Electroplated Ni-B films and Ni-B metal matrix diamond nanocomposite coatings

Electrodeposition of Ni-B films and Ni-B nanocomposite coatings with diamond nanoparticles on steel substrates was performed in a modified Watts bath. The influence of electrodeposition parameters such as saccharine content, concentration of boron precursor and the content of diamond nanoparticles in the electroplating bath were investigated. The impact of the nanodiamond size on the microstructure of the Ni-B nanocomposite coatings was investigated for sizes ranging from 5 nm to 100 nm. The effects of co-deposited nanodiamond on the hardness and corrosion potential of the coatings was assessed and related to the microstructure. It is demonstrated that the particle size of the nanodiamond affects the texture of the coatings as well as their susceptibility to electrochemical attack in 3.5% NaCl solution. The boron content in the coating has also a strong effect on their microstructure and hardness.