Research On New Type Microcrystalline Diamond Abrasive

In this article, a kind of new microcrystalline diamond abrasive with a certainshape and size was prepared by means of bonding micron diamond abrasivepowder with low temperature vitrified bond. The effects of different compositionof vitrified bond with the basic system of R₂O–B₂O₃–SiO₂ and specific additives(such as Li₂CO₃, Na3AlF6, SnO, CeO₂, Cu, Co) on the performance of vitrifiedbond and diamond abrasive were studied in this experiment. The refractorinessand the fluidity were tested to estimate the properties of vitrified bond. Diamondsingle particle compressive strength tester and scanning electronic microscope(SEM) were applied to value the properties of the new type of microcrystallinediamond abrasive. In addition, the influence of the sintering temperature, theholding time, the amount of vitrified bond as well as the grain size of diamondpowder on mechanical properties and the microstructure of the microcrystallinediamond abrasive were researched. The experiment results were as follows.(1) The properties of vitrified bond were the key factors to the performance ofdiamond abrasive. The refractoriness of vitrified bond should be lower than 700℃to achieve the low temperature sintering. The fluidity of vitrified bond wasdirectly related to the microstructure of microcrystalline diamond abrasive.Besides, the single particle compressive strength was closely related to themicrostructure of microcrystalline diamond abrasive. The microcrystallinediamond abrasive, prepared by the vitrified bond with higher fluidity, possesseduniform and dense microstructure and higher single particle compressive strength.(2) Different additives had different effects on the performance of bothvitrified and microcrystalline diamond abrasive. The additives of Li₂CO₃, Na3AlF6,SnO, CeO₂, Cu, Co could change the properties of vitrified bond in different ways,so that they could improve the mechanical properties and the microstructure ofmicrocrystalline diamond abrasive in varying degrees.(3) The sintering system had great influence on the properties ofmicrocrystalline diamond abrasive. The higher sintering temperature and thelonger holding time were helpful to yield more satisfying microcrystallinediamond abrasive. The optimal sintering systems for these experiments were asfollows: 800℃for sintering temperature and 120min for the holding time. The amount of vitrified bond also affected the performance of microcrystallinediamond abrasive. Increasing the addition of vitrified bond could make theproperties of microcrystalline diamond abrasive improve. However, it had anegative effect on the properties of microcrystalline diamond abrasive, if theaddition of vitrified bond was too much. In general, the appropriate amount ofvitrified bond is 30wt.%. Furthermore, both the microstructure and the mechanicalproperty of microcrystalline diamond abrasive were better, when themicrocrystalline diamond abrasive produced by finer diamond powder.