Ti_3Si_((1-x))Al_xC_2在900℃～1300℃空气中的氧化行为

High-Temperature Oxidation Behavior of Ti_3Si_((1-x))Al_xC_2 at 900℃～1 300℃ in Air

热压摩尔比为n(TiC):n(Ti):n(Si):n(Al)=2:1:1:0.2混合粉末制备的Ti3Si(1-x)AlxC2(0<x≤0.16)材料在900℃-1300℃空气中的恒温氧化行为遵循抛物线规律,但在1200℃和1300℃是一个两步抛物线过程。随着温度升高,氧化抛物线速率常数kp从900℃的2.45×10-10kg2·m-4·s-1增大到1300℃的5.71×10-9kg2·m-4·s-1,计算的氧化活化能为110kJ·mol-1±10kJ·mol-1。弥散分布在基体中的Al改变了Ti3SiC2材料的氧化机制,使试样表面形成由大量α-Al2O3和少量TiO2与SiO2组成的致密氧化层,从而提高了材料的抗氧化性。

The isothermal oxidation behavior at 900℃-1 300℃ for 20 h in air of bulk Ti3Si(1-x)AlxC2 sintered by hot pressing were investigated. The isothermal oxidation behavior of Ti3SiC2 generally obeys a parabolic law from 900℃-1100℃, whereas at 1200℃ and 1300℃, it follows a two-step parabolic rate law. As temperature increased, the parabolic rate constant gradually increased from 2.45×10-10 kg2m-4s-1 at 900℃ to 5.71×10-9 kg2m-4s-1 at 1 300℃. The calculated activation energy of isothermal oxidation is 110±10 kJ·mol-1. The oxide layers of oxidized samples consisted of a mass of α-Al2O3, and little TiO2 and SiO2 as a dense and adhesive protect scale. The oxidation mechanism varies due to the dispersed aluminum inside the matrix, which greatly improves the oxidation resistance of Ti3SiC2.