Study on the nano-composite electroless coating of Ni–P/Au

The nano-composite coating of Ni–P/Au was obtained by adding gold nanoparticles to the Ni–P electroless plating solutions. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and microsclerometer were used to characterize the compositions, structures, morphologies and hardness of the coatings, respectively. The Ni–P electroless coating contains 11.0 wt.% P while the composite coating of Ni–P/Au contains 9.85 wt.% P and 2.38 wt.% Au. The composite coatings, which contain gold nanoparticles, exhibit better properties of hardness, corrosion resistance and uniformity than the particle-free coatings. The coatings deposited from an electroless bath have the increased hardness after heat treatment due to the transformation of amorphous phase Ni–P to crystalline phase Ni3P. The composite coating with gold nanoparticles has bigger hardness value than Ni–P coating.