Development of empirical relationships to predict porosity and hardness of WC-10Co coatings on 35CrMo steel using DOE approach

Abstract

This paper studies at developing an empirical relation to forecast the porosity and micro-hardness, by means of High Velocity Oxy Fuel (HVOF) method, of WC-10Co coatings. For determining the coating performance, process parameters such as LPG fuel flow rate, oxygen flow rate, spray distance, flow rate of carrier gas and feed rate of the coating powder play a significant role. Five-elements, Five-level Central Composite Rotatable Design (CCD) was employed in this analysis to reduce the number of experiments by covering all possible combinations of the process variables. A Mathematical model was established to assess the porosity and microhardness of the coatings including HVOF process parameters and the appropriateness of the model was examined using Variance of Analysis. The optimization of HVOF parameters using RSM, as well as the correlation of spray variables with properties of the coating, enables the recognition of the framework of the characteristics to attain the preferred consistency of WC-10Co coatings.