The particulars of phase and structure formation during reaction sintering of materials based on boron carbide and silicon carbide are examined, and the actual technological aspects of reaction sintering are analyzed. The main physical and mechanical characteristics of reaction sintered material based on silicon carbide and boron carbide and their relation to the structure of the material are discussed.Reaction sintering of refractory covalent compounds attracts developers and manufacturers of materials made from solid high-strength ceramic by its practicability and low energy intensiveness compared with other methods of compaction, viz., hot pressing and free sintering. The materials obtained by reaction sintering of porous blanks based on silicon carbide (SiSiC, reaction sintered, or self-bound, silicon carbide [1 -4]) are widely used as durable, very hard, heat-resistant, and impact-resistant structural materials.In recent years successful attempts have been made to obtain a material based on boron carbide (RBBC) similar to similar reaction sintered silicon carbide [5 -12] and to develop a technology for its commercial production [13 -16]. In spite of the considerable differences characterizing the reaction sintering processes for SiC and B 4 C it was demonstrated that the technology of impregnating with silicon melt porous blanks based on B 4 C in order to obtain dense materials is in principle possible. The non-shrinking and non-porous composite based on very hard and light B 4 C, obtained at relatively low reaction-sintering temperatures, is a very promising alternative to reaction sintered SiC material.The composition, structure, and properties of reaction sintered boron carbide are determined by a number of factors: the granulometric composition of the initial powders, the phase composition and porosity of the blank, and the capacity of the silicon melt to wet the surface of all solid components of the blank with different technological parameters (sintering temperature, time). On the whole, these factors all affect the key parameter for silicon-impregnated materials: the amount of residual (unreacted) silicon present in the sintered material, which lowers the overall hardness level, strength, and cracking resistance.In the last ten years many researchers have studied from different positions the effect of the diverse physical and chemical aspects of obtaining reaction sintered boron carbide on its structure, phase composition, and properties. It is of great interest to colligate this information for current ceramic materials science and technology of reaction sintered materials.The granulometric composition of batch and the monoor polydispersity and morphology of the powders used affect the relative density and porosity of the blank at the pressing stage [6,12]. During impregnation the pore volume is filled with silicon melt, which is partially expended on the synthesis of silicon carbide. The amount of reacted silicon is determined by the amount of free carbon (or other source of carbon) present in the...

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Authors have studied the interaction between high-melting compounds from various classes, such as transition-metal carbides, borides, nitrides, and silicides, and covalent-bonded B4C, SiC, Si3N4, AlN etc. (over 160 phase diagrams), ternary B4C-SiC-MedB2, SiC-TiC-TiB2and other eutectics, which is important for optimizing the sintering temperature, material design and prediction of properties of many materials for high temperature applications including wear, aggressive, impact and radiation conditions. A vast identified group of eutectics with number of components n ≥ 2 has reduced eutectic temperature Тeut.(in some sistems reducing reaches 1200 °C). Noted, that increasing of n suppresses grain growth, which is particularly important for developing nanostructured ceramics via pressureless sintering and for controlling the ceramic's performance. Multiphase ceramics (SiC-TiC-TiB2, B4C-SiC-MedB2, B4C-W2B5-MedB2, B4C-LnB6-MedB2, etc.) feature improved mechanical parameters and high wear and impact resistance.