Research And Preparation Of Low Sintering Temperature And High Strength Vitrified Bond

Vitrified bond diamond abrasive tools with excellent properties,such as high grinding efficiency,low grinding temperature,high grinding accuracy and long operating life,etc.which are widely used in the processing of super hard materials,such as PCD,hard alloy,cast iron and cermet.Properties of vitrified bond directly affect the structure and properties of diamond abrasive tools.Therefore,it has been a hot research topic to prepare low sintering temperature,high bending strength and low thermal expansion coefficient of vitrified bond.DSC,XRD,FTIR and SEM were used to analyze the effect of additives on the microstructure,bending strength,thermal expansion coefficient of vitrified bonds and wettability to diamond abrasives was utilized to analyze the effect of additives on the properties of vitrified bond.FSEM and optical microscope were used to analyze the microstructure of vitrified bonds and diamond abrasives composite sintered.The effect of relative content of Al₂O₃ on SiO₂-B₂O₃-Al₂O₃-CaO based vitrified bond structure and performance was discussed in the paper.The results showed that Al vitrified bonds were mainly glass phase,which was beneficial to the wetting and coating of vitrified bond for diamond particles,but the main crystalline phase volume of SiO₂ and Al₂SiO₅ reduced with increasing Al₂O₃.Besides,thermal expansion coefficients increased and the optimal bending strengths corresponding to sintering temperature shifted towards higher temperature with increasing Al₂O₃.The Al-1 vitrified bond with better comprehensive performance was chosen as a basic vitrified bond.The effect of relative content of Li₂O on the Al-1 vitrified bond structure and performance was discussed in the paper.The results showed that Li vitrified bonds formed the new main crystal phase of LixAlxSi3-xO6 in the sintering process,and the content of SiO₂ and Al₂SiO₅ and Li_xAl_xSi_3-xO₆ crystal increased with increasing Li₂O.At the same time,thermal expansion coefficients increased and the optimal bending strengths corresponding to sintering temperature shifted towards lower temperature with increasing Li₂O.Compared with Al set of data,the average bending strengths of Li vitrified bonds were greatly improved,the sintering temperatures were obviously reduced,and the thermal expansion coefficients had no obvious change,the comprehensive performance of vitrified bonds was greatly improved.The Li-4 vitrified bond with much better comprehensive performance was chosen as a basic vitrified bond.The effect of relative content of BaO on the Li-4vitrified bond structure and performance was discussed.The results showed that the crystallization products of Ba vitrified bonds were still SiO₂ and Al₂SiO₅ and LixAlxSi3-xO6 crystal in the sintering process with increasing BaO.Meanwhile,the optimal bending strength corresponding to sintering temperature shifted towards lower temperature with increasing BaO.Compared with the Li set of data,the maximum bending strength of the Ba vitrified bond was basically unchanged,the sintering temperature was further reduced,the thermal expansion coefficients were slightly reduced,comprehensive performance was further improved.