关键词: TiZrO2系, 金属陶瓷, 反应热力学, 氧化动力学, 显微结构

Abstract: The oxidation dynamics of hot pressed Ti ZrO 2 metal_ceramics with the composition of 50 vol.% Ti and 50 vol.% ZrO 2 has been studied. Thermodynamic analysis shows that Ti could react with O 2 but not with N 2 in the oxidizing process of Ti ZrO 2 composites at 0.1 MPa air. The oxidation dynamic behavior of Ti ZrO 2 composites is analogous to that of pure Ti. The activation energy for the oxygen diffusion in Ti ZrO 2 composites is higher than that in Ti solutions, for the presence of ZrO 2 restrains the oxygen diffusion in Ti ZrO 2 composites.At early stage the oxidation of Ti ZrO 2 composites follows a parabolic rate law between 700 and 1 000 ℃. The main reaction products in the oxide scale are rutile modification of TiO 2 with little amount of ZrTiO 4 determined by XRD and TEM. SEM observations show that there are two kinds of cracks in the oxide scale. One exists at the ZrO 2/Ti interfaces arising from the thermal expansion mismatch between ZrO 2 and Ti or TiO 2. The other kind of cracks resulting from the thermal expansion mismatch between the oxide scale and the substrate is often parallel to the sample surface. The presence of ZrO 2 in Ti ZrO 2 composites can restrain the extension of the second kind of cracks.