Fiber-bundle-missing defects of four severity levels (no missing bundle, 1/3 bundle missing, 2/3 bundle missing, and an entire bundle missing) are precisely introduced into 2.5D braided SiC fiber preforms by deliberate defect engineering, and the corresponding SiC_f/SiC composites are fabricated via a combined chemical vapor infiltration (CVI) and polymer infiltration and pyrolysis (PIP) process. The effects of fiber bundle missing defects on the flexural properties and failure mechanisms of the composites are investigated using XRD, SEM, and CT characterization together with three-point bending tests. The results show that the as-fabricated SiC_f/SiC composites possess a well-bonded BN interphase and a dense matrix microstructure. The severity of fiber bundle missing exhibits a significant negative correlation with the flexural performance of the material. The defect-free specimens exhibit the highest and most stable flexural properties, with an average flexural strength of 349.2 MPa and a coefficient of variation of 1.98%. As the severity of bundle missing increases, the flexural strength decreases progressively, reaching a minimum of 246.6 MPa for the specimens with an entire bundle missing. Specifically, the failure mode evolves from a stochastic, fiber-dominated failure in the defect-free condition, through an uncertainty-driven failure induced by local fiber absence, to a deterministic, defect-dominated failure when an entire bundle is missing. Microstructural analysis reveals that fiber bundle missing not only directly reduces the load-bearing cross-section, but also degrades the load-carrying capacity of the material by inducing local stress concentration and altering the crack propagation path.

Composite rotor blade becomes one of the important components in the aerospace and energy industries, owing to its advantages of lightweight, high specific strength and modulus, and tunable mechanical properties. Determining the effects of material parameters and layup on structural load-bearing capacity is valuable for engineering application. With energy method, a theoretical model for strength evaluation, stiffness analysis, and layup optimization of this structure are proposed. Based on Rayleigh-Ritz method, theoretical models about the simulating specimen for composite rotor blade under different loading conditions are established, including the blade solely under centrifugal force and the blade under combined centrifugal force and uniform pressure. The theoretical model is verified by the finite element method (FEM). And a higher order of the trial function induces higher prediction accuracy of the model. Finally, the effects of different layups on the strength and stiffness of the rotor blade simulator with ply drops are evaluated with this model. The results show that the prediction error of the theoretical model in radial deformation is lower than 6%. And for transverse deformation prediction, the error is no higher than 15%. The theoretical analysis aligns well with simulation results in predicting stress distribution. Besides, it shows that the layup significantly influence the mechanical performance of the structure. The deformation in x-direction of the structure with [0]_n layup is the smallest, followed by the structure with [0/90]_ns layup and [±30]_ns layup. The deformation in x-direction of the structure with [±45]_ns layup is the largest. The increase in proportion of 0° plies improves the structural stiffness. As for stress along the principal material axes, the structures with [0]_n, [±30]_ns and [±45]_ns layups have similar magnitude, which are smaller than that of the structure with [0/90]_ns layup. The theorical model proposed in this paper provides a method for efficiently evaluating the mechanical properties of the composite rotor blade. Compared to traditional method, this model can shorten the design period and improve the efficiency, which is helpful for optimal design of composite power components.

The five-component high-entropy boride ceramic (Zr_0.2Ti_0.2Ta_0.2Nb_0.2Cr_0.2)B₂ is successfully prepared via hot-press sintering at 1800 ℃. A systematic investigation is conducted on its phase composition, microstructure, mechanical properties and high-temperature stability. The results show that the ceramic primarily consists of a single high-entropy phase, with minor localized enrichments of Zr and Ta. The Vickers hardness and three-point flexural strength reach 19.03 GPa and 279.76 MPa, respectively, with the fracture surface exhibiting typical brittle transgranular fracture characteristics. After heat treatment at 1500 ℃ for 50 h, the microstructure of the high-entropy ceramic remains stable, showing no grain growth or precipitation of new phases. Neither hardness nor strength undergos significant changes, demonstrating excellent high-temperature structural stability and retention of mechanical properties.

The United States General Electric Company (referred to as GE) has conducted research on SiC_f/SiC composite materials since the 1980s. The successful application and commercialization of GE’s SiC_f/SiC composites in engine systems were achieved after 30 years of continuous investment (nearly 1.5 billion USD) and the collaborative efforts of hundreds of scientists and engineers. This paper details the spiral development history of GE’s prepreg-melt infiltration (MI) SiC_f/SiC composites, focusing on their innovative applications in hot-section components for gas turbines and aero-engines. Through case studies of several critical hot-section components, GE’s research paradigm of “demand traction, technology verification, and engineering iteration”is elucidated. Furthermore, the 10-year progressive design iteration path of the 7FA engine turbine shroud is systematically analyzed, revealing the synergistic optimization logic between service failure feedback and forward design validation. In light of international advancements, this paper interprets GE’s establishment of a“material-process-test”technological barrier through vertical supply chain integration, digital twin-driven process optimization, and machine-learning-based inspection systems. GE’s experience demonstrates that technological breakthroughs require a balance between long-term fundamental research and agile engineering iteration. For domestic development, a closed-loop“design-manufacturing-assessment”research and development process should be established, guided by critical components, alongside multidisciplinary collaboration mechanisms. Additionally, China should strengthen foundational capabilities by leveraging universities and national research and development centers for mechanistic studies, implement multi-dimensional optimization under thermo-mechanical-chemical coupling constraints, accelerate industrial ecosystem construction, integrate fragmented resources, and build rapid“industry-academia-research”verification platforms. A digital transformation strategy encompassing full-chain data acquisition and AI integration is also essential. Finally, by synthesizing successful international practices and adapting them to China’s context, an autonomous development roadmap covering“basic research, pilot verification, standard formulation, and industrial synergy”is proposed, providing methodological guidance for advancing ceramic matrix composite technologies in high-thrust-to-weight-ratio aero-engine applications.

SiC_f/SiC composites were prepared by melt infiltration（MI）process, chemical vapor infiltration combined with precursor infiltration and pyrolysis（CVI+PIP）process and precursor infiltration and pyrolysis（PIP）process, respectively. The microstructures, compositions and properties of SiC_f/SiC composites prepared by different processes before and after water-oxygen corrosion at 1300 ℃ were characterized by scanning electron microscopy and its accompanying EDS and X-ray diffractometer. The results show that the distributions of oxygen elements of the fracture surface is obviously different in the composites prepared by different processes, and the phases after corrosion are closely related to the preparation processes. The strength retention rate and modulus retention rate of SiC_f/SiC composites prepared by MI process are 84% and 76% after water oxygen corrosion at 1300 ℃ for 50 hours. The strength retention rate of SiC_f/SiC composites prepared by CVI+PIP is 64%, and the modulus is increased by 6%. The SiC_f/SiC composites prepared by PIP process has a strength retention rate of 49% and a modulus increase of 17%. The composite materials prepared by MI process show oxidation mass gain, while the composite materials prepared by CVI+PIP and PIP process show oxidation mass loss, which are mainly related to its microstructures and compositions.

Carbide ceramic fibers are of significant importance for application in the high-tech areas of advanced aircraft engines, aerospace vehicles, and the nuclear industry due to their excellent properties, such as high tensile strength and elastic modulus, excellent high-temperature resistance, and oxidation resistance. This paper reviews the preparation and application of different carbide ceramic fibers, including SiC fibers and transition metal carbide (e.g., ZrC, HfC, and TaC) ceramic fibers. The preparation methods of carbide ceramic fibers are discussed in terms of different fiber diameters, represented by SiC fibers with variable weaving properties and functions due to their differences in diameter. Subsequently, the application of carbide ceramic fibers as high-temperature-resistant structural materials, catalyst carriers, sensors, and supercapacitors are summarized, and strategies for the future development of carbide ceramic fibers are proposed. This review aims to help researchers enhance their understanding of the preparation and utilization of carbide ceramic micro/nanofibers, advancing the development of high-performance carbide ceramic fibers.