Effect Of RO And R₂O On The Properties Of Vitrified Bond Of Diamond Wheel

Ceramic bonded diamond grinding wheels are widely used in various fields.In this paper,the effects of different alkali metals and alkaline earth metal oxides on the performance of ceramic binders are studied.Firstly,the effect of SiO₂/B₂O₃ ratio on the properties of the binder was explored.The sintering temperature and thermal expansion coefficient of the binder were controlled.Then the effect of different alkaline earth metal oxides and alkali metal oxides on the properties of the ceramic binder was investigated.The as-prepared samples were analyzed by X-ray diffraction,SEM,three-point bending,axial compression and other related properties such as phase analysis,microstructure inspection,bending strength,and compressive strength.The experimental results show that with the increase of relative content of B₂O₃,the sintering temperature and bending strength of the binder decrease,the bending strength of the binder is 136 MPa when the ratio of SiO₂ and B₂O₃ is 53:20?wt.%?,and the coefficient of thermal expansion is 6.74×10^-6/°C and the main phase is glassy phase.The properties of alkaline-earth metal oxide binders with equal mass percentages are not much different.The main phase is the glass phase.The ceramic binder with SrO added has more?-quartz solid solution precipitated after sintering.The ratio of the maximum elastic strain to the ultimate failure strain in the compression test is taken as the ratio of brittleness,Vickers hardness and fracture toughness as brittleness,compressive strength and impact strength as brittleness.These three evaluation methods get similar conclusions that the binder containing SrO has better brittleness.It has a good wetting state with diamond.The alkali metal oxides Li₂O,Na₂O and K₂O are mixed in two equal masses,and the sintering temperature of the binder after Na₂O and K₂O are mixed is higher.Li₂O and Na₂O mixed binders have good brittleness,and the binding agent and diamond have better wetting state;the ratio of Li₂O to Na₂O is adjusted when the ratio of the two is 2.5:7.5?wt.%?.The binding state of the binder and diamond is good,and the main phase after sintering is?-quartz solid solution.The bending strength of the sample after adding different concentrations of diamond was significantly improved.When the diamond concentration was 100%?25 vol.%?,the bending strength was 201 MPa,and the bending strength of the diamond sample with200%?50 vol.%?added was 192 MPa.The main crystal phase in the sintered sample is diamond phase,and the relative content of?-quartz solid solution increases obviously,and diamond induces the precipitation of?-quartz solid solution.