Enhanced holding ability between resin and silanization modified diamonds through sintering Si-N bond formation at low temperature

Resin-bonded diamond tools often suffer from poor durability and short lifespan due to the agglomeration of abrasive diamonds and the poor holding ability between diamonds and resin, resulting in diamond detachment during the working process. Modifying the diamond surface is necessary to improve the dispersion of diamonds and the holding ability between diamond and resin. However, common metallic modification methods can cause fine-grained diamonds (FGDs) to agglomerate, and metal plating cannot form a chemical bond with resin at low temperatures for preparing resin-bonded diamond tools. A practical non-metallic method for modifying diamond surfaces was proposed to address these issues, utilizing a silane coupling agent to enhance the binding forces between diamonds and binding agents. A uniform amorphous SiO2 film, with a thickness of 30-40 nm, was developed on FGDs with the hydrolysis and condensation reactions of tetraethylorthosilicate in a water and alcohol mixed solution. The SiO2 layer formed with the C-O, C--O, and C-O-Si chemical bonds can increase electrostatic repulsion between diamonds, overcoming diamond agglomeration. FGDs modified with SiO2 were combined with phenolic resin and pressed at 170 degrees C, forming Si-N bonds between the resin and SiO2 film and improving the bonding force. Moreover, the Si-N bonds can be produced at low temperatures, reducing the risk of diamond detachment during their operation. Hence, the lifespan of modified diamond wheel increase by 22 % than that of pristine diamond wheel. This study provides valuable guidance for developing high-performance, long-lasting, resin-bonded diamond tools.