Plasma and Detonation Gun Ceramic and Cermet Coatings in Gas Turbine Engines

Plasma and detonation gun coatings of ceramic and cermet materials have achieved widespread application throughout gas turbine engines, and their use continues to grow. The coatings are used in increasingly demanding environments, thus successful utilization requires a thorough understanding of their structure/property relationships and close control of the parameters of deposition. The areas of application within the engine can be roughly separated into low and high temperature regimes. At low temperature, impact/fretting wear, erosion resistance, gas path seals, and various seals and bearings are of concern. Each area requires one or more coating types to satisfy the specific requirements of a given engine. The most common coating types include tungsten carbide-cobalt, alumina, chromium carbide-nickel chromium, a new family of cobalt-base alloys with alumina or chromia dispersions, and magnesium zirconate or stabilized zirconia. The characteristics of major significance of these coatings and their applications will be discussed.