EFFECT OF Li2O ON STRUCTURE AND PROPERTIES OF GLASS-CERAMIC BONDS

SiO2-B2O3-Al2O3-CaO vitrified bonds are widely used in the diamond abrasive tools preparation. The effect of Li2O on structure and properties of the glass-ceramic bonds was investigated. The structure of the glass-ceramic bonds was analyzed by XRD and FTIR. The bending strength, the sintering properties of different glass-ceramic bonds and the thermal expansion coefficient were tested at meantime. The sintering and interfacial bonding state between L-4 glass-ceramic bonds and diamond grains were observed by SEM. The results showed that with the increasing of Li2O, the sintering temperature of the glass-ceramic bonds was impactful reducing. When the content of Li2O was 4 wt. %, the sintering temperature corresponding to the optimal bending strength was 630 degrees C, which had a certain reduction compared with other studies. The main crystal phase precipitated in the glass-ceramic bonds was LixAlxSi3-xO6. With the increase of Li2O, the number of crystals in the glass-ceramic bonds gradually increased. The highest bending strength could attain about 136 MPa. Meanwhile, the bending strength performed regular change as the rising of temperature accompanied by the linear shrinkage rate. The L-4 glass-ceramic bonds and diamond grains were found to have very good wetting property and the interfacial bonding strength was insured enhance. The average bending strength of the composite sinter of the glass-ceramic bonds and diamond was up to 87.8 MPa.