Continuous Fiber-reinforced Ceramic Matrix Composites Research Articles

Mode I interlaminar fracture toughness of two-dimensional continuous fiber reinforced ceramic matrix composites using wedge-loaded double cantilever beam method

In this study, the wedge-loaded double cantilever beam (W-DCB) method was applied to evaluate the mode I interlaminar fracture toughness of two-dimensional (2D) continuous fiber-reinforced ceramic matrix composites (CMCs). Based on the elastic foundation theory, a W-DCB model was built and its compliance formula was derived by considering the axial force effect, shear effect, asymmetric propagation, and incomplete interlaminar contact. The friction effect was analyzed and measured using the theory of error transfer and a quasi-in-situ measurement method, respectively. The results reveal that rational selection of the wedge angle and friction coefficient can reduce the friction effect. Meanwhile, the W-DCB formula was comprehensively verified by compliance curves, crack tip behaviors, and the cohesive zone of 2D CMCs, which demonstrates its accuracy in conjunction with the experimental data. Finally, the energy release rate (ERR) of the 2D CMCs calculated using the W-DCB theory was consistent with the measured data.

Improving mechanical properties of SiCw/SiC composite by phase content optimization via reactive melt infiltration

Inspired by the preparation methods of continuous fiber reinforced ceramic matrix composites (CFCCs), a novel silicon carbide whiskers (SiCw)-toughened SiC CMC with isotropic high strength and toughness, high density, and relatively low cost and short manufacturing cycle is prepared by a combination of gel-casting (GC) and reactive melt infiltration (RMI). The content and degree of graphitization of resin carbon during RMI are altered by annealing the SiCw/C mixture and adjusting the amount of SiCw to optimize phase composition and improve the mechanical properties of SiCw/SiC composites. The results reveal that the content of SiC phase is directly related to the flexural strength, reaching a maximum value of 339 MPa at 83 vol%. Also, the increase in C content increases the fracture toughness, reaching a value of 6.2 MPa m1/2 at carbon content of 4.6 vol%. The toughening of SiCw/SiC composites is realized by SiCw toughening, residual SiCw/C toughening and SiC particle toughening.

Drilling process of Cf/SiC ceramic matrix composites: Cutting force modeling, machining quality and PCD tool wear analysis

Cf/SiC composites are continuous fiber-reinforced ceramic matrix composites with excellent properties, such as high-temperature resistance, high specific strength, and low coefficient of thermal expansion. However, Cf/SiC composites often cause severe tool wear and quality problems. In this paper, tool wear is studied during the machining of Cf/SiC materials. The cutting force model is applied to understand the correlation between cutting force and tool wear. Polycrystalline Diamond (PCD) tools with various point and clearance angles are designed to carry out drilling experiments on Cf/SiC composites with different machining parameters. During experimental investigations, force and acoustic emission signals are analyzed, and PCD tool wear and material machining quality are observed using scanning electron microscopy. Results indicate that PCD tools with a point angle of 140° and a clearance angle of 20° demonstrate the lowest tool wear during machining. Moreover, low-speed and feed machining parameters can effectively reduce tool wear and prolong its life. By observing fracture patterns of hole wall fibers and chip shapes at different stages of tool wear, and combined with the frequency domain distribution of AE signal, the effects of tool wear on the material removal mechanism are summarized. Before tool wear, fiber fracture is flatter, the matrix is mainly removed via crushing. After tool wear, although fiber fracture is more uneven, the matrix is changed from crushing to friction removal, leading to lower surface roughness of the hole wall.

Damage analysis of a SiCf/SiC ceramic matrix composite under stepwise fatigue loading with acoustic emission

Continuous fiber-reinforced ceramic matrix composites (CMCs) exhibit different damage mechanisms at multiple scales under cyclic loading. In this paper, the tension-tension fatigue behavior of a plain woven SiCf/SiC CMC was investigated, and damage accumulation and evolution process were studied in detail via acoustic emission (AE) method. With the increase of cycles, the material exhibits obvious hysteresis behavior affected by interfacial slip and wear mechanisms. Most of the fibers with radial fracture characteristic have relatively high strength, showing excellent toughening property. In the stepwise cyclic loading process, the Kaiser effect of AE determines the initiation of AE activities at each initial loading moment, which shows obvious nonlinear damage accumulation behavior of the material. High-energy events are related to significant matrix cracking and fiber fracture, and the evolution process of material damage initiation and propagation is monitored in real time.

A novel low-damage and low-abrasive wear processing method of Cf/SiC ceramic matrix composites: Laser-induced ablation-assisted grinding

• Laser-induced ablation-assisted grinding (LIAAG) method is first proposed. • C f /SiC composites occur chemical transformation, resulting in loose SiO 2 . • Grinding force and temperature are significantly reduced with laser ablation. • Surface morphology of C f /SiC composites shows as microfracture and crushing. • Cleavage fracture of diamond grain is reduced during LIAAG. Continuous fiber-reinforced ceramic matrix composites are promising materials for advanced hot end components and safety-critical components of aeronautics and astronautics; however, the difficult-to-process problem of these materials has been one of the technical bottlenecks restricting their high-performance service. The present work proposed a novel high-efficiency, low-damage, and low-abrasive wear processing method based on the chemical properties of the materials, which used lasers to ablate workpieces before grinding—laser-induced ablation-assisted grinding (LIAAG). The material removal mechanism of C f /SiC composites was investigated by single-grain scratching tests; the grinding performances of LIAAG in terms of grinding force, grinding temperature, surface integrity, abrasive wear, grinding chips were evaluated by a contrast abrasive belt grinding test. It was found that C f /SiC composites were chemically transformed into relatively loose and homogeneous ablation products (SiO 2 and recrystallized SiC) at high laser ablation temperatures, which were easier to remove during grinding. In this case, surface morphologies displayed the microfracture and crushing of carbon fibers and SiC matrixes, and the grinding-induced damages, such as macro fracture, fiber pull-out, interface debonding, were significantly contained. Abrasive belt was primarily worn in micro-adhesion and micro-abrasion, rather than cleavage fracture and the fall-off in traditional grinding. Under optimum parameters, the grinding force, grinding temperature, and average surface roughness of belt grinding were reduced by 47 %, 40 %, and 26 %, respectively. Consequently, the surface integrity was improved greatly, and the abrasive wear was reduced significantly. The work provides a vital high-performance processing method for ceramic matrix composites components.

Damage and failure analysis of a SiCf/SiC ceramic matrix composite using digital image correlation and acoustic emission

The analysis of failure behaviors of continuous fiber-reinforced ceramic matrix composites (CMCs) requires the characterization of the damage evolution process. In service environments, CMCs exhibit complex damage mechanisms and failure modes, which are affected by constituent materials, meso architecture, inherent defects, and loading conditions. In this paper, the in-plane tensile mechanical behavior of a plain woven SiC f /SiC CMC was investigated, and damage evolution and failure process were studied in detail by digital image correlation (DIC) and acoustic emission (AE) methods. The results show that: the initiation of macro-matrix cracks have obvious local characteristic, and the propagation paths are periodically distributed on the material surface; different damage modes (matrix cracking and fiber fracture) would affect the AE energy signal and can be observed in real-time; the significant increase of AE accumulated energy indicates that serious damage occurs inside the material, and the macroscopic mechanical behavior exhibits nonlinear characteristic, which corresponds to the proportional limit stress (PLS) of the material.

Material removal behavior of Cf/SiC ceramic matrix composites as a function of abrasive wear during diamond abrasive belt grinding

Continuous fiber-reinforced ceramic matrix composites are promising materials in aerospace, energy, transportation, and other fields due to their excellent thermodynamic properties. However, their high hardness, brittleness, and anisotropy cause great challenges to grinding, such as poor grinding quality, severe grinding wheel wear, and low grinding efficiency. In the present study, abrasive belts were used for the first time to grind Cf/SiC composites. The material removal behavior and abrasive wear of Cf/SiC composites were investigated by using two types of abrasive belts. It was found that diamond abrasive grains on the abrasive belts were worn in the form of falling off, cleavage fracture, micro-adhesion, and abrasive clogging. The electroplated diamond abrasive belt manifested better wear resistance and grinding performance than the bonded diamond abrasive belt. Carbon fibers and the SiC ceramic matrix were crushed and plastically deformed during abrasive belt grinding. The formation of flow chips and powder chips indicated that the ductile material removal of Cf/SiC composites was significant during abrasive belt grinding because of its flexible contact characteristics. Moreover, the ductile material removal behavior became more significant with the increasing abrasive wear intensity because of the strengthening of abrasive grain extrusion.

Thermal performance affected by the mesoscopic characteristics of the ceramic matrix composite for hypersonic vehicle

The rigorous thermal environment brought by long-time high-speed flight is imposed severe requirements on the structural bearing capacity and structural thermal safety of the aircraft. The integrated non-ablative thermal protection system based on continuous fiber-reinforced ceramic matrix composites is becoming a hot spot on the design of aircraft structures. However, the multi-scale, non-linear, non-uniform features of such materials, as well as complex thermal and mechanical characteristics, pose serious challenges to structural design and evaluation. Under the aero heating environment, the non-uniform temperature rising and thermal matching between different components in the continuous fiber-reinforced ceramic matrix composites are extremely complicated, which has a significant influence on the thermal safety performance of the structure. In this paper, based on the commonly used 3D orthogonal weaving process and the thermal characteristics prediction method of fiber bundles considering the effect of PyC interface layer, the fluid-structural strong thermal coupling characteristics of different woven parameters in typical aircraft structure is carried out. Quantitatively characterizing the heat transfer characteristics of this new material under the actual flight condition of the aircraft can further to improve the accuracy of the thermal property parameters obtained based on the ground test. The analysis results show that increasing the proportion of fiber bundles in a certain direction is the most effective method to increase the thermal conductivity in this direction. At the same time, the arrangement of the coupling yarns will also have a greatly influence on the thermal conductivity of the material. These results is of great significance for the design of the materials.

Mechanical Properties and Failure Behavior of 3D-SiCf/SiC Composites with Different Interphases.

Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiCf/SiC) are promising as thermal structural materials. In this work, the microstructure and static mechanical properties of 3D-SiCf/SiC with PyC, SiC, and PyC/SiC and without an interface prepared via polymer infiltration and pyrolysis (PIP) were investigated systematically in this paper. The results show that the microstructure and static mechanical properties of SiCf/SiC with an interphase layer were superior to the composites without an interlayer, and the interface debondings are existing in the composite without an interphase, resulting in a weak interface bonding. When the interphase is introduced, the interfacial shear strength is improved, the crack can be deflected, and the fracture energy can be absorbed. Meanwhile, the shear strength of the composites with PyC and PyC/SiC interfaces was 118 MPa and 124 MPa, respectively, and showing little difference in bending properties. This indicates that the sublayer SiC of the PyC/SiC multilayer interface limits the binding state and the plastic deformation of PyC interphase, and it is helpful to improve the mechanical properties of SiCf/SiC.

Effect of the distribution of lip-shaped matrix cracks in continuous fibre reinforced ceramic matrix composites on failure progress under transverse tension

ABSTRACT This paper develops a numerical model that contained random lip-shaped matrix cracks based on the maximum energy release rate criterion for the prediction of failure progress of Continuous Fibre-reinforced Ceramic Matrix Composites (CFCC) under transverse tension. Fibre distribution layout is created based on the actual microstructure and the Random Sequential Adsorption algorithm is used to generate the distribution of lip-shaped matrix cracks. The influence of the lip-shaped matrix crack distribution and crack density on the failure progress and stress–strain response was investigated. It was found that the onset of damage initiation commenced from the lip-shaped matrix crack when the interface fracture energy was smaller than the critical interface fracture energy. The failure progress and the predicted results were in good agreement with the experimental results. The different matrix cracks distribution affected the failure progress. Finally, the tensile strength and the elastic modulus both decreased with the crack density increasing.

Research progress of high temperature microwave-absorbing ceramic matrix composites

Microwave-absorbing ceramic matrix composites play an important role in the development of heat-resisting stealthy materials due to their excellent high-temperature mechanical property, superior corrosion resistance and oxidation resistance. In this paper, the micro to macromultiscale design principle of microwave-absorbing ceramics is introduced. The latest research progresses of microwave-absorbing materials such as modified SiC ceramics, doped BaFe12O19 (BFO) ceramics, polymer derived ceramics (PDCs), 3D printed porous ceramics/ceramic-honeycombs, multiscale-designed continuous fiber reinforced ceramic matrix composites (CFCMC) and other new ceramic matrix composites are overviewed. The development trend of ceramic matrix composites with integrated structure absorbing is prospected, and the fiber reinforced ceramic matrix composites with multiscale structure design of micro-macro is proposed to be an important development direction in the field of high-temperature stealth materials in the future.

Research progresses on multi-functional integration MAX phases modified continuous fiber-reinforced ceramic matrix composites

Research progresses on multi-functional integration MAX phases modified continuous fiber-reinforced ceramic matrix composites

A hysteresis energy dissipation based model for multiple loading damage in continuous fiber-reinforced ceramic-matrix composites

In this paper, a hysteresis energy dissipation based damage model for fiber-reinforced ceramic-matrix composites (CMCs) subjected to multiple loading stress levels is developed. Considering the combination effects of multiple loading sequences and multiple fatigue damage mechanisms, i.e., matrix cracking, fiber/matrix interface debonding and interface wear, the evolution of the fiber/matrix interface debonding and sliding, fatigue hysteresis loops, fatigue hysteresis dissipated energy and fatigue hysteresis modulus changing with increasing applied cycles are analyzed. The effects of fiber volume fraction, matrix crack spacing, fatigue peak stress and fatigue stress range on the damage development inside of CMCs are discussed. The difference of the fiber/matrix interface shear stress existed between the interface wear region and new interface debonded region affects the fiber/matrix interface debonded length and loading carrying ability of intact and broken fibers. The damage evolution for C/SiC and SiC/SiC composites subjected to multiple fatigue loading sequences are predicted using the hysteresis energy dissipation damage model. Under multiple loading stress, the fatigue hysteresis dissipated energy increases when high peak stress and stress range increases due to the increase of fiber/matrix interface sliding range. However, when the low peak stress increases, the evolution of fatigue hysteresis dissipated energy depends on the interface debonding and sliding state.

Modeling Multiple-Step Loading Damage Evolution in Continuous Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures

AbstractIn this paper, the multiple-step loading damage evolution in two-dimensional (2D) SiC/SiC ceramic-matrix composites (CMCs) at room and elevated temperatures and subjected to different appli...

Research Progress on Micro-mechanical Property of Continuous Fiber-reinforced Ceramic Matrix Composites

Research Progress on Micro-mechanical Property of Continuous Fiber-reinforced Ceramic Matrix Composites

Mechanical behavior of 2D and 3D weaved SiC-matrix, carbon-continuous-fibre-reinforced composites: Part 2. Fracture toughness under static loading conditions

Advanced materials such as Continuous Fibre-reinforced, Ceramic-matrix Composites (CFCCs) offer significant enhancements in variety of properties, especially tensile stress to fracture, flexural stress and most importantly, the fracture toughness (especially the propagation fracture resistance), as compared to their bulk monolithic counterparts. However till date, there are hardly any scientific studies reported in the open literature on the effects of fibre weaving conditions on the fracture toughness of carbon-fibre based advanced ceramic composites, where SiC is used as the matrix. The present paper discusses the fracture toughness behavior of these CFCCs in 2D and 3D woven conditions, obtained by static loading conditions using 3-point bend/flexural testing. Fracture behavior and principal fracture modes are also evaluated and analyzed to account for the differences in the fracture toughness properties. The variation in plain strain fracture toughness and elastic plastic fracture toughness is also compared. The study showed that the relative difference in the fracture toughness is more or less controlled by the nature of fracture, which is dictated by the differences in the fibre/matrix interface characteristics and to a greater extent by the weave condition.

Influence of Specimen Geometry and Surface Quality on the Bending Strength of Short Fiber-Reinforced C/SiC

For continuous fiber-reinforced ceramic matrix composites, there is an extensive knowledge of the influence of specimen geometry on the failure mode and the determined strength in bending tests. In contrast, there are almost no studies on this topic for short-fiber-reinforced CMC, and as a consequence no testing standard for bending tests for such materials exists. In the present work, the influence of the specimen cross-section and the span width on the calculated mean and variance of the bending strength of different short fiber CMC (C/SiC with 3 mm and 10 mm fiber length) were examined. Below a certain specimen cross-section a decrease of the determined bending strength was observed. The relationships between the orientation of fiber bundles in the loaded area of the bending sample, the region of failure initiation and measured failure stress was investigated by high resolution X-ray CT in order to obtain further insight into the causes of strength scatter in these materials. The effect of different surface qualities prepared by grinding and milling on the measured bending strength in short fiber C/SiC was found to be negligible.

Approach to evaluation of the overall strengthening and toughening effect of continuous fiber-reinforced ceramic matrix composites

Abstract Continuous fiber-reinforced ceramic matrix composites (CFCCs) are considered to be very promising thermal structural materials due to their strength and toughness. An approach for describing the strength and toughness of CFCCs based on knowledge of the toughening and strengthening mechanisms of CFCCs and analyses of the related energies during loading of CFCCs is proposed in the present work. Comparative analyses were undertaken on the mechanical properties of different CFCCs and the results of the proposed approach. Results showed that the proposed approach could be adopted simply and conveniently to evaluate the overall strengthening and toughening effect of CFCCs.

Nondestructive Evaluation of Microstructure of SiCf/SiC Composites by X-Ray Computed Microtomography

Continuous fiber-reinforced ceramic matrix composites (CFCCs) have a complex distribution of porosity, consisting of interfiber micro pores and interbundle/interply macro pores. Owing to the complex geometry of the pores and fiber architecture, it is difficult to obtain representative microstructural features throughout the specimen volume with conventional, destructive ceramographic approaches. In this study, we introduce X-ray computed microtomography (X-ray μCT) to nondestructively analyze the microstructures of disk shaped and tubular SiC f /SiC composites fabricated by the chemical vapor infiltration (CVI) method. The disk specimen made by stacking plain-woven SiC fabrics exhibited periodic, large fluctuation of porosity in the stacking direction but much less variation of porosity perpendicular to the fabric planes. The X-ray μCT evaluation of the microstructure was also effectively utilized to improve the fabrication process of the triple-layered tubular SiC composite.

Ultrasonic characterization of delamination in aeronautical composites using noncontact laser generation and detection

The characterization of delamination in composite plates with ultrasonic waves generated and detected by lasers is presented. Composite materials have become one of the most important structural materials in the aviation industry because of their excellent mechanical properties, such as high specific stiffness and antifatigue. This paper reports a new application of the laser ultrasonic technique to perform nondestructive detection of carbon-fiber-reinforced plastic (CFRP) and continuous-fiber-reinforced ceramic matrix composites (CFCCs) containing artificial internal defects, based on propagation characteristic of ultrasonic waves generated by pulse laser with a wavelength of 1064 nm and pulse duration of 10 ns. A laser interferometer based on two-wave mixing is used to measure ultrasonic wave signals. The main advantage of this technique over conventional ultrasonic testing techniques is the ability to carry out detection without using coupling agents. The research results prove that the laser ultrasonic technique is effective for the detection of internal defects in both CFRP and CFCC composite components, which should promote and expand the application of the technique in the aviation industry.