Effect Of Additives On Properties Of Diamond Wheel Vitrified Bond

Vitrified bond diamond grinding wheels are widely used in the machining industry due to their excellent performance.However,the main problems of vitrified bond at present are low strength and poor wetting with diamond.In this paper,the vitrified bond used in the preparation of diamond abrasive tools is deeply studied for this problem.The basic system of Li₂O-B₂O₃-Al₂O₃-SiO₂ as vitrified bond was studied.The effects of Na₃AlF₆,WO₃ and V₂O₅ and the molar ratio of Li₂O/（B₂O₃+Al₂O₃）on the properties of vitrified bond were studied.The high temperature fluidity and bending strength of the bond were tested by the planar flow method and the three-point bending method;the average linear expansion coefficient of the bond at 20⁵00℃was measured by PCY-III thermal expansion coefficient tester;the SJY-II image was used.The sintering apparatus tests the wetting angle between the vitrified bond and the diamond;In addition,the phase analysis and microstructure analysis of the bond are also performed.The experimental results show that with the increase of Na₃AlF₆ content,the wetting angle between the vitrified bond and diamond first decreases and then tends to be unchanged.When the content of Na₃AlF₆ is 1 mol.%,the test temperature is 800℃,the wetting angle at 45°,it was reduced by 48.8%compared to the absence of Na₃AlF₆.When the addition amount of Na₃AlF₆ is 0.75 mol.%,the bending strength of the diamond-containing sample fluctuates little with the sintering temperature,which is about100 MPa.WO₃ has different effects on the properties of the bond.As the amount of WO₃increases,the wetting angle between the vitrified bond and the diamond decreases first and then increases.When the WO₃ content is 0.3 mol.%,the test temperature is at 780℃,the wetting angle is the smallest,50°,which is 40%lower than without WO₃.When the amount of WO₃ added was 0.2 mol.%,the diamond-containing sample had the highest bending strength of 126 MPa.The introduction of V₂O₅ into the formulation of the vitrified bond can improve the wetting ability of the vitrified bond and diamond at high temperature.When the amount of V₂O₅ is 0.3 mol.%,the wetting angle is the minimum at 58°at the test temperature of780℃.When V₂O₅ was added,the reduction was 30%.When the V₂O₅ addition amount was 0.4 mol.%,the bending strength of the diamond-containing sample fluctuated with the sintering temperature to be small,about 110 MPa.Changing the molar ratio of Li₂O/（B₂O₃+Al₂O₃）can change the mechanical properties of the diamond abrasive sample and change the wetting between the bond and the diamond.At the test temperature of 750℃,When the molar ratio of Li₂O/（B₂O₃+Al₂O₃）is 0.9,the wetting angle is the smallest;at 59°.when the molar ratio of Li₂O/（B₂O₃+Al₂O₃）is 1,the bending strength of the diamond-containing sample reaches 135 MPa.