Cold spray deposition of Ni-WC composite coating and its dry sliding wear behavior

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ConferenceConference on Metallurgical Coatings and Thin Films, 2016-04-25, San Diago, CA, USA
SubjectCold spray; Metal matrix composite; Friction; Mechanically mixed layer (MML); WC; Subsurface microstructure
AbstractTungsten carbide based composites are highly wear resistant materials that are often fabricated as coatings by thermal spray processes. However, the high temperature of thermal spray may result in decarburization and a deterioration of the wear resistance. An alternative is to use cold spray to deposit WC based composite coatings. The Iower temperature allows one to retain the composition of initial WC feedstock but the cold spray process is only recently being researched for development of composite coatings. In this study, Ni and Ni-WC coatings were fabricated by cold spray. The WC and Ni powders were fed to a de Laval nozzle from separate hoppers with independent feed rates. By adjusting feedrates, a blend of Ni-50vol.% WC was sprayed, which resulted in a composite coating of Ni-10.5vol.% WC.The influence of WC on Ni deposition was examined via microstructural characterization, including morphology of the coating's top surface and polished cross sections. Mechanical properties of coatings were improved by incorporation of WC into the Ni matrix. The wear behavior of coatings was studied with sliding wear tests using a 6.35 mm diameter WC-Co ball. Ali tests were conducted in dry air with a sliding speed of 3 mm/sec, a track Iength of 10 mm, and normal load of 5 N. WC-Ni coatings were more wear resistant than cold-sprayed Ni coatings. The correlations between wom surface morphologies, subsurface microstructure induced by wear and the wear behavior of the coatings was discussed. Microstructural analyses showed a mechanically mixed layer (MML) on the top of wom surfaces consisting of compacted oxides. It was revealed that the presence of hard particles in the Ni-WC coating facilitated fast development of the MML, as well as stabilized the MML, characterized by Iess plastic flow, fewer cracking and higher hardness.
Publication date
AffiliationAutomotive and Surface Transportation; National Research Council Canada
Peer reviewedYes
NPARC number23000756
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Record identifier7136df1f-b0b4-4988-8af1-cde5f3c48b48
Record created2016-09-12
Record modified2016-09-12
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