Fretting wear mechanism of plasma-sprayed CuNiIn coating on Ti-6Al-4V substrate under plane/plane contact

Abstract

The fretting wear mechanism of plasma-sprayed CuNiIn coating on Ti-6Al-4V substrate under plane/plane contact conditions was investigated systematically using a bench level test. The obtained experimental results showed that the fretting wear mechanism of the CuNiIn coating can be divided into three stages: (I) In the initial stage, the asperities on the rough surface were flattened to form debris and fill the nearby pits. The contact surface gradually flattened, which was accompanied by slight abrasive wear. (II) With increasing number of fretting cycles, the fretting wear process of the CuNiIn coating entered the delamination wear stage. Under the action of alternating shear loads, the lamellar structure and pores in the CuNiIn coating rapidly cracked and propagated to the surface. In addition, some fatigue cracks propagated into the matrix along the direction of maximum shear stress. (III) Eventually, the CuNiIn coating entered a stable wear state under the lubrication of a third body, which was accompanied by local delamination. The lamellar structure greatly enhanced the fretting wear resistance of the CuNiIn coating. In the process of fretting wear, the lamellar structure of the CuNiIn coating effectively hindered fatigue crack growth, guided crack deflection along the lamellar interface, and induced crack bifurcation. In addition, the pores can blunt the crack tip. • A new self-balancing device was developed to improve geometrical adaptation of friction pairs with plane/plane contact. • The fretting wear resistance of CuNiIn coating was better than that of Ti-6Al-4V. • The wear rate of the CuNiIn coating was non-monotonic with increasing number of cycles. • The lamellar structure of CuNiIn coating was conducive to delamination wear. • The lamellar structure of CuNiIn coating could induce crack deflection, stop crack propagation, and guide crack bifurcation.