The effect of Cr2O3 additions on sinterability and mechanical properties of liquid-phase sintered SiC ceramics

摘要

In this study, the effect of using Cr(2)O(3 )with Al2O3 and Y2O3 additives on physical and mechanical properties of SiC-matrix composites was investigated. The samples were sintered at 1900 degrees C for 1.5 h in argon atmosphere. The phases, microstructure and chemical composition of the samples were studied using X-ray diffraction analysis (XRD), scanning electron microscopy (FESEM) and X-ray diffraction spectroscopy (EDX). The results showed that addition of Cr2O3 nanoparticles up to 5 wt % results in densification improvement of samples. Due to weak interface of SiC grains and grain boundary phase, crack propagation path is mainly grain boundaries. The highest density, elastic modulus, hardness and indentation fracture resistance were respectively 97.45%, 403 GPa, 28.19 GPa and 6.2 Mpa.m(1/2), attributed to specimen containing 5 wt % Cr2O3. Microscopic studies showed that, formation of microcracks, crack deflection, crack bridging and crack branching mechanisms are the most important mechanisms in indentation fracture resistance improvement of composites. (C) 2020 Elsevier B.V. All rights reserved.