Oxidation Resistance Of Carbon Fibers Research Articles

Anti-oxidative quartz/carbon-braided fiber reinforced ceramizable composites modified with B4C and AlB2: Mechanical robustness, phase evolution and anti-oxidation mechanism

Carbon fiber reinforced ceramizable phenolic resin matrix composites (Cf/CPR) have been widely used in the field of thermal protection materials. However, the industrial application of the Cf/CPR is restricted by its easy oxidation failure under high temperature condition. In this work, a novel antioxidative ceramizable composites modified with AlB2 and B4C (Cf-Qf/CPR) were prepared by using quartz fiber-coated carbon fiber (Cf-Qf) as reinforcements via co-weaving technique. The thermal stability, mechanical properties, interfacial phase evolution and anti-oxidation mechanism of the composites were investigated. The residue yield and the flexural strength of the composites after treatment at 1200°C for 15 min were 93.4 % and 62.4 MPa, increased by 5.4 % and 67.3 % compared with those of Cf/CPR. Quartz fiber and ceramic protective layer showed synergistic effect to improve the oxidation resistance of carbon fiber and PyC, confirming good high temperature mechanical properties and oxidation resistance of as-received composites.

Tuning microstructures of polyacrylonitrile-based carbon fibers by catalytic influence of boron for enhancement of mechanical properties and oxidation resistance

Boron catalytic graphitization of carbon fibers (CFs) is an effective methodology for reducing energy costs with the enhancement of tensile and oxidation resistance properties by re-constructing the crystal structure of CFs. Herein, a microwave plasma graphitization system for boron catalytic graphitization was devised. The effect of boron on microstructure and properties of CFs during boron catalytic graphitization process was investigated and analyzed. The mechanism of boron doping in different graphitization times was proposed. Furthermore, the results show that the tensile properties and oxidation resistance of CFs are improved and directly related to the microstructure of CFs, which depends on the different boron catalytic graphitization stages. This work provides the effect of boron on microstructure and properties of CFs during microwave plasma catalytic graphitization in different graphitization times and has important implications for deeply understanding the boron catalytic graphitization process which is beneficial for the preparation of CFs with excellent performance.

Improving the oxidation resistance of carbon fibers via B4C coating by modified boron oxide chemical vapor deposition

Carbon fiber is one of the engineering materials frequently used in high-temperature applications despite its very poor oxidation resistance. To enhance the oxidation resistance of C fibers and improve the service temperature, boron carbide coatings were prepared by the modified reactive boron oxide chemical vapor deposition (BOCVD) method. For the coating process, a tube furnace system was utilized. Experiments were performed at 1100–1400 °C for up to 6 h under a flowing Ar atmosphere. Coatings were analyzed by SEM, Raman, XRD, and XPS analysis. B4C coatings were found to be in nodular form around 30–50 nm. Oxidation tests performed in flowing air up to 1500 °C by DTA-TG analysis and oxidation mechanisms were explained in details. We revealed that the base oxidation resistance increased up to 180 °C with no net mass gain or loss.

Oxidation resistance improvement of carbon fiber nonwoven fabrics through SiC coating technology

The oxidation resistance of carbon fiber (CF) was enhanced by SiC coating layer. A hybrid sol–gel approach and chemical vapor reaction (CVR) were utilized to produce coating layer. SiO2 was applied to the CF surface, after which SiOx and SiH4 vapor were added via CVR method to intensify SiC formation and bonding. Interfacial bonding was further reinforced by the addition of graphene oxide (GO) prior to heat treatment. Three different samples were generated, and the gas liberated upon conversion to SiC was evaluated to determine relationships with microstructure. The amount of gas released differed depending on the chemical used in the sol–gel, and the mechanism of SiC formation under different conditions was also distinct. The results of a flame test indicated approximately 20% improvement in oxidation resistance compared to CF. The proposed SiC coating can circumvent the restricted process method that necessitates specialized equipment to manufacture high-quality CF with improved oxidation resistance.

Influence of pressure on the oxidation resistance of carbon fiber reinforced ZrB2/SiC composites at 2000 and 2200 °C

The influence of pressure on the oxidation resistance of C-ZrB2/SiC composites was studied. Materials were tested in air at 2000−2200 °C at 1−900 mbar. SEM analysis on the tested samples revealed the formation of an outer compact layer of ZrO2 and an intermediate layer of ZrO2-SiO2 as well as a porous interface layer of ZrO2. SiC increase was beneficial up to 1650 °C, then the trend was inverted. At 1 mbar all samples were visibly less damaged and displayed similar performance both at 2000 and 2200 °C, indicating that oxidation resistance is mostly dominated by fiber consumption, which is more severe at ambient pressure.

ZrO2f-coated Cf hybrid fibrous reinforcements and properties of their reinforced ceramicizable phenolic resin matrix composites

Carbon fiber-reinforced ceramicizable phenolic resin matrix composites have been widely used in the field of thermal protection materials. In this paper, the ZrO2f-coated Cf (ZrO2f/Cf) hybrid fibrous reinforcements were designed to improve oxidation resistance of carbon fiber and ceramicizable composites reinforced by ZrO2f/Cf hybrid fibrous reinforcements were prepared to investigated oxidation resistance and mechanical properties of the composites at high temperature. The results show that ZrO2f/Cf hybrid fibrous reinforcements have good thermal stability and high oxidation resistance, and its ceramicizable composites have good bending strength at high temperature. Weight loss rate of the composites is only 21 %, and bending strength can be as high as 39 MPa when ablation time was 12 min at 1400 °C.

Improvement of high-temperature resistance on carbon fiber felt/portland cement composite friction material by Al2O3 sol–gel coating

The extrusion impregnation method is used to prepare carbon fiber felt/portland cement (CFF/PC) composite materials. The samples are placed into muffle furnace for ablation, but carbon fiber is oxidized at around 450 °C. To improve the oxidation resistance of carbon fiber, Al2O3 sol–gel (AS) is prepared to coat the surface of carbon fiber. The extrusion impregnation method is also used to prepare AS–CFF/PC composite materials. The samples are also ablated into muffle furnace at different temperatures. The results indicate that carbon fiber is uniformly dispersed and closely arranged in the matrix, presenting a three-dimensional network distribution. The bending and compressive strengths of CFF/PC composite materials are increased by 200% and 12% when compared with that of PC material at room temperature. The AS coating layer can effectively improve the antioxidant capacity of carbon fiber at high temperatures. The comparison reveals that AS–CFF/PC composite materials exhibit improved high-temperature resistance performance.

Process Technology, Applications and Thermal Resistivity of Basalt Fiber Reinforced SiOC Composites

Promising lightweight composite materials, bridging the gap between Polymer and Ceramic Matrix Composites, are manufactured as polymer derived ceramics by the use of polysiloxanes and basalt fibers. Such competitive free formable Hybrid Composites are supposed to be capable for lightweight applications in a temperature range between 300 °C and 850 °C and short time exposure up to over 1000 °C, even in oxidative atmosphere. Cheap raw materials like basalt fibers and siloxane resins in combination with performing manufacturing technologies can establish completely new markets for intermediate temperature composites. These attributes enable the Hybrid Composites as ideal material for fire retardant applications in automotive engineering and public transportation, as well as in fire protection systems in electrical and civil engineering applications. In this study, the most prominent fields of application and engineering solutions for Hybrid-CMC are reviewed and the results of the thermal resistivity analysis effectuated on basalt fiber reinforced SiOC samples are presented. This study consisted of several air exposures between 1 h and 50 h and temperatures in the range of 650 °C to 1100 °C. Remaining mechanical resistance was characterized by Impulse Excitation Technique (IET) and Interlaminar Shear Strength (ILSS) tests. Basalt fiber reinforced samples exhibited a decent level of mechanical performance even after the most demanding exposures. Due to the poor oxidation resistance of carbon fibers, Cf/SiOC composites were completely degraded after long-term exposure at 500 °C in air.

Improvement of oxidation resistance of carbon fibers by coating SiC

SiC-coated carbon fibers (CFs) were prepared by spark plasma sintering, and their phase compositions and microstructures were identified by x-ray diffraction and characterized by field-emission scanning electron microscope, respectively. The oxidation behaviors of the SiC-coated CFs was examined through thermo gravimetric analysis and compared with that of pristine CFs. The effects of Si content in the SiC coatings on the surfaces of the CFs were also investigated. SiC coating with 25 wt% Si contributing to the reaction was thicker than that with 10 wt% Si but had weaker oxidation-resistant properties. When coated with SiC, the CFs exhibited considerable improvement in their oxidation resistance, and the temperature for its oxidation increased nearly by 140 °C.

Ceramic Interfacial Coating on Carbon Fibers Based on Polycarbosilane and Oligovinylsilazane

The formation of a ceramic interfacial coating (IC) on carbon fibers by the polymer infiltration and pyrolysis (PIP) method with the use of polycarbosilane and oligovinylsilazane as the preceramic polymer precursors is discussed. It is shown, that the use of a preceramic polymer concentration higher than 3 wt % results in the formation of clumps with an uneven distribution of the ceramic matrix. The use of a preceramic polymer concentration lower than 3 wt %, an inert atmosphere, and time-temperature regime treatment, calculated for a steady heat release and mass loss, results in the formation of a uniform IC and leads to a high level of oxidation resistance of carbon fibers. The oxidation products of carbon fibers with the deposited IC are hollow SiO2 structures.

Oxidative protection of carbon fibers with carborane-containing polymer

To improve the oxidation resistance of carbon fibers, a series of carborane-containing polymer-based coatings were prepared. The oxidation resistance and microstructure of the coatings were investigated. According to XPS, FT-IR and XRD analysis, the high oxidation resistance of the polymer-based coatings was attributed to the boron oxide protective layer formed from the oxidation of carborane groups in the coating. Ceramic coatings were prepared from heat treatment of polymer-based coatings under argon at 1300°C for 2h. The great oxidation resistance of the ceramic coating was attributed to the existence of boron carbide in coating.

Coating of poly(carborane-carbosilane-phenylacetylene) on carbon fibers with excellent oxidation protection

Linear carborane-carbosilane-phenylacetylene co-polymer has been synthesized as precursor for thermosets and ceramics for the protection of carbon fibers from oxidation in an oxidizing environment. The novel linear co-polymers can be processed conveniently and converted into thermoset or ceramics since they are either liquids or low melting solids at room temperature and are soluble in most organic solvents. Treatment of carbon fibers with poly(carborane-carbosilane-phenylacetylene) by precursor infiltration and pyrolysis (PIP) process can provide a protective barrier at elevated temperatures. Tensile strength measurement revealed that the coated carbon fiber maintained 81.39% of its original strength. It was found that the novel co-polymer is highly efficient in protecting the carbon fibers from oxidation breakdown when used as a matrix material (ceramic). Boron and CC group appear to be the key to the unique oxidative stability of the composite compositions. The derived ceramic coatings on carbon fibers were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Anti-oxidation studies were performed by thermogravimetric analyses (TGA). The results showed that the oxidation resistance of carbon fibers has been promoted obviously by the ceramic coatings.

Preparation and oxidation behavior of a double-layer coating for three-dimensional braided carbon fiber

Abstract Double-layer coatings, with Pyrolytic carbon (PyC) as inner layer and SiC/SiO 2 as outer layer by a precursor infiltration and pyrolysis (PIP) process, were prepared on the surface of three-dimensional (3-D) braided carbon fiber. The double-layer coatings (PyC-SiC/SiO 2 ) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The microstructure, tensile strength and the oxidation resistant properties of the carbon fiber with and without coating were studied. Result showed that the best coating quality obtained was use of 10 wt% polycarbosilane (PCS) with 5 wt% methyltriethoxysilane (MTES) precursor in divinylbenzene (DVB) pyrolyzed to 1400 °C for 2 immension–pyrolysis cycles. The oxidation resistance of carbon fibers was improved obviously by the PyC-SiC/SiO 2 coatings. Tensile strength measurement revealed that the PyC-SiC/SiO 2 coated carbon fiber maintained 87.7% of its original strength.

Enhanced oxidation resistance of carbon fiber reinforced lithium aluminosilicate composites by boron doping

Carbon fiber reinforced lithium aluminosilicate matrix composites (Cf/LAS) modified with boron doping were fabricated and oxidized for 1h in static air. Weight loss, residual strength and microstructure were analyzed. The results indicate that boron doping has a remarkable effect on improving the oxidation resistance for Cf/LAS. The synergism of low viscosity of LAS matrix at high temperature and formation of graphite crystals on the surface of carbon fibers, is responsible for excellent oxidation resistance of the boron doped Cf/LAS.

Study on Antioxidant Properties of the Carbon Fibers Coated with Oxide-Alumina-Silica Film

An oxide-alumina-silicacoating which would to improve the oxidation resistance of carbon fibers was prepared by sol-gel method. XRD and SEM were used to characterize the surface appearance and phase transition about the carbon fibers with oxide-alumina-silica coating. The oxidation resistance of carbon fibers was also analyzed with the DSC-TG and the isothermal oxidation experiment. It was shown that the antioxidant properties of the carbon fibers with oxide-alumina-silica coating improved significantly. The concentration of precursor sol had an influence on the coating of carbon fibers and the antioxidant properties of the carbon fibers with oxide alumina silica coating increased 300°C compared to uncoated ones.

Preparation of an anti-oxidative SiC/SiO2 coating on carbon fibers by a sol–gel method

A SiC/SiO2 ceramic coating on carbon fibers was prepared by a sol–gel method followed by heat treatment at high temperature. The structure and the morphology of the SiC/SiO2 coating were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. The oxidation resistant properties of the carbon fibers with and without the coating were compared by thermogravimetric analysis. Results indicate that a uniform and continuous coating can improve the oxidation resistance of carbon fibers. The oxidation resistance of the coated carbon fibers increased with increases in the sol concentration and heat treatment temperature. A coating of thickness 300 nm increased the onset oxidation temperature by about 200 ° C and the single fiber tensile strength was decreased by 37.7% compared with the pristine carbon fibers. After isothermal oxidation at 700 ° C for 90 min, the single fiber tensile strength of the coated carbon fibers was decreased to 1.37 GPa. The oxidation resistance of the fibers was decreased when the coating thickness exceeded 400 nm due to the spallation of the coating. [New Carbon Materials 2013, 28(3): 208–214]

Effect of Temperature on the Synthesis of SiC Coating on Carbon Fibers by the Reaction of SiO with the Deposited Pyrolytic Carbon Layer

The influence of reaction temperature on the preparation of SiC coating on carbon fibers by the reaction of silicon monoxide with the deposited pyrolytic carbon (PyC) layer has been discussed. With rising reaction temperature, the thickness of SiC layer increases and the SiC grain is coarsening. The apparent activation energy for the synthesis of SiC layer is about 103.3 kJ/mol. The oxidation resistance of carbon fiber can be improved by the SiC/PyC layers significantly. The initial oxidation temperature of the SiC/PyC coated carbon fiber is about 300°C higher than that of the uncoated carbon fiber. The oxidation of the SiC/PyC coated carbon fiber is owing to the diffusion of oxygen through the cracks generated by the mismatch of thermal expansion.

Oxidation protection of carbon fibers by coatings

SiC coatings prepared by chemical vapor deposition and from polycarbosilane (PCS) solution; also, SiO 2 and Al 2O 3 coatings by Sol-Gel method were investigated in detail, to improve the oxidation resistance of carbon fibers as important reinforcement in advanced composites. A β-SiC coating was obtained on carbon fibers by pyrolysis of CH 3SiCl 3 and H 2 at 1373–1573 K. The coating thickness could be controlled according to the requirements in practice. A uniform and fine SiC coating was also obtained by immersion and pyrolysis of PCS solutions with PCS contents of 5–15 wt%, and was composed of a mixture of SiC, SiO 2, and free carbon after pyrolysis in argon. Fine and dense SiO 2 and Al 2O 3 coatings could be obtained from silica and alumina sols, respectively, under exact control of process parameters. All coatings had good effects on the oxidation resistance of carbon fibers in the sequential order of CVD SiC, PCS-SiC, SiO 2, and Al 2O 3. A composite coating of CVD SiC and a mixing coating of SiO 2 and Al 2O 3 was suggested to decrease defects like pores and microcracks in individual coatings to obtain the best oxidation protection for carbon fibers.

Influence of Boron-doping on Structure and Thermal Oxidation Property of Carbon Fibers

Influence of boron-doping through different methods was investigated on d-spacing and apparent crystallite size, and oxidation resistance of carbon fibers with different microstructure. With diffusion of boron into carbon fiber, d (002) spacing decreased and crystallite size, Lc (002) , increased. However, the change of the X-ray parameter was different among carbon fibers with different microstructre. Many small grains of precipitates were formed on fiber surface by reaction of carbon and boron in the cases of using B2O3 or B4C powder as boron-dopant. With formation of the precipitates, degradation in strength was observed and the degradation was considered to be due to formation of defects around the precipitates. In all cases, weight-loss curve with oxidation temperature shifted about 50-150°C to higher temperature side than those of non-doped fibers. However, formation of pits by oxidation was observed for the carbon fiber boron-doped by B2O3 and B4C powder method. However, formation of precipitates and defects were not so remarkable on the surface for the fibers boron-doped with vapor deposition method, and this suggested that homogeneous boron-doping is preferable to improve oxidaation resistance of carbon fiber.

Oxidation resistance of carbon fibers with protective coatings

1. It is shown that the atmospheric oxidation resistance of carbon fibers with pyrolytic silicon and zirconium carbide coatings is one order higher than that of uncoated fibers. 2. The oxidation resistance of carbon fibers with pyrolytic carbide coatings is two to three orders higher in a carbon dioxide atmosphere than in air. 3. The strength of coated carbon fibers is independent of both the nature of the oxidizing atmosphere and oxidation test temperature.