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. © 2005 Elsevier B.V. All rights reserved.