Synthesis, microstructures, and corrosion behaviors of multi-components rare-earth silicates

Multi-components and equimolar rare earth monosilicates, (Y 1/3 Dy 1/3 Er 1/3 ) 2 SiO 5 , (Y 1/3 Dy 1/3 Lu 1/3 ) 2 SiO 5 , (Y 1/4 Dy 1/4 Ho 1/4 Er 1/4 ) 2 SiO 5 and (Yb 1/4 Dy 1/4 Ho 1/4 Er 1/4 ) 2 SiO 5 , were prepared by solid-state reactions and the following hot-pressing. Dense microstructures with uniform elemental distributions were obtained for all samples. These investigated multi-components monosilicates exhibit low thermal conductivities and similar coefficients of thermal expansion with SiC. Moreover, they exhibit high corrosion resistances in 1400 °C water vapor , especially, four-components (Y 1/4 Dy 1/4 Ho 1/4 Er 1/4 ) 2 SiO 5 and (Yb 1/4 Dy 1/4 Ho 1/4 Er 1/4 ) 2 SiO 5 experienced almost invariable weights after small weight losses during the initial 0.5 h. All those results indicate that multi-components rare earth monosilicates are promising candidates of environmental barrier coatings for SiC/SiC composites.