The synthesis of thermochemically stable single phase lanthanum titanium aluminium oxide
The synthesis of thermochemically stable single phase lanthanum titanium aluminium oxide
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DOI：
10.1016/j.ceramint.2015.10.117
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发表时间：
2016-02
影响因子：
5.2
通讯作者：
Peng Zhang;K. Choy
中科院分区：
文献类型：
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作者：
Peng Zhang;K. Choy
采用固相反应合成的镧钛铝氧化物（LaTi2Al9O19， LTA）是一种很有前途的热障材料。而固相反应合成LTA需要1500℃以上的高温处理24 h。本文采用溶胶-凝胶法在较低温度下（1350℃）合成了单相LTA，并对其工艺参数、相组成和相对热性能进行了研究。采用两步煅烧法制备了LTA细粉。根据x射线衍射，溶胶-凝胶合成LTA的最佳煅烧温度为1350℃。XRD结果也表明，溶胶-凝胶合成的LTA在1500℃以内不与al2o3发生反应，热化学稳定性良好。与固相反应合成的LTA相比，溶胶-凝胶合成的LTA具有更高的热膨胀系数（CTEs），在950℃时，CTEs的热膨胀系数约为10.2×10 - 6°C - 1°C，这与CTEs的尺寸依赖性有关。因此，溶胶-凝胶合成的LTA可以作为镍基高温合金的热障材料。
Lanthanum titanium aluminium oxide (LaTi2Al9O19, LTA) synthesized by solid state reaction has been proven to be a promising thermal barrier material. However, LTA synthesized via solid state reaction requires a high processing temperature of at least 1500 °C for 24 h. In this paper, single phase LTA was synthesized by sol–gel at a lower temperature (1350 °C) and the process parameters, phase composition, and relative thermal properties were investigated. Two-step calcination was used to obtain fine LTA powders. According to X-ray diffraction, the best calcination temperature of sol–gel synthesized LTA is 1350 °C. XRD results also showed the thermochemical stability of sol–gel synthesized LTA, which does not react with Al2O3up to 1500 °C, to be excellent. Compared to LTA synthesized by solid state reaction, sol–gel synthesized LTA has higher coefficients of thermal expansion (CTEs) which are circa 10.2×10−6°C−1at 950 °C, related to the size dependent characteristic of CTEs. Therefore, sol–gel synthesized LTA can be a promising candidate as a thermal barrier material on Ni-based superalloys.