Production of cobalt anti-corrosion coating on AISI 430 steel-Optimization using Box–Behnken experimental designs

Abstract

Corrosion-resistant cobalt coating has been prepared by the pack-cementation method on AISI 430 ferritic stainless steel. In order to investigate the corrosion properties of the coating, the polarization technique is employed using a 3.5 wt. % NaCl solution. Experimental design with a response surface methodology and a Box-Behnken design is used to investigate the effective parameters of the coating process. In this method, three factors, namely cobalt concentration, activator concentration, and heat treatment temperature, have been examined at three levels, and the optimized conditions for the corrosion properties of the coating are obtained. The surface morphology of the cobalt coating is characterized by scanning electron microscope. In addition, the chemical composition and structure of the coating are analyzed by EDS and XRD. The results show that the statistical model is valid when it comes to describing the corrosion properties of the coating using various variables. Optimized conditions to achieve excellent corrosion-resistant coating have been obtained using the variables 10.63% cobalt, 2.90% activator, and 840°C temperature for the heat treatment.