Influence of process variables on the qualities of detonation gun sprayed WC Co coatings
Hao Du, Weigang Hua, Jiangang Liu, Jun Gong, Chao Sun, Lishi Wen
Materials Science
Abstract
Detonation gun (D-gun) spraying is one of the most promising thermal spray technology for high quality wear resistant coatings. Of all the ceramic materials that can be D-gun-sprayed, WC is the most widely established and these coatings have already gained industrial acceptance for diverse applications. The use of D-gun-sprayed WC Co coating as protection against aggressive environment requires a precise knowledge of the inuence of spraying process parameters on the coating characteristics and p...Moreroperties (porosity, adherence, roughness, hardness, etc.). In this article, experimental results are presented in terms of the structure, including surface roughness, XRD patterns and porosity, as well as adhesion strength, hardness, and fracture toughness of D-gun-sprayed WC Co coatings as a function of spraying distance from nozzle exit to substrate and ratio of O2:C2H2. It is found that both the spraying parameters inuence structure and properties of D-gun-sprayed WC Co coatings. The decarburization of WC Co powders during the spraying is little even when the highest oxygen fuel ratio was employed. When the higher oxygen fuel ratio was employed, hardness and adhesion increase, while, porosity and fracture toughness decrease, which can be attributed to the higher temperature and velocity feed powders obtained from the detonation wave. On the other hand, denser microstructure, higher adhesion strength and higher hardness appear when the coating was deposited at spraying distance of 110 20 mm, while fracture toughness is a little lower, which may come from the best compromise of decreasing velocity and lagging of heat transfer process for the particles to obtain a good molten state.
keywords:Detonation gun spraying; Microstructure; Fracture toughness; Adhesion; Vickers Hardness; WC–Co coating
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