Structure and mechanical properties of Ni-P electrodeposited coatings

The coatings with different phosphorus contents were obtained by varying the concentration of H3PO3 in the electroplating bath. With the increase of phosphorus content, the structure of the Ni-P electrodeposited coatings transformed from microcrystalline to a mixture of nanocrystalline and amorphous phases, then to amorphous phase. A high hardness value of 710 HV0.1 of as-deposited Ni-P coating was obtained at 8.3 at.% phosphorus content, and high wear resistance was accordingly achieved. The refined nanocrystalline grains with average size of about 7 nm were found to be responsible for the high hardness and improved wear resistance of the as-deposited Ni-P electrodeposited coating.