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Preparation of anti-oxidative carbon fiber at high temperature
Applied Surface Science 257 (2010) 662–664
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Short communication
Preparation of anti-oxidative carbon fiber at high temperature Bo-Hye Kim a , Su Yeun Kim a , Chang Hyo Kim a , Kap Seung Yang a,∗ , Young-Jun Lee b a Department of Polymer & Fiber System Engineering and Alan G. MacDiarmid Energy Research Institute (AMERI), Chonnam National University, Gwangju 500-757, Republic of Korea b T7 Group Digital Appliance Research Laboratory, LG Electronics, Republic of Korea
a r t i c l e
i n f o
Article history: Received 2 April 2010 Received in revised form 2 July 2010 Accepted 3 July 2010 Available online 23 July 2010 Keywords: Carbon fiber Oxidation resistance SiC coating Polyacrylonitrile solution
a b s t r a c t In this paper, carbon fibers with improved thermal stability and oxidation resistive properties were prepared and evaluated their physical performances under oxidation condition. Carbon fibers were coated with SiC particles dispersed in a polyacrylonitrile solution and then followed by pyrolyzed at 1400 ◦ C to obtain the SiC nanoparticle deposition on the surface of the carbon fiber. The SiC coated carbon fiber showed extended oxidation resistive property as remaining 80–88% of the original weight even at high temperature 1000 ◦ C under air, as compared with the control of zero weight at 600 ◦ C. The effects of the coating conditions on the oxidation resistive properties of the coated fibers were studied in detail. © 2010 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Carbon fibers are mainly used for reinforcement in advanced composite materials in the area of “lighter but stronger”, such as those with applications to the aeronautics, aerospace, sports and leisure industries [1–3]. Those properties are sustained temperatures up to higher than 2000 ◦ C in vacuum and inert atmospheres. However, they have low oxidation resistance in an oxidative environment at above 500 ◦ C in air, and they are therefore not widely used either in metal–matrix and ceramic–matrix composites or in high-temperature polymer–matrix composites [4–5]. Such a drawback could be overcome by protecting the carbon by a ceramic matrix which acts as a diffusion barrier between oxygen and the carbon surface [6]. In the present study, carbon fibers (CFs) were coated with SiC particles dispersed in a polyacrylonitrile (PAN) solution and then pyrolyzed continuously at 1400 ◦ C under the inert atmosphere to obtain CFs/SiC nano-composite. The SiC nanoparticles were evenly dispersed on the carbon fiber and showed extended oxidation resistance from the carbon fibers.
2.1. Materials Poly(acrylonitrile) (PAN) based carbon fibers (12 K single filaments per tow, tensile strength was 4.90 GPa, tensile modulus was 2230 GPa, average diameter was 7 m, density was 1.80 g/cm−3 , CF) were used from Toray Industries Inc. PAN (molecular weight, 150,000), silicon carbide (particle size, ca. 400 mesh; SiC), and dimethylformamide (≥99.9%, DMF) were obtained from Aldrich Chemical Co. (USA). 2.2. Preparation of CFs/SiC composite 5 and 7 wt% PAN were dissolved in DMF, respectively. And then SiC was dispersed in each PAN solution in a mixture ratio of 1:1 by weight to improve the adhesion between CFs and SiC particles. The carbon fibers were coated with SiC which was dispersed in each PAN resin solutions. After drying in air, the SiC coated carbon fibers were sintered at 1400 ◦ C in argon. 2.3. Characterization of CFs/SiC composite
∗ Corresponding author. Tel.: +82 62 530 1774; fax: +82 62 530 1779. E-mail addresses: [email protected], [email protected] (K.S. Yang). 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.07.052
Surface analysis of the fibers was performed by scanning electron microscopy (SEM) (S-4700, Hitachi, Tokyo, Japan). The crystalline structure of SiC particles on carbon fiber were characterized by X-ray diffraction (XRD, D-Max-2400 diffractometer), equipped with graphite monochromatized Cu K␣ radiation ( = 0. 15,418 nm). Thermogravimetric analysis (TGA) was car-
B.-H. Kim et al. / Applied Surface Science 257 (2010) 662–664
663
Fig. 1. Scanning electron micrographs of pristine SiC particles (a, b) and CFs/SiC composite. Concentration of PAN resin solution: (c, d) 5, (e, f) 7 wt%.
ried out in a Shimadzu TGA 50 (Shimadzu Inc., Columbia, MD (21046)). 3. Results and discussion The sizes of the pristine SiC particles were dispersed from 35 m (Fig. 1a) to less than 1 m (Fig. 1b) and the large particles transformed to reduced size of uniform beads in the heat treatment process at 1400 ◦ C. The SEM images (Fig. 1c–f) show the presences of uniform SiC nanoparticles on carbon fibers surface after 1400 ◦ C pyrolysis. They represent that the nanoparticles are spherical in shape and uniformly dispersed on carbon fibers. It is interesting to note that the SiC dispersed in 5 wt% PAN solution introduced particles with smaller size (average diameter of ca. 200 nm) and with denser dispersion on the carbon fibers in comparison with those in the 7 wt% PAN solution. This behavior must come from
the viscosity differences of the PAN solution (5 wt% PAN resin: 830 cP, 7 wt% PAN resin: 1050 cP at 19.5 ◦ C) and interfacial tension between the resin and SiC particles. At the initial stage, the PAN solution with lower viscosity would introduce better contact between the SiC particles, and at the followed pyrolyzing stage, it could introduce better affinity between the carbon fiber and SiC particles. From the XRD patterns (Fig. 2), broad peak located at around 2 = 25◦ assigned as the d002 layer of the carbon fiber. Mainly, SiO2 in form of ␣-cristobalite and SiC were detected in all samples. The SiC nanoparticles on carbon fiber pyrolyzed at 1400 ◦ C exhibited a complete  type crystal (cubic lattice) as suggested by its diffraction peaks (1 1 1, 2 0 0, 2 2 0). TGA was operated in the air flow to analyze the oxidation resistive property of the samples (CF, SiC, CFs/SiC composite) at elevated
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B.-H. Kim et al. / Applied Surface Science 257 (2010) 662–664
were almost burnt out. The TGA yields of CFs/SiC composite at 1000 ◦ C were 88% from 5 wt% PAN solution, and 81% from the 7 wt% PAN solution. This represents that smaller size of SiC nanoparticles could efficiently cover the carbon fiber surface resulting improved oxidation resistivity at the elevated temperatures. 4. Conclusion Carbon fibers were coated with SiC particles dispersed in PAN solutions and then pyrolyzed continuously at 1400 ◦ C. After exposure to air at 1000 ◦ C, the residual weight of the composite was 80–88%. The CFs/SiC composites became a mixture of SiC and SiO2 on the carbon fiber by sintering in the inert atmosphere, and resulted in improved oxidation resistivity from the carbon fibers. The TGA yield of CFs/SiC composite was 88% from 5 wt% PAN solution, and 81% from the 7 wt% PAN solution. This implies that smaller size of SiC nanoparticles can efficiently cover the carbon fiber surface resulting improved oxidation resistivity. Acknowledgements Fig. 2. X-ray diffraction spectrum of CFs/SiC composite (concentration of PAN resin solution is 5 wt%).
This work was supported by Mid-career Researcher Program through NRF grant funded by the MEST (No. R01-2008-00020898-0) and Basic science research program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2010-0003266). We also greatly appreciate the support of GPP in K20602000009-10E020000910. References
Fig. 3. Thermogravimetric analysis of the samples in air flow of 10 ml/min at heating rate of 10 ◦ C/min.
temperature. The weight loss of the CFs/SiC composite is presented in Fig. 3. It is clear that the yield improve with SiC coating. The CFs/SiC composite starts to oxidize above 700 ◦ C and reaches to 10–12% weight loss at 1000 ◦ C, while the as-received carbon fibers
[1] A.K. Gupta, D.K. Paliwal, P. Bajaj, Acrylic precursors for carbon fibers, J. Macromol. Sci., Rev. Macromol. Chem. Phys. C31 (1991) 1–89. [2] A. Serkov, G. Budnitskii, M. Radishevskii, V. Medvedev, L. Zlatoustova, Improving carbon fibre production technology, Fibre Chem. 35 (2003) 117–121. [3] K.E. Perepelkin, Oxydized (cyclized) polyacrylonitrile fibres-oxypan. A review, Fibre Chem. 35 (2003) 409–416. [4] K.L. Luthra, Oxidation of carbon/carbon composites—a theoretical analysis, Carbon 26 (1988) 217–224. [5] N.I. Baklanova, V.N. Kulyukin, N.Z. Lyakhov, Modifying carbon materials with boron compounds, Inorg. Mater. 33 (1997) 682–684. [6] R. Gadiou, S. Serverin, P. Gibot, C. Vix-Guterl, The synthesis of SiC and TiC protective coatings for carbon fibers by the reactive replica process, J. Eur. Ceram. Soc. 28 (2008) 2265–2274.
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Short communication
Preparation of anti-oxidative carbon fiber at high temperature Bo-Hye Kim a , Su Yeun Kim a , Chang Hyo Kim a , Kap Seung Yang a,∗ , Young-Jun Lee b a Department of Polymer & Fiber System Engineering and Alan G. MacDiarmid Energy Research Institute (AMERI), Chonnam National University, Gwangju 500-757, Republic of Korea b T7 Group Digital Appliance Research Laboratory, LG Electronics, Republic of Korea
a r t i c l e
i n f o
Article history: Received 2 April 2010 Received in revised form 2 July 2010 Accepted 3 July 2010 Available online 23 July 2010 Keywords: Carbon fiber Oxidation resistance SiC coating Polyacrylonitrile solution
a b s t r a c t In this paper, carbon fibers with improved thermal stability and oxidation resistive properties were prepared and evaluated their physical performances under oxidation condition. Carbon fibers were coated with SiC particles dispersed in a polyacrylonitrile solution and then followed by pyrolyzed at 1400 ◦ C to obtain the SiC nanoparticle deposition on the surface of the carbon fiber. The SiC coated carbon fiber showed extended oxidation resistive property as remaining 80–88% of the original weight even at high temperature 1000 ◦ C under air, as compared with the control of zero weight at 600 ◦ C. The effects of the coating conditions on the oxidation resistive properties of the coated fibers were studied in detail. © 2010 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Carbon fibers are mainly used for reinforcement in advanced composite materials in the area of “lighter but stronger”, such as those with applications to the aeronautics, aerospace, sports and leisure industries [1–3]. Those properties are sustained temperatures up to higher than 2000 ◦ C in vacuum and inert atmospheres. However, they have low oxidation resistance in an oxidative environment at above 500 ◦ C in air, and they are therefore not widely used either in metal–matrix and ceramic–matrix composites or in high-temperature polymer–matrix composites [4–5]. Such a drawback could be overcome by protecting the carbon by a ceramic matrix which acts as a diffusion barrier between oxygen and the carbon surface [6]. In the present study, carbon fibers (CFs) were coated with SiC particles dispersed in a polyacrylonitrile (PAN) solution and then pyrolyzed continuously at 1400 ◦ C under the inert atmosphere to obtain CFs/SiC nano-composite. The SiC nanoparticles were evenly dispersed on the carbon fiber and showed extended oxidation resistance from the carbon fibers.
2.1. Materials Poly(acrylonitrile) (PAN) based carbon fibers (12 K single filaments per tow, tensile strength was 4.90 GPa, tensile modulus was 2230 GPa, average diameter was 7 m, density was 1.80 g/cm−3 , CF) were used from Toray Industries Inc. PAN (molecular weight, 150,000), silicon carbide (particle size, ca. 400 mesh; SiC), and dimethylformamide (≥99.9%, DMF) were obtained from Aldrich Chemical Co. (USA). 2.2. Preparation of CFs/SiC composite 5 and 7 wt% PAN were dissolved in DMF, respectively. And then SiC was dispersed in each PAN solution in a mixture ratio of 1:1 by weight to improve the adhesion between CFs and SiC particles. The carbon fibers were coated with SiC which was dispersed in each PAN resin solutions. After drying in air, the SiC coated carbon fibers were sintered at 1400 ◦ C in argon. 2.3. Characterization of CFs/SiC composite
∗ Corresponding author. Tel.: +82 62 530 1774; fax: +82 62 530 1779. E-mail addresses: [email protected], [email protected] (K.S. Yang). 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.07.052
Surface analysis of the fibers was performed by scanning electron microscopy (SEM) (S-4700, Hitachi, Tokyo, Japan). The crystalline structure of SiC particles on carbon fiber were characterized by X-ray diffraction (XRD, D-Max-2400 diffractometer), equipped with graphite monochromatized Cu K␣ radiation ( = 0. 15,418 nm). Thermogravimetric analysis (TGA) was car-
B.-H. Kim et al. / Applied Surface Science 257 (2010) 662–664
663
Fig. 1. Scanning electron micrographs of pristine SiC particles (a, b) and CFs/SiC composite. Concentration of PAN resin solution: (c, d) 5, (e, f) 7 wt%.
ried out in a Shimadzu TGA 50 (Shimadzu Inc., Columbia, MD (21046)). 3. Results and discussion The sizes of the pristine SiC particles were dispersed from 35 m (Fig. 1a) to less than 1 m (Fig. 1b) and the large particles transformed to reduced size of uniform beads in the heat treatment process at 1400 ◦ C. The SEM images (Fig. 1c–f) show the presences of uniform SiC nanoparticles on carbon fibers surface after 1400 ◦ C pyrolysis. They represent that the nanoparticles are spherical in shape and uniformly dispersed on carbon fibers. It is interesting to note that the SiC dispersed in 5 wt% PAN solution introduced particles with smaller size (average diameter of ca. 200 nm) and with denser dispersion on the carbon fibers in comparison with those in the 7 wt% PAN solution. This behavior must come from
the viscosity differences of the PAN solution (5 wt% PAN resin: 830 cP, 7 wt% PAN resin: 1050 cP at 19.5 ◦ C) and interfacial tension between the resin and SiC particles. At the initial stage, the PAN solution with lower viscosity would introduce better contact between the SiC particles, and at the followed pyrolyzing stage, it could introduce better affinity between the carbon fiber and SiC particles. From the XRD patterns (Fig. 2), broad peak located at around 2 = 25◦ assigned as the d002 layer of the carbon fiber. Mainly, SiO2 in form of ␣-cristobalite and SiC were detected in all samples. The SiC nanoparticles on carbon fiber pyrolyzed at 1400 ◦ C exhibited a complete  type crystal (cubic lattice) as suggested by its diffraction peaks (1 1 1, 2 0 0, 2 2 0). TGA was operated in the air flow to analyze the oxidation resistive property of the samples (CF, SiC, CFs/SiC composite) at elevated
664
B.-H. Kim et al. / Applied Surface Science 257 (2010) 662–664
were almost burnt out. The TGA yields of CFs/SiC composite at 1000 ◦ C were 88% from 5 wt% PAN solution, and 81% from the 7 wt% PAN solution. This represents that smaller size of SiC nanoparticles could efficiently cover the carbon fiber surface resulting improved oxidation resistivity at the elevated temperatures. 4. Conclusion Carbon fibers were coated with SiC particles dispersed in PAN solutions and then pyrolyzed continuously at 1400 ◦ C. After exposure to air at 1000 ◦ C, the residual weight of the composite was 80–88%. The CFs/SiC composites became a mixture of SiC and SiO2 on the carbon fiber by sintering in the inert atmosphere, and resulted in improved oxidation resistivity from the carbon fibers. The TGA yield of CFs/SiC composite was 88% from 5 wt% PAN solution, and 81% from the 7 wt% PAN solution. This implies that smaller size of SiC nanoparticles can efficiently cover the carbon fiber surface resulting improved oxidation resistivity. Acknowledgements Fig. 2. X-ray diffraction spectrum of CFs/SiC composite (concentration of PAN resin solution is 5 wt%).
This work was supported by Mid-career Researcher Program through NRF grant funded by the MEST (No. R01-2008-00020898-0) and Basic science research program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2010-0003266). We also greatly appreciate the support of GPP in K20602000009-10E020000910. References
Fig. 3. Thermogravimetric analysis of the samples in air flow of 10 ml/min at heating rate of 10 ◦ C/min.
temperature. The weight loss of the CFs/SiC composite is presented in Fig. 3. It is clear that the yield improve with SiC coating. The CFs/SiC composite starts to oxidize above 700 ◦ C and reaches to 10–12% weight loss at 1000 ◦ C, while the as-received carbon fibers
[1] A.K. Gupta, D.K. Paliwal, P. Bajaj, Acrylic precursors for carbon fibers, J. Macromol. Sci., Rev. Macromol. Chem. Phys. C31 (1991) 1–89. [2] A. Serkov, G. Budnitskii, M. Radishevskii, V. Medvedev, L. Zlatoustova, Improving carbon fibre production technology, Fibre Chem. 35 (2003) 117–121. [3] K.E. Perepelkin, Oxydized (cyclized) polyacrylonitrile fibres-oxypan. A review, Fibre Chem. 35 (2003) 409–416. [4] K.L. Luthra, Oxidation of carbon/carbon composites—a theoretical analysis, Carbon 26 (1988) 217–224. [5] N.I. Baklanova, V.N. Kulyukin, N.Z. Lyakhov, Modifying carbon materials with boron compounds, Inorg. Mater. 33 (1997) 682–684. [6] R. Gadiou, S. Serverin, P. Gibot, C. Vix-Guterl, The synthesis of SiC and TiC protective coatings for carbon fibers by the reactive replica process, J. Eur. Ceram. Soc. 28 (2008) 2265–2274.