不同工艺制备的SiC_(f)/SiC复合材料水氧腐蚀行为

Water-oxygen corrosion resistance behavior of SiC_(f)/SiC composites prepared by different processes

分别采用熔渗(melt infiltration,MI)工艺、化学气相渗透结合前驱体浸渍裂解(chemical vapor infiltration combined with precursor infiltration and pyrolysis,CVI+PIP)工艺及前驱体浸渍裂解(precursor infiltration and pyrolysis,PIP)工艺制备SiC_(f)/SiC复合材料,采用扫描电镜及其附带的能谱仪、X射线衍射仪等表征分析不同工艺制备的SiC_(f)/SiC复合材料在1300℃水氧环境腐蚀前后的微观结构、组成及性能变化。结果表明:不同工艺制备的复合材料氧化后断口氧元素分布有明显不同,氧化后的物相与制备工艺密切相关;经1300℃/50 h水氧腐蚀后,MI工艺制备的SiC_(f)/SiC复合材料强度保留率为84%,模量保留率为76%;CVI+PIP工艺制备的SiC_(f)/SiC复合材料强度保留率为64%,模量增加6%;PIP工艺制备的SiC_(f)/SiC复合材料强度保留率为49%,模量增加17%;MI工艺制备的复合材料表现为氧化增重,而采用CVI+PIP及PIP工艺制备的复合材料表现为氧化失重,主要与其微观结构及组成相关。

SiC_(f)/SiC composites were prepared by melt infiltration(MI)process,chemical vapor infiltration combined with precursor infiltration and pyrolysis(CVI+PIP)process and precursor infiltration and pyrolysis(PIP)process,respectively.The microstructures,compositions and properties of SiC_(f)/SiC composites prepared by different processes before and after water-oxygen corrosion at 1300℃were characterized by scanning electron microscopy and its accompanying EDS and X-ray diffractometer.The results show that the distributions of oxygen elements of the fracture surface is obviously different in the composites prepared by different processes,and the phases after corrosion are closely related to the preparation processes.The strength retention rate and modulus retention rate of SiC_(f)/SiC composites prepared by MI process are 84%and 76%after water oxygen corrosion at 1300℃for 50 hours.The strength retention rate of SiC_(f)/SiC composites prepared by CVI+PIP is 64%,and the modulus is increased by 6%.The SiC_(f)/SiC composites prepared by PIP process has a strength retention rate of 49%and a modulus increase of 17%.The composite materials prepared by MI process show oxidation mass gain,while the composite materials prepared by CVI+PIP and PIP process show oxidation mass loss,which are mainly related to its microstructures and compositions.