ELECTROLESS QUATERNARY NI-CU-CO-P ALLOY DEPOSITION MECHANISM IN ACIDIC BATH USING CYCLIC VOLTAMMETRY MEASUREMENT

Abstract

Quaternary nickel alloy of Ni-Co-Cu-P has been successfully deposit on Fe substrate for corrosion resistant material. However, the reaction mechanism of quaternary nickel alloy deposition is less known and requires investigation. In this study, using similar bath component is used to produce electroless Ni-Cu-Co-P alloy. Cyclic voltammetry (CV) study is done in various plating bath component at bath pH 4.50, 4.75 and 5.00. A coating of Ni-Cu-Co-P alloy was deposited on a Fe substrate to evaluate surface morphology and composition. From CV results, higher bath pH, increases the [H2PO2-] oxidation peak and shifted the oxidation potential towards less noble potential. The reduction potential of the Ni alloy moved to noble potential, hence, elevate deposition rate from 3.95 to 5.95 mm/hr. The Ni-Cu-Co-P alloy composition on Fe substrate in descending manner is Ni (68.55 – 82.09 wt%), Cu (14.11 – 27.80 wt%) and Co (1.32 - 1.52wt%). The P content remained lower than 3.00 wt%. Hence, Co act as reaction inhibitor, while Cu act as both reaction accelerator and stabilizer.