Influence of LiO Addition on the Performance of Vitrified Bond and Vitrified Diamond Composites

In order to develop high-performance diamond wheels, the vitrified bond with different contents of LiO addition and corresponding diamond composites were prepared. The experimental results show that the addition of a small content of LiO leads the formation of the mullite phase in vitrified bond. When the LiO content is 3wt%, the mullite content in the vitrified bond reaches the maximum. Whereas, the vitrified bond turns into a pure glass phase when the LiO content further increases to 5wt%. The softening temperature of vitrified bond, wetting angle between the vitrified bond and the diamond film decrease with the increasing of the LiO content. The softening point of the vitrified bond with 5wt% LiO is 537 °C and the contact angle is 32°, which are 44 °C and 44° lower than those of the sample without LiO. The CTE (coefficient of thermal expansion), the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the LiO content. When the LiO addition is 3wt%, the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB, respectively, which are 43.1% and 12.6% higher than those of the sample without LiO.