Study On Preparation And Application Of ZnO-B₂O₃-SiO₂ Vitrified Bond For Diamond Grinding Wheel

The ceramic bond diamond grinding wheel has outstanding strength,excellent hardness,good thermal stability and high grinding efficiency which has become a widely used high-speed grinding tool in the contemporary industrial and processing field gradually.However,the present insufficient performance of the binder is an important factor restricting the development of diamond grinding wheel abrasive tool.Therefore,this article focuses on the design and preparation of low refractoriness,high strength,low thermal expansion coefficient and well matching between ceramic bond diamond grits.Through determining the content proportion of abrasive and binder,sintering process and the amount of pore-forming agent added,ceramic bond diamond grinding wheel abrasive tool is prepared with high speed grinding performance.Above all,the four component glass and multielement glass are prepared by the addition of Al₂O₃and alkali metal oxide Li₂O,Na₂O in the ZnO-B₂O₃-SiO₂ ternary glass and their effect on the performance is also investigated.Furthermore,the diamond grinding wheel is prepared by adjusting the content proportion of abrasive and binder,sintering process and pore-forming agent and their respective influence on the performance of the grinding wheel is characterized.Finally,the low melting high strength ceramic bond diamond grinding wheel is prepared.The specific research results are as follows:?1?The ternary,four component and multielement glass are designed and prepared.The results show that,with the increase of the ZnO content in the system,the refractoriness,bending strength and Vickers hardness firstly increase and then decrease,but all of them perpetually decrease with the ratio of the boron and silica molar increasing.?2?In the four component glass system,the ceramic bond's refractoriness,strength and hardness are enhanced with the addition of Al₂O₃.After the crystallization process,the precipitated crystal phases include the main crystals of ZnAl₂O₄ and the time crystals of ZnB₂O₄.?3?With the increase of Li₂O content in the system,the refractoriness,strength and hardness of the multiple glass are gradually reduced,but the thermal expansion coefficient increase.By comparison,D40303?6%Li₂O,2%Na₂O?is selected as the optimal diamond grinding wheel ceramic bond formula.?4?The influence of the content proportion of abrasive and binder,sintering process and pore-forming agent content on the strength,porosity,microstructure and blade height are studied.The results show that,with the increase of the content proportion of abrasive and binder,the bending strength increases from 38 MPa to 46 MPa,while the porosity rate decreases from 28%to 22%.With the increase of sintering temperature,the strength of the grinding wheel increases at first and then decreases,while the porosity rate always decreases.?5?Under the sintering condition of 730°C,the strength of the grinding wheel reaches the maximum of 47.3 MPa and its porosity is 23.3%.With the increase of NH₄HCO₃,the grinding wheel abrasive porosity increases regularly.When the diamond grinding wheel abrasive porosity increases from 25.7%to 39.6%,the removal rate increases by 7.5 times?under 40 N plus loading?and the wheel's grinding efficiency is also improved.