Effect of the Content of SiC on Properties of ZrB2-SiC-Zr2Al4C5 Composite Ceramics

Abstract:

The ZrB₂/SiC/Zr₂Al₄C₅ composite ceramics with various content of SiC were sintered at 1800 _oC and 20 MPa by spark plasma sintering. The sintering behavior, microstructure, mechanical properties and oxidation resistance were studied. The results indicate that SiC promoted the sintering of the composite ceramics and suppressed the growth of ZrB₂ grains. When the content of SiC was 20 vol%, the composite ceramic showed a toughness of 4.81 MPa×m_1/2. As increasing the content of SiC, the oxidation resistance of composite ceramics was obviously enhanced. The oxidation-resulted increase in weight of composite ceramic with 20vol% SiC was the best performance in oxidation resistance at 1500 _oC. The high-temperature oxidation resulted in dense and stable Al₂O₃, B₂O₃-Al₂O₃, SiO₂ and Al-Si-O glass due to adding SiC into the composite ceramics, those resulting products effectively blocked the oxygen atoms entering into the ceramic matrix, which led to the apparent enhancement of the oxidation resistance.