Thermal cycling tests were performed on thermal barrier coatings (TBCs) to evaluate the influence of temperature gradients in the ceramic topcoat on overall lifetime and performance. The coating system tested consists of an Inconel 738 substrate, a cold-sprayed NiCoCrAlTaY bond coat, and an atmospheric plasma sprayed YSZ topcoat. YSZ surface temperatures were 1150, 1200, and 1250 °C, corresponding to temperature gradients of 150, 200, and 250 °C across the 250 µm thick layer. Heating and cooling times were set at 120 sec for each thermal cycle. The results of the study show that lifetime decreases with increasing temperature gradient, although the gradient has little effect on the failure mode.

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