Research On Preparation Method Of Nickel-tungsten Alloy Coating For Polishing Diamond

Diamond has excellent physical and chemical properties.Since the development of artificial diamond technology,it has been applied more and more widely in many fields,such as optics,electricity,acoustics,thermology and so on.However,the shape and surface quality of artificial diamond cannot directly meet the application requirements,and it needs to be processed through multiple processes.However,the excellent performance of diamond makes it difficult to process.Many processing methods have problems such as low efficiency and high cost.In order to solve the problem of diamond processing,dynamic friction polishing method is used to semi finish diamond,so as to realize the efficient and simple processing of diamond.Dynamic friction polishing uses the violent friction and catalysis between diamond and catalyst polishing disk to graphitize the diamond surface and realize the rapid removal of diamond.This method has fierce polishing conditions and high requirements for the wear resistance of polishing discs.But the existing polishing discs have poor wear resistance or high preparation cost.Therefore,it is urgent to improve the preparation method of polishing discs.Electroplating method can be used for preparing dynamic friction polishing discs with excellent wear resistance rapidly at low cost.In this paper,Ni-W alloy coating was prepared by pulse electroplating method,and the feasibility of dynamic friction polishing diamond was verified.The main research contents and conclusions are as follows:(1)Under different bath composition and current parameters of pulse electroplating,the variations of microhardness,internal stress and deposition rate of coatings with current parameters were analyzed by measuring the composition,phase structure and micro morphology of coatings.Based on this,appropriate current parameters were selected to prepare a low W content Ni-W alloy polishing discs with uniform composition and microhardness of472.76 HV,thickness of about 0.35 mm,W content of about 1.32 wt.%,and a high W content Ni-W alloy polishing disc with microhardness of 623.84 HV,thickness of about 80 μm,W content of about 27.80 wt.%.(2)To verify the feasibility of dynamic friction polishing diamond with electroplated discs,the dynamic friction polishing diamond experiments were carried out with two kinds of polishing discs,and the contrast experiments were carried out with cast iron discs.Among them,the surface roughness of polished diamond with low W content electroplating disc was about46 nm,and its removal rate was about 0.71 μm/min,and the grinding ratio was 94.25.The diamond surface roughness of polished diamond with high W content electroplating disc was about 60 nm and the removal rate was about 4.76 μm/min.Its wear resistance was better than others,but due to its thin thickness,the service life still reached the limit during the polishing process.The results showed that low W content Ni-W alloy polishing disc had good polishing effect and it was suitable for semi finishing diamond.