电压对脉冲电弧放电法制备C-AlPO_4抗氧化性能的影响

Influence of voltage on anti-oxidation C-AlPO_4 coating prepared by pulse arc discharge deposition

采用脉冲电弧放电法在 SiC-C/C 复合材料表面制备方石英型磷酸铝（C-AlPO4）抗氧化涂层.借助X射线衍射（XRD）、扫描电子显微镜（SEM）和等温静态氧化实验对涂层的晶相组成、显微结构和抗氧化性能进行了表征与测试.研究了脉冲电压对C-AlPO4涂层显微结构的影响,分析了 C-AlPO4涂层在1773 K下的氧化行为.结果表明,330~420 V 范围内,当脉冲电压为390 V 时制备的涂层致密均匀；C-AlPO4涂层具有较好的抗氧化性能,在1773 K氧化156 h后失重率仅为0．83％；C-AlPO4涂层在1773 K 下的氧化能力下降主要是由于长时间氧化后偏磷酸盐玻璃层不能及时有效地填补涂层中的缺陷,涂层在高温下产生了较多贯穿性孔洞所致的.

A C-AlPO4 anti-oxidation coating was prepared on SiC pre-coated C/C composites by novel pulse arc discharge.The phase compositions,microstructures and anti-oxidation properties of the as-prepared coatings were characterized by XRD,SEM and isothermal oxidation tests.The influence of pulse voltage on the microstructure was investigated.Results show that the dense and homogeneous of the C-AlPO4 coating was achieved when the pulse voltage reaches 390 V.The as-prepared coatings exhibit excellent anti-oxidation property,which could effectively protect C/C composites from oxidation at 1 773 K in air for 156 h with a weight loss of 0.83%. The anti-oxidation capability decrease of the coating at 1 773 K was due to the generation of cross-holes in the coating,which can not be self-cured by the metaphosphate glass layer after oxidation for a long time.