The performance evaluation of WC/Co-Cr coating for developing hard, wear, and corrosion resistance surface using TIG arc source

In this experimental investigation, three different combinations of WC/Co-Cr powder have been selected to prepare a hard, wear, and corrosion resistant coating layer on low carbon steel utilizing an economical tungsten inert gas (TIG) arc source. This study evaluates the coating performance of surface prepared with a commercially available WC-10Co-4Cr powder along with two other powder combinations, i.e., WC-40Co-10Cr and WC-30Co20Cr. The microstructure of WC/Co-Cr coating shows the formation of equiaxed and columnar growth of reinforcement element and at higher current cellular growth of matrix material with base material's Fe. XRD results depict formation of W2C, Co3W3C, Fe3W3C, Co2W4C, Fe7W6, Cr23C6, Co3C phases during coating process. The coating prepared with WC-10Co-4Cr powder shows highest hardness (1480 HV0.1) with 70 A current. However, coatings' hardness is reduced in all combination of WC/Co-Cr powder at higher current of 90 A, 110 A. The WC/ Co-Cr coating shows excellent abrasive resistance in all powder combination with minimum scratches and negligible ploughing and delaminated layer. Results show WC/Co-Cr coating exhibits excellent resistance to corrosion in 3.5 wt% electrolyte. However, the surface modified with WC-30Co-20Cr powder combination shows better resistance to corrosion compared to the surface prepared with WC-40Co-10Co and WC-10Co-4Cr powder. Corrosion results display strong passive layer formation in surface treated with WC-30C-20Cr powder as compared to WC-10Co-4Cr, WC-40Co-10Cr powder combination. The coating surface prepared with WC-30Co20Cr powder shows 14 % enhancement in corrosion potential (Ecor) and almost 86 % reduction in current density (Icor) compared to the surface treated with WC-40Co-10Co and WC-10Co-4Cr powder.