Combustion Synthesis of Ceramic Powders with Controlled Grain Morphologies

Abstract

Combustion synthesis, which is also known as self-propagating high-temperature synthesis (SHS), is a facile and economic technique to prepare a large variety of advanced materials, such as ceramics, intermetallics, composites, and functionally-graded materials [1-4]. By this technique, new materials are synthesized from self-sustained exothermic chemical reactions instead of long-time heat treatment by furnace. Once the reactants are ignited, a large amount of heat energy is produced to support the reaction to continue. With the propagation of combustion wave through the whole sample, the reactants are converted into products. Because exothermic combustion reactions occur quickly, a non-equilibrium state is usually involved in combustion synthesis and characterized by high temperatures and fast heating or cooling rates. This non-equilibrium reaction state offers an opportunity for controlling the microstructure of products. Among the extensive applications of combustion synthesis, the fabrication of advanced ceramic powders is an important and successful practice. By combustion synthesis, many kinds of ceramic powders have been prepared, including nitrides (Si 3 N 4 , AlN, TiN, BN, SiAlON, etc.), carbides (SiC, TiC, ZrC, Ti 3 SiC 2 , Ti 3 AlC 2 , Ti 2 AlC, etc.), borides (MgB 2 , TiB 2 , ZrB 2 , etc.), silicides (e.g. MoSi 2), and oxides (e.g. ferrites, Y-Ba-Cu-O superconductors). The grain size and morphology of the ceramic powders can be manipulated by controlling the processing parameters, such as proportion of diluents, porosity of green compacts, and particle size distribution of raw materials. This chapter presents some recent results on combustion synthesis of ceramic powders, with an emphasis on the investigation of crystal growth kinetics and control of final grain morphologies. Four kinds of ceramic powders (TiN, SiC, SiAlON, and Ti-Al-C) with different grain morphologies are reported as examples. The grain growth mechanisms involved in combustion synthesis of these ceramic powders are discussed in detail. 2. Combustion synthesis of TiN powders with different grain morphologies The nitrides of transition metals have received increasing attention because of their unique chemical and physical properties. Among these materials, TiN is particularly interesting due to its superior hardness, good thermal stability, high wear resistance, excellent corrosion resistance, and relatively high electrical conductivity [5]. It can be used as a coating material www.intechopen.com Advances in Ceramics-Synthesis and Characterization, Processing and Specific Applications

Understanding reaction sequences and mechanisms during synthesis of nanocrystalline Ti2N and TiN via magnetically controlled ball milling of Ti in nitrogen

“…Similarly, TiN synthesis has been explored by ball milling or deformation of elemental titanium powder under different media and powder mixtures including air (mixture of nitrogen, oxygen and carbon dioxide) [8], pyrazine compound (C4H4N2) [9], ammonia gas [4,10,11] and urea [12]. Other methods such as combustion synthesis by thermal heating of Ti under nitrogen gas or ammonia gas [13,14], direct heating of Ti-Si ingot under combined atmosphere of N2-H2-Ar [15] and direct reaction of titanium powders with nitrogen gas at very high temperature [16] have been reported as typical routes to produce TiN. More recently, electrical dischargeassisted mechanical milling (EDMM) of titanium powders under nitrogen plasma has been carried out to produce TiN [17].…”

Review of melt casting of dense ceramics and glasses by high gravity combustion synthesis

“…This method was discovered about 40 years ago by Merzhanov and Borovinskaya 5 during their study on the phenomenon of solid flame. Since then, a great diversity of inorganic materials has been produced by combustion synthesis, [6][7][8][9][10] including many ceramic powders. [11][12][13][14][15][16] In high gravity combustion synthesis, combustion synthesis is combined with a high gravity field, where highly exothermic combustion reactions are used to produce ceramic melts and a high gravity field is applied to promote the separation between the ceramic melts and other concomitant phases (e.g.…”

Low-temperature capacitive sensor based on perovskite oxides

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