Friction and wear properties of wide-velocity range high-energy plasma sprayed CuSn–NiCr solid self-lubricating coatings under heavy load

As one of important copper-based solid self-lubricating coatings, the low wear resistance of Cu–Sn coatings greatly limits its application in some heavy-duty cases. In the present work, two types of CuSn–NiCr composite powders designed by electroless plating (E-CN) and mechanical mixing (M − CN) methods, respectively. The friction and wear properties of wide-velocity range high-energy plasma sprayed CuSn–NiCr coatings were studied. The results suggested that, the fracture toughness of E-CN and M − CN coatings increased by 1.38 times and 1.55 times compared with as-sprayed Cu–Sn coatings, and the wear rate decreased by 29 % and 50 % correspondingly. Due to the tribofilm formation and micro-pores storage effect, the M − CN coating with 10 wt% addition ratio of Ni–Cr phase exhibited the lowest friction coefficient and the smallest wear rate. With the increase of Ni–Cr phase, the wear mechanism was transformed from adhesive to abrasive, and accompanied by fatigue step-shaped spallation. Friction and wear model of the CuSn–NiCr coatings was divided into rapid, stable and declining stages.