Microstructure and Thermal Conductivity of Thermal Barrier Coatings Processed by Plasma Spray and Physical Vapor Deposition Techniques

Autor: K. An, S. L. Semiatin, R.E. Dutton, K. S. Ravichandran
Rok vydání: 1996
Předmět:
Zdroj: MRS Proceedings. 434
ISSN: 1946-4274
0272-9172
DOI: 10.1557/proc-434-27
Popis: Improvements in the efficiency of gas turbine require the highest operating temperatures possible. Because the Ni-base superalloys used as turbine materials rapidly lose strength and oxidize above 1,000 C, a reduction in service temperature is often accomplished by the use of thermal barrier coatings. The temperature dependence of the thermal conductivity of multilayer coatings made by a plasma spray technique as well as some coatings made by physical vapor deposition (PVD) was investigated. The multilayer coatings consisted of a varying number of layers of Al{sub 2}O{sub 3} and ZrO{sub 2} stabilized by 8% Y{sub 2}O{sub 3}. Plasma sprayed coatings exhibited a large reduction in thermal conductivity at all temperatures when compared to the bulk monolithic materials. This reduction was found to be due to porosity as well as thermal resistance brought about by interfaces in the coatings. A comparable reduction in thermal conductivity was achieved in monolithic ZrO{sub 2} as well as in a composite coating deposited by the PVD technique. Microstructural factors that may be responsible for this reduction are discussed.
Databáze: OpenAIRE
Externí odkaz: