Properties of SiO₂ -B₂O₃ -Li₂O-ZnO-Al₂O₃ glass-ceramic-coated diamond particles prepared by sol-gel method

During the process of sintering diamond/ceramic composites, the wettability between diamond and the ceramic matrix is poor, and there are many irregular pores in the composites, which leads a low bending strength of the composites and easy shedding of diamond. In order to solve these problems, SiO2-B2O3-Li2O-ZnO-Al2O3 glass-ceramic coated diamond was prepared by a sol-gel method, and the properties of the coated diamond abra -sive particles were studied. The SBLZA glass-ceramic-coated diamond exhibited high thermal stability and excellent oxidation resistance, making it a good protective material for diamond. The oxidation resistance of the SBLZA glass-ceramic-coated diamond was determined by thermogravimetric analysis (TGA). The uncoated diamond abrasive particles began to oxidize at 723 degrees C, while the coated abrasive particles were resistant to oxidation at temperatures up to 1000 degrees C. The glass-ceramic coating significantly improved the bonding between diamond and the ceramic matrix. The use of SBLZA glass-ceramic-coated diamond instead of uncoated diamond in the composites sintered at 750 degrees C resulted in a decrease in the volume expansion rate of the diamond/ceramic composites from 37.2 % to 28.5 %, and an increase in the bending strength from 38.4 MPa to 61.5 MPa.