Technique Study Of Electroless Nickel-plating On WC-Ni Cemented Carbide Powders

Due to its high hardness,high strength,good wear resistance and corrosion resistance,cemented carbide is the first choice for wear resistance and corrosion resistance protective coating material,and it is widely used in high technology fields such as aerospace,military,nuclear power and so on.And in recent years,with the rapid development of the domestic technology and productivity,the market demand of cemented carbide continues to increase.The best preparation method of WC-Ni cemented carbide coatings is high-velocity oxygen-fuel spray(HVOF),it has the merits of high speed and high efficiency.However,WC decarburization due to oxidation is inevitable in the current spraying process,causing brittle phases and pores in the coatings.In this work,we coat a Ni layer on the surface of WC-Ni cemented carbide powders through electroless plating,and study the parameters which influence the effect of electroless nickel-plating.By the means of stepwise discussion of the sub module,the key factors that affect the coating thickness and integrity were found.Furthermore,the inhibition effect of nickel layer on WC decarburization in HVOF was studied as well.The experimental results show that the ratio of nickel salt to WC-Ni is the most important factors that affects structure of the nickel coating layer deposited on WC-Ni cemented carbide powders.In addition,the stirring efficiency is also an important factor affecting the efficiency of electroless nickel plating.The nickel layer on the surface of WC-Ni powders has a good inhibition effect on WC decarburization during spraying,which will be of great significance in improvementof coating quality by HVOF of cemented carbide powders.