Abstract

MAGAGULA, N.B.S.; SACKS, N.  and  BOTEF, I.. Slurry abrasion of WC-4wt%Ni cold-sprayed coatings in synthetic minewater. J. S. Afr. Inst. Min. Metall. [online]. 2016, vol.116, n.4, pp.333-337. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2016/v116n4a5.

Low-pressure cold gas dynamic spraying was used to deposit WC-4wt%Ni and WC-4wt%Ni-1wt%Mo coatings onto mild steel. Dense coatings with very low porosities were produced. No decarburization occurred during deposition and no deleterious phases were formed. The coatings were subjected to standardized material characterization tests, as well as slurry abrasion testing to assess their wear behaviour. The wear tests were conducted in synthetic minewater-silica slurries, while distilled water-silica slurries were used as a control. The hardness of the coatings, 512HV₀₃ and 458HV₀₃ for WC-4wt%Ni and WC-4wt%Ni-1wt%Mo respectively, are comparable to those achieved using high-temperature coating processes. The abrasion wear rates for both coatings were less than 5 mg/min and 10 mg/min in the distilled water-silica and synthetic mine water-silica slurries respectively. The approximately 50% increase in wear rate in the synthetic minewater slurry is attributed to a synergistic corrosive wear mechanism. The predominant wear mechanisms were identified as binder smearing and delamination, with carbide grain fracture and pull-out.

Keywords : tungsten carbide; nickel; cold spray; coatings; abrasion; minewater.

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