A potential ZrO2 doped scandium tantalite ceramics for thermal/environmental barrier coating material

Despite scandium tantalite (ScTaO4) has great potential application for thermal/environmental barrier coating system, it is necessary to reduce the thermal expansion coefficient difference between them to lower the thermal stress in practical applications. In this paper, (ZrO2)x-(ScTaO4)1-x (x = 0.1, 0.2) material was prepared by doping ZrO2 into scandium tantalite ceramics, and its thermal expansion coefficient and calcium-magnesium-aluminosilicate (CMAS) corrosion behavior were studied. After the CMAS corrosion experiments of (ZrO2)x-(ScTaO4)1-x material, the phase composition and microstructures of samples were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. The main results show that the alloying effect of ZrO2 doping can reduce the thermal expansion coefficient of ScTaO4 and then alleviate the thermal expansion coefficient difference in thermal/environmental barrier coating system. Besides, Zr4+ ions are separated from (ZrO2)x-(ScTaO4)1-x lattice by molten CMAS under high-temperature corrosion condition and (ZrO2)x-(ScTaO4)1-x material is decomposed into ScTaO4 and t-ZrO2 finally. In addition, only t-ZrO2 is defected in the corrosion products without other crystal type of ZrO2 in the XRD results of the corrosion products, which indicate that ScTaO4 can increase high-temperature phase stability of t-ZrO2 and prevent phase transformation from t-ZrO2 to m-ZrO2.

Automated summary

This study investigated the effect of ZrO2 doping on the thermal expansion coefficient of ScTaO4 material, showing that ZrO2 doping can reduce the thermal expansion coefficient of ScTaO4 and alleviate the thermal expansion coefficient difference in thermal/environmental barrier coating systems. Under high-temperature corrosion conditions, Zr4+ ions are separated from the alloy, leading to the decomposition of the material into ScTaO4 and t-ZrO2. Additionally, only t-ZrO2 is found in the corrosion products, indicating that ScTaO4 can enhance the high-temperature phase stability of t-ZrO2 and prevent phase transformation to m-ZrO2.