Development of the high-precision incremental-step hole-drilling method for the study of residual stress in multi-layer materials: influence of temperature and substrate on ZrO2–Y2O3 8 wt.% coatings

The aim of this study was to determine internal stress locked in a zirconia ZrO2–Y2O3 8 wt.% coating and substrate produced by plasma spray. Zirconia layers are suitable for thermal barrier coatings due to their high thermal isolation. We varied the spraying temperature and the type of substrate in order to show the technological conditions that play an important role in determining coating quality. The deposit studied consisted of partially stabilised zirconia used in the aircraft industry as a thermal barrier in combustion chambers. The high-precision incremental-step hole-drilling method was used to determine the residual stress introduced into nine samples. We obtained the residual stress gradient in the test specimen. Compressive residual stress has a beneficial effect on fatigue life, crack propagation, material lifetime and coating adhesion. The stress was measured in zirconia coatings deposited on stainless steel, aluminium and cast iron substrates at spraying temperatures of 85, 150 and 210 °C.