RANKING PROTECTIVE COATINGS - LABORATORY VS FIELD EXPERIENCE

Environmentally protective coatings are used on a wide range of gas tu rbine components for survival in the harsh operating conditions of eng ines. A host of coatings are commercially available to protect hot-sec tion components, ranging from simple aluminides to designer metallic o verlays and ceramic thermal barrier coatings. A variety of coating-app lication processes are available, and they range from simple pack ceme ntation processing to complex physical vapor deposition, which require s multimillion dollar facilities. Detailed databases are available for most coatings and coating/process combinations for a range of laborat ory tests. Still, the analysis of components actually used in engines often yields surprises when compared against predicted coating behavio r from laboratory testing. This paper high-lights recent work to devel op new laboratory tests that better simulate engine environments. Comp arison of in-flight coating performance as well as industrial and fact ory engine testing on a range of hardware is presented along with labo ratory predictions from standard testing and from recently developed c yclic burner-rig testing.