Tribological characterization of Nb ion implanted WC-5wt%Ni cold sprayed coatings in dry sliding contact

Abstract Niobium ions were implanted into WC-5wt%Ni cold sprayed coatings at an acceleration voltage of 60 keV. The ion dosages were varied as 2 × 1016, 5 × 1016, and 8 × 1016 ions cm−2, and the resulting influence on surface, friction, wear, and stress properties of the Nb-implanted layers, in comparison to the non-ion implanted coating, was investigated. Dry sliding wear behaviour was assessed using a ball-on-disk tribometer, with 100Cr6 stainless steel balls as the counterface, at a sliding velocity of 0.05 ms−1 and an applied load of 1 N. The Nb ion dosage of 8 × 1016 ions cm−2 produced the best coating surface properties, achieving a high hardness (14.58 GPa), low plasticity index (53.83), low wear rate (35.7 × 10−12 m2 N−1), low wear coefficient (0.52), high shear strength (891 MPa) and a high local maximum von Mises yield strength (1546 MPa). This coating also produced a low Rq roughness value (10.22 nm), great mean radius of asperities (35.88 × 10−2 nm), and a high reciprocal value of the comprehensive roughness fraction (4.77 × 10−3). The wear mechanisms of all the coatings were found to be similar, showing oxidation, scratching, ploughing, smearing, material transfer, and tribo-layer formation.