MECHANICAL PROPERTIES OF PRESSURELESS SINTERED SiC-AIN COMPOSITES OBTAINED WITHOUT SINTERING BED

摘要

High density (>98 percent T.D.) SiC-AIN composites were obtained by means of a pressureless sintering process which did not require the powder bed to protect sample against weight loss. Sintered sample showed a fine microstructure formed by 2H SiC-AIN solid solution with Y_(10)Al_2Si_3O_(18)N_4 as grain boundary phase. Mechanical properties (hardness, toughness and flexural strength) were determined and compared to the properties of SiC-AIN sample obtained with different sintering processes (hot pressing, gas pressure sintering, pressureless sintering with powder bed). Microstructural analysis confirmed that a mullite scale protects material against oxidation up to 1400 deg C.