Correlation between PVD coating strength properties and impact resistance at ambient and elevated temperatures

The performance of PVD films depends on the operational mechanical and thermal loads of coated tools or components. To withstand these loads, sufficient film strength properties, at ambient and elevated temperatures are required. The present paper deals with the mechanical properties and the impact resistance of a TiAlN coating at temperatures up to 400°C. Nanoindentations were conducted by a nanoindentation device, enabling measurements at room and elevated temperatures in an inert gas atmosphere. The obtained results were evaluated using appropriate FEM algorithms for determining the film's stress-strain curves, at the temperatures of the conducted nanoindentations. Moreover, perpendicular impact tests on the coated specimens were carried out up to 400°C, for investigating the film's impact behaviour. The developed impressions were recorded by scanning electron microscopy and white light confocal measurements. The attained results demonstrate a non-linear dependence o f the film fatigue properties versus the temperature, whereas a significant impact resistance improvement at approximately 150°C develops. Finally, a convergence between the yield and the fatigue endurance stress versus the temperature was revealed.