Comparative Evaluation of HVOF-Sprayed WC-12Co Coatings: Load and Contact Effects on Cross-Sectional Scratch Resistance and Dry Sliding Wear

WC-12Co coatings deposited by liquid-fuel high-velocity oxy-fuel (HVOF) spraying at kerosene pump frequencies of 33, 35, and 37 Hz were evaluated by cross-sectional scratch testing at 5–25 N and dry sliding at a constant load of 10 N. F35 exhibited the highest mean Martens hardness (9.42 GPa), whereas F33 had the smallest mean projected scratch-damage area at 5–15 N. On ground surfaces, F35 showed the lowest specific wear rates in reciprocating and ball-on-disc tests: 3.61 × 10−6 and 5.69 × 10−5 mm3 N−1 m−1, respectively. For the as-sprayed surface under reciprocating sliding, the lowest value was obtained for F37. Wear results represent one test per coating in each configuration. SEM/EDS observations were consistent with local material removal, transfer from the steel counterbody, and the formation of oxygen-enriched regions. The different rankings obtained from hardness, scratch damage, and wear measurements show that the coating response depends on the deformation scale and contact conditions.