Optimization of Process Parameters for Atmospheric Plasma‐Sprayed Alumina Coatings Using Orthogonal Experimental Design

The service life of grinding rolls in wheat flour mills is severely limited by surface wear. This study optimizes atmospheric plasma‐sprayed (APS) alumina coatings on HT250 cast iron using an L9(3 3 ) orthogonal array, investigating current (500–700 A), hydrogen flow rate (8–12 L/min), and spraying distance (80–120 mm). Spraying distance most significantly influences α‐Al 2 O 3 content. Multiresponse optimization with weights of 0.4 (wear rate), 0.35 (hardness), and 0.25 (bonding strength) identifies the optimal parameters: 600 A, 12 L/min H 2 , and 80 mm. The orthogonal test sample prepared under these parameters exhibits superior performance: a hardness of 1493.8 HV (6.4× substrate), wear rate of 3.3 × 10 −6 mm 3 /(N·m) (78.3% reduction), and bonding strength of 39 MPa. ANOVA confirms current's statistically significant effect ( p < 0.05) on overall performance. Subsequent validation experiments were conducted by fabricating new samples under the identical optimal parameters, with relative errors below 5% for all three indicators (hardness: 1502.4 HV, wear rate: 3.2 × 10 −6 mm 3 /(N·m), bonding strength: 40.2 MPa), verifying the reproducibility and reliability of the optimized process. This work provides a systematic framework for designing high‐performance APS ceramic coatings for industrial wear components.