Mechanical properties of new vitrified bonds for cBN grinding wheel

In this study, three ZnO-B2O3-SiO2 frit compositions with low softening point were investigated in order to lower the firing temperature of cBN-based vitrified bonded wheel. It was tried to develop a new composition of vitrified bond with lower firing temperature and compatible mechanical properties compared with conventional bond by evaluating the mechanical properties of each frit composition. Suggested bonds have softening points of 500°C to 520°C and bending strengths of 60 to 90% compared to the conventional bond. The maintenance of bending strength of bond composition even with less network former is attributed to the growth of Gahnite, which has submicron size and relatively large thermal expansion coefficient. On the other side, Willemite (ZnO·SiO2) with large crystalline size and low thermal expansion resulted in the deterioration of bending strength. The Rockwell hardness used as common measure of bonding of grinding wheel showed no statistically significant difference among frit compositions in the results.