Development Of A New Tool Material With Cemented Carbide Powder Coated By Diamond

With the advantages of high hardness,high elasticity modulus,high thermal conductivity,strong wear resistance,good chemical stability,low friction coefficient and low coefficient of thermal expansion,diamond coated tools can be used for machining non-metallic hard and brittle materials,composite materials,high silicon aluminum alloy and non-ferrous metals.In the current research,the preparation of diamond coating is limited to the surface of the bulk substrate.The interface bonding strength between the prepared coating and the matrix material is low,the coating is easy to peel off,and the tool life of the diamond coating tool is reduced after the peeling off of coating.Once the coating is peeled off,the quality of the recycled cutting tool after regrinding or recoating process is difficult to guarantee,which limits its application.In this paper,the cutting tool made of surface coating diamond on cemented carbide powder was successfully fabricated.A new method for electrophoretic deposition of diamond on the surface of cemented carbide powder was proposed.The sintering parameters and material component ratio of diamond coated on the surface of cemented carbide powder were optimized.A tool material of surface coating diamond on cemented carbide powder with good mechanical properties and cutting performance was developed.In this paper,the diamond coating was prepared on the surface of cemented carbide powder by electrophoretic deposition method.The cemented carbide WC powder was used as the matrix,the diamond powder was used as the coating material,MgCl2·6H2O was used as the ionic additive,absolute ethanol was used as the electrophoretic liquid medium,and the ratio of matrix and diamond was determined.The micro-morphology of powder and Energy Dispersive Spectrometer(EDS)results of the coated cemented carbide powder were analyzed,and the results showed that the diamond coating was successfully prepared on the surface of cemented carbide powder.The effect of the content of cemented carbide powder and the content of ionic additive on the coating deposition quality was studied,and the results showed that when the content of cemented carbide powder was low or MgCl2·6H2O was high,the prepared coating would be excessively thick and uneven,and the coating powder usually showed an irregular shape,when the content of cemented carbide powder was high or MgCl2·6H2O was low,the coating would be excessively thin and uncompacted.When the cemented carbide powder in the electrophoresis liquid was 84 wt%,the diamond powder was 13 wt%,and the MgCl2·6H2O was 3wt%,the prepared diamond coating has a good density and uniform coating.The sintering parameters and material component ratio of the surface coated diamond on cemented carbide powder tool material were optimized.The effects of sintering temperature,holding time,binder content,diamond content and diamond type on the mechanical properties of the tool material were studied.Ni was selected as the binder,and the binder addition method was selected as the wet ball milling method.The optimum sintering parameters and composition content ratio were obtained,and the sintering optimum temperature was 1500 ?,the optimum holding time was 19 min,the optimum binder content was 6 wt%,and the optimum diamond content was 5 wt%.The mechanical properties of the prepared tool materials were with a hardness of HV12.98GPa,a flexural strength of 654MPa.a relative density of96.58%.The fracture mode of the cemented carbide powder surface coating diamond tool material is intergranular fracture and transgranular fracture.The cutting performance for the tool material of cemented carbide powder surface-coated diamond was studied in wet cutting TA 1 titanium alloy.The tool wear mechanism of cemented carbide surface coating diamond tool was analyzed.The cutting parameters were optimized,and the results showed that the optimum cutting parameters were cutting speed v = 70 mm/min,depth of cut ap = 0.3 mm,and feed rate f = 0.05 mm/r.The tool life of the tool cutting TA1 titanium alloy is 30 min under the optimal cutting parameters.The tool failure mode is mainly the flank wear,and the main wear mechanism is adhesive wear.