Preparation And Machining Performance Of Aggregated Diamond Abrasive

Diamond,with high hardness and wear resistance,is widely used in the machining fied.However,as the diamond abrasives abrade,they will lose machining capacity totally or partially.This paper attempted to design and prepare a newtype aggregated diamond.It has not only the inherent properties as diamond,but also other excellent processing performances,which are high material removal rate and good self-sharpening.In this paper,the aggregated diamonds were bonded into a polycrystalline stucture by ceramic binder under atmospheric pressure.The influences of different technical parameters in preparation process were compared.The lapping experiments of FAP(Fixed Abrasive Pad)embedded with aggregated diamonds were carried out,which aim at exploring the effect of polycrystalline structure on its lapping performance.The main tasks were as follows:(1)The effcts of the original diamond particle size,the proportion of binder,as well as the sintering temperature on the yield and the microscopic morphology of the aggregated diamond abrasives were explored.Results showed that the small particle size original diamonds could be made into aggregated diamonds with more micro edges on the surface and less pores inside.The yield increased firstly and then decreased as the proportion of binder increased,and the bonding between binder and diamonds were changed from punctiform to lamellar.The rise in sintering temperature increased the yield,and the hardness and structure compactness of aggregated diamonds were enhanced.(2)The lapping performance of the FAP embedded with aggregated diamonds were compared with that embedded with single diamonds while lapping quartz glass.The surface roughness of quartz glass lapped with aggregated diamond FAP was almost the same as that lapped with single diamond FAP.However,the aggregated diamond FAP behaved a higher and more stable material removal rate,as well as a smaller subsurface damage depth which was only about 1/2 of the original diamond particle size.(3)The effects of original diamond particle size and sintering temperature on the lapping performance on sapphire were compared by single factor experiments.The results pointed out that increasing the original diamond particle size was helpful in improving the material removal rate,which could reach the maximum value when the particle size is 10-14?m,but the surface roughness of sapphire increased after lapping.The excessively high sintering temperature did harm to the self-sharpening and degraded the surface quality after processing.Aggregated diamond sintered at 660? showed a better processing performance.(4)The efficient machining mechanism of aggregated diamond in FAP was proposed.Models of the number of effective abrasive particles in FAP,average cutting depth and material removal rate were established.The aggregated diamond could guarantee a higher and more stable material removal rate,for it could enhance the average cutting depth and reduce the lapping pressure consumed by resin bulges.