T700 Carbon Fiber Research Articles

Study on thermal stability of typical carbon fiber epoxy composites after airworthiness fire protection test

SummaryThe thermal stability of the T700 carbon fiber epoxy composites, which had been tested under different conditions (nonvibration plus nonscrubbing airflow, vibration, scrubbing airflow, and vibration plus scrubbing airflow), were investigated according to the obtained weight loss behavior, integral program decomposition temperature (IPDF), and activation energies (E) by using thermogravietry‐differential thermal analyzer. The results indicate that the weight loss ratio, IPDF, and E of T700 carbon fiber epoxy and its residues in the third and fourth layers are similar under the nonvibration plus nonscrubbing airflow and vibration, and the thermal stability under the vibration condition is slightly stronger. In addition, the weight loss ratio, IPDF, and E of the epoxy and its residues in materials are also similar under scrubbing airflow and vibration plus scrubbing airflow, and the thermal stability under vibration plus scrubbing airflow is better. However, it is significantly less than the thermal stability of materials under nonvibration plus nonscrubbing airflow and vibration. Therefore, it can be found that the vibration exacerbates the flame severity and the scrubbing airflow has a significant cooling effect on the material during the airworthiness fire protection test, which have guiding significance on the airworthiness fire prevention items formulation of carbon fiber composite.

Applicability of mode II interlaminar fracture toughness testing methods for characterization of thermoplastic laminates with woven fabric reinforcements

The scope of both existing standardized methods for the determination of quasistatic mode II interlaminar fracture toughness, ASTM D7905/D7905M – 14 and ISO 15114:2014, is limited to testing laminates with unidirectional reinforcement. Furthermore the precision round-robins conducted as a part of the development of these procedures focused mainly on laminated with epoxy resin matrix. This paper compares the testing methods for quasistatic mode II interlaminar fracture toughness with the focus on their applicability to testing thermoplastic laminates with woven fabric reinforcement.Two standardized testing methods were used to determine the mode II fracture toughness of a laminate made of polyether ether ketone matrix reinforced with T300 carbon fibers in the form of 5 harness satin woven fabric. The testing methods were compared in terms of the set-up complexity, testing efficiency, the data reduction methods, the type of properties determined, the results scatter and the applicability to testing thermoplastic-based laminates with woven fabric reinforcement. The methods produced similar and consistent results. Both of them can be successfully applied to testing thermoplastic laminates with woven fabric reinforcement after including modifications discussed in the paper.

Tensile Fracture Behavior of Carbon Fiber/Al Composites Produced by the Liquid Extrusion Infiltration Technique

The liquid extrusion infiltration technique was used to fabricate two 2D CF/Al composites with T700 and T300 carbon fiber fabrics. Microstructure examination demonstrated their different macroscopic infiltration morphology, but the infiltration effect was perfect. The coefficient of thermal expansion of those two composites was shown to be much lower than that of the matrix alloy below 673 K (400°C). At a temperature higher than 673 K (400°C), this value for a T300 CF/Al composite was equivalent to only 22.6%, which was much smaller than that of the matrix alloy. The ultimate tensile strength of T700 CF/Al and T300 CF/Al composites was improved by factors of 2.007 and 2.467 than that of the matrix alloy, respectively. The differences in the thermal expansion coefficient and ultimate tensile strength stem from carbon fiber volume fractions and its grades of the two different fabrics. The fracture morphology of tensile specimens was also influenced by the fiber orientation in fabrics. A T300 CF/Al composite displayed better tensile and thermal expansion properties than a T700 CF/Al composite, which were prepared and designed for further industrial applications.

Microstructure and thermal expansion behavior of a novel Cf-SiCNWs/AZ91D composite with dual interface

Abstract In this study, a novel composite with dual interface, namely T-700 carbon fibers grafted with SiCNWs reinforced AZ91D (Cf-SiCNWs/AZ91D), was designed. The microstructure of the Cf-SiCNWs/AZ91D composite was fully characterized and its thermal expansion behaviors from 25 to 450 °C investigated. The results show that the Cf-SiCNWs/AZ91D has dual interface of Cf/AZ91D and SiCNWs/AZ91D. In the alloy matrix, the nanowires are uniformly distributed without any agglomerates and showing a good bond with the matrix. Near the interface of SiCNWs/AZ91D, considerable dislocations were observed, which can be attributed to the different thermal expansions of SiCNWs and AZ91D matrix. It was found that the thermal expansion behavior of the Cf-SiCNWs/AZ91D composite was significantly influenced by its interfacial configuration, which can reduce the coefficients of thermal expansion and improve the stability of the composite.

English

The main objective of this study is to investigate the effect of meteorites and debris impact on thermal fatigue life of unidirectional T700 carbon fiber/epoxy composite material. This composite material may be applied in space structures for space missions. These structures are exposed to thermal cycles as they go in and out of the planet’s shadow. If in this environmental condition, meteorites and debris impact with the structure, they may have effect on the thermal fatigue life of the structure. It means that the impact may decrease or increase the thermal cycles to failure of the structure in the presence of meteorite and/or debris. In this study, by applying experimental results and using analytical method attempt was made to estimate the thermal fatigue life in the presence of meteorite and/or debris impact, and thermal cycle condition. The results of this research can contribute to predict the thermal fatigue life in the presence of debris and/or meteorites impact to structure in possible future space missions. Furthermore, the results of this study have shown that the impact of debris and/or meteorites can increase the interlaminar shear stress between the T700 carbon fiber and epoxy which may result in crack formation and decrease the thermal fatigue life. Key words: T700 carbon fiber, meteorite and debris, space structures, thermal fatigue life, impact effect, unidirectional composite. &nbsp

Thermal Properties of Carbon Plastics

T-700 (Toray) and UMT 45-12K-EP (Umatex) carbon fibers and resin-impregnated reinforcing fabrics (prepregs) based on them are investigated by thermogravimetric analysis and differential scanning calorimetry. By thermogravimetric analysis of carbon fibers from different manufacturers and prepregs prepared with different time–temperature profiles, the content of volatiles is determined, along with possible prepreg structures and the content of carbon fibers. The influence of carbon fibers from different manufacturers on the characteristic temperatures of the epoxy binder and the binder content in the prepreg is assessed. Thermogravimetric analysis shows that, for UMT 45-12K-EP carbon fibers, the content of oxygen-bearing surface complexes is higher than for T-700 carbon fibers. In the prepreg based on T-700 carbon fibers, the content of epoxy binder is about 35%, which is 4–5% higher than for prepregs based on UMT 45-12K-EP carbon fibers. That indicates different wettability of the fibers from different manufacturers.

Acoustic-Emission Testing of Failure in Samples of CFRP Exposed to Static and Heat Loads

The results of testing samples made of T700 carbon fiber reinforced plastic with a stress concentrator in the form of a hole 14 mm in diameter are considered. Some of the samples were heated to a temperature of +100°C, followed by exposure to a static tensile load, with the remaining samples statically loaded at a temperature of +20°C. In the process of loading, information was recorded using the method of acoustic emission. At first, the samples were loaded statically up to 50 kN, which was 50% of the average breaking load. Then the load was increased in increments ΔP = 10 kN until sample failure. It was observed that the simultaneous exposure of samples to static and heat loads decreased the load capacity of the samples.

Effect of fiber heat treatment on microstructure and mechanical properties of 2.5D T700 carbon fiber reinforced SiC composites

T700 carbon fibers were heat treated at 1300 °C and 1600 °C to investigate the effect on microstructure of pyrolytic carbon (PyC) interphase and mechanical properties of 2.5D T700 carbon fiber reinforced SiC (2.5D Cf/SiC) composites, and the untreated carbon fiber acts as a comparison. The flexural strength was measured using three-point bending test and the fracture toughness was evaluated by a single-edge notched beam test. Results show that heat treatment at 1300 °C leads to highest mechanical properties of 2.5D Cf/SiC composites, with the flexural strength in warp direction of 248.6 ± 12.3 MPa, the flexural strength in weft direction of 421.6 ± 15.1 MPa, and the fracture toughness of 18.7 ± 1.7 MPa · m1/2. Nevertheless, both the unheated and heat treatment at 1600 °C result in a decrease in mechanical properties. The microstructural investigations revealed that the bonding strength between the carbon fiber and PyC is best when the heat treatment of carbon fiber at 1300 °C.

Influence of the hybrid ratio and stacking sequence on mechanical and damping properties of hybrid composites

A study on the correlation between the performances and configurations of plain weave composites reinforced by T300 carbon and aramid fibers is presented in this paper. Laminations with various hybrid ratios and stacking sequences were fabricated by vacuum‐assisted resin transfer molding (VARTM), and then tensile, flexural, interlaminar shear, and damping properties were investigated. The results indicate that the tensile modulus of hybrid composites is determined only by hybrid ratio, while tensile strength is also affected by stacking sequence at an identical hybrid ratio. The concentration of carbon fibers in the center of these configurations leads to a greater tensile strength. For flexural properties, obvious classification characteristics are observed in the load–displacement curves, and both flexural modulus and strength are determined by the stacking sequence. While the flexural properties of all configurations are insensitive to the hybrid ratio, a structure of “Carbon/Aramid” in the outer layer is shown to be detrimental to flexural strength. The study on the damping property shows that both hybrid ratio and stacking sequence have a great influence on the loss factors of these composites. The effect of hybrid interface in energy consumption cannot be ignored, as the interlaminar shear strength test demonstrates that the interface between carbon and aramid layers is superior to that of pure aramid layers. POLYM. COMPOS., 40:2368–2380, 2019. © 2018 Society of Plastics Engineers

Evaluation of the effect of PyC coating thickness on the mechanical properties of T700 carbon fiber tows

Nanostructured uniform pyrolytic carbon (PyC) coatings with different thicknesses were prepared on surface of T700 carbon fiber by chemical vapor deposition (CVD). The effect of coating on tensile strengths of the carbon fibers was studied by tow tensile strength test. The morphological change, roughness, microstructures, and thermal stability of carbon fibers with PyC coating (PyC-Cf) were investigated by SEM, AFM, XRD, Raman, and Tg. It was found that with increase of the deposition time, the thickness of coating varied from 100 to 320 nm with increase in coating surface roughness. The coating adhered well with the carbon fiber substrates and the coating thickness is uniform. The oxidation resistance of PyC-Cf was significantly higher than uncoated carbon fibers. However, the fiber became brittle after the coating and the coating is very sensitive to tensile stresses, which decreased the tensile strength of the fiber tows. The tensile strength measurement revealed that the carbon fiber with a 100 nm thickness of PyC coating maintained ∼69.4% of its original strength, and the 320 nm thickness of PyC-coated fibers showed the lowest strength because of the embrittlement caused by the PyC coating.

Synthesis and characterization of silicon-containing arylacetylene ether of bisphenol a resins and their composites

Two novel resins, silicon-containing arylacetylene ether of bisphenol A (PSAP-A) and 1, 3-diethynylbenzene-terminatedsilicon-containing arylacetylene ether of bisphenol A (DPSAP-A), were synthesized from dipropargyl ether of bisphenol A (BADPE) and dimethyldichlorosilane through Grignard reaction. The structures of the resins were characterized by protonnuclearmagnetic resonance(1H-NMR), and thermal properties was explored by thermogravimetric analysis(TGA)and dynamic thermo-mechanical analysis (DMA). In addition, T300 carbon fiber(T300CF) reinforced PSAP-A composite (T300CF/PSAP-A)and T300 carbon fiber reinforced DPSAP-A composite (T300CF/DPSAP-A) were prepared by a solution-impregnation process using tetrahydrofuran as solvent. The results showed that the cured PSAP-A resin and DPSAP-A resin displayed good heat resistance and processing properties. Degradation temperatures of the cured PSPA-A resin and DPSAP-A resin at 5% weight loss (Td5) were 421.5°C and 486.3°C, respectively. The flexural strengths of T300CF/PSAP-A and T300CF/PSAP-Acomposites reached 458.2 MPa and 287.6 MPa, respectively.

Strength Characteristics of the Filaments and a Basalt Fiber Roving at Different Clamping Lengths and Deformation Rates

The strength properties of filaments and a basalt fiber roving of industrial production were investigated at different clamping lengths and deformation rates. The deformation rate for filaments was varied from 1 to 20 mm/min, but the clamping lengths selected were 10, 20, 30, and 50 mm. No clamping-length-dependence of strength parameters of the roving in the range of 350-600 mm was detected. The results found for basalt fiber filaments were compared with published data for Kevlar29 aramid, T300 carbon, and Advantex glass fiber filaments.

Carbon fiber reinforced ceramic matrix composites with an oxidation resistant boron nitride interface coating

Toughening a ceramic in a ceramic matrix composite (CMC) depends on an ability of the composite to tolerate an accumulation of matrix cracks. When the reinforcement phase is carbon fiber, these cracks leave the fiber susceptible to destructive oxidation by ingress of air during high temperature exposure. Generally, a graphitic carbon interface coating is applied to carbon fibers because it provides for a weak bond between fiber and matrix that is required to promote toughening. This investigation seeks to utilize a BN coating instead of a C coating in order to promote oxidation resistance. Like graphitic carbon, BN is soft and easily cleavable. Preliminary observations that C/BN/SiC CMC's using Toray T300 carbon fibers were highly brittle and of low strength lead to a requirement of heat treating the fibers prior to the CVD of BN for toughened composites to be fabricated. It is likely heat treating removed reactive functionalities from the fiber surface to yield a weakly adhered and compliant interface.

Effect of Thermal Cycles on the Thermal Expansion Behavior of T700 Carbon Fiber Bundles

The relationships between the coefficient of thermal expansion(CTE) of T700 carbon fiber bundles(CFBs) and the thermal cycles were investigated. The microstructure of T700 CFBs was analyzed with Raman spectra and XRD before and after the thermomechanical test. The results indicated that the T700 CFBs exhibited negative expansion in the direction of parallel fibers in the temperature range of‒150―150 °C. The thermal strain that occurred during the heating and the cooling thermal cycle had an unclosed curve that served as the loop. When the experimental load was the same, the position of strain loop tended to move upward, and the length of the specimen increased continuously with the thermal cycles increasing. The microstructural analysis suggested that the degree of structural order and the degree of orientation along the fiber axis were improved with the increase of thermal cycles. The change of microstructure parameters could be the primary cause of the negative CTE’s variation within the T700 CFBs.

Study on interfacial and mechanical improvement of carbon fiber/epoxy composites by depositing multi-walled carbon nanotubes on fibers

To improve the interfacial properties between carbon fiber (CF) and epoxy resin (EP), T300 carbon fibers were coated with multi-walled carbon nanotubes (MWCNTs) using aqueous suspension deposition method. The carbon fiber/epoxy laminated composites were prepared by molding process. The wettability and interfacial properties between MWCNTs deposited carbon fibers (MWCNTs-T300) and EP were studied. The mechanical properties of carbon fiber/epoxy laminated composites were tested, and the mechanism of the interface strengthening was discussed. The results show that the surface energy of T300 carbon fiber is obviously increased after MWCNT deposition. The contact angle between MWCNTs-T300 and EP is reduced, and the interfacial energy and adhesion work are greatly improved. The MWCNTs-T300/EP laminated composites have excellent mechanical properties, the flexural strength is 822 MPa, the tensile strength is 841 MPa, and the interlaminar shear strength (ILSS) is 25.68 MPa, which are increased by 15.1%, 17.6% and 12.6% compared with those of the original carbon fiber/EP laminated composites (original T300/EP) respectively. The MWCNTs-T300/EP composites have good interface bonding performance, low porosity and uniform fiber distribution. Interfacial friction and resin toughening are the main mechanisms for the interface enhancement of MWCNTs-T300/EP composites.

On the Oxidative Ablation and Mechanical Properties of T300 Carbon Fibers at Elevated Temperatures

Abstract Carbon fibers are the main component and load carrier within many high-temperature composites. Oxidative ablation of carbon fibers is the main failure mechanism of high-temperature composites and significantly affects the mechanical properties of the composites. The effects of the ablation of carbon fiber at high temperatures on carbon fiber mechanical properties, nevertheless, have not been systematically studied in the available literature. In the present investigation, the oxidative ablation behavior of carbon fibers from room temperature to 900°C has been systematically investigated by employing a thermogravimetric analyzer and in situ video detection. Detectable carbon fiber weight loss was initiated when the temperature was elevated to 600°C within the air environment. The video images showed that the color of the carbon fiber surfaces changed dramatically and then the fibers disappeared gradually, indicating that the carbon fibers underwent a chemical reaction, i.e., oxidative ablation. The static mechanical strength of carbon fiber at various temperatures was investigated and was found to start decreasing significantly at temperatures above 500°C, even though no obvious oxidative ablation occurred. X-ray photoelectron spectroscopy (XPS) and Raman spectrum reveal that the microstructure transition from graphite to nongraphite carbon is the main reason for strength reduction.

Compression test of a single carbon fiber in a scanning electron microscope and its evaluation via finite element analysis

A longitudinal compression test for a single polyacrylonitrile-based carbon fiber (T300) was performed using a scanning electron microscope. The compressive stress/strain behavior was initially linear, but subsequently became nonlinear. The longitudinal tangent modulus decreased with increasing compressive strain. A cyclic compression test revealed that the T300 carbon fiber deformed elastically up to ~90% compressive strength. The variability in the compressive strength was evaluated using Weibull analysis. The representative compressive strength of the T300 carbon fiber was nearly the same as the tensile strength. The compressive strength of the T300 carbon fiber was almost same as that of the high-tensile strength T800S carbon fiber. Finite element analysis was performed to investigate the validity of the test method. The results showed that the longitudinal compressive stress on the carbon fiber varied during longitudinal compressive loading. The maximum longitudinal compressive stress in the carbon fiber was slightly higher than the average compressive strength applied at the end. However, the variability in the measured compressive strength was much higher than that in the longitudinal compressive stress on the carbon fiber, which does not affect the former.

Effect of Load on the Thermal Expansion Behavior of T700 Carbon Fiber Bundles.

T700 carbon fiber bundles (CFBs) are the primary material used for manufacturing cable-net in a deployable antenna. In this paper, the relationships between the coefficient of thermal expansion (CTE) of T700 CFBs and the experimental load were investigated. The microstructure of T700 CFBs was analyzed with Raman spectra and XRD before and after the thermomechanical test. The measured results indicated that the T700 CFBs that were parallel to the axis had negative expansion characteristics when in a temperature range of −150–+150 °C. The thermal strain that occurred during the heating and the cooling thermal cycles had an unclosed curve that served as the loop. When the thermal cycles were the same, the position of the strain loop and the length of the sample exhibited regular change. The average of the CTEs decreased as the experimental load increased. The microstructural analysis suggested that the degree of structural order and the degree of orientation along the fiber axis improved with the experimental load increase. The change of microstructure parameters could be the primary cause of the negative CTE’s variation within the T700 CFBs. The experimental results provide some guidelines for improving the cable-net material selection.

Small angle X-ray scattering study of microvoid evolution and pertinence of microvoid and mechanical properties in γ-irradiated CFs.

To explore the mechanism of microvoid evolution and the pertinence of microvoid and mechanical behavior of carbon fibers (CFs) in γ-irradiation, T700 CFs were exposed to γ-rays under epoxy chloropropane (ECP) and argon (Ar) at room temperature. The results from small angle X-ray scattering (SAXS) showed that the average microvoid radius of the CFs decreased gradually from 4.8406 nm for pristine fibers to 3.6868 nm (ECP) and 3.4223 nm (Ar), indicating that γ-irradiation could obviously decrease the microvoid in CFs owing to annealing and rearrangement effects. More significantly, active media would enlarge the surface microvoid of fibers, thus the microvoid of CFs irradiated in ECP was overall larger than that in Ar. The tensile strength of CFs was increased from 5.74 GPa for the pristine fibers to 6.78 GPa (Ar) and 6.18 GPa (ECP) for the irradiated CFs along with a decrease in the microvoid. Therefore, this would provide a key to investigate the evolution of the CF microvoid during γ-irradiation, which was conducive to improving the mechanical properties of γ-irradiated CFs.

Stress analysis and fracture toughness of notched polyacrylonitrile (PAN)-based and pitch-based single carbon fibers

The stress analysis and fracture toughness of high tensile strength polyacrylonitrile (PAN)-based (T1000GB, IMS60, and T300), high modulus PAN-based (M60JB), high modulus pitch-based (K13D), and high ductility pitch-based (XN-05) single carbon fibers were investigated using notched specimens and a focused ion beam. The maximum stress of T1000GB, IMS60, T300, M60JB, K13D, and XN-05 single fibers was calculated as 30.5, 29.4, 25.6, 44.3, 68.6, and 15.5 GPa, respectively. The critical stress intensity factor of T1000GB, IMS60, T300, M60JB, K13D, and XN-05 single carbon fibers was calculated as 1.91, 1.82, 1.67, 3.09, 4.84, and 1.02 MPa m1/2, respectively. The critical energy release rate of T1000GB, IMS60, T300, M60JB, K13D, and XN-05 single carbon fibers was calculated as 478, 502, 763, 3064, 13266, and 237 J/m2, respectively. These results indicate that a linear relationship exists between the fracture toughness (critical stress intensity factor and critical energy release rate) and tensile modulus and maximum stress. The results indicate that the maximum stress is an effective parameter for evaluating the fracture toughness of PAN-based and pitch-based single carbon fibers.