Repeated Thermal Shock Properties of Functionally Gradient Plasma Sprayed Coatings under the Temperature Gradient Condition.

In the study of the functionally gradient material (FGM) systems as for the high temperature structural materials, designing of these and evaluation of their thermal shock properties under the temperature gradient condition would be the most essential problems to be investigated. In this study, ZrO2/NiCrAlY functionally gradient plasma sprayed coatings were produced on the stainless steel substrates. Simple heating-cooling thermal shock testing apparatus was made, and repeated thermal shock resistance properties of the coating specimens under the temperature gradient conditions were investigated using this apparatus. Conventional thermal shock test regulated by JIS was also conducted. Moderate coating configuration for minimizing the thermal stress were estimated by the simple analytical model.The results obtained are summarized as follows, (1) Feasibility of the functionally gradient coating were verified by the temperature gradient thermal shock testing conducted using the simple apparatus made.(2) The effect of coating configuration on the repeated thermal shock resistance properties could be evaluated by the temperature gradient test condition.(3) From the results of simple numerical analysis, the moderate coating configuration profile of the functionally gradient coatings was given as the compositional distribution parameter P of less than 1.