Coating 11
Coating 11 : Erosion: Although test methodologies to evaluate the erosion of coatings and substrate alloys in turbine environments have been used extensively, standards for generally accepted techniques have not been developed. ASTM G76-83 (Standard Practice for Conducting Erosion Tests by Solid Particle Impact Using Gas Jets), for example, uses large particles at low velocities at temperatures of 18-28?C. Typically, evaluation tests for turbine materials are conducted in burner rigs that use particle injection or in high-temperature furnaces using particles entrained in high-velocity gas streams. Specimen evaluation usually consists of a measurement of surface recession and the data provide a ranking of the materials examined. The degree of erosion damage is influenced by particle properties (e. g. , size and hardness), impact angle, and velocity. These influences are in addition to coating properties (e. g. , hardness and microstructure) that may vary with temperature and long-term exposure to operating conditions. These parametric difficulties may render standard erosion tests that provide data for accurate performance prediction an unrealistic expectation
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