Adding Carbon Fiber Research Articles

High velocity impact characteristics of MWNT added CFRP at LEO space environment

In this paper, multi-wall carbon nanotube (MWNT) added carbon fiber reinforced plastics (CFRP) composites are suggested as solutions to improve the impact energy absorbing capability of CFRP for spacecraft application because it was proven that the resistance against LEO environment and the quasi-static material properties of CFRP can be improved by adding MWNT in previous papers. To verify the effect of MWNT on the impact energy absorbing capability of composite materials, normal CFRP and MWNT-reinforced CFRP were prepared and tested by using a two-stage light gas gun that can accelerate an aluminum ball of a diameter of 5.56 mm to 1 km/s. And the applicability of MWNT against hypervelocity impact of space debris was studied. In addition, accelerated ground simulation experiments were performed for each material model to simulate the aging of composite materials to verify the effect of LEO environmental aging on impact absorbing capability of composites. For the aging experiment, the impact specimens were simultaneously exposed to high vacuum, atomic oxygen, ultra violet light, and thermal cycling. After being exposed to simulated LEO environment, high velocity impact tests were performed for each material. As a result, MWNT did not have a significant improvement on the impact energy absorbing capability of CFRP under high velocity impact, even though the quasi static material properties are improved by adding MWNT. This is caused by the early generation of fiber breakages on the impact surface before enough generation of progressive failure which is one of the impact energy absorbing mechanism. Similarly, MWNT has less effect on the impact energy absorbing capability of CFRP under LEO environment.

Salinity and Conductivity Amendment of Soil Enhanced the Bioelectrochemical Degradation of Petroleum Hydrocarbons.

The extreme salinity and high internal resistance of saline-alkali soil contaminated by petroleum hydrocarbons were two key limitations for using the bioelectrochemical remediation. In order to solve two problems, we simply rinsed soil, added carbon fiber to polluted soil. The charge output was enhanced by 110% with increase of the maximum current densities from 81 to 304 mA·m−2 while hydrocarbons degradation rate enhanced by 484%, especially the high molecular weight fractions (C28–C36 of n-alkanes and 4–6 rings of PAHs). These effects were possibly due to the selective enrichment of species belonged to δ-Proteobacteria (Proteobacteria), Flavobacteriia (Bacteroidetes) or Clostridia (Firmicutes), the activities of biological electron transfer and enzymes. As we know, oxygenase gene that directly decided the process of degradation, was surveyed for the first time in soil bioelectrochemical remediation system. The results confirmed that the bio-current stimulated the activities of naphthalene dioxygenase and xylene monooxygenase and thus the hydrocarbons degradation and the electricity generation. Given that electricity generation and the remediation performance are governed by multiple factors, understanding of microbial community and enzyme gene is crucial to promote the power yield and the bioelectrochemical remediation applicability.

An empirical approach to evaluate creep responses in polymers and polymeric composites and determination of design stresses

This study presents determination of design stresses for high temperature polymer PMR-15 and carbon fiber/PMR-15 composites. The main purpose is to support design of structural components made of polymeric composites for high temperature applications. At elevated temperatures, polymers and polymeric composites show significant creep responses. Depending on the loading conditions (stress and temperature levels) and duration of loading, both transient and steady state creep responses are observed. An empirical model that is typically used for describing transient and steady state creep behaviors for metals and alloys at elevated temperatures is adopted to model creep responses of PMR-15. The rationale behind choosing the model is that the macroscopic creep responses of PMR-15 at elevated temperature are similar to the ones of metals and alloys tested at high temperatures. This creep model has been successfully used to determine design stresses for various metals and alloys operating at elevated temperatures. In order to determine creep responses of carbon fiber/PMR-15 composites a rule of mixture approach is adopted. A design criterion, which is to limit the permanent deformation to 0.2%, is considered for both polymer and composites. The design stresses and design spaces that satisfy the above design criterion are constructed for PMR-15 polymer, unidirectional carbon/polyimide lamina and [0/90]S symmetric laminate. As expected the mechanical performance of PMR-15 can be improved by adding carbon fiber. The proposed design spaces are useful in determining the maximum capacity of the materials under various loading conditions and duration, taking into account creep behaviors in materials, during the component design process.

Additive manufacturing of carbon fiber reinforced thermoplastic composites using fused deposition modeling

Additive manufacturing (AM) technologies have been successfully applied in various applications. Fused deposition modeling (FDM), one of the most popular AM techniques, is the most widely used method for fabricating thermoplastic parts those are mainly used as rapid prototypes for functional testing with advantages of low cost, minimal wastage, and ease of material change. Due to the intrinsically limited mechanical properties of pure thermoplastic materials, there is a critical need to improve mechanical properties for FDM-fabricated pure thermoplastic parts. One of the possible methods is adding reinforced materials (such as carbon fibers) into plastic materials to form thermoplastic matrix carbon fiber reinforced plastic (CFRP) composites those could be directly used in the actual application areas, such as aerospace, automotive, and wind energy. This paper is going to present FDM of thermoplastic matrix CFRP composites and test if adding carbon fiber (different content and length) can improve the mechanical properties of FDM-fabricated parts. The CFRP feedstock filaments were fabricated from plastic pellets and carbon fiber powders for FDM process. After FDM fabrication, effects on the tensile properties (including tensile strength, Young's modulus, toughness, yield strength, and ductility) and flexural properties (including flexural stress, flexural modulus, flexural toughness, and flexural yield strength) of specimens were experimentally investigated. In order to explore the parts fracture reasons during tensile and flexural tests, fracture interface of CFRP composite specimens after tensile testing and flexural testing was observed and analyzed using SEM micrograph.

Effect of Water Absorption and Resin Particle on Interfacial Shear Strength of CF/MAPP

In this study, effects of water absorption and adding resin particles around fiber on interfacial shear strength of carbon fiber (CF)/maleic anhydride grafted polypropylene (MAPP) were investigated. In water absorption test, CF/MAPP specimen was immersed in distilled water at room temperature for four weeks. Micro debonding test of water absorbed CF/MAPP was conducted. Micro debonding test of Resin particle added Carbon Fiber (RCF)/MAPP was also conducted. The resin particle size was less than 5μm. Fracture surface of RCF/MAPP was observed by using Scanning Electron Microscope (SEM). As a result, following conclusions are obtained. In case of water absorbed CF/MAPP, the interfacial shear strength decreased 34% compared with that of virgin. The reason is thought that the interface between fiber/matrix was weakened by absorbing water. In case of resin particle, interfacial shear strength of RCF/MAPP increased 34% compared with that of CF/MAPP. From fracture morphology of RCF/MAPP, resin particles on CF surface were found. Therefore, interfacial shear strength of CF/MAPP was increased by the friction on the surface of carbon fibers.

Research on the Preparation of Calcium Silicate Hydrates Insulating Material

The hard silicon calcium stone slurry were synthesized by dynamic hydrothermal synthesis in this article, the influence of water solid ratio and carbon fiber on the performance of the calcium silicate thermal insulation material was studied. The results showed that when the water-solid ratio of 40, sodium dodecyl benzene sulfonate cited as a foaming agent, the sphericity of spherical particles was well, and xonotlite fiber developed well. The added carbon fiber could significantly increase the flexural and compressive strength and coefficient of thermal conductivity of the material. The microstructure of calcium silicate insulation material was observed and analyzed by scanning electron microscope.

Fabrication and mechanical properties of Cu-coatedwoven carbon fibers reinforced aluminum alloy composite

Cu-coatedwoven carbon fibers/aluminum alloy composite (Cf/Al) was prepared by spark plasma sintering. Microstructure and mechanical properties of the composite were investigated. Microstructure observation indicates that the interface reaction is evidently inhibited by Cu coating. Woven carbon fibers are adhered to the matrix alloy by anchor locking effect of matrix alloy immersing into the interstices between carbon fibers. Under the quasi-static and dynamic compressive conditions, the composite exhibits excellent ductility even when the strain reaches 0.8. Adding carbon fibers into ZL205A alloy has no obvious influence on compressive flow stress of the composite. The compressive true stress–true strain curves show that the composite is a strain rate insensitive material. During the tensile tests, the elongation of the composite shows a sharp increase from 4.5% to 13.5% due to the adding of woven carbon fibers. Meanwhile, the tensile strength of the composite is increased slightly from 168MPa to 202MPa compared to that of ZL205A alloy. The good ductility of the composite is ascribed to the cracks deflection, fibers pulling out, debonding and breakage mechanisms.

Effect of Air Oxidation Treated Carbon Fiber on Mechanical Properties of Carbon Fiber Reinforced Polyethylene Resin Composite

The composite of carbon fiber reinforced polyethylene resin was prepared by using a twin-screw extruder. The effect of carbon fiber oxidation treating on the mechanical properties of carbon fiber reinforced polyethylene resin composite was researched. The tensile fracture failure mechanism of composite was analyzed for both untreated and air oxidation treated specimen. The experimental results indicate that when carbon fiber content is equal, the tensile strength and the elastic modulus of air oxidation-treated carbon fiber-reinforced polyethylene composite are improved than that of the untreated. When the fraction of adding carbon fiber is 3.99%, compared with the pure polyethylene resin matrix, the tensile strength, elastic modulus is increased by 13.12% and 172.91%, respectively. Compared to the untreated carbon fiber reinforced polyethylene resin composite, the tensile strength and tensile modulus is increased by 4.71% and 13.14%, respectively.

Comparison Analysis of Absorption Properties for Microwave Absorbent

In order to compare the absorbing properties of different microwave-absorbing agents and their mixture, this paper has selected two typical microwave-absorbing agents which respectively are carbon fiber resistance microwave-absorbing agents and ferrite magnetism microwave-absorbing agents, and took them as monolayer absorbing materials. Then used MG formula to calculate the effective electromagnetic parameter of their mixture under different proportion at X band, and finally analyzed their absorbing properties separately. Then through contrasting the impedance matching characteristic and attenuation coefficient of the materials, it is proved that adding carbon fiber in ferrite can not improve absorption properties. Although the ability of attenuating electromagnetic wave would be enhanced when resistance materials and magnetism materials are blend with each other, doping will destroy the materials’ impedance matching characteristic because most resistance materials have high permittivity. It makes reflection strengthen and can not improve absorbing properties.

Properties of Graphite Matrix Composite Bipolar Plate Reinforced by Short Carbon Fiber

Short carbon fiber is used to reinforce phenol formaldehyde (PF) resin/graphite composite. With carbon fiber by thick nitric acid liquid-phase oxidative surface treatment (TNALPOST) and its content 3.wt%~ 4.wt%, the composite flexural strength is increased highly and electrical conductivity is also increased on some degree. To PF resin/graphite matrix material without carbon fiber added, if PF resin content is 15.wt%, its flexural strength is 49.0MPa and electrical conductivity is 111S/cm. But with adding carbon fiber by TNALPOST and the same PF resin content , the composite flexural strength and electrical conductivity approach 68MPa、122S/cm respectively, both mechanical property and electrical property satisfy the requirement of USA Department of Energy on carbon filler/polymer composite bipolar plate. The PF resin/graphite composite without carbon fiber added presents brittle fracture mode, but with carbon fiber added, it presents ductile fracture mode. According to the fracture morphology by scanning electron microscopy, carbon fiber and matrix is on relatively weak boundary bonding state accompanied by fiber de-bounding、sliding、pulling-out and bridge-making to crack, they are main factors contributed to improving composite toughness.

Improvement of tensile properties of CFRP composites under LEO space environment by applying MWNTs and thin-ply

Multi-wall carbon nanotube (MWNT) added carbon fiber reinforced plastics (CFRP) and thin-ply composites are suggested as solutions to improve resistance against low earth orbit (LEO) environment and mechanical properties. Accelerated ground simulation experiments were performed for CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP. The used ground simulation facility can simulate high vacuum, atomic oxygen, ultraviolet (UV) light and thermal cycling simultaneously. The aging experiment was performed for 20 h. After the aging experiment, total mass loss (TML) and tensile properties were measured. As a result, by applying thin-ply thickness and MWNT fillers, the tensile strength was improved at ground conditions. Under an LEO space environment, while thin-ply composites cannot relieve the degradation rate, the composites with MWNT can do so. Highly improved tensile strength was observed by simultaneously applying the thin-ply techniques and MWNT under both LEO aged and LEO non-aged conditions.

Effect of adding carbon fiber textiles to methanogenic bioreactors used to treat an artificial garbage slurry

To compare the performances and microbial populations of methanogenic reactors with and without carbon fiber textiles (CFT), we operated small-scale (200 ml) reactors using a slurry of artificial garbage. For both types of reactors, the organic loading rate (OLR) was stepwisely and rapidly increased in the same manner. Start-up period was shortened by adding CFT. Reactors with CFT showed greater efficiency for removal of suspended solid and volatile suspended solid than reactors without CFT at a long hydraulic retention time (HRT) between 8 and 13 days. The reactors with CFT maintained stable methane production at an OLR of 15.3 g dichromate chemical oxygen demand (CODcr)/l/day and DNAs from microorganisms were highly concentrated in adhering fractions on CFT. As shown by quantitative PCR analysis, the proportions of methanogenic archaea were conserved more than 25% in adhering fractions on CFT in reactors with CFT. By contrast, reactors without CFT showed accumulation of volatile fatty acid and deteriorated at an OLR of 2.4 gCODcr/l/day. Methanogenic proportions dropped to 17.1% in suspended fractions of reactors without CFT. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that all archaeal DGGE bands in both types of reactors were related to methanogens, but more bands were observed in reactors with CFT. Thus the higher performance of reactors with CFT likely reflects the greater abundance of microorganisms and methanogenic diversity.

Wettability of tundish periclase lining by steel

Results of a study of the wettability of the tundish periclase lining by molten steel using a sessile drop method are presented. The wetting angle θ tends to decrease with increase in temperature and contact time on adding glass fiber and Fe2O3 powder in excess of 2% to the magnesite powder; a similar effect is observed in steels high in manganese. An increase in angle θ is observed on adding carbon fiber or glass fiber (not in excess of 1%) to the magnesite powder; the angle θ tends to increase with increase in MgO powder grain size and with carbon contained in steel in excess of 0.04%.

Preparation and characterization of carbon nanotube reinforced silicon nitride composites

Multiwall carbon nanotube (MWNT) reinforced silicon nitride ceramics matrix composites have been prepared. The hot isostatic press (HIP)-sintering method was used for composite processing. Bending strength and elastic modulus of MWNT-silicon nitride composites showed a considerable improvement compared to matrices with added carbon fiber, carbon black or graphite. However, the silicon nitride samples without any carbon addition, because of higher densities present an even higher value. In the case of carbon fibers addition, a deterioration during sintering has been observed. The increasing pressure and sintering time resulted in carbon nanotube free structures.

817 熱駆動小型 MH (Metal Hydride) 冷凍システムの熱的最適化に関する研究

In order to optimize the heat driven type MH refrigeration system thermally, the calculation model based on one-dimensional thermal diffusion equation and the experimental using demonstrational system were made. At first, we investigated the thermal optimized driving temperature condition and the best MH alloy's mass ratio. But even though under the thermal optimization condition, the refrigeration performance of this system was not good to compare with traditional one. The reason of it is that the effective thermal conductivity of MH alloy bed is extremely low (about 1 W/m ・K). Then, in order to enhance the refrigeration performance, the mixing carbon fiber into the MH bed is used in this study. The effect of adding the carbon fiber on the refrigeration performance is also analyzed by the above-mentioned calculation model and demonstrational system. As shown in the results of these analyses, we are able to increase the cooling load by carbon fiber mixing. Furthermore, the decrease of COP by adding carbon fiber is not remarkable. Eventually, the mixing carbon fiber is good refrigeration performance enhancement method for this system.

A chemical heat pump using carbon fibers as additive. Part I: enhancement of thermal conduction

To use carbon fibers as additive in a chemical heat pump, based on a solid–gas reaction, three mixtures of carbon fibers with the reagent compounds are proposed: simple mixture, impregnation of the carbon fibers with reagent compounds and intercalation of the reagent compounds into graphite fibers. By adding carbon fibers, the thermal conductivity of the reagent bed is enhanced. While using the different mixtures, the performances of a chemical heat pump were compared. As a result of this study, impregnation and intercalation compounds gave the best performances. The comparison between these compounds shows that impregnation preparation is easier, while the intercalation compounds are stronger.

Effect of volume fraction of carbon fibers on wear behavior of Al/Al 2O 3/C hybrid metal matrix composites

Wear behavior of Al/Al 2O 3/C hybrid metal matrix composites fabricated by squeeze casting method was characterized. The effects of volume fraction of carbon fiber on wear behavior of hybrid composites was investigated. Wear behavior of Al/Al 2O 3/C composites was characterized by the dry spindle wear test under various sliding speeds. The wear resistance of Al/Al 2O 3/C composites was remarkably improved over Al/Al 2O 3 composites by adding carbon fibers to Al/Al 2O 3/C composites. Specifically, at the intermediate sliding speed the wear resistance of Al/Al 2O 3/C composites containing 8 vol.% carbon fiber was found to be better than that of the rest of the carbon hybrid composites. From fractographic studies, damaged sections in wear surfaces of hybrid composites at intermediate sliding speed were not observed due to the formation of solid lubrication film. The solid lubrication film which was formed as a result of adding carbon fibers improved the wear resistance of carbon hybrid composites because this film reduced the high friction force between MMCs and counter material.

Mechanical Properties and Solid Lubricant Wear Behavior of Al/Al2O3/C Hybrid Metal Matrix Composites Fabricated by Squeeze Casting Method

In this study, mechanical properties and wear behavior of Al/Al2O3/C hybrid metal matrix composites fabricated by squeeze casting method was characterized. The effects of volume fraction of carbon fiber on mechanical properties of hybrid composites was investigated. Tensile strength of Al/Al2O3/C composites was decreased by increasing the addition of carbon fiber. The carbon fiber additions were seen to be less effective in strength than when only alumina fibers were incorporated, because carbon fibers in hybrid systems are difficult to wet by molten aluminum alloys and react with a matrix alloy to form brittle aluminum carbide (Al4C3). Ductility was considerably reduced by increasing the incorporation of carbon fiber. Wear behavior of Al/Al2O3/C composites was characterized by the dry spindle wear test under various sliding speeds. The wear resistance of Al/Al2O3/C composites was remarkably improved over Al/Al2O3 composites by adding carbon fibers to Al/Al2O3/C composites. Specifically, at the intermediate sliding speed the wear resistance of Al/Al2O3/C composites containing 8 vol.% carbon fiber was found to be better than that of the rest of the carbon hybrid composites, but amounts of carbon volume fraction were of little effect on wear resistance at high sliding speed of 3.62 m/sec. From fractographic studies, damaged sections in wear surfaces of hybrid composites at intermediate sliding speed were seldom observed due to the formation of solid lubrication film. The solid lubrication film which was formed as a result of adding carbon fibers improved the wear resistance of carbon hybrid composites because this film reduced the high friction force between MMCs and counter material. Wear model of Al/Al2O3/C composites was also suggested by the examination of worn surfaces.

Improving the bonding between old and new concrete by adding carbon fibers to the new concrete

The addition of short carbon fibers in the amount of 0.35 vol.% resulted in mortars that bonded more strongly to old mortars. The increase in shear bond strength was up to 89%. This effect is attributed to the lowering of the drying shrinkage by the fiber addition. The effect is largest when the fibers were used with latex, which was in the amount of 20% of the cement weight.