Effects of Y2O3 addition on structure and properties of LZAS vitrified bond for CBN grinding tools application

The effects of Y2O3 addition on the structure and properties of Li2O–ZnO–Al2O3–SiO2 (LZAS) vitrified bonds were firstly investigated for CBN grinding tools application. Glasses and glass-ceramics were characterized using differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy and infrared spectroscopy. The thermal expansion coefficient (TEC), microhardness, bending strength and chemical durability of the obtained products were also evaluated. Results showed that Y2O3 acted as the network former in the track of SiO4 tetrahedrals. Introducing Y2O3 in the glasses increased the glass transition temperature and crystallization temperature. The crystallization of the main β-quartzss phase increased with increase of Y2O3 content. The morphology of the crystals was dependent on the Y2O3 content. The TEC (5.15×10−6/°C) of vitrified bond containing 1.0 mol% Y2O3 (Y1.0) was very close to the TEC (5.0×10−6/°C) of CBN grains. Moreover, Y1.0 vitrified bond exhibits a high microhardness (5.98 GPa), a high bending strength (202 MPa) and a good chemical durability (20 days, DR=2.8×10−9 g/cm2 min), suggesting that it would be a promising material for CBN grinding tool.