Development and evaluation of sub-element testing of SiC/SiC ceramic matrix composites at elevated temperatures

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

“…Therefore, SiC/SiC composites have a wide range of application prospects in aviation, aerospace, and nuclear fusion. [1][2][3] SiC/SiC composites mainly comprise SiC fiber, SiC matrix, and interfacial phase. SiC fibers are the primary bearing part of SiC/SiC composites and play a decisive role in the performance of the ceramic matrix composites.…”

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.

“…Continuous silicon carbide fiber reinforced silicon carbide matrix composites (SiC/SiC) are promising for a wide range of applications in aerospace engines due to their excellent properties, such as low density, high-temperature resistance and high specific strength. [1][2][3] However, SiC/SiC composites are subjected to long-term stress cycling loads F I G U R E 1 Monotonic tensile stress-strain curves for SiC/SiC composites at room temperature in air.…”

Section: Introductionmentioning

confidence: 99%

Fatigue resistance and damage mechanisms of 2D woven SiC/SiC composites at high temperatures

Zeng

Xue

et al. 2023

Fatigue resistance and damage mechanisms of 2D woven SiC/SiC composites at high temperatures were investigated in this research. Fatigue behavior tests were performed at 1200°C and 1000 • C at 10 Hz and stress ratio of 0.1 for maximum stresses ranging from 80 to 120 MPa, and the fatigue run-out could be defined as 10 6 cycles. Evolution of the cumulative displacement and normalized modulus with cycles was analyzed for each fatigue condition. Fatigue run-out was achieved at 80 MPa and 1000 • C. It could be found that the cycle lifetimes of the composites decreased sharply with the increasing maximum stress and temperature conditions significantly affected the fatigue performance under matrix cracking stress. The cumulative displacement showed no noticeable increase before 1000 cycles and the modulus of the failed specimens decreased before fracture. The retained properties of composites that achieved fatigue run-out, as well as the microstructures, were characterized in order to understand the fatigue behavior and failure mechanisms. The composites exhibited similar fracture morphology with matrix crack extension and glass phase oxidation formation under different conditions. In general, the high-temperature fatigue damage and failure of composites could be affected by combination of stress damage and oxidative embrittlement.