关键词: SiC纤维, SiC纤维烧结陶瓷, 力学性能, 氧化性能

Abstract:

SiC fiber-bonded ceramics (FBCs), representing a novel class of SiC materials, synthesized via direct sintering of SiC fibers and characterized by lack of a matrix phase, porosity below 3% and fiber volume fraction exceeding 90%, exhibit remarkable properties, including high-temperature resistance, high strength, and robust resistance to oxidation and irradiation. Consequently, they are a promising contender for future aero-engine and advanced nuclear energy applications. Herein, SiC(Al) FBCs were prepared by pre-treating the fibers to form in-situ graphite (iG) layers on their surface, followed by direct sintering the fibers using a hot-press sintering process. Then, macroscopic/microscopic structures, mechanical properties and oxidative properties of the fibers and bulk ceramics were characterized. The results show that pre-treatment of SiC(Al) fibers leads to forming a 300-400 nm thick carbon layer, adhering well to the fibers. Density of the hot-press sintered iG/SiC(Al) FBCs is 3.15 g/cm³, with a porosity of only 0.52%. Meanwhile, the matrix is completely dense, the fibers are deformed in a new form of hexagonal prisms, and the well-defined interfaces are present between the fibers. Furthermore, bending strength, fracture toughness, and work of fracture of the bulk ceramics are 320 MPa, 9.5 MPa·m^1/2 and 1169 J·m^-2, respectively. After oxidation at 1500 and 1600 ℃ for 100 h in air, the retention rates of the flexural strength remain as high as 86% and 72%, respectively, while maintaining a quasi-plastic fracture mode.

Key words: SiC fiber, sintered SiC fiber-bonded ceramic, mechanical performance, oxidation performance