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Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/41696
- Performance of thermal barrier coatings in high heat flux environments
- Miller, Robert A.; Berndt, C. C.
- Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kw plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0. 038 cm ceramic layer was about 1100 degree C after 0. 5 sec in the flame. An as-sprayed ZrO//2-8%Y//2O//3 specimens survived 3000 of the 0. 5 sec cycles with failing. Surface spalling was observed when 2. 5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 1 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO//2-12%Y//2O//3 or ZrO//2-20%Y//2O//3 were shown to be unsuited for use under the high heat flux conditions of this study.
- Publication type
- Technical report
- NASA Technical Reports
- Publication year
- Plasma devices; Protective coatings; Thermal barrier coatings; Torches
- National Aeronautics and Space Administration, Scientific and Technical Information Office
- Publisher URL