Effect of Ni underlayer thickness on the hardness and specific wear rate of Cu in the laminated Ni/Cu coatings produced by electroplating

摘要

In this work, the effect of the Ni underlayer with different thicknesses on the mechanical properties of Cu surface was studied. A laminated structure of Ni/Cu layer was prepared using electroplating on carbon steel substrates. The nickel layer was firstly plated on the steel using a current voltage of 2.3 V and varied plating times using 30, 60, 90, 120 and 150 minutes. The copper layer was subsequently electroplated on the nickel surface using a fixed current voltage of 1.9 V and plating time of 30 minutes. The result showed that XRD pattern observed on the surface of Ni/Cu coating indicates the formation of Cu single phase instead of Ni/Cu alloy. Application of plating time variations on the Ni underlayer using 30, 60, 90, 120 and 150 minutes produced an average thickness of Ni underlayer with 19.9, 48.4, 50.1, 62.1 and 64.9 μm, respectively. The thickness of Cu as the outer layer for different thickness of Ni was kept constant at approximately 23.66 μm. The hardness measurement on the Cu underlayed by Ni deposited using different plating times indicated that the hardness of Cu was 91.63, 93.20, 97.93, 102.60 and 106.1 HV, respectively. Whereas, the specific wear rates of Cu were 6.59 × 10~(-6), 6.11 × 10~(-6), 5.99 × 10~(-6), 3.63 × 10~(-6) and 3.55 × 10~(-6) mm~3/kg.m, respectively. The present study showed that the mechanical properties of Cu layer surface with a fixed layer thickness were influenced by the application Ni underlayer with different thicknesses. An increase of Ni underlayer thickness has increased the hardness and specific wear rate of the Cu layer.