高温循环下SiC-C/SiBCN复合材料的力学性能研究

Effect of Thermal Cycling on Mechanical Properties of SiC-C/SiBCN Composites

摘要:

采用化学气相沉积（CVD）结合前驱体浸渍裂解（PIP）技术制备了SiC涂层的C/SiC和C/SiBCN复合材料，研究了高温循环氧化对两种复合材料弯曲性能的影响。与SiC-C/SiC相比，SiC-C/SiBCN复合材料的平均室温弯曲强度约为605 MPa，增幅达到126.6%。在1000℃和1200℃循环3次后，SiC-C/SiBCN的剩余弯曲强度分别为417和342 MPa，强度保留率分别为68.9%和56.5%，显著优于SiC-C/SiC复合材料。与PIP SiC陶瓷基体相比，SiBCN基体的孔隙率更低，高温下SiBCN氧化后形成SiO2和B2O3，可以更好地降低O2的透过率，提高材料的抗氧化性能和强度保留率。

Abstract:

SiC coated C/SiC and C/SiBCN composites were prepared by chemical vapor deposition (CVD) combined with polymer infiltration and pyrolysis (PIP) techniques. The effects of thermal cycling on bending properties of these composites were studied. Compared with SiC-C/SiC, the average bending strength of SiC-C/SiBCN was measured as around 605 MPa at room temperature, which increased by 126.6 %. After the oxidation at 1000 °C and 1200 °C for 3 cycles, the residual bending strength of SiC-C/SiBCN was separately measured as 417 and 342 MPa. The corresponding strength retention rates at 1000 °C and 1200 °C were 68.9 % and 56.5 %, respectively. Compared to the SiC ceramic matrix by PIP, the porosity of SiBCN ceramic matrix was lower. Meanwhile, SiO2 and B2O3 were formed during the oxidation of SiBCN, which could decrease permeation ration of the oxygen. Thus, the oxidation resistance and strength retention rate of SiC-C/SiBCN were significantly better than SiC-C/SiC composite.