Developing Empirical Relationship to Predict Hardness in WC- 10Co-4Cr HVOF Sprayed Coatings

Abstract

Surface treatments of engineering materials have recently become important for serviceable engineering components. Many techniques such as thermal and thermo-chemical surface treatments have been used to develop surface characteristics of materials. Presently, high velocity oxy-fuel (HVOF) spray is considered as the best method of producing a high-quality hard metal coating due to its moderate process temperatures and high gas velocities. Hardness is the most important property, which influences considerably service life characteristics of coatings. HVOF spray parameters, namely oxygen flow rate, LPG flow rate, powder feed rate, spray distance playsa major role in determining the hardness of coating. In this study, WC-10Co-4Cr coatings were deposited on naval brass substrates by high velocity oxy-fuel (HVOF) spray process. The aim of this work is to develop an empirical relationship to predict the hardness of WC-10Co-4Cr coatings incorporating HVOF spray parameters using statistical tools such as design of experiments, analysis of variance and regression analysis. Statistical calculations showed that the effects of the four variables on the hardness were different. Moreover, the results of this study may help to control the spray parameters of HVOF process to achieve higher coating hardness.