Materials Science and Engineering B132(2006)
307–310
唐山市环保局
Preparation and characterization of carbonfibers coated by
Fe3O4nanoparticles
Jing Xu a,Haibin Yang a,b,∗,Wuyou Fu a,Yongming Sui a,
Hongyang Zhu a,Minghui Li a,Guangtian Zou a
a National Laboratory of Superhard Materials,Jilin University,Changchun130012,PR China
b Institute of Materials Science&Engineering,Henan Polytechni
c University,Jiaozuo454003,PR China
Received4March2006;received in revid form24April2006;accepted29April2006
Abstract
Carbonfibers have been successfully coated with Fe3O4nanoparticles coating layers via sol–gel method combined with annealing under vacuum. The pha structures and morphologies of the composite have been characterized by XRD and FESEM.The results show that a complete and unifo
rm Fe3O4nanoparticles coating on carbonfibers can be obtained in the temperature range of300–550◦C.The coating layers with thickness ca.800nm are compod by Fe3O4nanoparticles of mean sizes ca.30nm.The surface properties of Fe3O4nanoparticles detached from carbon fibers/Fe3O4composite have been analyzed by XPS and FTIR.
©2006Elvier B.V.All rights rerved.
Keywords:Fe3O4nanoparticles;Carbonfibers;Sol–gel
1.Introduction
With the fast development of information and communication technology in recent years,microwave absorptive materials draw more and more attention becau of their widespread applica-tions for electromagnetic compatibility(EMC)[1–3].They are important parts of stealthy defen system for aircraft,a or land vehicles,and esntial parts of absorbing and shielding the environmental pollution from microwave irradiation.Magnetic absorption materials continue to play a leading role in the inves-tigation and application of microwave absorption materials[4]. However,the conventional absorption materials,such as ferrite and metal,are quite heavy.The problem restricts their uful-ness in many applications[5,6].One of the ways to overcome the problem is to couple ferrite and met
al materials with low den-sity materials.Carbonfibers(CFs)are dominant in low density materials becau of their low density,high strength,and per-fect electrical property[7,8].CFs coated by magnetic materials can decrea the weight of the microwave absorptive compos-ite,and improve the conductivity and strength of the composite. It has been demonstrated that iron-coated CFs can be obtained ∗Corresponding author.Tel.:+864315168763;fax:+864315168258.
E-mail address:yanghb@jlu.edu(H.Yang).by electrochemical method and ud as electromagnetic radia-tion absorptive composite[9,10].Huang ported nickel and copper/nickel can be loaded on CFs for EMI shielding by electroless method[11].
However,very little work has been done for combining ferrite with CFs.Huang et al.prepared CFs coated with barium ferrite by sol–gel method and analyzed its electromagnetic properties theoretically[12].Even though the composite is an absorbing microwave absorbing materials,it still has some limitations, such as high density and high-temperature treat.Magnetite (Fe3O4)has attracted long-standing interest in nanostructure synthesis becau of its extensive applications in ferrofluid,and ultrahigh density magnetic storage media[13,14].Magnetite (Fe3O4)as a type of relatively low density ferrite can be obtained in a relatively low temperature(compared with barium ferrite). However,little work has been done to couple CFs with Fe3O4 nanoparticles so far.
In this paper,Fe3O4nanoparticles have been coated on CFs by sol–gel method bad on the reaction of ferric nitrate and ethylene glycol under vacuum in the temperature range of300–550◦C.The Fe3O4coating layers with thickness ca. 800nm are compod by Fe3O4nanoparticles of mean sizes ca.30nm.The Fe3O4coating on CFs surfaces can be further functionalized with a large variety of other nanostructure mate-
0921-5107/$–e front matter©2006Elvier B.V.All rights rerved. doi:10.1016/j.mb.2006.04.038
308J.Xu et al./Materials Science and Engineering B 132(2006)
307–310
Fig.1.The scheme of the procedure ud to synthesize the CFs/Fe 3O 4composite.
rials by utilized the chemistry of Fe 3O 4nanoparticles to create novel multilayer coating on CFs.And the magnetic,thermal,and microwave absorption properties of CFs/Fe 3O 4would be considered in near future.2.Experimental 2.1.CFs and chemicals
PAN-bad CFs with 6–8m in diameter and 3mm in length were supplied by Jillin Carbon Group Co.,Ltd.Chemicals,ferric nitrate (Fe(NO 3)3·9H 2O),ethylene glycol (C 2H 6O 2),nitric acid (HNO 3,65%)and acetone (C 3H 6O),ud in the experiment are of analytical grade and ud without further purification.2.2.Preparation of CFs/Fe 3O 4composite
The synthesis procedure for the CFs/Fe 3O 4composite is illustrated in Fig.1and exhaustively described as follows:before deposition,CFs were immerd in acetone for 2h to clean the CFs surfaces,then CFs were treated with HNO 3(65%)for 24h at room temperature to introduce various functional groups (such as COOH,OH,and CO)on CFs surfaces.The functional groups can act as nucleation sites for Fe 3O 4nanoparticles on CFs.A 0.2mol ferric nitrate was firstly dissolved in 100ml ethy-lene glycol with vigorously stirring for 2h at 40◦C,to be ud
as
Fig.2.TG-DTA curves of CFs/precursor in N 2.
coating solution.Then 2g of acid-treated CFs were immerd in the above sol.The system was ultrasonically disperd for 2h at room temperature,and then the excess sol was filtered from CFs with the precursor of Fe 3O 4(CFs/precursor).After being dried at 120◦C,CFs/precursor was further annealed at different temperatures under vacuum for 2h.After repeating the process veral times,CFs would be coated by a uniform Fe 3O 4nanoparticles layer.2.3.Characterization
The morphologies,particle size,and thickness of Fe 3O 4nanoparticles coating on CFs were investigated by a field emis-sion scanning electron microscopy (FESEM,JSM-6700F).The pha structures of CFs/precursor annealed were character-ized by X-ray powder diffraction (XRD,D/Max-rA)with Cu K ␣radiation (λ=0.15418nm).Thermal analysis (TG-DTA)of the CFs/precursor was conducted in N 2on a thermal ana-lyzer (TA,SDT-2960)at a heating rate of 10◦C/min from room temperature to 900◦C.The residual organic materials on the surface of Fe 3O 4nanoparticles were examined by X-ray diffraction photoelectron spectroscopy (XPS,ESCALAB Mark II)and Fourier transform infrared spectrophotometer (FTIR,安抚
UV-3101).
Fig.3.XRD patterns of CFs/precursor annealed at different temperatures under vacuum for 2h:(a)250◦C,(b)300◦C,(c)550◦C and (d)700◦C.
J.Xu et al./Materials Science and Engineering B132(2006)307–310309
3.Results and discussion
刘翔的励志故事3.1.Characterization of CFs/Fe3O4composite
A typical TG-DTA curve for CFs/precursor is shown in Fig.2. The TGA curve exhibits three distinct weight loss steps and the DTA curve shows three exothermic peaks.Thefirst obvi-ous weight loss step in the temperature range of150–250◦C is accompanied with an exothermic peak around200◦C in the DTA curve.We believe this result is due to the combustion of organic residue in the CFs/precursor.The cond weight loss step in the temperature range of250–320◦C and the broad exothermic peak around290◦C in the DTA curve are considered as a result of crystallization of Fe3O4pha.Almost no weight loss was obrved from300to530◦C,implying the unique prence of CFs/Fe3O4in this temperature range.The exothermic peak at 620◦C in the DTA curve and the weight loss process continued until about680◦C are presumed to be associated with the crys-tallization of␣-Fe pha.The XRD analysis was carried out to probe the composition at different temperatures(Fig.3)
,which confirmed the results of TG-DTA.
Fig.3shows the XRD patterns of CFs/precursor annealed at different temperatures under vacuum for2h.At250◦C(Fig.3a), no other diffraction peaks except the(002)peak of graphite appears,indicating that the Fe3O4coating layer on CFs has not been formed.Fig.3b and c illustrate that CFs/Fe3O4composite can be obtained in the temperature range from300to550◦C. The diffraction peaks at2θ=35.48◦,62.62◦,30.12◦,57.02◦, and43.12◦can be assigned to(311),(440),(220),(511) and(400)planes of Fe3O4(JCPDS88-0866),respectively.No other diffraction peaks can be obrved but tho of graphite and Fe3O4,indicating that the coating layer is only consisted of Fe3O4nanoparticles.When CFs/precursor were annealed at 700◦C(Fig.3d),the pha of␣-Fe appears and the(002)peak
of Fig.4.FESEM micrographs of(a)bare CFs,(b)multiple CFs/Fe3O4composite,(c)single CFs/Fe3O4composite,and(d)the magnified view of Fe3O4nanoparticles coating layer.
310J.Xu et al./Materials Science and Engineering B132(2006)
307–310
Fig.5.XPS spectrum of Fe3O4nanoparticles parated from CFs/Fe3O4com-posite of O1s.
graphite still remains,showing that the CFs/precursor changed to CFs/␣-Fe at high-temperature under vacuum.No obvious peaks corresponding to ferrite nitrite or other iron oxide,such as␣-Fe2O3and␥-Fe2O3,are detected(Fig.3).
Fig.4shows the FESEM micrographs of bare CFs, CFs/Fe3O4composite(CFs/precursor annealed at300◦C).The diameters of bare CFs with smooth surfaces are about6–8m (Fig.4a).The direct evidence of the formation of Fe3O4nanopar-ticles coating on CFs is given by FESEM in Fig.4b.It is apparent that almost all CFs have been fully coated with uniform Fe3O4 nanoparticles without parated Fe3O4nanoparticles conglom-erations next to the coating layers.The ca.800nm thickness of coating layer is obrved distinctly in Fig.4c,and Fig.4d is the magnified micrograph of Fe3O4nanoparticles coating, which reveals that the perfect coating are compod of Fe3O4 nanoparticles with sizes of about30nm.
3.2.The surface properties of Fe3O4nanoparticles detached from CFs/Fe3O4composite
To analyze the surface properties of Fe3O4nanoparticles, we parated Fe3O4nanoparticles from CFs/Fe3O4composite. XPS analysis(Fig.5)was performed to characterize the surface properties of Fe3O4nanoparticles detached from CFs/Fe3O4 composite.The oxygen1s peak is deconvoluted into three spec-tral bands at530.6,532.0,and533.4eV.The most inten peak at530.6eV is attributed to the lattice oxygen in the metal oxide. The532.0eV of binding energy is due to the carbonyl(C O) and the relatively small peak at533.4eV reprents C–O.The results indicate that some organic residual materials exist with the Fe3O4nanoparticles.To further confirm the results,FTIR analysis was carried out to probe the surface properties of Fe3O4 nanoparticles parated from CFs/Fe3O4composite(Fig.6). Vibrational features at3400,1634and1400cm−1are assigned to the O–H,C O and C–O stretching motion.The FTIR studies correctly agree with the results of XPS.Thus,we conclude
that Fig.6.FTIR spectrum of Fe3O4nanoparticles detached from CFs/Fe3O4com-posite.
some organic materials have been absorbed on Fe3O4nanopar-ticles.
苹果电脑备份4.Conclusions
Fe3O4nanoparticles have been successfully coated on CFs surfaces by sol–gel method.The CFs/Fe3O4composite is prent at300–550◦C,and the Fe3O4coating layers with thick-ness ca.800nm are compod by Fe3O4nanoparticles of mean sizes ca.30nm.The surface properties of Fe3O4nanoparti-cles parated from CFs/Fe3O4composite have been studied by XPS and FTIR analysis.The results indicate that some organic residue exist with Fe3O4nanocrystalline.CFs/Fe3O4compos-ite is potential microwave absorbing materials,and the magnetic properties and microwave absorption properties of CFs/Fe3O4 will be considered in our future work.
References
few[1]A.N.Yusoffa,M.H.Abdullah,J.Magn.Magn.Mater.269(2004)271.
[2]P.-H.Martha,J.Magn.Magn.Mater.215–216(2000)171.
[3]T.Giannakopoulou,L.Kompotiatis,A.Kontogeorgakos,G.Kordas,J.
关于教师的名言Magn.Magn.Mater.246(2002)360.
[4]H.How,C.Vittoria,J.Appl.Phys.69(1991)5183.
[5]K.Hatakeyama,T.Inui,IEEE Trans.Magn.20(1984)1261.
[6]M.Matsumoto,Y.Miyata,IEEE Trans.Magn.33(1994)4459.
明月照我还[7]G.Dorey,J.Phys.D:Appl.Phys.20(1987)245.
[8]J.B.Donnet,R.C.Bansal,M.J.Wang,CFs,Marcel Dekker,New York,
1990.
[9]Y.Yang,B.S.Zhang,W.D.Xu,Y.B.Shi,N.S.Zhou,H.X.Lu,J.Alloy
Compd.365(2004)300.
[10]Y.Yang,B.S.Zhang,W.D.Xu,Y.B.Shi,Z.S.Jiang,N.S.Zhou,B.X.
女射手Gu,H.X.Lu,J.Magn.Magn.Mater.256(2003)129.
[11]C.Y.Huang,W.W.Mo,M.L.Roan,Surf.Coat.Tech.184(2004)163.
[12]X.Z.Huang,X.D.Li,C.X.Feng,P.Peng,J.Funct.Mater.4(2000)
446.
[13]K.Raj,R.Moskowitz,J.Magn.Magn.Mater.85(1990)223.
[14]H.Zeng,J.Li,J.P.Liu,Z.L.Wang,S.H.Sun,Nature420(2002)395.
