Investigation of improving the thermophysical properties and corrosion resistance of RE <sub>2</sub>SiO <sub>5</sub>/RE <sub>2</sub>Si <sub>2</sub>O <sub>7</sub> multiphase silicates by component design with RE doping
Zeyu Chen, Yiling Huang, Zhaoxuan Zhang, Wei Zheng, Xuemei Song, Yaran Niu, Yi Zeng
Abstract
In this research, a novel method for regulating components in RE<sub>2</sub>SiO<sub>5</sub>/RE<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> multiphase silicates was developed, combining the benefits of suitable thermal expansion coefficient (CTE) and outstanding corrosion resistance against calcium-magnesium-alumino-silicate (CMAS). This approach enhanced the overall thermophysical properties. Additionally, the results from the CMAS corrosion resistance test indicated that (Lu<sub>1/3</sub>Yb<sub>1/3</sub>Tm<sub>1/3</sub>)<sub>2</sub>SiO<sub>5</sub>/(Lu<sub>1/3</sub>Yb<sub>1/3</sub>Tm<sub>1/3</sub>)<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> and (Lu<sub>1/4</sub>Yb<sub>1/4</sub>Tm<sub>1/4</sub>Er<sub>1/4</sub>)<sub>2</sub>SiO<sub>5</sub>/(Lu<sub>1/4</sub>Yb<sub>1/4</sub>Tm<sub>1/4</sub>Er<sub>1/4</sub>)<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> exhibited exceptional resistance to CMAS penetration, even at temperatures up to 1500 ℃. To comprehend the corrosion mechanism of CMAS on these silicates, we introduced a reaction-diffusion model, which involved observing interface changes between the corrosion product layer and the silicate block. This was achieved using Electron Back Scatter Diffraction (EBSD). These findings lay a theoretical basis for selecting rare earth elements in RE<sub>2</sub>SiO<sub>5</sub>/RE<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> multiphase silicates based on the radius of different rare earth cations.