A THERMOANALYTICAL STUDY OF OXIDATION OF TIC BY SIMULTANEOUS TGA-DTA-MS ANALYSIS

摘要

The oxidation of TIC powders was non-isothermally carried out by heating up to 900 degrees C at a rate of 5 degrees min(-1) and at an oxygen pressure of 2-60 kPa, using a simultaneous thermogravimetric analysis-differential thermal analysis-mass spectroscopy (TGA-DTA-MS) apparatus. It was found that oxidation was divided into four stages, I to IV. Stage I, covering the oxidation fraction, alpha, 0-20%, was probably due to formation of oxycarbide (TiCxO1-x, 0 < x < 0.5) with slight heat and CO2 evolution. Oxidation in stages II and III at 20-60% was affected by oxygen pressure; the higher pressure giving rise to very sharp exothermic and CO2 evolution peaks in stage II, which are correlated with the formation of anatase. Oxidation in stage III proceeded gradually with increasing rutile phase. The sample amount also exerted a similar effect on oxidation as the oxygen pressure. [References: 12]