Carbon Fiber Reinforced Matrix Composite Research Articles

Multiscale numerical scheme on shear failure feature of 3DOWC/Cs bar incorporating microlevel uncertainties and coupled constitutive behavior

In contrast to prevalently utilized carbon fiber reinforced plastics (CFRP), the carbon fiber reinforced carbon matrix composites (C/Cs) frequently present significantly divergent mechanics features. The current investigation dedicates to a robust multiscale finite element strategy on shear failure characteristics of three-dimensional orthogonal woven C/Cs (3DOWC/Cs) bolt bar together with relevant experimental measurement for validation, while the off-axial orientation sensibility of structural load-bearing performance and damage mechanism are systematically evaluated. In view of the complicated internal fabric architecture, the predictions are received via hierarchical numerical simulation at micro-, meso-, as well as macroscales. The random distributions of voids and fibers are incorporated to precisely capture the material properties, meanwhile the constitutive laws which embed the combining of Hashin and Puck criterions judging for yarn initial damage, multilinear rule for carbon matrix, and trilinear cohesive zone model (CZM) for interface, are implemented to render the coupling impacts of material behaviors. Besides, the extracted global load-displacement curves and local progressive failure morphologies from macroscale simulation are separately compared with experimental acquisitions to verify the accuracy of proposed modelling and to expose the damage mechanism of specimens with various off-axis angles. The contribution of this research lies in accurate quantification for microlevel uncertainties via modified stochastic algorithms, and applicable constitutive frame severally matching each material component to portray the distinctive mechanical particularities of 3DOWC/Cs.i

Synthesis, structure, and properties of carbon/carbon composites artificial rib for chest wall reconstruction

In this work, braided carbon fiber reinforced carbon matrix composites (3D-C/C composites) are prepared by chemical vapor infiltration process. Their composite structure, mechanical properties, biocompatibility, and in vivo experiments are investigated and compared with those of traditional 2.5D-C/C composites and titanium alloys TC4. The results show that 3D-C/C composites are composed of reinforced braided carbon fiber bundles and pyrolytic carbon matrix and provide 51% open pores with a size larger than 100 μm for tissue adhesion and growth. The Young’s modulus of 3D-C/C composites is about 5 GPa, much smaller than those of 2.5D-C/C composites and TC4, while close to the autogenous bone. 3D-C/C composites have a higher tensile strength (167 MPa) and larger elongation (5.0%) than 2.5D-C/C composites (81 MPa and 0.7%), and do not show obvious degradation after 1 × 106 cyclic tensile loading. The 3D-C/C composites display good biocompatibility and have almost no artifacts on CT imaging. The in vivo experiment reveals that 3D-C/C composites artificial ribs implanted in dogs do not show displacement or fracture in 1 year, and there are no obvious proliferation and inflammation in the soft tissues around 3D-C/C composites implant. Our findings demonstrate that 3D-C/C composites are suitable for chest wall reconstruction and present great potentials in artificial bones.

Comparison of microstructure and ablation behavior of Si-Mo-Ti/Al/Zr infiltrated C/C composites prepared at different infiltration temperature

In order to produce an anti-ablation composite for high temperature structure applications, porous carbon fiber reinforced carbon matrix composites(C/C) have been infiltrated by mixed Si-Mo-X powder (X=Ti, Al, Zr) at different temperature. Microstructure and ablation behavior of the infiltrated composites have been investigated and compared. The results show that composites infiltrated at higher temperature are denser with Ti addition while composites infiltrated at lower temperature are denser with Al or Zr addition. Distribution of ceramic phases in the infiltrated composites is determined by the infiltration process. Three distinct kinds of interface between carbon and ceramic phases can be distinguished according to the chemical compositions of the ceramic phases. Furthermore, a multi-step infiltration model is proposed according to the distribution of ceramic phases and analysis of interface. Composites infiltrated at lower temperature by Si-Mo-Ti and Si-Mo-Zr powder exhibit better ablation resistance, which mainly benefits from their phase compositions.

Anti-Ablation Property of MoSi<sub>2</sub> Coatings Deposited by APS

Carbon fiber reinforced carbon matrix composites (C/C) have received much attention due to their excellent high-temperature strength, high thermal conductivity, low coefficient of thermal expansion (CTE), good thermal shock resistance. However, the poor ablation resistance of the C/C restricts its high temperature ablating applications. Making a thin anti-ablation coating on the C/C has been proved to improve the performance effectively. In order to improve the anti-ablation property of the composite, MoSi2 coatings were deposited by Atmosphere Plasma Spraying (APS) on the SiC covered C/C matrix. The SiC coatings were prepared by pack cementation. Oxyacetylene flame torch was selected to simulate the ablation situation. The ablation temperature was 1800°C. XRD and SEM were employed to discover the diversification of the coatings structure and composition. And the mechanism of anti-ablation of the MoSi2 coatings system was investigated in this paper.

Cure kinetics and thermal stability of multifunctional epoxy/anhydride containing release agent and carbon fiber

The investigations were carried out into the cure kinetics and thermal stability of multifunctional epoxy/anhydride/imidazole/release agent system (matrix) and carbon fiber reinforced matrix composite. Two experimental techniques were applied: dynamic differential scanning calorimetry (DSC) at different heating rates, and non‐isothermal thermogravimetric analysis (TGA). The results were indicated that the two‐parameter model was found to describe the cure kinetics for the matrix and the composite. The kinetic parameters such as pre‐exponential factor, apparent activation energy, and reaction orders were calculated. And, the carbon fiber had a significant effect on the apparent activation energy and the thermal stability. POLYM. COMPOS., 35:596–601, 2014. © 2013 Society of Plastics Engineers

Wear of carbon fiber reinforced carbon matrix composites: Study of abrasive, oxidative wear and influence of humidity

The wear of C/C composites has been studied using a subscale aircraft brake dynamometer linked with a mass spectrometer. A disc-on-disc configuration allowed for simulation of various aircraft landing energy conditions (12.5%, 25%, 50%, and 100% of normal landing energy of a Boeing 737 aircraft) performed at 50% and 90% relative humidity levels. The microstructure of composite brakes was altered by applying three different heat treatment temperatures: 1800, 2100, and 2400°C, respectively. A mass spectrometer linked to an environmental chamber of the subscale dynamometer was utilized to measure the in situ CO2 release during the wear tests. The relationships between microstructure, hardness of individual components of composites and wear performance at varied conditions are presented. Carbons obtained at higher heat treatment temperatures are most vulnerable to abrasive wear, while the less ordered carbons, typical for samples heat treated at lower temperatures, showed significant amount of oxidative wear. Oxidative wear was related to excessive heating of materials. Optimization of wear behavior of C/C composite is only possible by understanding the mechanisms of the microstructural changes of materials, corresponding mechanical properties and the nature of wear under various environmental conditions.

Full-field analysis of notch effects of 3D carbon/carbon composites

Carbon fiber reinforced carbon matrix composites (C/Cs), as important candidate aviation and aerospace materials, have good prospects for application in extreme environments. However, notch effects of C/Cs have not been studied adequately. In this work, the notch effects of 3D-C/C composites were investigated by the full-field measurement digital image correlation method. Six kinds of specimens with different notch patterns including one central hole, multi-holes, and double edge notches, were examined to analyze their mechanical properties. The tests were carried out on MTS 809 testing machine and the deformations of specimens were monitored by a CCD camera. Using the full-field measurement, both the local mechanical properties (stress concentration, shear damage, and fracture behavior) and the globe properties (notch sensitivity and tensile behavior) were studied. The results indicated that the fracture stress on the net cross section was constant and it was independent on the material heterogeneity, notch patterns, and notch depth.

Microstructure and tribological behaviors of C/C–BN composites fabricated by chemical vapor infiltration

In this paper carbon fiber reinforced carbon–boron nitride binary matrix composites (C/C–BN) were prepared by chemical vapor infiltration (CVI). The infiltration of BN in the CVI process was controlled by the diffusion of BCl3, and BN matrix was distributed homogeneously in the porous carbon fiber reinforced carbon matrix composites (C/C) due to the good infiltration ability of BN. The as-received C/C–BN composites were composed of 92vol% C and 8vol% BN. Both the friction coefficient and wear rate of C/C composites decreased significantly by the incorporation of BN. After heat-treated at 1600°C, the interlayer spacing of CVI BN decreased to 3.36Å, and CVI BN with high crystalline degree displayed the excellent lubricating effect, leading to the decrease of friction coefficient and wear rate. The improvement of the tribological properties also was partially attributed to the improved oxidation resistance and the formation of friction film by the incorporation of BN matrix.

Carbon-carbon materials and composites for experimental tracheal reconstruction

The Carbon fiber reinforced carbon matrix composites were employed for reconstruction of large circumferential defect of the cervical trachea. The biocompatibility and biofunctionality of the new type carbonaceous tracheal prosthesis were evaluated, and the feasibility for cervical tracheal reconstruction discussed. Two types of carbonaceous tracheal prosthesis with different weaving methods of carbon fiber were used on eight healthy canines. Three to six tracheal cartilage rings were resected circumferentially. The 2 cm long tracheal prosthesis was transplanted into canines and the anastomosis was completed by end-to-end, tracheal-into-prosthesis and prosthesis-into-tracheal method. The function of breathing, eating and infection was observed after surgery. Four months later, the five survival canines were sacrificed and the prosthesis with surrounding tissues was removed for observation by optical microscopy and scanning electron microscopy. All dogs had cough symptom in different degree lasted 1 - 4 weeks after surgery. Two dogs with tracheal-into-prosthesis anastomosis showed eating disorders in different degree. One canine died due to airway obstruction caused by dislocation of prosthesis within three weeks after operation. Another two deaths in 11th week and 12th week were attributed to suffocation because of hypergranulation and scar formation. Prosthesis was surrounded by connective tissues and anchored firmly to the neighboring tissues. Most part of the luminal surface of tracheal prosthesis was not covered by respiratory mucosa. However, the inner layer showed scant re-epithelialization beyond the anastomosis. The implantation of the carbonaceous tracheal prosthesis can maintain the normal respiratory function of the experimental canines, but hypergranulation and scar formation around the end of the tracheal prosthesis and epithelium on the luminal surface of the prosthesis are questions still remained to be solved.

Buckling Fracture of Two-Dimensional Carbon-Fiber Reinforced Carbon-Matrix Composite

Due to excellent high temperature resistivity on the strength, carbon fiber reinforced carbon matrix composites are thought to be one of attractive materials in a nuclear engineering field, e.g. the application to control rod sheath and so on in high temperature gas-cooled reactors as well as plasma facing components in fusion reactors. Prevention of the buckling fracture is placed as one of key subjects in the component design of C/C composites. The buckling fracture test was, therefore, carried out using 2-dimensional C/C composite (2D-C/C composite), and fracture surfaces were observed by SEM. From the buckling fracture test, it was found that there are three kinds of fracture modes; i.e. delamination fracture mode of fiber bundles at low aspect-ratio region, shear fracture mode of fiber bundles at middle aspect-ratio region and shear fracture mode of fiber bundles accompanying by fiber buckling at high aspect-ratio region.

Fatigue behavior of 2D laminate C/C composites at room temperature

Fatigue behavior was examined for three kinds of carbon fiber reinforced carbon matrix composites (C/Cs). The fatigue-tested materials included unidirectionally reinforced (UD), symmetric cross-ply laminated (CP) and symmetric quasi-isotropically laminated (QI) C/Cs. The fatigue fracture behavior of the C/Cs was classified into three regions based on applied strain, irrespective of the C/C types. In high applied strain region, fatigue fracture occurred in the same manner as in the static tensile tests. In the second region, where the applied stress is up to the fatigue limit, the strength of the C/Cs decreased slightly due to the degradation of the fiber strength caused by frictional wear along the fiber/matrix interface. The third region was at lower applied strain than the fatigue limit, in which no fatigue fracture occurred and the residual strength was recovered and sometimes enhanced due to damage at the fiber/matrix interface.

Focused ion beam preparation techniques dedicated for the fabrication of TEM lamellae of fibre-reinforced composites

Two Focused Ion Beam based transmission electron microscopy (TEM) thin film preparation techniques are introduced. One is dedicated to the preparation of single fibres, the other to fibre/matrix interfaces of fibre reinforced composites. Due to their thin film quality, reliability and predictable processing times both techniques are suited for routine applications in material science like TEM studies of fibre microtextures and fibre/matrix interfaces. Exemplarily they are applied to Carbon Fibres and Carbon Fibre reinforced Carbon Matrix Composites (C/C). The achieved preparation standard in both cases is substantiated by TEM investigations.

Detection of deep-lying defects in carbon fiber composites using SQUID-NDE system cooled by a cryocooler

In this paper, we present our latest progress in the studies on SQUID-NDE for carbon fiber composites (CFCs), including carbon fiber reinforced plastics (CFRPs) and carbon fiber reinforced carbon matrix composites (C/Cs). We have developed a new SQUID-NDE system for the CFCs utilizing a pulse tube cryocooler for more practical and easy-handling use. Electromagnets using U-shaped ferrite cores have been introduced to the system in order to induce enough eddy current density in the relatively low-electric-conductivity CFCs. By using this system, we demonstrated the detection of deep-lying defects in thick and/or multi-layer CFCs specimens, partly including metal layer upon/below CFCs layer. CFRP plates and multi-layer C/C plates with total thickness of 20 mm having deep-lying slots at various depths were prepared. The slots at 15 mm below the surface in the CFRP plate and multi-layer C/C plate were successfully detected. Defect detections on more “real” multi-layer structures, including aluminum plates upon/below C/C plates, were also examined.

Influence of fibre–matrix interface on the fracture behaviour of carbon-carbon composites

Abstract This paper studies the fracture behaviour of unidirectional carbon fibre reinforced carbon matrix composites and its relation with the type of fibre–matrix interface developed in the composite. Model unidirectional carbon–carbon composites were prepared using the same type of fibre and different pitches as matrix precursors. These included both commercial pitches and synthesized in the laboratory ones. The chemical composition of the matrix precursor determined the type of microstructure developed in the composite, this microstructure seems to govern the fibre-matrix bonding and in turn controls the fracture behaviour of the composite. In general, a matrix texture of mosaic (small size) seems to yield a good fibre-matrix bonding, making the materials to have higher interlaminar shear strength but having at the same time brittle fracture behaviour. On the other hand, composites where larger textures were developed in the matrix seem to have a poorer fibre-matrix bonding. This made the composites to have lower strength, but it allowed debonding of fibre and matrix during fracture. As a result, these materials showed pseudo-plastic failure behaviour. Other examples of both types of fracture behaviour associated with the change in microstructure and fibre–matrix interface are discussed.

Effect of Controlled Oxidation on Bending and Interfacial Shear Strength of 3-D Woven SiC Fiber Reinforced Carbon Matrix Composites

Effect of Controlled Oxidation on Bending and Interfacial Shear Strength of 3-D Woven SiC Fiber Reinforced Carbon Matrix Composites

Fracture toughness and fiber bridging of carbon fiber reinforced carbon composites

A fracture mechanics study is reported for two different types of carbon fiber reinforced carbon matrix composites, a short-fiber felt composite and a satin weave laminated-composite. It is emphasized prior to discussing their fracture mechanisms that the first matrix cracking is the most important fracture process in these C/C composites. Fiber pull-out and bridging processes in the wake of the propagating crack tip are discussed in relation to experimental R curves. The bridging tractions are estimated by the Dugdale model, from which the fiber bridging-enhanced toughening in lamina composites is demonstrated.