CVD SiC涂层的C/SiC复合材料的弯曲性能  

Flexural properties of CVD SiC coated C/SiC composites

作　　者：闫志巧[1] 熊翔[1] 肖鹏[1] 姜四洲[1] 谢建伟[1] 黄伯云[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2008年第6期1207-1212,共6页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金委员会创新研究群体科学基金资助项目(50721003);国家"973"计划资助项目(2006CB600908);新世纪优秀人才支持计划资助项目(NCET-05-0694)

摘　　要：以针刺整体毡为预制体制备C/SiC复合材料,在材料表面制备CVDSiC涂层,研究涂层试样氧化前、后的微观结构和室温弯曲性能。研究结果表明:CVDSiC涂层由球形颗粒熔聚体、裸露裂纹和附着裂纹组成,于1400℃氧化时附着裂纹发生愈合;C/SiC试样的弯曲强度为119.9MPa,涂层试样及其分别经1000,1200和1400℃连续氧化5h后,弯曲强度分别为188.5,41.0,60.7和104.5MPa;随氧化温度的升高,SiC涂层的保护作用增强是残留弯曲强度提高的根本原因;C/SiC试样、涂层试样和经1200和1400℃氧化的试样均表现为分层断裂,纤维束边缘区域炭的适度氧化弱化了纤维/热解炭界面,使氧化试样表现出明显的假塑性;经1000℃氧化的涂层试样,由于纤维束的严重氧化,表现为脆性断裂特征。C/SiC composites were prepared by densification of bulk needled carbon fiber felts and SiC coating was deposited via CVD. Microstructures and flexural properties of the coated samples at room temperature before and after oxidation were studied. The results show that CVD SiC coating consists of spherical clusters of fine grains, naked and adhesive cracks. The adhesive cracks can be self-sealed during oxidation at 1 400 ℃. The flexural strength of the C/SiC composites is 119.9 MPa, and those of the coated samples before and after 5 h continuous oxidation at 1 000, 1 200 and 1 400 ℃ are 188.5, 41.0, 60.7 and 104.5 MPa, respectively. The protection of SiC coating improves with the increase of oxidation temperature, which leads to higher residual strength. Delamination fracture is observed in C/SiC and also in the coated samples before and after oxidation at 1 200 ℃ and 1 400 ℃. In addition, moderate oxidation of carbon locating brim of fiber bundles weakens interface between the fiber and pyrocarbon, which improves the toughness and certain pseudo-plasticity appears. For the coated sample after oxidation at 1 000 ℃, brittleness fracture occurs due to the severe oxidation of the fiber bundles.

关 键 词：C/SIC复合材料 CVD SIC 弯曲性能 氧化 界面 

分 类 号：TB332[一般工业技术—材料科学与工程]