Enhanced Adherence, Brittleness, Corrosion, and Sliding Wear by Adding NiCrFeBSiC-Mo on WC-Co Coatings and Hardened Substrates

Within the metal-mechanic industry, WC-Co coatings are widely used to improve friction wear resistance, but normally, because of their high hardness when the contact load between the coating and the counterpart is high, these coatings behave brittle, and their resistance to wear is diminished. With this in mind, two coating systems, conventional WC-Co, and mixed WC-Co + NiCrFeBSiC, were fabricated by a High-Velocity Oxygen-Kerosene Fuel (HVOF) thermal spraying process. The effect of different substrate hardness induced by heat treatment on coating adherence, brittleness, and wear resistance was evaluated using the Rockwell C adhesion test based on the VDI 3198 standard method and the reciprocating sliding wear test. It was noted that as substrate hardness increases, adherence and brittleness of coatings are improved, and so do the wear resistance of both systems. Mix coatings were the ones that displayed lower brittleness and better adherence, positively influencing their wear resistance at higher loads (60N). Their corrosion resistance was also measured, indicating that mixed-coating displayed a more noble behavior (lower icorr and Ecorr) and improved corrosion resistance. Compared to the substrate, the corrosion rate of this system diminished by about two magnitude orders (from 1.45 to 0.9 mpy).