Research On Microstructure And Properties Of Carbide-reinforced Cu-Sn-Ti Brazed Diamond Joints

Single-layer brazed diamond tools are widely used in manufacturing hard and brittle materials because of the high hardness,high wear resistance and sufficient chip holding space.In industrial applications,Cu-Sn-Ti filler metals are commonly used to prepare diamond tools,but there are still some problems in production.The low exposure is not conducive to the cutting process.The low hardness,low strength and poor wear resistance of the filler metals,which causes the excessive abrasion of the fillers and reduction of the diamond bonding strength.To solve the above problems,considering to add carbide reinforcing phases to modify the Cu-Sn-Ti filler alloys,and conducting an experimental study on diamond joints brazed with the composite fillers.In this work,diamond particles were connected to steel by using Cu–Sn–Ti composite fillers reinforced with different contents of B₄C particles（10μm）,then brazed in a vacuum hot-pressing furnace to prepare diamond samples.It was observed through a stereo microscope that the diamond was well formed,and there was no obvious accumulation or collapse of the filler metals.The scanning electron microscope（SEM）and energy spectrometer（EDS）was used to characterize the microscopic morphology of diamond.The results showed that the strong fluidity of the brazing filler metals was weakened after adding 2 wt.%B₄C,and the exposure of diamond was higher.Moreover,Ti C and Cu_5.6Ti were formed on the diamond surface,which proved the metallurgical bonding of the interfacial layer.The microhardness of filler layers gradually increased with the addition of B₄C particles,and the wear resistance of brazed joints reached the best value when the addition is 2 wt.%.To explore the performance of diamond brazing with Cu-Sn-Ti composite filler metals with different contents of Zr C（10 wt.%,15 wt.%,20 wt.%and 25 wt.%）.The interfacial structure between diamond particles,fillers and matrixes were characterized by SEM,combined with EDS and XRD to characterize reaction of the interface.The results show that diamond exposure is the highest after added 15 wt.%Zr C,and there was no obvious burning loss.The formation of Cu_5.6Sn and Ti C confirmed the intermetallic reaction.With the addition of Zr C particles,the hardness of the brazing layers gradually increased,and the hardness of interface layers were affected by the presence of intermetallic compounds.At the same time,when the Zr C is 15 wt.%,the wear resistance of diamond particles also reached the peak.The results show that when the brazing temperature is 980℃and the holding time is 15min,the brazed joint with the best wear performance is obtained,and the climbing height of the brazing filler metals to the diamond were reduced,which caused the increase of exposure heightThe brazing diamond segments were prepared by Cu-Sn-Ti fillers with WC reinforcing phase particles.The microstructure of the joint was characterized by SEM.The results showed that climb of the diamond was suppressed,and the height of the diamond edge is relatively high when the WC contents were10,15 wt.%.And the results of EDS and XRD analysis showed that Ti C,Cu_5.6Sn,Cu₃Ti and other compounds are formed on the surface of the diamond.The metallurgical reaction promoted the high-strength connection between the diamond and the substrate.With the increase of WC addition,the microhardness of the filler layers increased from 170HV_0.05 to 280HV_0.05;and the hardness at the interface was higher than filler layers.The tensile test results showed that the maximum shear strength of the joint is 87MPa when 15 wt.%WC is added;while the brazed joint has the lowest grinding force,friction coefficient and diamond drop rate.Under the conditions of brazing temperature and holding time of980℃and 15min,the brazed joint with the best bonding strength and grinding performance were obtained.