Silicon nitride ceramics with light-melting sintering additive in CaO-TiO 2 system

The aim of this work was to obtain Si3N4/SiC composites, where silicon nitride served as the matrix, and the silicon carbide content varied from 3 to 50wt.%. To reduce the sintering temperature (hot pressing) of the ceramic, it is used a sintering additive of calcium aluminate eutectic. The charge was prepared as follows: the silicon nitride powder was mixed with 10 wt.% sintering calcium aluminates, then the charge was added over 100 % of silicon carbide in an amount of 3, 5, 7, 10, 15, 20 and 50 wt.% in a planetary mill. Ceramic materials were hot pressed at 1660 degrees C, the pressure was 30 MPa for 60 minutes in N-2 atmosphere. The 10 wt.% SiC composite has highest properties: 3.16 g/cm(3) density, 650 MPa bending strength, 22 GPa microhardness.