SiO_3~(2-)对TiAl合金微弧氧化陶瓷层的影响

The Effect of SiO_3~(2-) on Micro-Arc Oxidization Ceramic Layer of TiAl Alloy

摘要:

采用自行研制的脉冲微弧氧化设备,在TiAl合金表面制备了微弧氧化陶瓷层。测定了TiAl合金微弧氧化陶瓷层在高温循环氧化条件下的氧化动力学曲线。研究了在微弧氧化处理溶液中加入SiO32-对陶瓷层性能的影响。实验结果显示:经过微弧氧化处理后试样的高温氧化动力学曲线大致呈抛物线规律,其表面的陶瓷氧化膜具有保护性;在微弧氧化处理溶液中加入SiO32-后,微弧氧化处理的TiAl合金的使用温度可提高到1273K。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对陶瓷层的显微结构和物相组成进行分析,发现其物相组成为含量约占80%的Al2TiO5,11%的TiO2以及9%的SiO2。这表明SiO2能有效抑制Al2TiO5在高温下的分解,从而大幅提高TiAl合金的抗高温氧化性。

Abstract:

The micro-arc oxidization is an efficient and pollution-free technique of surface processing and can form in situ a ceramic layer on the surface of nonferrous metal. In this paper, the micro-arc oxidization ceramic layer was formed on the surface of TiAl alloy by using a self-designing pulse power supply equipment of micro-arc oxidization. The oxidation dynamics of the ceramic layer on the surface of TiAl alloy was studied in the cycle high temperature condition and the experimental results show that the oxidation dynamics curve of TiAl alloy micro-arc oxidization ceramic layer submitted a parabolic function, which indicates that the ceramic layer can protect the TiAl alloy. Moreover, the effect of SiO32- on the characteristics of the ceramic layer was also studied, the results show that the working temperature with a micro-arc oxidization ceramic layer can be increased to 1273 K after adding SiO32- in the solution of the micro-arc oxidization. Analyzing by SEM and XRD test, the TiAl alloy ceramic layer contained 80 percent Al2TiO5, 11 percent TiO2 and 9 percent SiO2, which indicates that the addition of SiO2 can effectively restrain the decomposition of Al2TiO5 at high temperature and thus significantly increase the anti-oxidation of the TiAl alloy.