Moderate-temperature annealing for enhanced mechanical and wear properties of Pt-doped CrN coatings: A comparative study at 400 °C and 800 °C

To improve the service life of molds utilized in precision glass molding (PGM) in harsh environments, this work puts forward a moderate-temperature annealing post-treatment strategy to address this challenge of insufficient mechanical and tribological properties of Pt-doped CrN coatings. Annealing at 400 °C effectively promotes moderate grain coarsening and retains Pt in solid solution within the CrN matrix, thereby significantly enhancing the overall coating performance. The optimized coating exhibits excellent mechanical properties (a hardness of 24.08 ± 1.02 GPa, a Young's modulus of 324.9 ± 6.15 GPa, a H/E ratio of 0.0744, a H³/E² ratio of 0.132) and outstanding wear resistance (a coefficient of friction of 0.43 and a wear rate of 4.59 × 10⁻⁷ mm³·N⁻¹·m⁻¹). In contrast, annealing at 800 °C induces outward diffusion of Pt along the grain boundaries and the formation of soft CrPt_x intermetallic precipitates, causing surface roughening, reduced hardness, and a dramatic deterioration in wear performance. This work elucidates the microstructure–property relationship governed by annealing temperature and provides important theoretical and practical guidance for designing high-performance protective coatings for harsh service environments.