Fabrication And Grinding Performance Of Graphene-modified Porous Metal-bonded CBN Grinding Wheel

At present,cubic boron nitride(CBN)grinding wheel as the important tools has been widely used to machine the difficult-to-cut materials,such as titanium alloys.However,these requirements,such as the desired high strength,lubricating ability and high porosity can hardly be met simultaneously for the CBN grinding wheel during the high-efficiency deep grinding titanium alloys.In order to overcome this problem,the new-type porous metal-bonded CBN grinding wheels are designed and fabricated by using spherical granulated carbamides as pore-forming agents and employing the graphene nanoparticles as the reinforced and lubrication phases.Firstly,the influences of the pore structures on mechanical strength and microstructure of the abrasive composites are preformed.Then,the mechanical strength and lubricating property of the abrasive composites containing graphene particles as the reinforced and lubrication phases are discussed.Finially,the grinding performance and wear characteristics of the graphene-modified porous metal-bonded CBN grinding wheels are analyzed.The main work and achievements are as follows:(1)The influences of the size,porosity and dissolution time of carbamide particles on the flexural and compressive strengths of porous composites are revealed.Meanwhile,the mechanical property and microstructure of composite samples affected by the graphene particles concentrations are evaluated.Additionally,the characteristics of bonding interface between the active filler alloy and CBN grain are presented.Enough flexural strength of porous CBN wheels has been achieved.(2)The addition of graphene particles is proposed in order to improve the lubrication ability of composite samples.In order to evaluate the lubricating mechanism of graphene particles inside composite samples,the pin-on-dics experiments are conducted with different graphene particles concentrations.The components of graphene particles concentrations,pores size and porosity of porous CBN composites are optimized.Accordingly,the porous metal-bonded CBN grinding wheels with high porosity,high flexural strength and excellent lubrication ability are fabricated.(3)The graphene-modified porous CBN grinding wheels are used to grind titanium alloys.The grinding performance of porous CBN wheels is evauated in terms of the grinding force and force ratio,grinding temperature,grinding specific energy and surface roughness.In addition,the wear characteristics of porous CBN wheels is analyzed.The result shows that the sharpness of porous CBN wheels can keep stable in a longer term due to the dynamic changes of the chip storage provided by porous structures and self-sharpening of CBN abrasive grains.Based on the present investigation work,a tool and technology support could be provided for the high quality and high efficiency grinding of difficult-to-cut materials,such as titanium alloy,which would play an important role in theory and application aspects.