Dual layer SiC coating on matrix graphite sphere prepared by pack cementation and fluidized‐bed chemical vapor deposition. Issue 8 (22nd April 2017)

• Record Type: Journal Article
• Authors: Zhou, Ping; Zheng, Zujie; Liu, Rongzheng; Liu, Xiaoxue; Liu, Malin; Wang, Taowei; Li, Ziqiang; Shao, Youlin; Zhao, Hongsheng; Liu, Bing
• Is Part Of: Journal of the American Ceramic Society. Volume 100:Issue 8(2017)
• Page Start: 3415
• Page End: 3424
• Publication Date: 2017-04-22
• Subjects: chemical vapor deposition -- coating -- graphite -- oxidation resistance -- SiC; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.14906
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: A dual layer silicon carbide (SiC) coating including inner porous SiC ( p ‐SiC) layer and outer dense SiC ( d ‐SiC) layer was fabricated on the matrix graphite (MG) spheres of high‐temperature gas‐cooled reactor fuel elements by pack cementation and fluidized‐bed chemical vapor deposition process to improve the oxidation‐resistant property. Microstructure of the coating demonstrates different density and structure of the two SiC layers with no obvious boundaries between them. Weight gain curves of oxidation tests at 1773 K for 200 hours show that the coating could effectively protected the MG sphere by isolating the air infiltration with p ‐SiC layer as the main functional layer and d ‐SiC layer as the transition layer to improve the bond strength. Due to the transition function of p ‐SiC layer, the coated spheres could understand more than 50 times thermal shocking tests from 1773 K to room temperature with no stress cracking.