Comparative study of oxide and non-oxide additives in high thermal conductive and high strength Si3N4 ceramics

Abstract

A comparative study between oxide and non-oxide sintering additive was conducted to examine the thermal and mechanical properties of Si3N4 ceramics. The effects of additive types (oxide or non-oxide) on microstructure, thermal conductivity and mechanical strength were investigated. Replacement of oxide additives by non-oxide additives induced a decrease in the secondary phase and lattice oxygen contents of sintered samples. The use of non-oxide sintering additives increased the thermal conductivity of Si3N4 ceramics; however, the sintering additive had less impact on the ceramic flexural strength. The measured strengths of all samples ranged from 822 MPa to 916 MPa. Therefore, the thermal conductivity of ceramics incorporating non-oxide sintering additives increased while maintaining flexural strength; these materials possessed a flexural strength of 862 MPa and a thermal conductivity of 101.5 W/mK. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved