Slurry Erosion Behavior of HVOF-Sprayed WC-10Co-4Cr Coated SS 316 Steel with and Without PTFE Modification

Several hydro-machinery components such as impellers of the submersible pump and turbine blades generally suffer from slurry erosion during their operation. High-velocity oxy-fuel (HVOF)-sprayed coatings are promising materials to prevent such components from slurry erosion. Moreover, polytetrafluoroethylene (PTFE) is a well-accepted hydrophobic material, which has several attractive properties such as chemical inertness and considerable thermal stability. Therefore, PTFE coating has been explored as a topcoat for a HVOF-sprayed WC-10Co-4Cr coating, with an aim to enhance the performance of the latter and analyzed with different slurry erosion conditions. A slurry erosion test rig was used for experimentation, and the effect of four different erosion parameters, namely average particle size, slurry concentration, impact angle, and velocity of jet, was investigated. A comparative study between PTFE-modified HVOF-sprayed coating and the standalone HVOF-sprayed coating was also done with respect to slurry erosion behavior and hydrophobicity. The overall results indicate that the slurry erosion of the HVOF-sprayed coated SS 316 steel got enhanced after modification by PTFE topcoat. Furthermore, the topcoat of PTFE on HVOF-sprayed coating resulted in a remarkable improvement in hydrophobicity, showing a superhydrophobic behavior, which might have also provided a better slurry erosion resistance to the HVOF-sprayed steel.