Evaluation of the high temperature characteristics of the CrZrN coatings

Cr1 − xZrxN coatings are reported to have not only much improved mechanical properties, but also a very low surface roughness with increasing Zr content. In this study the high temperature characteristics of the coatings with various Zr contents after annealing at 500 °C in air were evaluated in terms of surface roughness variation, high temperature wear and impact behaviors and were compared with those at room temperature. Results showed that hardness values of the coatings after annealing at 500 °C were dependent upon the Zr content while those at room temperature increased with an increasing Zr content in the coatings. The surface roughness of the coatings after annealing at 500 °C showed a reverse dependency to the room temperature due to the surface oxidation, showing an increased roughness with increasing Zr content in the coatings. Average friction coefficients of Cr1 − xZrxN (x = 0.34) coatings at RT 300 °C and 500 °C were measured to be approximately 0.17, 0.65 and 0.9 respectively, which indicated that the friction coefficient increased significantly with an increase in the test temperature. Cr1 − xZrxN (x = 0.34) coatings after the impact test at 500 °C showed a localized failure at the surface and this indicated that the addition of Zr to the CrN coatings deteriorated the impact resistance of the coating.