Nano silylation modification of diamond powder surface and its oxidation resistance

Abstract

Using sol-gel technology and hydrolysis condensation reaction of tetraethyl orthosilicate (TEOS)，a nano silica amorphous gel film with a thickness of 2～10 nm and rich in active oxygen groups is coated on the surface of diamond powder. When the gel film is heated to a certain temperature, the silicon dioxide in it can change from amorphous phase to crystalline phase. The initial oxidation temperature of diamond powder in air increases from 500 ℃ of raw diamond to 550 ℃ after TEOS coating modification. After adding nano silicon powder to TEOS coating, the initial oxidation temperature of diamond powder sample in air can be further increased to 610 ℃. After 800 ℃ heat treatment, the residual amount of the sample is significantly higher than that of the raw diamond, which indicates that the high temperature oxidation resistance of diamond powder can be further improved by adding nano silicon powder to TEOS coating. The rich reactive oxygen groups in TEOS coating can produce chemical reaction with resin/ceramic bond, which is conducive to improving the holding force of bond on diamond, and can provide good functional modified raw materials for preparing high-performance resin/ceramic bond diamond tools.

Keywords

• diamond surface modification
• tetraethyl orthosilicate (teos)
• amorphous sio2 film
• sol-gel method
• differential thermal analysis