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The damage mechanism and fracture behavior of lithium hydride (LiH) ceramic are key to its design and application at elevated temperature in nuclear engineering. LiH ceramic is tested in a loading rate range of 0.001–2 mm/min from room temperature (RT) to 600 °C using digital image correlation (DIC) method combined with high-speed photography. At low temperature (up to 300 °C), LiH ceramic undergoes brittle fracture. At high temperature (up to 600 °C), LiH ceramic undergoes creep fracture at low loading rate and ductile fracture at high loading rate. The main crack growth rate of LiH ceramic with ductile fracture is higher than that of LiH ceramic with creep fracture, and is lower than that of LiH ceramic with brittle fracture. With the change of temperature and loading rate, three damage mechanisms, fatigue damage corresponding to SCG of inherent flaws, creep damage represented by creep microcracks and ductile damage symbolled by dimples, occur simultaneously and show competitive characteristics, one of which dominates the failure. At low loading rate, there is a transition of the dominant damage mechanism from fatigue to creep damage with increasing temperature. At high temperature, the dominant damage mechanism changes from creep to ductile damage with the increase of loading rate. [ABSTRACT FROM AUTHOR]

Material extrusion‐based additive manufacturing becomes interesting to fabricate oxide ceramic matrix composites. Herein, 0–30 vol% alumina fibers are added to zirconia‐toughened alumina powder mixture and extruded into filaments. Shrinkage and mechanical properties of filaments and 3D‐printed samples are investigated. Thermomechanical analysis is conducted on filaments with and without fiber content indicating lower shrinkage in the direction of fiber alignment during the sintering process. The flexural strength of the extruded filaments and printed bars is measured through a 4‐point bending test. Filaments containing 15 vol% fiber exhibit the highest flexural strength of 110 MPa, with additional fiber content leading to a reduction in flexural strength. Using Weibull calculation, it is observed that printed bars without fibers result in significantly lower bending strength in comparison to the filaments because of the presence of printing failures. Bars with 10 vol% fibers, printed with 0° infill orientation achieve the same mechanical properties as the filaments, even though in microcomputed tomography gaps between printed lines and voids between raster lines can be observed. These results demonstrate that fiber reinforcement of ceramics offers a great potential to avoid the reduction of mechanical properties by printing defects. [ABSTRACT FROM AUTHOR]

Large residual stress induced by significant difference in the coefficient of thermal expansion compromises the mechanical performance of a brazed joint between the WC–Co cemented carbide (YG20) and 3Cr13 stainless steel in a cutting tool of shield machine. In this study, a melamine formaldehyde foam precursor was utilized to produce a 3D hollow carbon foam (HCF) used as interlayer through a high‐temperature carbonization process to aid in the brazing process of YG20 and 3Cr13. First, the morphology and microstructure of the HCF interlayer were revealed as a defect‐rich carbon shell with a hollow structure. Afterward, the effects of introducing the as‐prepared HCF interlayer on the joint microstructure and shear performance were investigated. Results indicate that the HCF interlayer contributed to phase homogenization and, moreover, the residual stress relieving through in situ forming a core (metallic matrix)–sheath (ceramic shell) structure. This method outperformed the direct brazing approach without using an interlayer, with a 41% increase in the joint shear strength due to the synergistic strengthening mechanism of the HCF through residual stress reliving and joint seam toughening. Based on the results, in spite of the residual stress, the fast load transfer and the compensation from the matrix core to the ceramic sheath are responsible for the improved mechanical performance of the joint. [ABSTRACT FROM AUTHOR]

In this work, stacked SiC fibers paper‐reinforced SiC ceramic matrix composites (SiCnf/SiC CMCs) were prepared by nanoimpregnation and transient eutectic (NITE) process using ultra‐long single‐crystal SiC nanofibers. The effect of the SiCnf surface modification via boron nitride (BN) interphase deposition as well as the sintering additive (Al2O3–Y2O3) content on the density, microstructure, and mechanical properties of SiCnf/SiC CMCs has been investigated systematically. The results revealed that the laminated SiCnf/SiC CMCs feature a significant saw‐tooth‐like curve on the load–displacement test, which indicates that the obtained laminated structure with the weak interlayer binding owning to the BN coating treatment possesses significant toughening to the SiC ceramics. Specifically, the SiCnf/SiC CMCs with the sintering additive content of 12 wt% revealed a fracture toughness of over 10 MPa m1/2 after 60 min of BN interface deposition, which is 104.31% higher than that of the composites prepared without BN coating. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, two types of porous Cf/Cm composites were obtained by introducing pyrolytic carbon (PyC) and pyrolytic carbon/furan resin carbon (PyC/FRC). Subsequently, Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were prepared by introducing SiC and (ZrxHf1−x)C matrices into the porous Cf/Cm composites via the reactive melt infiltration method, specifically termed as Cf/PyC-SiC-(ZrxHf1−x)C and Cf/PyC/FRC-SiC-(ZrxHf1−x)C composites. The microstructures of the porous Cf/Cm and Cf/Cm-SiC-(ZrxHf1−x)C composites with different carbon matrices were examined, and a comprehensive analysis was conducted on microstructural evolution and mechanical behaviors of the Cf/Cm-SiC-(ZrxHf1−x)C composites. The results indicate that both Cf/Cm-SiC-(ZrxHf1−x)C composites underwent similar microstructural evolution processes, differing only in terms of evolution kinetics and final microstructure. Differences in the pore structures of porous Cf/Cm composites, as well as in the reactivities of carbon matrices, were identified as primary influencing factors. Additionally, both Cf/Cm-SiC-(ZrxHf1−x)C composites exhibited "pseudo-ductile" fracture characteristics, with flexural strengths of 214.1 ± 8.8 MPa and 149.6 ± 12.2 MPa, respectively. In the Cf/PyC-SiC-(ZrxHf1−x)C composite, crack initiation during loading primarily originated from the ceramic matrix, while in the Cf/PyC/FRC-SiC-(ZrxHf1−x)C composite, failure initially arose from the residual FRC matrix. Excessive fiber corrosion and the presence of residual low-modulus FRC matrix resulted in lower mechanical performance. [ABSTRACT FROM AUTHOR]

Fully reversed tension–compression fatigue of a hybrid material comprising polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC) was investigated. The PMC portion had a polyimide matrix reinforced with 15 plies of carbon fibers woven in an eight-harness satin weave (8HSW). The CMC portion had three plies of a quartz-fiber 8HSW fabric in a zirconia-based ceramic matrix. The hybrid PMC/CMC was developed for use in aerospace thermal protection systems (TPS). Hence, the experimental setup aimed to simulate the TPS service environment—the CMC side was kept at 329 °C, whereas the PMC side was open to laboratory air. Compression stress–strain response was studied, and compressive properties were measured at room and elevated temperature. Tension–compression fatigue tests were conducted at elevated temperature at 1.0 Hz. The evolution of tensile and compressive strains with fatigue cycles, as well as changes in the stress–strain hysteresis behavior and stiffness were examined. The tension–compression fatigue of a PMC with the same constituents and fiber architecture as the PMC portion of the PMC/CMC was studied for comparison. Tension–compression fatigue was found to be more damaging than tension–tension fatigue for both materials. The PMC outperformed the PMC/CMC in tension–compression fatigue. Post-test examination showed widespread delamination and striking non-uniform deformation modes of the PMC/CMC. [ABSTRACT FROM AUTHOR]

In this paper, a new micromechanical hysteresis loop constitutive model of C/SiC composites with different interphases was developed considering the probabilistic‐statistical matrix fragmentation process. The lengths of matrix fragmentation were divided into three types, that is, long matrix fragments (LMFs), medium matrix fragments (MMFs), and short matrix fragments (SMFs). The distributions of the LMFs, MMFs, and SMFs with increasing tensile stress were determined using the probabilistic‐stochastic model by assuming the two‐parameter matrix strength distribution. The micro stress field of the LMFs, MMFs, and SMFs upon unloading and reloading was obtained and adopted to determine the corresponding stress‐strain relations. The interaction of matrix fragmentation lengths, especially for the LMFs with large debonding energy (LDE) and SMFs, was considered in the closed‐form constitutive model and hysteresis‐based inverse tangent modulus (ITMs) damage parameter. Synergistic effects of the fiber volumes, peak stresses, and interface debonding energy on the interface damage state, mechanical hysteresis loops, and related ITMs with small debonding energy and LDE were also analyzed. Comparisons of the mechanical hysteresis loops using the new hysteresis models considering matrix stochastic fragmentation and hysteresis models considering constant matrix fragmentation were also discussed. Experimental cyclic tensile hysteresis loops and unloading/reloading ITMs of C/(PyC)/SiC and C/(PyC+SiC)/SiC composites with different interphase thickness (i.e., t = 300, 600, 1000, and 2000 nm) were predicted using the developed constitutive model. Evolution of the unloading/reloading interface slip ratio was analyzed for different tensile peak stresses. [ABSTRACT FROM AUTHOR]

Materials with a thermal expansion coefficient compatible with silicon carbide based ceramic matrix composites and low thermal conductivity at higher temperatures are crucial for developing environmental barrier coatings (EBCs) for aero-engines. Lately, high entropy silicate engineering has been a promising approach to develop optimized EBC materials. The solid solution reaction method was adopted for the fabrication of high entropy multicomponent (Dy 1/5 Er 1/5 Tm 1/5 Yb 1/5 Y 1/5) 2 SiO 5 or (5RE 1/5) 2 SiO 5 monosilicate. Scanning electron microscopy and X-ray diffraction show the homogenous distribution and a single-phase solution of (5RE 1/5) 2 SiO 5 monosilicate. Differential scanning calorimetry testing was done at 1450 °C which shows no exo/endothermic reaction has occurred. The value of the coefficient of thermal expansion (6 ppm/°C) up to temperature 1500 °C and low thermal conductivity values for (5RE 1/5) 2 SiO 5 monosilicate were observed (1.1–1.4 W/m°C) in the temperature range between 25 and 1500 °C. The water vapor corrosion resistance of (5RE 1/5) 2 SiO 5 monosilicate further confirms that the material is suitable for EBC applications due to the synergistic effect of different rare earth radii and stable crystal structure with a negligible weight loss value of 0.0005 mg/cm2 after 150 h corrosion time under 90 % H 2 O and 10 % O 2 at 1300 °C. The results of this work suggest that (5RE 1/5) 2 SiO 5 monosilicate can be used as a promising candidate for environmental barrier coatings. [ABSTRACT FROM AUTHOR]

The study addresses the limited fracture toughness of Al 2 O 3 ceramics by developing graphene-TiO 2 reinforced alumina nanocomposites through pressing. Mechanical properties, including hardness, fracture toughness, and elasticity, were examined, alongside the structural characterization via XRD analysis and microstructure evaluation using SEM. Cytotoxicity and cell adhesion tests were conducted for in vitro biological evaluation. The inclusion of a graphene additive led to a nearly threefold increase in fracture toughness, reaching up to 8.161 MPa m1/2. Graphene doping induced a discernible shift to lower angles in the XRD pattern, revealing the presence of Al 2 O 3 , Al 2 TiO 5 , and TiO 2 phases. Samples immersed in artificial body fluid for 14 days exhibited minimal ion release, with Titanium ion below 0.001 mg/L and aluminum ion below 0.05 mg/L, indicating a lack of significant ion release. The cytotoxic activity of the samples against NIH/3T3 cells was assessed through Alamar Blue analysis, revealing no significant change in cell viability after 48 h of exposure. [ABSTRACT FROM AUTHOR]

The major purpose of this study is to analyze the resistance of honeycomb ceramic matrix composites to penetration and to explore the effect of the performance characteristics of the filler materials on this capability. We used alumina ceramics, polyurea, quartz sand powder, and boron carbide powder to manufacture composite materials, and conducted impact tests and numerical simulations on them. The simulation results of Abaqus were found to be very consistent with the test results. The results demonstrate that the polyurea coating and filler materials may effectively improve the anti-penetration penetration performance of the composites, and different filler materials have varying energy absorption effects. Extended research on composites was carried out utilizing experimentally validated numerical models with filler materials comprising silicon carbide, aluminum nitride, and silicon nitride. After a comparative analysis of the simulation results of different composites, compared to quartz sand composites, the energy absorption efficiency of boron carbide composites increased by 12.03 %, silicon carbide composites increased by 14.63 %, aluminum nitride composites increased by 15.16 %, and silicon nitride composites increased by 18.29 %. Among the relevant materials in this study, there exists an optimal value of the stress wave impedance difference between the matrix material and the filler material. Honeycomb ceramic matrix composites with an ideal combination of stress wave impedance differences can considerably increase the anti-penetration efficiency of the composites. [ABSTRACT FROM AUTHOR]

Zirconium carbide (ZrC) is considered to be a potential candidate for ultra high temperature applications due to its high melting point, good chemical inertness, and ablation resistance, but the monolithic form suffers from low fracture toughness and hence poor thermal shock resistance. Reinforcing it using continuous carbon fibers (Cf) to create an ultra high temperature ceramic matrix composite is an obvious solution, however densifying ZrC requires the use of very high temperatures combined with significant pressure, such as obtained by using hot pressing or spark plasma sintering, which risks damaging fibers. In the present work, radio frequency‐assisted chemical vapor infiltration (RF‐CVI) has been investigated with a view to forming Cf/ZrC composites. These initial experiments revealed the ability to deposit pure, nano‐grained, and near stoichiometric ZrC with deposition occurring preferentially from the center of the sample due to the nature of the inverse temperature profile developed. The deposited ZrC grains were in the range of 4–9 nm in size and had a lattice parameter of 0.4750 nm. The work also showed that the use of RF‐CVI enabled the minimization of early pore sealing, a common problem for conventional CVI. [ABSTRACT FROM AUTHOR]

In the aerospace industry, lightweight can reduce the weight of the engine and improve the thrust-weight ratio of the engine. Ceramic matrix composites have attracted widespread attention in the industry due to their much lower density compared to high-temperature alloys and excellent high-temperature performance. SiC fiber-reinforced SiC ceramic matrix composites are the most outstanding representatives, but their long manufacturing cycle and high manufacturing costs limit their widespread use. Ti 2 AlC is a new type of ceramic material with the characteristics of low density, high melting point, high-temperature resistance, oxidation resistance, and corrosion resistance of ceramic materials, as well as the conductivity and machinability of metals. However, its mechanical properties are slightly inadequate. The use of chopped fibers for toughening can compensate for these deficiencies to a certain extent and improve mechanical properties. This article first explored the influence of various process parameters on the mechanical properties of pure-phase Ti 2 AlC ceramic materials in SPS preparation technology and then prepared Ti 2 AlC composites reinforced with 10 vol%, 20 vol%, and 30 vol% Al 2 O 3 chopped fibers. The results showed that the samples prepared at 1300 °C, 40 MPa, and 10 min had a flexural strength of 697 MPa and a fracture toughness of 9.83 MPa m1/2 when the volume ratio of the reinforcement phase was only 10 vol%, which was the same as that of the continuously fiber-reinforced SiC f /SiC composites. This study showed that the MAX phase matrix composites reinforced with chopped fibers have the potential to become high-temperature structural materials by adjusting the composite composition and optimizing the preparation process. [ABSTRACT FROM AUTHOR]

In this study, TiC particle-reinforced high-manganese-steel (Mn18Cr2) matrix composites were successfully prepared using an in-situ method, and a millimeter micrometer dual-scale architecture was constructed in the composites to further enhance their mechanical properties. The effects of different moderator contents in the precursor on the size, volume fraction, mechanical properties, and impact wear resistance of the generated TiC particles were primarily investigated. The results showed that the moderator considerably influenced the microstructure and mechanical properties of the composites. As the moderator content increased, the size, volume fraction, mechanical properties, and wear resistance of TiC particles decreased. The optimal comprehensive performance of the composites was obtained when the moderator content was 20 wt%., average TiC particle size was 1.21 μm, volume fraction was 64.9 %, bulk hardness was more than three times that of the matrix, compressive strength was ∼2 GPa, and relative wear resistance was 2.47 times that of the matrix. The main wear behaviors of composites included grooves, microcutting, pits, and plastic deformation. In conclusion, this study guides the design and synthesis of steel matrix composites with tunable in-situ ceramic particle sizes and volume fractions to enhance wear resistance. [ABSTRACT FROM AUTHOR]

This review paper investigates novel approaches to the fabrication of fiber-reinforced composites (FRCs) via additive manufacturing (AM), with a focus on improving mechanical properties in polymers, metals, and ceramics while reducing weight of the structures. FRCs have been regarded as the optimal material choice across the automobile, aerospace, and construction industries due to their exceptional characteristics, including high strength-to-weight ratio, elevated stiffness, commendable thermal stability, remarkable fatigue and impact resistance, as well as noteworthy chemical and corrosion resistance. AM plays a significant role in FRCs production by offering design flexibility, product customization, waste reduction, near net shape fabrication, cost-effectiveness, and fast prototyping. This paper initially categorizes AM of FRCs into three categories: AM of polymer-matrix, metal-matrix, and ceramic-matrix composites. These categories are further subdivided based on the types of matrix as well as fibers used. Subsequently, it emphasizes the roles of 4D printing and numerical simulation in AMFRCs. The review concludes by addressing potential applications, existing challenges, and scope of AMFRCs in future research and development. [ABSTRACT FROM AUTHOR]

Under cyclic‐fatigue loading, stochastic loading may occur and affect the fatigue limit stress (FLS) in C/SiC composites. In this paper, the FLSs in different C/SiC composites were predicted considering stochastic loading spectrums. Damage mechanisms of interface wear and fibers failure were considered in the global load sharing criterion to determine the fracture life and fiber's failure probability in three different stochastic loading spectrums, that is, constant, increasing and decreasing stochastic stress spectrum. Experimental FLS and fatigue life degradation rate were predicted using the developed micromechanical approach, and the effect of cyclic duration under stochastic spectrums on the FLS was analyzed. Relationships among the FLS, life degradation rate, stochastic spectrum, and cyclic duration were established. [ABSTRACT FROM AUTHOR]

The orthopedic application of Mg alloys suffers from excessive degradation. In this study, hydroxyapatite (HAP) nanoparticles are doped with MgO by high-energy ball milling, and then the obtained powders are compounded with WE43 powders and prepared into implants by laser powder bed fusion. During milling process, Mg2+ ions on MgO exchange some Ca2+ in HAP by mechanical collision and friction, which forms covalent bonds on the MgO/HAP interface. Subsequently, TEM observation showed that MgO on HAP forms semi-coherent interfaces with α-Mg, contributing to good bonding on the Mg/MgO interface. In this manner, strong bonding interfaces between ceramic particles and α-Mg were established, thereby preventing the agglomeration of nanoparticles. The well-dispersed ceramic particles provided more nucleation sites for apatite deposition, which benefits the formation of the passivation layer and thereby improves corrosion resistance. As a consequence, the composite exhibited a low corrosion density (20.1 ± 1.3 μA/cm2), high corrosion resistance (752.8 ± 19.7 Ω cm2), and low carrier concentration (1.28 ± 0.01 cm−3), indicating the formation of a more protective passivation layer. These findings suggested that the mHAP incorporated Mg composite may be a potential candidate for orthopedic implant. [ABSTRACT FROM AUTHOR]

Composites are versatile materials that can be tailored to meet the specific needs of various industries, including aerospace, automotive, and construction. This study focuses on investigating how the amount of titanium-di-boride (TiB2) particles (0%, 3%, 6%, and 9%) affects the physical, mechanical, microstructural, and fracture properties of Al7075/TiB2 composites produced using a liquid-state stir-casting process. The addition of TiB2 particles increases the hardness and tensile strength of the Al7075 alloy. This has been confirmed by X-ray diffraction analysis, which showed that these particles are dispersed throughout the aluminum matrix. The hardness increases from 60 HV to 90 HV and the tensile strength increases from 140 MPa to 211 MPa. The significance of increased wettability brought about by the addition of magnesium powder and the preheating of a ceramic reinforcement before pouring molten metal was revealed by scanning electron micrographs of the cast composites, which showed an even dispersal of reinforcements in the aluminum matrix, establishing the strong connection between the matrix and the reinforcement agents. Fracture surface scanning electron microscopy revealed that micro-void formation and nucleation in Al7075/TiB2 composites resulted in ductile material paves a way for manufacturing innovation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

SiCf/SiC composites, as promising materials for the hot‐section components of turbine engines, are susceptible to hot corrosion due to the steam environments. Especially, under rotational and thermal stress, numerous microcracks may be generated in the SiCf/SiC ceramic matrix, which can trigger the rapid invasion of corrosive gases and deteriorate the composite mechanical properties. Therefore, it is of great importance to investigate the degradation mechanisms of SiCf/SiC with precracks existing. Here, the corrosion behavior of precracked SiCf/SiC in the Na2SO4‐wet‐oxygen environment was evaluated. By comparing mechanical evolution under different corrosion conditions, microfailure mechanisms of SiCf/SiC were revealed. The results indicate that brittle cracking of the matrix and oxidation erosion of fibers are the key factors in reducing the tensile strain of composites. Specifically, the composite damage resistance increases at 67 MPa‐1300°C. At this point, the prestress level is moderate and close to the matrix cracking limit. The prefabricated microcracks can be healed at 1300°C by liquid oxidation products, which hinders cracks bridging large‐scale. This study is conducive to a better understanding of failure mechanisms of SiCf/SiC in complex service environments. [ABSTRACT FROM AUTHOR]

The long-term periodicity and uncontrollable interface properties during the preparation process for silicon carbide fiber reinforced silicon carbide-based composites (SiCf/SiC CMC) make it difficult to thoroughly investigate their mechanical damage behavior under complex loading conditions. To delve deeper into the influence of the interface strength and toughness on the mechanical response of microscopic representative volume element (RVE) models under complex loading conditions, in this work, based on numerical simulation methods, a microscale representative volume element (RVE) with periodic symmetric boundary conditions for the material is constructed. The phase-field fracture theory and cohesive zone model are coupled to capture the brittle cracking of the matrix and the debonding behavior at the fiber/matrix interface. Simulation analysis is conducted for tensile, compressive, and shear loading as well as combined loading, and the validity of the model is verified based on the Chamis theory. Further investigation is conducted into the mechanical response behavior of the microscale RVE model under complex loading conditions in relation to the interface strength and interface toughness. The results indicate that under uniaxial loading, increasing the interface strength leads to a tighter bond between the fiber and matrix, suppressing crack initiation and propagation, and significantly increasing the material's fracture strength. However, compared to the transverse compressive strength, increasing the interface strength does not continuously enhance the strength under other loading conditions. Meanwhile, under the condition of strong interface strength of 400 MPa, an increase in the interface toughness significantly increases the transverse compressive strength of the material. When it increases from 2 J/m2 to 20 J/m2, the transverse compressive strength increases by 28.49%. Under biaxial combined loading, increasing the interface strength significantly widens the failure envelope space under σ2-τ23 combined loading; with the transition from transverse compressive stress to tensile stress, the transverse shear strength shows a trend of first increasing and then decreasing, and when the ratio of transverse shear displacement to transverse tensile/compressive displacement is −1, it reaches the maximum. This study provides strong numerical support for the investigation of the interface properties and mechanical behavior of SiCf/SiC composites under complex loading conditions, offering important references for engineering design and material performance optimization. [ABSTRACT FROM AUTHOR]

Mullite-based fibers are promising candidates for reinforcement fibers for ceramic matrix composites. This paper summarizes the high-temperature properties of continuously produced mullite and zirconia-toughened mullite (ZTM) fibers. Special attention was devoted to the continuous sintering of fibers with complete mullite crystallization while avoiding grain growth. The fibers were annealed between 1000 and 1500 °C for 25 h in air and analyzed at room temperature. The addition of ZrO 2 did not significantly reduce the average matrix grain size. With increasing annealing temperature, notable changes in the phase composition occurred. Pristine fibers contained mullite and intermediary γ-Al 2 O 3 and an amorphous phase, leading to an ongoing mullite crystallization up to 1200 °C. Grain growth and changes in the phase composition led to a decrease in Weibull strength. ZTM fibers showed a lower relative strength retention than mullite fibers, but contained up to 76 % (1310 MPa) of their initial strength at 1300 °C. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites (CMCs) are a significant advancement in materials science and engineering because they combine the remarkable characteristics of ceramics with the strength and toughness of fibers. With their unique properties, which offer better performance and endurance in severe settings, these advanced composites have attracted significant attention in various industries. At the same time, lightweight ceramic matrix composites (LCMCs) provide an appealing alternative for a wide range of industries that require materials with excellent qualities such as high-temperature stability, low density, corrosion resistance, and excellent mechanical performance. CMC uses will expand as production techniques and material research improve, revolutionizing aerospace, automotive, and other industries. The effectiveness of CMCs primarily relies on the composition of their constituent elements and the methods employed in their manufacturing. Therefore, it is crucial to explore the functional properties of various global ceramic matrix reinforcements, their classifications, and the manufacturing techniques used in CMC fabrication. This study aims to overview a diverse range of CMCs reinforced with primary fibers, including their classifications, manufacturing techniques, functional properties, significant applications, and global market size. [ABSTRACT FROM AUTHOR]

Ceramic matrix composites (CMCs) are a category of advanced materials which have gained significant interest recently due to their remarkable mechanical and thermal characteristics. These composites are composed of ceramic fibers, particles, or other types of ceramics incorporated in a ceramic matrix and have shown the capability to be implemented in several sectors, including aerospace, energy, and biomedical engineering. This review paper will provide a synopsis of the current scenario and recent progress in CMCs, including materials and processing techniques, characterization methods, and applications. The paper discusses the advantages and limitations of CMCs, recent advancements, and future trends in research. The microstructural and mechanical properties of CMCs are also reviewed, highlighting their potential for various applications. The paper's conclusion delivers a summary of the essential findings and a discussion of future directions for CMC research. [ABSTRACT FROM AUTHOR]

SiBCN ceramics based on SiC, BN and Si3N4 structures have good comprehensive properties such as high-temperature resistance, oxidation resistance, creep resistance and long life, which makes it one of the very promising ceramic material systems in military and aerospace fields, etc. In this study, SiBCN ceramics, as well as Si3N4f/BN/SiBCN microcomposites, were prepared by a polymer infiltration pyrolysis method using PBSZ as the polymer precursor. The PBSZ was completely ceramized by pyrolysis at 900 °C. The weight loss and elemental bonding forms of the products after the pyrolysis of the precursors hardly changed from 600 °C to 900 °C. After pyrolysis at 600 °C for 4 h and using the BN coating obtained from twice deposition as the interfacial phase, a more desirable weak interface of fiber/matrix with a binding strength of 21.96 ± 2.01 MPa can be obtained. Si3N4f/BN/SiBCN ceramic matrix microcomposites prepared under the same pyrolysis conditions have a relatively good tensile strength of 111.10 MPa while retaining a weak interface between the fibers and the matrix. The results of the study provide more theoretical and methodological support for the application of new composite structural ceramic material systems. [ABSTRACT FROM AUTHOR]

Monotonic tensile behavior of plain-woven SiC f /SiC ceramic matrix composites is investigated at 1200 °C and 1350 °C in water–oxygen environments. In addition, tensile–tensile fatigue behavior at 1200 °C in water–oxygen environments is discussed. Specimens are prepared using chemical vapor infiltration (CVI) process. To enhance their resistance to oxidation in high-temperature water–oxygen environments, environmental barrier coatings (EBCs) are deposited on their surface. Two rows of film cooling holes (FCHs) with 0.5 mm diameter, each row consisting of five FCHs, are designed to compare the effects of two different hole spacings on specimen fatigue and tensile performance. The evolution of strain and normalized modulus during fatigue cycling is investigated in detail. Microstructures of specimens that failed under tensile and fatigue conditions are observed using scanning electron microscopy (SEM), and elemental analyses of specimens after fatigue test failure are performed using energy-dispersive spectroscopy (EDS). The results reveal that tensile strength of specimens with large FCH spacing is greater than that of specimens with small FCH spacing. However, fatigue performance of specimens with small FCH spacing was better than that of specimens with large FCH spacing. This phenomenon is caused by a reduction in strength due to stress concentration effect near holes with small FCH spacing. Holes with large FCH spacing are closer to the specimen edge during fatigue test, leading to high failure rate. The oxidation and embrittlement that surround holes caused by FCHs compromised structural integrity of the specimen and allowed water–oxygen environment to penetrate the specimen interior. This has significant impact on mechanical performance of the material. [ABSTRACT FROM AUTHOR]

Porous Si 3 N 4 has excellent properties such as high temperature resistance, corrosion resistance, high porosity, and high specific surface area, but the inherent brittleness limits the application of Si 3 N 4 in some special environments. Si 3 N 4f /RBSN porous ceramic composites were prepared by reaction bonding method using reaction-bonded silicon nitride(RBSN) as the matrix and continuous Si 3 N 4 fibers (fiber mats) as the reinforcement. The results show that the composite with Si/Si 3 N 4 = 70:30 in the raw material has a superior nitridation rate and flexural strength of 96.5% and 23.5 MPa, respectively. The nitridation process of the Si 3 N 4f /RBSN matrix is dominated by the vapour-phase reaction between SiO and N 2 , and the products are mainly α-Si 3 N 4 whiskers. The residual flexural strength of the composites is essentially unchanged after 10 thermal cycles in air at 800 °C. The composites have excellent thermal shock resistance and can be used as the reusable crucible. [ABSTRACT FROM AUTHOR]

The traditional high-temperature sintering method cannot achieve the combination of ceramics and polymers for the huge sintering temperature difference. The insufficient interfacial bonding strength of the ceramic matrix is the difficulty in the low-temperature preparation of ceramic-polymer composites. To improve the interfacial bonding strength of Si 3 N 4 (Silicon nitride) ceramic matrix composite, an easy-bonding SiO 2 (Silica) shell was introduced onto the surface of the hard-bonding Si 3 N 4 core by Stober method, to obtain Si 3 N 4 @SiO 2 composite. Si 3 N 4 @SiO 2 /PEEK (Polyetheretherketone) composites were prepared by the cold sintering process (500 MPa, 240 °C, and transient liquid phase is NaOH solution). The dry tribological properties of Si 3 N 4 @SiO 2 /PEEK composites with different PEEK percentages were studied by a ball-disc contact form. It is shown that an amorphous SiO 2 shell with a thickness of 25 nm is chemically bonded onto the surface of the Si 3 N 4 core. The presence of the SiO 2 shell improves the interface bonding strength between Si 3 N 4 ceramic particles. The friction coefficients of Si 3 N 4 @SiO 2 /PEEK composites decrease with the increase of PEEK percentage. Compared with Si 3 N 4 @SiO 2 composite, the friction coefficient and wear rate of Si 3 N 4 @SiO 2 /50 vol% PEEK composite decrease by about 40% and 26%, respectively. The main wear forms of Si 3 N 4 @SiO 2 /PEEK composites are abrasive wear and adhesive wear. A mixed lubrication layer, mainly including PEEK, Si 3 N 4 , and SiO 2 , exists simultaneously on the surfaces of Si 3 N 4 @SiO 2 /PEEK composite and the counterpart ball, respectively, playing the role of reducing friction and wear. [ABSTRACT FROM AUTHOR]

The present study investigates the influences of SiC incorporation on the microstructure and corrosion behavior of B4C–nSiC composites in molten FLiNaK salt at 800°C. The corrosion characteristics and mechanisms of B4C–nSiC composites in molten FLiNaK salt were thoroughly characterized and extensively discussed. The B4C–nSiC composites exhibited a more refined grain size and lowered apparent porosity as the SiC content increased. Additionally, the concentration of high‐angle grain boundaries (HAGBs) in B4C–nSiC composites increased as the SiC content increased. The incorporation of 10 wt.% SiC improved the corrosion resistance of B4C–nSiC composites against molten FLiNaK salt. However, the incorporation of excessive SiC (≥20 wt.%) did not improve the corrosion resistance. The best corrosion resistance of B4C–10% SiC ceramic composite was attributed, on the one hand, to its relatively low apparent porosity and the low concentration of HAGBs with high structural disorder. On the other hand, the selective corrosion of B4C in B4C–10% SiC ceramic composite rapidly formed a sufficiently thick and highly graphitized C‐rich layer on its surface during the initial stages of the corrosion test. The C‐rich layer maintained the integral structure of the ceramic and prevented subsequent corrosive medium from penetrating into the ceramic. [ABSTRACT FROM AUTHOR]

Silicon carbide fiber‐reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) based on a domestic KD‐SA SiC fiber were exposed to a wet oxygen atmosphere for 135 h at 800, 1100, and 1300°C. The evolution of the microstructure and mechanical properties of SiCf/SiC CMCs have been systematically investigated following oxidation. For weight change, CMC‐1300 showed the greatest gain (0.394%), followed by CMC‐1100 (0.356%) and CMC‐800 (0.149%). The volatilization of boron oxide (B2O3) combined with the slight oxidation of the SiC matrix at 800°C caused crack deflection and fiber pull‐out. The complete dissipation of the interphase could be found when the oxidation temperature increases to 1100°C, generated a fracture surface with brittle fracture characteristics. At 1300°C, crystalline SiO2 hindered oxygen diffusion, with evidence of fiber pull‐out. Based on thermodynamic calculations and microscopic observations, we propose a mechanism to explain the thermal degradation of SiCf/SiC CMCs. This work offers valuable guidance for the fabrication of SiCf/SiC CMCs that are suitable for high‐temperature applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A simple method for the direct transformation of Sr-exchanged titanosilicate with the sitinakite structure (IONSIV) into ceramic material through cold pressing and subsequent sintering at 1100 °C for 4 h is presented. The temperature transformation of Sr-exchanged sitinakite showed the stages of recrystallization of the material with the formation of Sr-Ti phases matsubaraite (Sr4Ti5[Si2O7]2O8), jeppeite (SrTi6O13), tausonite (SrTiO3), and rutile. Leaching experiments showed the efficiency of fixation of Sr cations in a ceramic matrix; extraction into water does not exceed 0.01% and desorption in 1 M HNO3 solution is only 0.19% within three days. The leaching rates of immobilized Sr demonstrate the structural integrity of the formed phases in the ceramic (2.8 × 10−5–1.0 × 10−5 g/(m2·day). The decrease in the crystallinity of the initial Na-sitinakite, which is achieved by reducing the synthesis temperature from 250 to 210 °C, does not affect the sorption capacity and the fixation of cations in the ceramic matrix. The obtained results confirm the prospect of using inexpensive precursors, titanium ore enrichment waste, for the synthesis of sorption materials. [ABSTRACT FROM AUTHOR]

Low-temperature and short-time sinter-forging has been used to obtain a dense WC/Y–TZP–Al 2 O 3 hybrid ceramic–matrix composite with dispersed Hadfield steel with high fracture toughness. The hardness and К 1С fracture toughness were 13.7 ± 0.3 GPa and 7.4 ± 0.4 MPa m1/2, respectively. The composite contained phases such as Y–TZP–Al 2 O 3 eutectics and hypereutectic grains, WC agglomerates, γ-Fe particles as well as small amounts of Al 2 (WO 4) 3 and MnFe 2 O 4. No t -ZrO 2 →m-ZrO 2 transformational toughening occurred during mechanical loading so that enhanced fracture toughness resulted from forming a dense microstructures with ductile metallic interlayers between ceramic and tungsten carbide grains. [ABSTRACT FROM AUTHOR]

This paper deals with the evolution of thermal residual stress (TRS) in Ceramic Matrix Composites (CMC) with environmental barrier coating (EBC) for aeroengine applications. In particular, in hot section component applications, where the durability requirement is of primary concern, CMC/EBC materials seem to be the most fascinating solution for effective and performant design. In this work, a numerical analysis has been conducted to study the effect of TRS on the damage mechanism in the 2.5D woven CMC coated with EBC. To figure out the heterogeneous and stochastic evolution of TRS in the coatings and substrate, a micromechanical finite element model of the composites containing the coatings was established based on the concept of representative volume elements. Especially, the variation of microstructure characteristics and constituents properties were taken into account in the micromechanical model. A series of simulations were performed to investigate the evolution of TRS during the cooling process after preparation and the thermo-mechanical loading process. Then, the thermal stress in coatings and substrate was calculated, and the influence mechanism of TRS on the failure was analyzed by comparison. The driven mechanism of the delamination crack and vertical crack was discussed based on the TRS results with uncertain characteristics. Based on this, uncertainty quantification can be performed to predict the durability life of the CMC/EBC system. [ABSTRACT FROM AUTHOR]

In this article, the dielectric properties of a Li4Ti5O12 (LTO) ceramic at the radio frequency (RF) and microwave (MW) regions were evaluated. X-ray diffraction showed that LTO was obtained without the presence of spurious and/or secondary phases. Complex impedance spectroscopy (CIS) analysis was conducted, whereas an activation energy (Ea) of 0.88 eV was observed. The temperature capacitance coefficient (TCC) was also calculated and demonstrated that LTO could be employed as a Class 1 ceramic capacitor. In the MW region, LTO presented ε'r = 25.4, tan δ = 5.7 × 10–4, and τf = -14.5 ppmºC−1, values that are interesting for devices that operate in the MW region. Numerical simulation demonstrated values of a realized gain of 4.78 dBi, a bandwidth of 227 MHz, and a radiation efficiency of 98%. Moreover, LTO was evaluated as a temperature sensor operating in the MW region and demonstrated a sensitivity of -0.06 MHz ºC−1. The values presented demonstrate that LTO could be employed in devices that operate in RF and MW regions. [ABSTRACT FROM AUTHOR]

SiBCN fiber reinforced SiBCNmatrixmini-composites (SiBCN/SiBCN) as a new type of the ceramic matrix composite were fabricated by precursor infiltration and pyrolysis (PIP) process. Various degumming methods for continuous SiBCN fibers resulted in different properties and surface conditions, further affecting the interfacial bonding strength (IFBS) and mechanical properties of the composites. The relationship between fiber degumming modes, fiber states, and properties of compositeswas discussed and the strengtheningmechanisms of the SiBCN/SiBCN mini-composites were explored. With a degumming treatment of N,N-dimethylformamide (DMF) soaking, the flexural strength and modulus of mini-SiBCN/SiBCN composites achieved 508 ± 68 MPa and 79 ± 12 GPa, respectively. The novel strengthening mechanism of the microcrystalline SiBCN fiber reinforced microcrystalline SiBCN matrix composites will enrich and be helpful to understand the strengthening and tougheningmechanisms of ceramic matrix composites. [ABSTRACT FROM AUTHOR]

Three multi-phase tantalum carbide composites (TaC z -Ta 5 Si 3) were fabricated by Spark plasma Sintering (SPS) using Ta, TaC and SiC powders. SiC was added to control the C:Ta ratio (z = 0.6, 0.74, 1.0), regulating the phase composition and grain morphology while also serving as a deoxidizer. Composite TaC 0.6 -Ta 5 Si 3 had Ta 2 C as the major phase and contained Ta 4 C 3−x , TaC and Ta 5 Si 3. It exhibited an excellent combination of high flexure strength (714 ± 21 MPa) and toughness (13.9 ± 0.2 MPa·m1/2), despite a low Ta 4 C 3−x fraction, a phase known to have very high toughness. The outstanding performance was attributed to the elongated Ta 2 C grain morphology, highly laminated intra-granular Ta 4 C 3−x laths, and the refined Ta 2 C grain size. Composite TaC 0.74 -Ta 5 Si 3 , characterised by equiaxed grain morphology, exhibited good flexure strength (571 ± 36 Mpa) and toughness (7.6 ± 1.1 MPa·m1/2) due to the presence of Ta 4 C 3−x laths in the c-TaC. Lastly, composite TaC 1.0 -Ta 5 Si 3 , composed of c-TaC and Ta 5 Si 3 , exhibited moderate strength (545 ± 25 MPa) and toughness (5.3 ± 0.1 MPa·m1/2). • Ta 2 C-dominant and TaC-dominant composites (TaC z -Ta 5 Si 3) are fabricated using Ta, TaC and SiC. • SiC additives control the C:Ta and effectively promoted the sintering through oxide removal. • TaC 0.6 -Ta 5 Si 3 has the best toughness due to the elongated Ta 2 C grains and intra-granular laths. • TaC 0.74 -Ta 5 Si 3 with the equiaxed TaC has good toughness due to the intra-granular laths. • TaC 1.0 -Ta 5 Si 3 with the equiaxed TaC is free of intra-granular laths and has the lowest toughness. [ABSTRACT FROM AUTHOR]

In this study, the Method of Fundamental Solutions (MFSs) is adopted to model Chemical Vapor Infiltration (CVI) in a fibrous preform. The preparation of dense fiber-reinforced silicon carbide composites is considered. The reaction flux at the solid surface is equal to the diffusion flux towards the surface. The Robin or third-type boundary condition is implemented into the MFS. From the fibers' surface concentrations obtained by MFS, deposition rates are calculated, and the geometry is updated at each time step, modeling the pore filling over time. The MFS solution is verified by comparing the results to a known analytical solution for a simplified geometry of concentric cylinders with a concentration set at the outer cylinder and a reaction at the inner cylinder. MFS solutions are compared to published experimental data. Porosity transients are obtained by a combination of MFSs with surface deposition to show the relation between the initial and final porosities. [ABSTRACT FROM AUTHOR]

With the rapid development of processing technology, increasing processing efficiency is no longer the only goal but also the utilization of green and clean manufacturing procedures is required. Consequently, the development of an efficient processing strategy for ceramic matrix composites (CMCs) is of great importance. In this work, the orthogonal test of single-grain scratches was conducted under different lubrication modes. From the acquired results, the utilization of minimum quantity lubrication (MQL) from vegetable oil showed the best results, with the average scratch force of 44.4 N and the average surface elevation of 26.893 μm. The reduction compared to dry lubrication was 48.3% and 48.4%, respectively. The reason is the ability to form a pure lubricant film in the contact area between the workpiece and the tool. In addition, the response surface method was used to demonstrate that the scratch depth and scratch angle are the key factors affecting the machining quality, and the optimal combination of scratch parameters was obtained. The dominant mode of material removal of the SiCf/SiC composites was a brittle fracture, and the damage characteristics mainly included natural fiber fracture, matrix breakage, fiber pullout, and fiber exposure. The increase of the processing ratio of 0° and implementation of vegetable oil for MQL was proven as one of the best methods. [ABSTRACT FROM AUTHOR]

Hafnium carbide (HfC) is an ultrahigh‐temperature ceramic with high melting point, chemical stability, hardness, and wear resistance. However, its low fracture toughness and poor thermal shock resistance limit its structural applications in extreme environments. In this study, co‐curing of liquid precursors was carried out prior to complete pyrolysis of individual polymeric precursors. First, HfC preceramic polymer precursor was cured, followed by silicon carbonitride (SiCN) precursor curing on a 2D carbon fiber (CF) cloth using the drop‐coating process. The infiltrated CFs were pyrolyzed at 800°C to achieve CF/HfC‐SiCN ceramic mini‐composites. The cross‐linked precursor‐to‐ceramic yield was observed to be as high as 65% when the procedure was carried out in an inert environment. Although stable up to 1200°C, CF/HfC‐SiCN samples demonstrated susceptibility to oxidation at 1500°C in ambient air. The oxidation of HfC in the presence of SiC leads to the formation of a hafnium‐containing silicate (HfxSiyOz) along with hafnia (HfO2). This compound of silicate and hafnia limits oxygen diffusion better than SiO2 and HfO2 individually. The incorporation of SiCN in HfC ceramic led to improved phase stability compared to a neat HfC system. The results of this study also show that the use of liquid‐phase precursors for HfC and SiCN in the polymer‐infiltrated pyrolysis method is a promising approach to fabricating high‐temperature structural ceramic matrix composites with good oxidation resistance. [ABSTRACT FROM AUTHOR]

In this study, ceramic particle (WC) reinforced AlCoCrFeNi 2.1 eutectic high entropy matrix composites (WC x /HEA 1-x , x = 0, 5, 10 wt%) were prepared by using laser powder bed fusion (LPBF) technology. The microstructure evolution and wear behavior of the printed WC x /HEA 1-x composites were analyzed, and the strengthening mechanism and anti-wear mechanism of the WC x /HEA 1-x composites were extensively studied. The results show that the reinforcement ceramic particles (WC) were uniformly distributed in the HEA matrix and a good metallurgical bonding layer between the reinforced phase WC and the HEA matrix were found. The maximum width of the bonding layer is about 330 nm. Under the strong irradiation of high-energy laser, WC was decomposed into W and C elements, and diffused into the HEA matrix. Its reaction with Co, Fe, Ni elements produced M x C (M = Co, Fe, Ni) carbides. Part of W and C elements were soluble in the HEA. The wear resistance of the printed composite is found affected by the content of added ceramic particle (WC). The ranking of the wear resistance of the printed composites was found to be WC 0.05 /HEA 0.95 > HEA ≈ WC 0.10 /HEA 0.90. The improvement of wear resistance by adding WC was found due to interfacial load transfer strengthening of WC particles, solution strengthening of W and C atoms; and the second phase strengthening of various carbides M x C (M = Co, Fe, Ni). [ABSTRACT FROM AUTHOR]

A study has been carried out to examine the impact of fibre architecture on the infiltration permeability, constituent phase volume fractions, and matrix porosity of the carbon fibre (C f)-ZrB 2 -20 vol% SiC ceramic matrix composites prepared through slurry infiltration, followed by hand lay-up and hot pressing. Unidirectional (UD) C f -fibres in 0/0° and 0/90° orientations, as well as 8H satin woven C f -fibres, have been utilized as reinforcement in the composites, which were subsequently densified through hot pressing after infiltration. Revelation of the 3D internal structure of the composites by X-ray microscopy has facilitated a thorough qualitative and quantitative evaluation of infiltration. The fraction of matrix (ZrB 2 - 20 vol% SiC) present along three orthogonal axes (X, Y and Z) of the scanned composite blocks has been calculated, with Z representing the direction of infiltration. This study has revealed that the composites processed from UD C f -fibre preform exhibits greater infiltration, because of higher intra-bundle infiltration compared to the 8H woven C f -fibre, and the accompanying analysis provides insight into the formation mechanisms of matrix porosities. [ABSTRACT FROM AUTHOR]

Under multi-step cyclic fatigue loading, the mechanical hysteresis loops of ceramic-matrix composites (CMCs) were affected by coupled multiple damage mechanisms. In this paper, the hysteresis-based inverse tangent modulus (ITMs) was developed to characterize the cyclic fatigue mechanical hysteresis behavior in 2D SiC/SiC composite under multi-step loading. The micromechanical multi-step hysteresis constitutive models were developed for the damage state of interface partial and complete debonding. Relationships between the cyclic-dependent interface wear, hysteresis loops, interface slip damage state, and ITMs were established. Effects of multi-step peak stress level, cycle number, and interface properties on the evolution of hysteresis stress-strain curves and ITMs were analyzed. Experimental multi-step cyclic fatigue hysteresis loops and ITMs of 2D SiC/SiC composite under different peak stresses of 1.2, 1.3, 1.4, and 1.5 PLS (proportional limit stress) were predicted. Compared with other hysteresis-based damage parameters, e.g., hysteresis width, hysteresis modulus, peak and residual strain, and loops area, the damage parameter of ITMs can better reveal the interface debonding and slip damage state in CMCs under multi-step cyclic fatigue loading. [ABSTRACT FROM AUTHOR]

Silicon carbide fibers have superior flexural properties and chemical stability compared to glass fibers. We investigated the flexural strength and modulus of an experimental, short silicon carbide fiber-reinforced resin. Short silicon carbide fibers with lengths of ~0.5, 1, 2, and 3 mm were prepared and silanized. Urethane dimethacrylate and triethylene glycol dimethacrylate were mixed at a 70:30 wt% ratio and used as the matrix resins. Each length of short silicon carbide fibers and the matrix resin were combined using a mixing machine and then used for specimen preparation. The three-point bending test conditions were in accordance with ISO 4049:2009. The fracture surfaces of the specimens after the three-point bending test were observed using secondary electron images. The data were statistically analyzed with a one-way analysis of variance and Tukey's HSD test (α = 0.05). The flexural strength and modulus of the specimens containing 2 mm or 3 mm silicon carbide fibers were significantly higher than the other specimens. The river pattern was observed more clearly in specimens containing shorter silicon carbide fibers, although this pattern was observed in all specimens. [ABSTRACT FROM AUTHOR]

In this study, the filling and solidification processes of squeeze-casting SiC3D/Al composites were analyzed by the ProCAST simulation software (ver. 2018.0). A practical squeeze-casting experiment was conducted to verify the accuracy of the simulation results. A series of orthogonal experiments were conducted on the initial preheating temperature of various components to identify the optimal parameters in order to achieve better porosity and stress concentration values. According to the results and analyses, the preheating temperature of the mold was the most important determining factor. Under a pouring temperature of 700 °C, mold preheating temperature of 200 °C, and SiC skeleton preheating temperature of 600 °C, the maximum principal stress at the bottom of the products was decreased by about 41.9%, and the shrinkage volume inside the composite was decreased about by about 61.6%. Thus, by adjusting the initial preheating temperature of various components, the squeeze-casting SiC3D/Al composites could achieve better performance and fewer internal defects. [ABSTRACT FROM AUTHOR]

Continuous fiber-reinforced silicon carbide composites have received significant attention due to their high-temperature mechanical stability. However, their widespread implementation has been hindered by intricate fracture mechanisms and limited toughness. This study presents a real-time approach for identifying damage type in 2.5D SiCf/SiC composites and highlights the significant impact of minor eccentric loading angle on the fracture behavior and mechanical properties using acoustic emission (AE). Even a slight degree of eccentric loading angle can significantly alter the fracture behaviors, leading to a significant increase in fracture toughness. The fracture damage evolution law of 2.5D SiCf/SiC under varying eccentric loading angles was investigated with the help of the AE damage identification, fracture morphology and finite element analysis. These findings provide valuable insights for multi-axis stress analysis of 2.5D high-performance composites.