【作者】 曾俊；

【导师】 徐金城；

【作者基本信息】 兰州大学 ， 材料物理与化学， 2009， 博士

【摘要】 作者研究了粉末冶金方法制备的碳纤维增强无铅锡青铜基复合材料(基体成分质量分数：Sn 4％和Zn 6％其余为铜)的力学性能以及减摩擦抗磨损性能。并探讨了热氧化方法制备的CuO纳米线／碳纤维复合材料的磁性和吸波性能。(1)研究了镀铜时的PH值、镀铜时间和镀铜工艺次序对碳纤维表面镀铜薄膜质量的关系，制备了铜薄膜厚度约2μm质地均匀的镀铜碳纤维。基本解决了碳纤维与锡青铜基体之间润湿性差的问题，为制备高强度、耐磨损、减摩擦的碳纤维增强铜基复合材料奠定了坚实的基础。也为制备宽频、强吸收、轻质的纳米氧化物吸波复合材料提供了优良的前驱体。(2)通过温压、复压复烧的方式制备出了高致密度、高硬度、高抗拉强度和减摩耐磨的碳纤维增强锡青铜基复合材料。通过性能表征显示9％体积分数的碳纤维增强锡青铜基复合材料的硬度、抗拉强度、比磨损率、摩擦系数都优于ZQ663锡青铜合金。其中碳纤维体积分数为9％左右时，复合材料的硬度达到最大值HV138．2 MPa，与ZQSn663锡青铜合金的硬度相比提高了大约80％。复合材料的抗拉强度也达到了最大值302 MPa，与ZQSn663锡青铜合金的抗拉强度相比提高了大约68％。且复合材料的比磨损率只有ZQ663锡青铜合金的比磨损率的1％，摩擦系数也远小于ZQ663锡青铜合金。所制备的金属基复合材料，取代了锡青铜(ZQ663)基体中全部的铅和部分贵金属锡；使复合材料不仅对环境无害，而且降低了成本，节约了资源，是一种符合生态环境协调性要求的金属基复合材料。(3)通过热氧化的方法在400℃焙烧4 h条件下，制备了CuO纳米线／碳纤维复合材料，其纳米线长度从几百纳米到几个微米不等，直径在50 nm到100 nm不等。通过VSM在室温条件下表征，结果显示CuO纳米线／碳纤维复合材料表现出微弱的磁性。通过Agilent E8363BPNA矢量网络分析仪测试了50％质量分数的CuO纳米线／碳纤维复合材料在电磁波频率1～18 GHz范围内的电磁参数。其最强吸收在7．9 GHz，达到了-32 dB(吸收率＞99．9％)，厚度仅为1．8 mm。CuO纳米线／碳纤维复合材料在反射率分别小于-4 dB和-10 dB时，电磁波频率分别覆盖了2．5～18 GHz和3～16．4 GHz，满足了高频和宽频吸收的要求。反射率小于-20 dB(吸收率＞99％)的条件下，吸收电磁频率也覆盖了3～9．8 GHz，满足了在低中频强吸收的需要。本试验制备的复合材料与报道的相同吸收率的材料相比，具有更薄的厚度。(4)通过热氧化方法在400℃的条件下，制备了CuO纳米线／钴／碳纤维复合材料。其中氧化铜薄膜的厚度约50 nm，钴薄膜的厚度约200 nm，涂层表面有稀疏的直径约10 nm的纳米线，其余部分以纳米小颗粒的形态存在。在外加磁场从-9000 Oe到9000 Oe的范围内，CuO／钴／碳纤维复合材料的饱和磁化强度达到了29．8 emu／g，大约是CuO／碳纤维复合材料饱和磁化强度的1 150倍。质量分数为30％的CuO纳米线／钴／碳纤维复合材料具有更低的反射率，且当厚度为2 mm和外加频率在10．75 GHz时，复合材料具有最低的反射率-42．7 dB(吸收率＞99．9％)。当复合材料的厚度在1．3～2．2 mm的范围内，CuO纳米线／钴／碳纤维复合材料的强吸收(反射率＜-10 dB，吸收率＞90％)覆盖了频率8．72～18 GHz。在强吸收和相同厚度的前提条件下(反射率＜-10 dB，吸收率＞90％)，CuO纳米线／钴／碳纤维复合材料具有较宽的吸收频率(3 GHz)。因此，CuO纳米线／钴／碳纤维复合材料是一种较优异的吸收材料。(5)通过热氧化方法在400℃合成了ZnO纳米片状结构。根据发光性能测试，结果表明了ZnO纳米片结构／碳纤维复合材料在325 nrn激发条件下表现的橙红光是由碳的间隙原子和锌的间隙原子所致，绿光由材料内部的氧空位产生。(6)结合粉末冶金和热氧化方法制备了纳米注射器结构和微米正四面体结构MgZnO。随着焙烧温度增高，MgZnO形貌发生了改变，发光谱也明显红移(从500 nm移向560 nm)，这表明光致发光性能与其形貌密切相关。(7)通过粉末冶金和热氧化方法制备SnZnO材料并对其光致发光性能进行了研究。结果发现SnZnO为纳米纤维结构，其直径大约50 nm，长度大约60μm。在325 nm激发的条件下，纳米纤维结构的SnZnO在室温条件下激发出较强的绿光(493 nm)。(8)通过电化学沉积和热氧化方法制备了微米仙人球状CuO，并对其进行了表征。在350℃条件下热氧化4 h后薄膜表面合成了微米尺寸仙人球状CuO，球体表面为发散状的CuO纳米线，球体直径大约6微米。更多还原

【Abstract】 The lead free tin bronze matrix composite with chemical composition of Cu-4wt.%Sn-6wt.%Zn reinforced by carbon fibers (CF/tin bronze composite)is prepared bypowder metallurgy,and the mechanical,tribological and wear properties areinvestigated.The preparation and microwave absorbing properties of cupric oxidenanowire/carbon fiber composites (CuONW/CF composites)prepared by thermaloxidation are also investigated.(1)In order to prepare the high strength,anti-friction and anti-wear CF/tin bronzecomposite,the effects of plating solution PH,plating time and plating processes areinvestigated and the coated copper carbon fibers (Cu/CFs,2μm in thickness)areprepared.In addition,the Cu/CFs are used as starting reagent to prepare the effectivemicrowave absorption materials with the properties of wide frequency range,strongabsorption,low density and high resistivity.(2)The CF/tin bronze composites are prepared by warm pressing,repressing andre-sintering (powder metallurgy).The CF/tin bronze composites show high relativedensity,high hardness,high tensile strength,excellent anti-friction and anti-wearproperties.The hardness,tensile strength,friction and wear rate of 9 vol.% CF/tinbronze composites are better than that of the tin bronze ZQ663.In particular,the 9 vol.% CF/tin bronze composite has hardness of HV138.2 MPa,which is about 1.8 timeshigher than that of tin bronze 6-6-3.The 9 vol.% CF/tin bronze composite shows atensile strength of 302 MPa,which is about 1.68 times higher than that of tin bronzeZQ663.The wear rate of 9 vol.% CF/tin bronze composite is only 1% of that of tinbronze ZQ663.The friction coefficient of 9 vol.% CF/tin bronze composite is far lowerthan that of tin bronze ZQ663.Additionally,since lead in tin bronze is harmful to theenvironment and tin is a kind of valuable metal,CF/tin bronze composites eliminatelead and reduce tin addition in the composite matrix that show the excellent propertiesof the environment compatibility.(3)The CuONW/CF composites are synthesized by thermal oxidation of Cu/CFsat 400℃for 4 hours in air.The results of transmission electron microscope images indicate that the nanowires are about 50 nm in diameter and several microns in length.The magnetic properties of CuO nanowires are measured with a vibrating samplemagnetometer (VSM).It is interesting that the CuO nanowires on the carbon fibersshow ferromagnetic at room temperature.Agilent E8363B PNA vector networkanalyzer is used to measure microwave absorption property of CuONW/CFs.Theelectromagnetic parameter of 50 wt.% CuONW/CFs is measured by the coaxial linemethod at 1-18 GHz.The results show that the lowest reflectivity of CuONW/CFs is-32 dB (absorptivity＞99.9 %)at 7.9 GHz,and the corresponding thickness is 1.8 mm.The reflectivity of CuONW/CFs is less than-4 dB over the range of 2.5～18 GHz,-10dB over the range of 3～16.4 GHz and-20 dB over the range of 3～9.8 GHz.TheCuONW/CFs is thinner than those in other reports when the reflectivity is equivalent.(4)The CuONW/Co/CF composites are synthesized by thermal oxidation ofCu/CFs at 400℃for 4 hours in air.The thicknesses of cobalt and CuO are about 200and 50 nm,respectively.CuO nanowires (10 nm in diameter)and nanoparticles areobtained on the film surfaces.Due to the function of cobalt the saturation magnetizationvalue of CuO/Co/CF composites is raised to 28.7emu/g at an external field of 9 kOe,which is 1150 times higher than that of CuO/CF composites.The strongest reflectivityloss is further enhanced to-42.7 dB at 10.8 GHz for a layer of 2.0 thickness of thecomposites,and the strong absorption (RL＜-10 dB)is between 8.72 and 18 GHz withthe thickness of 1.3-2.2 mm.The reflectivity loss bandwidth of CuO/Co/CF compositesis more than 3 GHz when the thickness and absorption of materials are fixed.TheCuO/Co/CF composites are believed to be ideal for making a lightweight,strongabsorption and wide-frequency microwave absorbing materials.(5)The ZnO nanosheet/carbon fiber composites are synthesized by thermaloxidation of Zn/carbon fiber composites at 400℃for 4 hours in air.The opticalproperties were characterized with photoluminescence (PL)spectrum by RF-540 in 325nm.The results show that a broad orange-red emission covering range from 620nm to700nm by 325 excitation wavelength at room temperature.It is indicated that theorange-red emission is resulted from the interstitial carbon atoms of ZnOnanosheet/carbon fiber composites,and green emission results from the oxygen vacancies.(6)The nanosyringe-like and micromethane-like ZnMgO are synthesized byannealing the ZnMg alloy at 400℃for 4 hours in air.ZnMg alloys are prepared bycold press and sintering (powder metallurgy).The red shift from 500nm to 560nm ismore pronounced with increasing annealing temperature.The nanosyringe-like samplesexhibit broad green and yellow defect emission.The optical properties of ZnMgO arerelated to the morphologies.(7)The ZnSnO nanofibers are synthesized by thermal oxidation of ZnSn alloys.ZnSn alloys are prepared by powder metallurgy.The diameter and length of ZnSnOnanofibers are about 50nm and 60μm,respectively.The room temperaturephotoluminescence spectra of ZnSnO nanofibers show the near-band-edge emission at～391 nm and a broad green emission at～493 nm.(8)The radial structure CuO microspheres are synthesized by thermal oxidationof copper deposited on Indium Tin Oxides conducting glass.The microspheres areabout 6 microns in diameter.更多还原