Polyfunctional interface coatings for high temperature resistant ceramic composite of SiC/SiC type

• Published in: Key engineering materials 1999-01, p.399-402
• Main Authors: Tsirlin, A M, Gerlivanov, V G, Florina, E K, Pronin, Y E, Syrkin, V G, Uelskii, A A, Grebenschikov, A V, Khatsernov, M A
• Format: Article
• Language: English
• ISSN: 1013-9826

Preliminary results are presented of fabricating protective MoSi2 coating and 'rheological' SiC coating on both SiC/C and SiC-coreless fibers. The study is carried out in order to solve one of the major problems in creating highly oxidation-resistant ceramic matrix composites (CMCs) of the SiC/SiC type for protracted operation at 1800-2100 K. CVD, reactive vapor deposition, (RVD) and preceramic polymer deposition were explored. The fibers of Nicalon and SiC/C types were coated. CVD protective coatings deposited under a mild regime (less than 1100 K) in the Mo(CO)6 and SiH4 systems had a multiphase composition: MoSi2, Mo5i3, Si, and Mo were identified by XRD. The consecutive deposition of Mo- and Si-layers followed by a heat treatment demonstrated the impossibility of coating the Nicalon first with Mo-layer. Molybdenum disappeared quickly at heat treatment working temperatures due to its interaction with initial oxygen of coreless SiC-fibers. Consideration is given to the protection of fibers from the environment and the perfection of their internal composition and structure. The rheological SiC-coating on the Nicalon fiber was successfully prepared by polymer pyrolysis deposition. (Author)