Effect of Inter-Splat Bonding Quality on the Dependence of Wear Behavior of Plasma-Sprayed Stainless Steel Coating on Applied Load

304 stainless steel (304SS) powder and novel Mo-cladded 304SS (304SS-Mo) powder were used as feedstocks to prepare metallic coatings with different inter-splat bonding qualities. Wear test was conducted to examine the dependence of wear behavior on the inter-splat bonding quality. The results showed that poor inter-splat bonding leads to much lower wear resistance in conventional 304SS coating relative to that of 304SS bulk, especially at high loading conditions (>75 N), where the wear rate increased to 5.53 × 10⁻³ mm³/(m⋅N) by 3.5 times higher than that at low-load range. However, the novel 304SS-Mo coating with metallurgical inter-splat bonding and minimized oxide inclusions exhibited a low wear rate comparable to that of 304SS bulk. Failure analysis of worn samples suggests that splat delamination contributes to low wear resistance of the 304SS coating; conversely, the absence of splat delamination results in higher wear resistance of the 304SS-Mo coating. Using Mo-cladded powders, significantly enhanced inter-splat bonding enables the use of plasma-sprayed metallic coating under high-load wear conditions. The strong dependence of wear resistance on the load in conventional coating implies that evaluation of wear performance of thermally sprayed metallic coating should consider both the wear rate and critical load.