A novel high-entropy material, (Yb0.2Y0.2Lu0.2Sc0.2Gd0.2)2Si2O7 ((5RE0.2)2Si2O7) was prepared by the sol-gel method and investigated as a promising environmental barrier coating (EBC) for SiC-based composites. The results of X-ray diffraction and transmission electron microscopy indicated that rare-earth elements were distributed homogeneously in the single monoclinic phase. Moreover, it was found that the new material (5RE0.2)2Si2O7 had good phase stability, well-matched coefficient of thermal expansion with SiC-based composite, and excellent resistance to water-vapor corrosion. The water-vapor corrosion test of (5RE0.2)2Si2O7 coated Cf/SiC composites further confirmed that (5RE0.2)2Si2O7 was suitable for application as EBC material and could provide effective protection to Cf/SiC composites from water-vapor damage.

High-entropy environmental barrier coating for the ceramic matrix composites

Rare earth silicate environmental barrier coatings: Present status and prospective

Machining of SiC ceramic matrix composites: A review

Three-dimensional (3-D) needled Cf/ZrC–SiC composites were successfully fabricated by polymer infiltration and pyrolysis combined with ZrC precursor impregnation. The microstructure and mechanical properties of the composites were studied using XRD, SEM and three-point bending test. The composite with PyC interphase between fiber and matrix had a bulk density of 2.20 g/cm3, an open porosity of 13%, and a bending force of 356 N, and exhibited a nonbrittle failure behavior due to propagation and deflection of cracks, and fracture and pullout of fibers. The mass lose and linear recession rate of the 3-D needled Cf/SiC–ZrC composite during oxy-propane torch test were 0.010 g/s and 0.001 mm/s, respectively. The formation of ZrSiO4 melt on the surface of the composite contributed mainly the excellent high-temperature property.

H. Immich

Papers

Advanced ceramic matrix composite materials for current and future propulsion technology applications