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Phenomenological Study of the Behavior of Some Silica Formers in a High Velocity Jet Fuel Burner

出版	National Aeronautics and Space Administration, 1985
URL	http://books.google.com.hk/books?id=a3pGAQAAIAAJ&hl=&source=gbs_api
EBook	FULL_PUBLIC_DOMAIN

註釋Silicon based materials are under consideration of a number of applications in aircraft and automative gas turbine engines. The majority of these are monolithic components which benefit from the excellent high temperature strength of some of these materials, eg. sintered alpha silicon carbide and reaction bonded silicon nitride. Another possible application is employing these materials in turbine tip gas path seals. The structural requirement of this application is minimal, however dimensional stability is crucial. The silicon based material are unstable in the presence of oxygen at the high temperatures experienced in the engine. Protection from gross reaction is afforded when an adherent film of Si02 forms on the surface during oxidation. This film serves as a barrier across which mass transport must occur for further oxidation, leading to parabolic scale growth kinetics. The class of materials which displays this behavior is termed silica formers. Samplers of four silica formers: single crystal SiC, sintered alpha-SiC, reaction sintered Si3N4 and polycrystalline MoSi2, were subjected to a Mach 1 jet fuel burner for 1 hr, at a sample temperature of 1375 C (2500 F). Two phenomena were identified which may be deleterious to a gas turbine application of these materials.