study on carbon fibre (original) (raw)

Thermal properties of carbon fibers at very high temperature

Carbon, 2009

Thermal properties such as specific heat C p , thermal diffusivity a, and thermal conductivity k of carbon fibers are important parameters in the behaviour of the carbon/carbon composites. In this study, the specific heat and the thermal diffusivity are measured at very high temperatures (up to 2500 K). The experimental thermal conductivity estimated by the indirect relation k = aqC p is presented as a function of the temperature. Validations are carried out on isotropic metallic (tungsten) and ceramic (Al 2 O 3 ) fibers. Measurements were obtained on three carbon fibers (rayon-based, PAN-based and pitch-based). Thermal conductivity results allow us to classify fibers from the most insulated to most conductive.

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iv V  High-heat-treatment carbon fibers (HTT), where final heat treatment temperature should be above 2000°C and can be associated with high-modulus type fiber.

Thermomechanical properties of carbon fibres at high temperatures (up to 2000 °C)

Composites Science and Technology, 2002

A high-temperature fibre-testing apparatus has been designed. It is dedicated to the determination of various properties at very high temperatures, including electrical conductivity, Young's modulus, thermal expansion coefficient, strength. Test temperatures as high as 3000 C can be applied to carbon fibres. Two types of carbon fibres (a PAN-based and a Rayon-based fibre) have been investigated at temperatures up to 2000 C. The measured properties are discussed with respect to microstructural features. #

IJERT-Properties of Carbon Fiber and its Applications

International Journal of Engineering Research and Technology (IJERT), 2013

https://www.ijert.org/properties-of-carbon-fiber-and-its-applications https://www.ijert.org/research/properties-of-carbon-fiber-and-its-applications-IJERTV2IS110139.pdf Over the ages as we have evolved, so has our engineering and researching skill sets. Even today, we are constantly innovating, researching and developing technology in pursuit of a sustainable future. Throughout this evolution, researches and engineers have found themselves in constant search for new and better materials to optimally manage the performance cost trade-off in the construction sector. Many new raw materials have been discovered and many groundbreaking composite have been developed, of which not all but some have proved to be a phenomenal success.

Effects of HF Treatments on Tensile Strength of Hi-Nicalon Fibers

1998

Tensile strengths of as-received Hi-Nicalon fibres and those having a dual BN-SiC surface coating, deposited by chemical vapour deposition, have been measured at room temperature. These fibres were also treated with HF for 24 h followed by tensile strength measurements. Strengths of uncoated and BN-SiC coated Hi-Nicalon fibres extracted from celsian matrix composites, by dissolving away the matrix in HF for 24 h, were also determined. The average tensile strength of uncoated Hi-Nicalon was 3.19<0.73 GPa with a Weibull modulus of 5.41. The Hi-Nicalon-BN-SiC fibres showed an average strength of 3.04<0.53 GPa and Weibull modulus of 6.66. After HF treatment, the average strengths of the uncoated and BN-SiC coated Hi-Nicalon fibres were 2.69<0.67 and 2.80<0.53 GPa and the Weibull moduli were 4.93 and 5.96, respectively. The BN-SiC coated fibres extracted from the celsian matrix composite exhibited a strength of 2.38<0.40 GPa and a Weibull modulus of 7.15. The strength of the uncoated Hi-Nicalon fibres in the composite was so severely degraded that they disintegrated into small fragments during extraction with HF. The uncoated fibres probably undergo mechanical surface damage during hot pressing of the composites. Also, the BN layer on the coated fibres acts as a compliant layer, which protects the fibres from mechanical damage during composite processing. The elemental composition and thickness of the fibre coatings were determined using scanning Auger analysis. Microstructural analyses of the fibres and the coatings were done by scanning electron microscopy and transmission electron microscopy. Stengths of fibres calculated using average and measured fibre diameters were in good agreement. Thus, the strengths of fibres can be evaluated using an average fibre diameter instead of the measured diameter of each filament.

Effects of HF treatments on tensile strength of Hi-Nicalon fibres

Journal of Materials Science, 2000

Tensile strengths of as-received Hi-Nicalon fibres and those having a dual BN-SiC surface coating, deposited by chemical vapour deposition, have been measured at room temperature. These fibres were also treated with HF for 24 h followed by tensile strength measurements. Strengths of uncoated and BN-SiC coated Hi-Nicalon fibres extracted from celsian matrix composites, by dissolving away the matrix in HF for 24 h, were also determined. The average tensile strength of uncoated Hi-Nicalon was 3.19<0.73 GPa with a Weibull modulus of 5.41. The Hi-Nicalon-BN-SiC fibres showed an average strength of 3.04<0.53 GPa and Weibull modulus of 6.66. After HF treatment, the average strengths of the uncoated and BN-SiC coated Hi-Nicalon fibres were 2.69<0.67 and 2.80<0.53 GPa and the Weibull moduli were 4.93 and 5.96, respectively. The BN-SiC coated fibres extracted from the celsian matrix composite exhibited a strength of 2.38<0.40 GPa and a Weibull modulus of 7.15. The strength of the uncoated Hi-Nicalon fibres in the composite was so severely degraded that they disintegrated into small fragments during extraction with HF. The uncoated fibres probably undergo mechanical surface damage during hot pressing of the composites. Also, the BN layer on the coated fibres acts as a compliant layer, which protects the fibres from mechanical damage during composite processing. The elemental composition and thickness of the fibre coatings were determined using scanning Auger analysis. Microstructural analyses of the fibres and the coatings were done by scanning electron microscopy and transmission electron microscopy. Stengths of fibres calculated using average and measured fibre diameters were in good agreement. Thus, the strengths of fibres can be evaluated using an average fibre diameter instead of the measured diameter of each filament. ᮊ

A review of heat treatment on polyacrylonitrile fiber

Polymer Degradation and Stability, 2007

Developing carbon fiber from polyacrylonitrile (PAN) based fiber is generally subjected to three processes namely stabilization, carbonization, and graphitization under controlled conditions. The PAN fiber is first stretched and simultaneously oxidized in a temperature range of 200e300 C. This treatment converts thermoplastic PAN to a non-plastic cyclic or a ladder compound. After oxidation, the fibers are carbonized at about 1000 C in inert atmosphere which is usually nitrogen. Then, in order to improve the ordering and orientation of the crystallites in the direction of the fiber axis, the fiber must be heated at about 1500e3000 C until the polymer contains 92e100%. High temperature process generally leads to higher modulus fibers which expel impurities in the chain as volatile by-products. During heating treatment, the fiber shrinks in diameter, builds the structure into a large structure and upgrades the strength by removing the initial nitrogen content of PAN precursor and the timing of nitrogen. With better-controlled condition, the strength of the fiber can achieve up to 400 GPa after this pyrolysis process.