Evaluation of microstructure, property and performance of detonation sprayed WC-(W,Cr)2C-Ni coatings

WC-Co coatings have been extensively used in the applications requiring high abrasion and erosion resistance. However, they are not known to have significant corrosion resistance. In this regard, WC-(W,Cr)2C-Ni is a possible candidate material to replace WC-Co for applications requiring a combination of superior tribological and corrosion performance. In the present study, WC-(W,Cr)2C-Ni coatings are deposited on mild steel (MS) substrates using Detonation Spray Coating (DSC) technique and compared with the properties of WC-12Co coatings. The microstructure and phases present in the feedstock as well as coatings are analyzed. The major part of matrix phase is (W,Cr)2C phase in WC-(W,Cr)2C-Ni feedstock and coatings with traces of Ni-Cr phases. High speed nanoindentation testing was used to map the hardness of the feedstock and coatings. The average hardness value of (W,Cr)2C phase is found to be around 15 GPa with a range from 12 to 20 GPa. Three body abrasive wear and corrosion properties of the coatings were evaluated and correlated with the corresponding microstructure and mechanical properties. While the wear resistance of WC-(W,Cr)2C-Ni coating is marginally better than WC-12Co coatings with the presence of (W,Cr)2C hard phase as a matrix phase and the presence of Ni and Cr and its associated phases in WC-(W,Cr)2C-Ni coatings are responsible for exhibiting nobler corrosion potential and significantly reduced corrosion current densities therefore confers superior corrosion resistance compared to WC-12Co coatings.