Plasma Spraying Al ₂ O ₃ and TiO ₂ ‐Doped Al ₂ O ₃ Ceramics Coatings for the Repair of Worn Electrostatic Chuck

This study presents a cost‐effective plasma spraying strategy for regenerating worn alumina electrostatic chuck (ESC) surfaces. Different coating compositions and heat treatment temperatures were investigated to optimize the repair conditions. x‐Ray diffraction (XRD) analysis reveals that α ‐Al 2 O 3 partially transforms into γ ‐Al 2 O 3 during rapid quenching after spraying, while subsequent heat treatment reverses this transformation. After thermal treatment, interfacial porosity is eliminated and coating adhesion is significantly improved, which is attributed to enhanced grain diffusion, densification, and stabilization of the thermodynamically stable α ‐Al 2 O 3 phase. Nanoindentation results show that plasma spraying followed by heat treatment increases the hardness up to 1074 Hv. Moreover, the wear rate is reduced to 3.6 × 10 −6 mm 3 /(N·m) for Al 2 O 3 + 3% TiO 2 coatings treated at 1400°C. Al 2 O 3 /TiO 2 plasma spraying combined with heat treatment is expected to be an effective and low‐cost approach to regenerate worn ESC coatings with comparable microstructural integrity, mechanical performance, and electrical properties.