Electrodeposited Ni–B coatings: Formation and evaluation of hardness and wear resistance

The formation of electrodeposited Ni–B alloy coatings using a dimethylamine borane (DMAB) modified Watt's nickel bath and evaluation of their structural characteristics, hardness and wear resistance are discussed. The boron content in the electrodeposited Ni–B alloy coating is determined by the ratio of rate of reduction of nickel and rate of decomposition of DMAB. The boron content of the electrodeposited Ni–B coating decreases as the current density increased from 0.4 to 4 A dm−2. XRD diffraction pattern of electrodeposited Ni–B coatings in their as-plated condition exhibits the presence of Ni (1 1 1), (2 0 0) and (2 2 0) reflections with (1 1 1) texture. Heat treatment at 400 °C for 1 h has resulted in the formation of nickel boride phases, which results in an increase in hardness and wear resistance. The mechanism of wear in electrodeposited Ni–B coatings is intensive plastic deformation of the coating due to the ploughing action of the hard counter disk.