PROTECTION OF MOLYBDENUM FROM OXIDATION BY MOLYBDENUM DISILICIDE BASED COATINGS

摘要: Vapor-deposited molybdenum disilicide coatings on prevented oxidation for 200 hr at 1450 deg C and similar ones were still protective after six months 1000 C. This protection was reduced to three hours under thermal cycling between 20 By adding either iron or chromium the silicide cyclic life trebled, with no effect above resistance C, though it 20--80 hr. Failure in test due cracks propagating through coating, whereas failure stable conditions occorred when replaced by less oxidation-resistant silicides Mo/sub 3/Si 5/Si/sub 3/. Maximum obtained approximately 30 mu thick, static thicker coating longer life. The unaffected preparation of surface prior structure, but lowering temperature improved it. (auth)