Abstract
In order to reveal the mechanism of high temperature oxidation resistance improvement of double-layer thermal barrier coatings (TBCs) by La, two kinds of TBCs were prepared by atmospheric plasma spraying, whose ceramic coating were single-layer ZrO2Y2O3 (YSZ) and double-layer La2Zr2O7(LZ)/YSZ, respectively. Subsequently, the two TBCs were oxidized at 1100 °C. The experimental results show that the presence of LZ prevented the rapid oxidation of bonding coating and the rapid growth of thermal growth oxide (TGO), which led to the decrease in frequency of TGO bulges and the number of spinel oxides in TGO. La3+ can control the phase transformation of TGO, i.e. reduce the transition rate from metastable phase θ-Al2O3 to stable phase α-Al2O3, thereby reduce the residual stress. La3+ made the diffusion of cations in bonding coating to be obstructed, thus the formation of spinel phase was inhibited further, which was beneficial to the adhesion between TGO and coating. Therefore, double-layer LZ/YSZ TBCs exhibited superior high temperature oxidation resistance to single-layer YSZ due to the presence of LZ ceramic coating.
Published Version
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