Lanthanum-titanium-aluminum oxide: A novel thermal barrier coating material for applications at 1300 °C

摘要

Considerable efforts are being invested to explore new thermal barrier coating (TBC) materials with higher temperature capability to meet the demand of advanced turbine engines. In this work, LaTi_2Al_9O_(19) (LTA) is proposed and investigated as a novel TBC material for application at 1300°C. LTA showed excellent phase stability up to 1600°C. The thermal conductivities for LTA coating are in a range of 1.0-1.3 Wm~(-1) K~(-1) (300-1500 °C) and the values of thermal expansion coefficients increase from 8.0 to 11.2 X 10~(-6)K~(-1) (200-1400 °C), which are comparable to those of yttria stabilized zirconia (YSZ). The microhardness of LTA and YSZ coatings were in the similar level of ~7 GPa, however, the fracture toughness value was relatively lower than that of YSZ. The lower fracture toughness was compensated by the double-ceramic LTA/YSZ layer design, and the LTA/YSZ TBC exhibited desirable thermal cycling life of nearly 700 h at 1300 °C.