Composite material Si 3 N 4 /SiC with calcium aluminate additive

Abstract

The aim of this work was to obtain Si 3 N 4 /SiC composites, where silicon nitride served as the matrix, and the silicon carbide content varied from 3 to 50 % by weight. To reduce the sintering temperature (hot pressing) of the ceramic, a sintering additive of calcium aluminate eutectic. The charge was prepared as follows. The silicon nitride powder was mixed with 10 wt.% sintering calcium aluminate. Then the charge was added over 100 % of silicon carbide in an amount of 3, 5, 7, 10, 15, 20 and 50 % by weight in a planetary mill. Ceramic materials were obtained by hot pressing at a temperature of 1660°C, a pressure of 30 MPa, for 60 minutes in an atmosphere of N 2 . The highest properties were achieved on the material with 10 wt.% SiC: density of 3.16 g/cm 3 , bending strength 650 MPa, microhardness 22 GPa.