An Investigation In Processes And Properties Of Detonation Gun Sprayed WC Coatings

Detonation gun(D-gun) spraying is one of the most promising thermal spray technologies for high quality wear resistant coatings.Due to the advantage in combination of hardness and toughness,tungsten carbide/cobalt cermets coatings deposited by D-gun,have been widely used in many areas to enhance the wear resistance of engineering components.However,during thermal spraying of WC-Co powders by D-gun which employed C₂H₂ and O₂ previously,decarburization gives rise to the formation of W₂C,even to metallic tungsten,which is undesirable for resistance to fracture toughness and wear resistance of the coatings.In this paper,the WC coatings were prepared by DNB3 D-gun spraying system. First of all,the coatings by D-gun spraying were compared with plasma spraying and HVOF;Then,experiment.improved process parameters of D-gun spraying by adding mixed C₃H₈ to reduce the decarburization of WC powders,and studied the relationship between the flow of gas and the phase composition,microstructures,hardness of coatings,as well as deposition rate of powder;Finally,tested the change of coating's wear resistance after adding mixed C₃H₈.The main conclusions are as follows:1.Compared with plasma spraying and HVOF,the coatings which prepared by D-gun spraying have lower porosity and higher hardness,but the WC powders have a serious decarburization during the spraying;2.Holding the flow of O₂,when the flow of C₂H₂ increases,the degree of decarburization decreases;after adding mixed C₃H₈,when the flow of C₃H₈ increases, the degree of decarburization will further decreases;3.After adding mixed C₃H₈,the degree of decarburization can be decrease,and the microstructure and hardness of coatings will not be affected,but the deposition rate of powder will decreases;4.The coating which prepared by spraying with adding mixed C₃H₈ has better wear-resistant property.