Study of the Effect of Heat Treatment and Layer Thickness on the Hardness of Chemically Heated Nickel Coating

Abstract

This study aims to analyze the effect of heat treatment on the phase transformation of a thin nickel layer on a steel plate substrate. The plating process is electroless plating using a chemical solution. This work requires a nickel solution as the main component of the coating. The substrate was electroless nickel plated at pH 7.5 and the temperature was 85℃ for 100 minutes with heat treatment at 320℃ and 340℃ for 30 minutes. In addition, the substrate is analyzed by metallography to obtain a visual representation of its thickness on the surface of the plate. The result shows that the layer on the steel surface has the same thickness. Based on the hardness test, the heated plate resulted in better performance compared to the unheated one. The surface hardness increased from 134 to 646 with a coating thickness of 17.49 mm, and the XRD characteristic showed a broadened Ni peak. After heat treatment at 320℃ and 340℃, the surface hardness increased to 851VHN and 1020VHN.