHS can be performed in fine powders, thin films, liquids, and gases. The most popular are
Green mixture may burn in
1.2. Chemical Classes of ReagentsThe elements, individual compounds, and their mixtures that are reactive at high temperatures can be used as reagents while inert compounds, as fillers or diluents.The most popular reactants are given below:
Mineral raw materials and industrial waste can also be used as starting reagents. SHS reagents must comply with the following requirements:
2. Process and its Characterization2.1. Combustion in SHS processes (also termed solid flame or solid–flame combustion)For SHS systems, the most popular are the following modes of combustion:
2.2. InitiationReaction is normally initiated from the sample surface with a heat flux (heated wire, electric spark, laser beam, etc.). After initiation, reaction proceeds in the mode of self-propagation. The duration of heating is markedly shorter than the time of reaction (combustion).In some cases (e.g., low-caloric reactions), reaction may be initiated by bulk heating in a furnace and carried out in the mode of
thermal explosion
2.4. Combustion ThermogramsCombustion thermogram gives evolution of temperature at a given point of charge during SHS. A simplest thermogram has an irregular-bell shape. More complicated thermograms exhibit breakpoints, inflexions, and isothermic plateaus. In case of unsteady combustion, thermograms may exhibit temperature oscillations within an ascending portion of the curve.
2.5. Front, Wave, and Post-ProcessesBesides heat release, chemical reaction in the combustion wave gives rise to a number of physicochemical processes. The combustion wave is extended and comprised of several zones:
2.6. Process ParametersThe process of wave propagation is characterized by:
2.7. Chemical Classes of SHS ReactionsFor SHS processes, the type of starting reagents is insignificant. Much more important is relation between the heat release in reaction, on one side, and such parameters as the mode of heat release/transfer, state of aggregation for reactants/products, kinetics of phase/structure transformations, etc., on the other.Therefore, the chemistry of SHS is versatile. The most important examples are given below.
3. Products3.1. Morphology and Macroscopic StructureSolid SHS products may appear in the form of powders, particle conglomerates, foams, cakes, ingots, films, whiskers,
fibers, and crystals. The batch weight depends on charging and the type of process.
In case of premixed green mixtures, the macrostructure of product is normally uniform. For the solid–gas systems, the product composition may be expected to vary over the sample cross section. In some cases, the product macrostructure is intentionally made nonuniform, e.g., multilayer and
functionally graded materials Product contamination depends not only on the purity of starting reagents but also on the extent of self-purification during combustion. Products synthesized under optimized conditions exhibit low content of unreacted components and contaminants.
The porosity of products ranges between zero (compact materials) and 90–95% (foam materials).
4. SHS Research4.1. Three levels of experimental diagnosticsLevel I: PhenomenologyDetecting a wave propagation mode (steady, pulsating, spinning) and measuring the following readily measurable parameters:
Level II: Zone structure of the combustion waveExperimental techniques: thermography and time-resolved pyrometry. The obtained temperature profiles shed light on the mechanism of physicochemical transformations in and structure of the combustion wave.
Level III: Mechanism and dynamics of phase/structure transformations behind the combustion frontExperimental techniques:- time-resolved x-ray diffraction .
Example: time-resolved x-ray diffraction patterns for the Ni-Al system;
- quenching (arresting) the wave propagation.
4.2. Means of ControlTask objective:controlling
5. Fundamentals of SHSSHS is a science-intensive process. Its comprehension requires erudition in thermodynamics, chemical kinetics, general and structural macrokinetics, materials science, and other allied fields of knowledge.5.1. ThermodynamicsFor SHS reactions, thermochemical calculations can be performed either in a concise form for determining only the adiabatic combustion temperature or in the full form for determining both the combustion temperature and product composition.- Thermodynamics for liquid-flame combustion in "hot" systems of a thermite type
- Thermodynamic analysis for combustion in the Ta-C system
- Composition diagram for the TiO2-B2O3-Mg system
5.2. Chemical KineticsThe kinetics of chemical reactions in SHS systems provides information about the rate of heat release at high temperatures. The latter is normally assessed from the dependence of the burning velocity on combustion temperature as well as from the thermograms of combustion or electrothermal explosion. For reactions of metal with gases, similar data can be assessed from electrothermographic measurements.5.3. Combustion TheoryWave propagation and wave structure are readily described in terms of the combustion theory. The latter is based on joint analysis of the equations of heat conduction with nonlinear heat sources (heat release in chemical reaction) and chemical kinetics (ideal solid-flame combustion). Calculations may also take into account the processes of melting and capillary spreading (solid-flame combustion with a melting interlayer), infiltration of a gaseous reagent (infiltration combustion), various heat transfer processes (heterogeneous combustion), etc.
To date, infiltration combustion and have been theoretically analyzed in terms of not only the 1D but also
2D Mathematical modeling of SHS was also performed with regard to the constitution diagram.
6. SHS Production Methods6.1 Technological Types of SHSSHS production has much in common with: preprocessing of raw materials/synthesis/product processing. Instead of furnaces and plasmotrons, SHS is performed in reactors.
Six technological types (TTs) of SHS are known:
Worth mentioning is also in-line SHS production.
7. Applications7.1. SHS ProductsSHS products find their application in mechanical engineering, metallurgy, chemical industry, electrical and electronic engineering, aerospace industry, building industry, etc. SHS products are also used in medicine
- SHS materials with shape memory for use in surgery ,
- SHS implants ,
scientific instruments, space experiments - First microgravity SHS experiment (related paper (in russian),
this document in MS Word97 format, zip-compressed, 40Kb ),
- Formation of the combustion product in the NiO–Ni–Al system (related paper in PDF-format 489Kb),
- "Contactless" SHS in space (related paper in PDF-format 467Kb),
- Gasless SHS in Particle Clouds under Microgravity: Experiments Aboard the MIR Space Station, etc. 7.2. SHS-Based ProductionIn the former Soviet Union, SHS was implemented for production of high-temperature heaters (Kirovakan), TiC powders and appropriate abrasive pastes (Baku, Poltava), nitrided ferroalloys (Izhevsk, Chusovaya), silicon nitride (b-phase) and titanium hydride powders (Makeevka; Transcarpathia), high-temperature insulators (Kuibyshev), lithium niobate (Dzerzhinsk), etc.
In Russia, there exist pilot-scale SHS production lines at ISMAN (Chernogolovka, Moscow), at MISIS–ISMAN Research and Educational Center (Moscow), and at SHS Engineering Center (Samara). In China, SHS is used to manufacture
ceramic-lined steel pipes In Japan and the USA, SHS products are reportedly being produced by some companies. In Spain,
a plant
8. History and State-of-Art8.1. DiscoverySHS naturally flew out of the discovery of the solid flame phenomenon. This discovery (officially named as "The Phenomenon of the Wave Localization of Solid-State Autoretarding Reactions") was made (in 1967) by A.G. Merzhanov, I.P. Borovinskaya, and V.M. Shkiro at the Research Center of the USSR Academy of Sciences (Township of Chernogolovka, 30 miles north-east of Moscow).
The very first paper on self-propagating high-temperature synthesis can be seen
here The discovery was made during a search for a model of the so-called gasless combustion (iron–aluminum thermite with alumina added as ballast). Another line of this research was synthesis of copper and silver acetylenides that could be expected to burn with no gas evolution. In the author's opinion, the precursors of SHS are the Beketov–Goldschmidt out-of-furnace metallothermy and the Semenov–Zel'dovich combustion theory.
8.3. SHS in the CIS countriesAfter collapse of the Soviet Union and economical reforms, the following SHS centers has remained active (in the CIS countries):
8.4. SHS all over the World1982 Initiation of SHS studies at the US Army Research Center and Lawrence Livermore National LaboratoryImpetus: Crider J.F., Self-propagating high-temperature synthesis: a Soviet method for producing ceramic materials , Ceram. Eng. Sci. Proc., 1982, vol. 3, nos. 9-10, pp. 519-528.
Initiation of SHS studies in Japan in the beginning of the 80s. Since the 80s: "Self-propagation" of SHS R&D in Poland, Korea, China, Italy, Spain, France, India, etc. The highest place of advance is achieved in China. To date, SHS publications have been submitted by researchers from 47 countries all over the world. Most active in the field are the following institutions:
The worldwide spread of SHS research was prompted by regular (since 1991) International Symposia on SHS and publication (since 1992) of Int. J. SHS by Allerton Press, New York.
8.6. Some Important Directions of Research
8.7. Symposia-Workshops-SeminarsAll-Union SHS Workshops and Seminars
Topical sessions of the Scientific Council of the USSR Academy of Sciences on the
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Alexander G. Merzhanov. Self-Propagating High-Temperature Synthesis: Twenty Years of Search and Findings. Chernogolovka: ISMAN, 1989, 91 pp. |
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SHS-Bibliography (1967–1995). Int. Journal of SHS, vol. 5, N 4, 1996, 513 pp. |
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Chemistry of Combustion Synthesis. Ed. M. Koizumi. Moscow: Mir Publ., 1998, 247 pp. (Russian translation). |
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Combustion Synthesis. Ed. Yin Sheng, Beijing, 1998, 444 pp., (in Chinese). |
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E.A. Levashov, A.S. Rogachev, V.I. Yukhvid, I.P. Borovinskaya. Physico-Chemical and Technological Foundations of Self-Propagation High-Temperature Synthesis. Moscow: Binom, 1999, 176 pp., (in Russian). |
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A.G. Merzhanov. Combustion Processes and Materials Synthesis. Chernogolovka: ISMAN, 1998, 512 pp., (in Russian). |
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Carbide, Nitride and Boride Materials Synthesis and Processing. Ed. Alan W.Weimer, London–Weinheim–New York–Tokyo–Melburne–Madras: Chapman & Hall, 1997, 671 pp. |
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Sharivker, S.Yu. and Merzhanov, A.G. SHS-Produced Powders and Their Processing, Borovinskaya, I.P., Ed., Chernogolovka: Izd. ISMAN, 2000, 123 pp., 21 tables, 30 figs., 273 refs. |
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Merzhanov, A.G. Solid Flame Combustion (in Russian) Chernogolovka: Izd. ISMAN, 2000, pp. 224, 27 tables, 116 figs., 409 refs book announcement |
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Self-Propagating High-Temperature Synthesis: Theory and Practice (in Russian). Ed. A.E.Sytschev, Chernogolovka, Territory, 2001, pp.432.book announcement |
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Self-Propagating High-Temperature Synthesis of Materials, Edited by Anatoli A. Borisov, Luigi De Luca, and Alex Merzhanov Translated by Yury B. Scheck book announcement |
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Êîíöåïöèÿ ðàçâèòèÿ càìîðàñïðîñòðàíÿþùåãîñÿ âûñîêîòåìïåðàòóðíîãî ñèíòåçà êàê îáëàñòè íàó÷íî-òåõíè÷åñêîãî ïðîãðåññà, Ed. A.G.Merzhanov, Chernogolovka, Territory, 2003, pp.368.  Adobe Acrobat document (7.7Mb) |
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Corbin, N.D., and McCauley, J.W., Self-Propagating High Temperature Synthesis (SHS): Current Status and Future Prospects, MTL MS 86-1, Watertown, MA, May 1986 |
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Frankhouser, W.L., Brendley, K.W., Kieszek, M.C., and Sullivan, S.T., Gasless Combustion Synthesis of Refractory Compounds, Noyes Publications, 1985 |
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Combustion and Plasma Synthesis of High Temperature Materials, Munir, Z.A., and Holt, J.B., Eds., VCH Publishers, 1990 |
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A.G. Merzhanov, A.S. Mukasyan, Tverdoplamennoe gorenie (Solid-Flame Combustion), Moscow: Torus Press, 2007, 336 pp. |
