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研究了热压烧结的Ti3AlC2(含有2.8%(质量分数)的TiC)在900~1300℃空气中的恒温氧化行为.结果表明,该材料具有良好的抗高温氧化性能,其氧化行为遵循抛物线规律.随着温度升高,氧化抛物线速率常数kp从900℃的1.39×10?10增大到1300℃的5.56×10?9kg2·m?4·s?1,计算得到的氧化活化能为136.45kJ/mol.在900~1100℃时,氧化产物为α-Al2O3和TiO2;当温度达到1200℃时,TiO2开始部分地转变为Al2TiO5;氧化温度升高到1300℃,Ti在氧化层中完全以Al2TiO5的形式存在.氧化过程由Al3+和Ti4+的向外扩散和O2?的向内扩散控制.Al3+和Ti4+的快速向外扩散在基体与氧化层界面处导致大量的缺陷的形成.
The temperature-programmed oxidation behavior of hot-pressed Ti3AlC2 (containing 2.8% TiC) in the air at 900 ~ 1300 ℃ was studied.The results show that the material has good high-temperature oxidation resistance and its oxidation follows the parabolic law. As the temperature increases, the oxidation parabolic rate constant kp increases from 1.39 × 10 ?10 at 900 ℃ to 5.56 × 10 ?9kg2 · m ?4 · s ?1 at 1300 ℃, and the calculated oxidation activation energy is 136.45kJ / mol. At 900 ~ 1100 ℃, the oxidation products were α-Al2O3 and TiO2. When the temperature reached 1200 ℃, TiO2 began to partially transform into Al2TiO5. The oxidation temperature increased to 1300 ℃. The oxidation process is controlled by the outward diffusion of Al3 + and Ti4 + and the inward diffusion of O2 ~. The rapid outward diffusion of Al3 + and Ti4 + leads to the formation of a large number of defects at the interface between the substrate and the oxide layer.