Experimental Investigation and Parameter Optimization of Al2O3-40% TiO2 Atmospheric Plasma Spray Coating on SS316 Steel Substrate

Abstract

SS316 steel is a commercial stainless steel used in various applications. Ceramic coating of the wear areas of SS316 steel enhances the MTBF. The ultimate quality of the coating depends mainly on the coating thickness, surface roughness, coating microhardness, abrasion rate and coating porosity. Study depicts an experimental investigation to optimize the Atmospheric Plasma Spray process input parameters of Al2O3-40% TiO2 ceramic coatings to get the best quality of coating on SS316 steel substrate. The experiments are conducted with a three-level L18 Orthogonal Array (OA) design of experiments (DoE). Critical input parameters considered are: nozzle distance, substrate speed, arc current, carrier gas flow and coating powder flow rate and output parameters considered are: coating thickness, surface roughness, coating microhardness, abrasion rate, and% of porosity. Mathematical models are generated for individual output parameters. The Analytic Hierarchy Process (AHP) is applied to generate weights for individual output parameters considering them as objective functions and a combined objective function is generated. An advanced optimization method, Teaching-Learning-Based Optimization algorithm (TLBO), is applied to the combined objective function to optimize the values of input parameters to get the best output parameters. The influence of spray input parameters on output parameters are studied in detail.