SiC含量对ZrB2-SiC-Zr2Al4C5复相陶瓷性能的影响

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

摘要:

本论文采用放电等离子体烧结（SPS）技术制备不同SiC含量的ZrB2/SiC/Zr2Al4C5复相陶瓷，并对其烧结特性、显微结构、力学性能和氧化性能进行了研究。结果表明：掺入SiC化合物促进了复相陶瓷的致密化过程，抑制了ZrB2晶粒长大；当SiC掺入量为20vol%时，ZrB2/SiC/Zr2Al4C5陶瓷的断裂韧性值为4.81 MPa×m1/2。掺入SiC化合物后，复相陶瓷的抗氧化性能得到明显改善，当SiC化合物的含量为20vol%时，其抗氧化性能最佳，分析其机理发现当掺入SiC化合物后，复相陶瓷高温氧化后在其表面生成了具有致密的和稳定的Al2O3、B2O3-Al2O3、SiO2和Al-Si-O玻璃相等物质，从而阻止了氧原子进入到陶瓷基体中，提高了复相陶瓷的抗氧化性能。

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.