Effects of Nano-Cr₂O₃ Doping on Properties and Microstructures of Vitrified Bond CBN Grinding Tools

Nano-Cr2O3 was added to vitrified bond CBN grinding tools to improve their properties. Effects of nano-Cr2O3 on properties and microstructures of vitrified bond CBN grinding tools were investigated. The samples were characterized by differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and related detecting techniques. Results show that the refractoriness of vitrified bond firstly decreases and then increases with the addition of nano-Cr2O3, but the fluidity has the opposite change. Compared with basic vitrified bond, the refractoriness and fluidity of vitrified bond (4 wt.% nano-Cr2O3) are reduced by 25℃ and increased by 5.4%, respectively. The bending strength of CBN grinding tools can be enhanced obviously with the addition of nano-Cr2O3, and it has the maximum bending strength (59.27MPa) when adding 4 wt.% nano-Cr2O3. SEM result shows that CBN grinding tool has the most dense structure and the least pore when adding 4 wt.% nano-Cr2O3.