Structure, mechanical and sliding wear properties of WC–Co/MoS 2–Ni coatings by detonation gun spray

Abstract

At present, more and more investigations are being carried out to improve properties of thermal spray coatings, in particular for the dry contact situation. We have deposited a series of WC–Co/MoS 2–Ni coatings by detonation gun (D-gun) spray, using a commercial WC–Co powder and a MoS 2–Ni powder, with a proper spray condition in view of both powders. The structure, mechanical and sliding wear properties of these coatings were characterized. The results by SEM, EMPA, XRD and XRF indicate that the MoS 2 composition was kept and distributed homogeneously in the WC–Co/MoS 2–Ni coatings and its content is a little higher than the feed powder. The results also indicate that hardness, fracture toughness and adhesion of the WC–Co/MoS 2–Ni coatings decrease with the increasing MoS 2 content in the coating, while porosity and roughness the same, comparing with a pure WC–Co coating deposited under the same condition. It is found that this WC–Co/MoS 2–Ni coating possesses self-lubricating property. Furthermore, the MoS 2 composition in the WC–Co/MoS 2–Ni coatings shows a contribution in lowering wear rate under dry sliding conditions when its content is lower than 4.9 wt.%. However, the wear rate is higher when the content is 7.2 wt.%, which indicate that the MoS 2 content should be proper for an improvement of the D-gun sprayed WC–Co/MoS 2–Ni coating on wear resistance.