A novel ultra-high-temperature oxidation protective MoSi2-TaSi2 ceramic coating for tantalum substrate. Issue 7 (July 2019)

• Record Type: Journal Article
• Authors: Cai, Zhenyang; Zhang, Daxu; Chen, Xinxiang; Huang, Yuntong; Peng, Yuqing; Xu, Canhui; Huang, Siyu; Pu, Rong; Liu, Sainan; Zhao, Xiaojun; Xiao, Lairong
• Is Part Of: Journal of the European Ceramic Society. Volume 39:Issue 7(2019)
• Page Start: 2277
• Page End: 2286
• Publication Date: 2019-07
• Subjects: Tantalum -- Silicide ceramic coating -- Oxidation -- Slurry sintering -- Pack cementation; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2019.02.037
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: To protect refractory metal against oxidation at ultra-high temperatures, a MoSi2 -TaSi2 ceramic coating was prepared on a pure tantalum (Ta) substrate using a novel three-step process, which included dip-coating with a molybdenum slurry, vacuum sintering, and halide-activated pack cementation (HAPC). The original coating had a MoSi2 -TaSi2 double-layer structure from the surface to the substrate. After oxidation at 1700°C for 8 h in air, the coating exhibited a complex multi-layer structure composed of SiO2 -Mo5 Si3 -MoSi2 -(Mo, Ta)5 Si3 -TaSi2 -Ta5 Si3 from the outer layer to the inner layer, due to the high-temperature phase transition and diffusion of Si and O. The coating effectively protected the Ta substrate at 1700°C for 12 h without failure, thereby demonstrating great improvement to its service life in an ultra-high-temperature aerobic environment. The protective effect was attributed to the integrity of the ceramic coating and the formation of a dense, uniform SiO2 film that effectively lowered the inward oxygen diffusion rate.