Influence of heat treatment temperature on bonding and oxidation resistance of diamond particles coated with TiO2 film

摘要

In this paper, TiO2 films were coated on the surface of diamond particles using a sol gel method. The effects of heat treatment temperature on the morphology, composition, chemical bonds, oxidation resistance and compressive strength of diamond particles coated with TiO2 films were characterized through scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, thermogravimetric differential scanning calorimetry and compressive strength test. The results showed that when the temperature reached 600 degrees C, the amorphous TiO2 on the diamond particles surface exhibited as a dense anatase film and the Ti-O-C bond formed between TiO2 and the diamond substrates. When temperature reached 800 degrees C, TiO2 films were still in anatase phase and part of the diamond carbon began to graphitize. The graphitizated carbon can also form the Ti-O-C bond with TiO2 film, although TiO2 film would tend to crack in this condition. Meanwhile, the temperature had a serious influence on the oxidation resistance of diamond particles coated with TiO2 films in air. When the heat treatment temperature reached 600 degrees C, the initial oxidation temperature of the coated diamond particles reached the maximum value of 754 degrees C. When the diamond particles were oxidized at 800 degrees C for 0.5 h in air, the weight loss rate reached the minimum value of 6.7 wt% and the compressive strength reached the maximum value of 15.7 N.