Nonoxide High-Melting Point Compounds as Materials for Extreme Conditions

Abstract

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-TiB2 and 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.