Understanding the role of Pt addition on structure and thermal stability of CrWN glass molding coating in nitrogen molding atmosphere

A novel Pt doping was designed to improve the thermal stability of CrWN coating in a nitrogen atmosphere. The deposited CrWN coating possessed a multilayer structure and a coherent growth mode, resulting in considerable mechanical strength and large size grain. An uneven atomic migration also occurred during the coating deposition resulting in a coarse cluster surface. The W atom enrichment layer was rapidly oxidized during the nitrogen annealing and thus led to serious mechanical degradation. The doping of Pt atoms effectively blocks the coherent growth of the grains, which creates a significant mixing effect, leading to a smooth surface with uniform element distribution. Although local incoherent growth compromised the mechanical behavior of CrWN–Pt coating, but the prominent pinning effect of dispersed Pt oxides can reduce oxidative erosion rate and stabilize the oxide layer up to some extent during nitrogen annealing.