Local atomic structures and degradation behaviors of Ti1 − xZrxN coatings under laser thermal shock

Abstract

The degradation behaviors of Ti1−xZrxN coatings due to repeated thermal stress were investigated in terms of local atomic structural changes according to Zr substitution. The coating specimens deposited by TiZr compound targets with different Zr wt% ratios had the same growth orientations of TiN and ZrN, namely (111), (200), and (220). The lattice parameter and microhardness increased as the Zr ratio increased, which was attributed to the lattice distortion and increase in texture degree of the crystallites in the coating layer by Zr substitution to Ti sites. The coating with 10wt% of Zr showed spalling of the coating layer after repeated thermal shocks, and delamination was suppressed as ZrN formation increased. It was expected that the interatomic distance between (Ti, Zr)-N would decrease as Zr substitution to Ti sites increased, indicating an atomic diffusion path. The depth profiles revealed that the diffusion distance of the coating (Ti, Zr, N) and the substrate (Fe, Cr) elements decreased according to the Zr substitution.