Sliding wear behaviour of zinc-cobalt alloy electrodeposits

The wear behaviour of zinc-cobalt electrodeposited coatings on copper substrates was investigated, using a pin-on-disc wear apparatus. The composition of the zinc-cobalt alloy coatings was the following: Zn-0.6 wt.% Co and Zn-4 wt.% Co respectively. The friction coefficient of Zn-4 wt.% Co coatings against stainless steel was found to be similar to that of Zn-0.6 wt.% Co coatings against the same steel. The normalized weight loss of Zn-4 wt.% Co coatings was found to be higher than that of Zn-0.6 wt.% Co coatings. The main wear mechanism for the Zn-0.6 wt.% Co coatings was found to be severe shearing of the coatings surface layers, due to the plowing action of the stainless steel pins. For the Zn-4 wt.% Co coatings the predominant wear mechanism was noted to be intensive surface delamination leading to spalling and brittle fracture of the coatings surface layers.