Oxidation behavior of Ti3AlC2 powders in flowing air

Abstract

The oxidation behavior of Ti₃AlC₂ powders has been investigated in air by means of simultaneous TGA-DSC, XRD, Raman spectra, SEM, EDS and BET specific surface measurement to understand the intrinsic oxidation behavior of this newly developed ternary compound. The starting and complete oxidation temperatures determined by simultaneous TGA-DSC were 400 and 1120 °C, respectively. These temperatures are higher than those for TiC, suggesting that Ti₃AlC₂ is more oxidation resistant than TiC. An anomalous oxidation temperature range of 550–650 °C in which the final mass gains due to the isothermal oxidation of Ti₃AlC₂ powders at 550, 600 and 650 °C for 2 h are significantly greater than that at a higher temperature of 700 °C, was observed. This anomalous oxidation behavior suggests that direct reaction dominated with high oxidation kinetics in this temperature range, which was confirmed by SEM morphology observation and BET specific surface area measurement. The oxidation of Ti₃AlC₂ powders at temperatures below 700 °C resulted in two modifications of TiO₂ (anatase and rutile). At temperatures above 800 °C the oxidation products consisted of rutile TiO₂ and α-Al₂O₃.