EFFECT OF CU PARTICLES CONTENT ON THE SURFACE MORPHOLOGY AND MECHANICAL PROPERTIES OF NI-CU COMPOSITE COATING

Abstract

Nickel (Ni) coating is commonly used in many industrial applications. Still, the challenge has recently been encountered when Ni coatings experience aggressive stress and load, while their durability may not be sufficient to maintain performance in such conditions. Thus, Ni composite coating offers significant improvement in terms of mechanical properties and wear resistance. Therefore, in this study, metallic particles, such as copper (Cu) particles, can be added to Ni composite coating to refine the coating structure while increasing its durability. However, the conductivity of Cu particles in the electrolyte may influence the surface morphology while contributing to increasing the hardness of the composite coating. Thus, this study aims to determine how optimal Cu particle concentration influences coating surface morphology and hardness. The Cu particles in a range of 0.1–5 g/L were deposited in the Ni matrix, and the growth of composite coating was observed based on deposition times of 5, 10, 20 and 30 minutes. The coated surfaces were examined by surface morphological analysis, and mechanical properties were determined through microhardness testing. The result showed that the formation of a broccoli-like structure increased as the concentration of Cu particles in the Ni composite coating increased. The result also revealed that the higher hardness of Ni-Cu composite coating was achieved when 1 g/L of Cu was loaded into the electrolyte bath. Meanwhile, based on a growth study, Ni ions prefer to be deposited on the carbon steel substrate and at the Cu particles at the early stage of 10 mins. Subsequently, as time increased, Ni-coated Cu formed an accumulated, broccoli-like structure and was incorporated into the growing Ni deposits.