Development, Characterization, and Cavitation Erosion Analysis of High Velocity Oxy-Fuel (HVOF) sprayed TiC and (70Cu-30Ni)-Cr Based Composite Coatings on SS316 Steel

Abstract

Powders of Titanium Carbide (TiC) along with Cupronickel (70Cu-30Ni) and Chromium (Cr) as binders, were deposited over SS316 steel specimens by using High Velocity Oxy Fuel (HVOF) process for obtaining novel composite coatings. Characterization of the developed coatings were analyzed by using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM). Surface hardness, surface roughness, and porosity values of the developed coatings were evaluated. High stream water jet rig was availed for cavitation erosion tests, in which submerged specimens were pounded by high velocity water stream of water under variable impingement conditions comprising of stream velocity, Stand-off Distance (SOD), and angle of attack. Cavitation Erosion was evaluated and compared with coated and uncoated specimens. From the acquired data, it was deduced that HVOF coated specimens were more effective in resisting cavitation erosion with contrasted to uncoated steel specimens, owing to better microhardness. Moreover, coatings with titanium carbide (TiC) + 50% of cupronickel-chromium (70Cu-30Ni)-Cr were found to be more repellent to induced pressure waves than any other proportion of coatings for cavitation erosion tests due to the intermediate hardness and better damping effect imparted due to higher porosity. Further, mixed manner of failure was analyzed in case of TiC+50%(70Cu-30Ni)-Cr coating.