The desire to enhance the performance and efficiency of gas turbine engines has led to higher engine operating temperatures. To accommodate these higher temperatures, new superalloys and material systems have been developed, along with novel cooling techniques. However, with operating temperatures exceeding the acceptable maximum metal temperatures, thermal barrier coatings (TBC) are used for underlying metal surface protection. This paper reviews the art and technology of air plasma sprayed TBC coatings onto hot section components from a job shop perspective. The specification for such coatings and its practical implications are discussed. The issues in applying such coatings will be discussed, along with references to manufacturing issues on the shop floor. The difficulties inherent m applying a line-of-sight coating to complex geometry will be discussed, with particular reference to automated or robotic spraying. The utility of using a design-of-experiment approach to satisfy the user will be reviewed. Data will be presented to show the economic impact of process optimization.

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