Ceramic matrix composite

About: Ceramic matrix composite is a research topic. Over the lifetime, 7807 publications have been published within this topic receiving 117020 citations.

High-entropy environmental barrier coating for the ceramic matrix composites

Abstract: 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.

Pressureless Sintering of ZrB2–SiC Ceramics

Abstract: A pressureless sintering process was developed for the densification of zirconium diboride ceramics containing 10-30 vol% silicon carbide particles. Initially, boron carbide was evaluated as a sintering aid. However, the formation of a borosilicate glass led to significant coarsening, which inhibited densification. Based on thermodynamic calculations, a combination of carbon and boron carbide was added, which enabled densification (relative density > 98%) by solid-state sintering at temperatures as low as 1950°C. Varying the size of the starting silicon carbide particles allowed the final silicon carbide particle morphology to be controlled from equiaxed to whisker-like. The mechanical properties of sintered ceramics were comparable with hot-pressed materials with Vickers hardness of 22 GPa, elastic modulus of 460 GPa, and fracture toughness of ∼4 4 MPa· m 1/2 . Flexure strength was ∼ 460 MPa, which is at the low end of the range reported for similar materials, due to the relatively large size (∼ 13 μm long) of the silicon carbide inclusions.

Relationships between Hysteresis Measurements and the Constituent Properties of Ceramic Matrix Composites: II, Experimental Studies on Unidirectional Materials

Abstract: The use of hysteresis loop measurements for assessing the constituent properties of unidirectional CMCs is evaluated, using basic theory described in a companion paper. Results are obtained on SiC/CAS and SiC/SiC composites. These materials exhibit very different hysteresis characteristics, reflected in differences in sliding stress, T, and debond energy, Γ i . These interface properties are manifest in the respective tensile stress/strain curves.