Abstract

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 24h. 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 Al2O3 up 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−1 at 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.

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