Creep properties of melt infiltrated SiC/SiC composites with Sylramic™‐iBN and Hi‐Nicalon™‐S fibers

Boron nitride (BN) interfacial layer with controlled thickness and structure was prepared on the surface of near stoichiometric ratio SiC fiber preforms by a chemical vapor deposition process, and the SiC/SiC composites were obtained by polymer precursor infiltration and pyrolysis process. The microstructure of the BN interfacial layer and SiC/SiC composites was tested by scanning electron microscopy, and the mechanical behavior of SiC/SiC composites was characterized by a mechanical properties test. Results showed that BN interfacial layer was evenly distributed in the fiber preforms with excellent thickness consistency. As the thickness of the BN interfacial layer increased, the deflection path of the crack increased gradually, resulting in the flexural strength first increasing and then decreasing. The mechanical behavior mentioned above was mainly attributed to the dual effects of load transfer and crack propagation of the BN interfacial layer; that was, the crack propagation of ceramic matrix under external load lengthened the path of load transfer and formed a large number of fibers bridging and pulling out successively, which contributed to the energy dissipation mechanism.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of BN interfacial layer on the mechanical behavior of SiC fiber reinforced SiC ceramic matrix composites

Chen,

Qiu,

Zhao

et al. 2024

“…To some extent, the technical level and engineering capability of SiC fibers' development have become decisive factors in determining the development of SiC/SiC composites. [4][5][6] The SiC ceramic matrix is one of the critical components of SiC/SiC composites, which has important significance for modulus, hardness and environmental stability. The ceramic matrix is subjected to thermal shock, load shock, and gasparticle impact before the fiber and interface, which causes the matrix crack initiation and expansion of matrix cracks in the initial failure stages of ceramic matrix composites.…”

Section: Introductionmentioning

confidence: 99%

“…Under the action of external loading, the fracture strain of the SiC fibers is greater than that of the SiC matrix, which is the prerequisite for the ceramic matrix composites to have excellent strain capacity and damage tolerance. To some extent, the technical level and engineering capability of SiC fibers’ development have become decisive factors in determining the development of SiC/SiC composites 4–6 . The SiC ceramic matrix is one of the critical components of SiC/SiC composites, which has important significance for modulus, hardness and environmental stability.…”

Section: Introductionmentioning

confidence: 99%

Effect of PyC/BN interfacial phases on mechanical behavior of SiC/SiC composites

Qiu,

Zhang,

Luo

et al. 2024

PyC/BN multiphase interfacial phases were prepared on the surface of SiC fiber preform, then the near stoichiometric ratio SiC fiber reinforced SiC ceramic matrix composites were obtained by polymer impregnation and pyrolysis (PIP) process. The mechanical behavior of SiC/SiC composites was characterized by three‐point bending tests and fracture toughness tests. The stress release and load transfer effects of the interfaces under external loads were analyzed by scanning electron microscope (SEM). Results showed that with the increasing of PyC component thickness from .10 to.30 µm in the PyC/BN multiphase interfacial phases, the bending strength and fracture toughness both increased first and then decreased. The results occurred due to the competition between load transfer and stress release of the interfaces. The relatively optimized interfacial phase structure was that the thickness of the PyC interfacial phase and BN interfacial phase were .20 and.30 µm. The bending strength and fracture toughness of the optimized SiC/SiC composites reached 660.65 MPa and 29.01 MPa•m1/2. Respectively, many matrix cracks appeared in the horizontal and vertical directions, occupying almost the entire fracture section. The growth path of the matrix crack was significantly increased with many long fibers pulled out and broken, which was conducive to the strengthening and toughening of SiC/SiC composites.

“…Therefore, SiC/SiC composites are ideal thermal structure materials for application in aerospace aircraft thermal protection systems, engine hot-end components, and nuclear energy. [1][2][3][4][5][6][7][8][9] Near stoichiometric SiC fiber is the ceramic fiber with the highest temperature resistance and excellent mechanical properties. SiC/SiC composites prepared with near stoichiometric SiC fibers as reinforcement phase can withstand long-term service at 1350 • C and short-term service at 1500 • C, which can meet the environmental requirements of hot-end components of aero-engines with a thrustto-weight ratio of 10 and 12-15 levels.…”

Section: Introductionmentioning

confidence: 99%

Influence of precursor concentration on the densification efficiency and properties of SiC/SiC composites

Chen

Qiu

Zhang

et al. 2022

The SiC/SiC composites were manufactured by polymer precursor impregnation pyrolysis process with near stoichiometric SiC fiber 2D preform as the reinforcing phase, the mixed solution of polycarbosilane (PCS), and xylene as impregnant. The effects of PCS concentration on the densification process, microstructure, and mechanical behavior of SiC/SiC composites were investigated using mechanical property testing, scanning electron microscopy, and other characterization techniques. Results showed the porosity and flexural strength of SiC/SiC composites increased first and then decreased with the increase of PCS concentration. When the concentration of PCS was 55% and 60%, the flexural strength of SiC/SiC composites reached 565.77 and 573.02 MPa, respectively. The mechanical behavior of SiC/SiC composites presented typical pseudoplastic characteristics such as fiber pulling-out, fiber bridging, and interface layer peeling, which would meet the dual requirements of optimizing the matrix and interface structure.