Improved tribological performance and enhanced tensile adhesive strength of micro- to near-nanocrystalline WC-17 wt. %Co coatings sprayed using HVOF

Abstract

This study investigated the performances of micro- and near-nanocrystalline coatings of WC-17 wt.% Co applied to a steel substrate using the high-velocity oxy-fuel (HVOF) spraying method. The near-nanocrystalline coatings exhibited reduced decarburization, as shown by the XRD and Rietveld refinement analyses. SEM analysis revealed small grain size, low porosity, and uniform surface texture in the near-nanocrystalline coatings. These coatings exhibited superior properties, including a high hardness (∼1298 HV), high tensile adhesive strength (≈9890 PSI), low wear rate (∼0.0011 mm3/m), and minimal wear volume loss (∼0.022 mm3), surpassing microcrystalline coatings. Near-nanocrystalline coatings exhibited 52.17 % less wear volume loss, attributed to factors such as smaller particle size, denser coating structure, reduced porosity, limited decarburization, and the high hardness of near-nanocrystalline coatings. Triboscopic analysis further confirmed their exceptional wear resistance, low wear volume loss, and low coefficient of friction, suggesting that near-nanocrystalline coatings could be effective for protecting substrates in demanding critical conditions, align with the Boeing Standard BSS 7072 requirements, and hold promise as robust surface protection solutions.