CNTs/SiC/Cu复合材料制备及性能

以碳纳米管(CNTs)、碳化硅(SiC)粉体、锌(Zn)粉和CuSO_4·5H_2O为主要原料,用化学镀的方法制备CNTs /Cu复合粉体,再采用非均相沉淀法制备CNTs/SiC/Cu复合粉体.在750 ℃、100 MPa的制度下进行真空热压烧结后制得CNTs/SiC/Cu复合材料,其中Cu的含量(体积分数,下同)为70%,CNTs的含量(体积分数, 下同)分别为0,3%,5%,8%,12%.利用XRD、SEM分析样品的物相组成和显微结构;利用阿基米德排水法、显微硬度计、三点弯曲法测试了复合材料的密度、显微硬度和抗弯强度.结果表明,随着碳纳米管含量的增加,CNTs/SiC/Cu复合材料的密度、显微硬度和抗弯强度等性能发生相应变化,其中,抗弯强度呈现逐渐升高趋势.与未添加碳纳米管的30SiC/70Cu复合材料相比,添加12%CNTs的12CNTs/18SiC/70Cu 样品,抗弯强度提高了21.45 MPa.     

混杂增强(CNTs+TiB2)/Cu复合材料制备与性能

本文以碳纳米管（CNTs）和TiB2颗粒作为增强相,首先利用球磨、表面吸附和热压烧结相结合技术制备具有层叠结构的CNTs/Cu复合材料,改善了CNTs在铜基复合材料中易团聚问题。CNTs/Cu复合材料的致密度和导电率随CNTs含量增加而降低,抗拉强度和伸长率随CNTs含量增加先升高后降低,当含量为0.1 wt.%时综合性能最优,致密度、导电率和抗拉强度分别为97.57%、91.2 %IACS和252 MPa。而球磨后热压烧结的1 wt.% TiB2/Cu复合材料致密度、导电率和抗拉强度分别为97.61%、58.3 %IACS和436 MPa。在此基础上,将TiB2颗粒原位引入到具有层叠结构的CNTs/Cu复合材料,制备获得混杂增强(CNTs+TiB2)/Cu复合材料。相比单一CNTs（或TiB2）增强铜基复合材料,(CNTs+TiB2)/Cu复合材料的强度提升显著。其中,(0.1 wt.% CNTs+1 wt.% TiB2)/Cu复合材料的导电率和抗拉强度分别为56.4 %IACS和531 MPa,相比1 wt.% TiB2/Cu,其导电率仅降低3.3%,而抗拉强度则升高21.8%。这主要归因于片层间CNTs可起承担和传递载荷作用,同时片层间弥散分布的TiB2颗粒可以钉扎位错,两种强化机制共同作用使(CNTs+TiB2)/Cu复合材料的抗拉强度显著提升。     

Friction and wear properties of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes (CNTs) were coated by tungsten layer using metal organic chemical vapor deposition process with tungsten hexacarbonyl as a precursor. The W-coated CNTs (W-CNTs) were dispersed into Cu powders by magnetic stirring process and then the mixed powders were consolidated by spark plasma sintering to fabricate W-CNTs/Cu composites. The CNTs/Cu composites were fabricated using the simi-lar processes. The friction coefficient and mass wear loss of W-CNTs/Cu and CNTs/Cu composites were studied. The results showed that the W-CNT content, interfacial bonding situation, and applied load could influence the friction coefficient and wear loss of W-CNTs/Cu com-posites. When the W-CNT content was 1.0 wt.%, the W-CNTs/Cu composites got the minimum friction coefficient and wear loss, which were decreased by 72.1% and 47.6%, respectively, compared with pure Cu specimen. The friction coefficient and wear loss of W-CNTs/Cu composites were lower than those of CNTs/Cu composites, which was due to that the interfacial bonding at (W-CNTs)-Cu interface was bet-ter than that at CNTs-Cu interface. The friction coefficient of composites did not vary obviously with increasing applied load, while the wear loss of composites increased significantly with the increase of applied load.     

Cu-20vol%(Fe-Cr)原位复合材料中Cr元素的作用

通过冷拔变形制备了Cu—20vol％(Fe—Cr)和Cu—20vol％Fe原位复合材料，研究了Cu—20vol％(Fe—Cr)中Cr元素的作用。结果表明，Cr元素主要存在于增强相Fe中，铜基体中几乎是不含Cr的。Cr元素固溶强化增强相比，使Fe—Cr相比Fe相具有更高的硬度。在拉拔变形过程中，Fe—Cr相比Fe相的纤维细化困难，在同等冷拔变形量时，Fe—Cr纤维比Fe纤维要宽。Cr元素的加入使Cu—20vol％(Fe—Cr)具有比Cu—20vol％Fe更高的力学稳定性。     

EBSD characterization of Al7075/graphene nanoplates/carbon nanotubes composites processed through post-deformation annealing

The effects of the post-deformation annealing on the microstructural evolution of hot rolled Al7075 matrix composites reinforced with CNTs and GNPs were investigated. The multi-pass hot rolling was applied on the stir cast samples. Annealing was then applied to the composites at 450 °C for 4 h. Microstructural evolution was examined by SEM, EDS, and EBSD techniques. EBSD data showed that the addition of 0.87 vol.% (GNPs + CNTs) significantly inhibited the occurrence of recrystallization. Also, in the composite with 0.96 vol.% CNTs, recrystallization was partially inhibited. Whereas, in composites with 0.92 vol.% of GNPs, the occurrence of recrystallization through particle stimulated nucleation (PSN) mechanism was significantly accelerated. The volume fraction of recrystallized grains depends significantly on the occurrence of PSN in the presence of reinforcements. The intensity and type of the main components of the texture as well as the FCC fibers depend on the type of reinforcement.     

碳纳米管增强铜基复合材料的制备、力学性能及电导率

以CNTs、电解Cu粉、Cu(CH_3COO)_2·H_2O为原料,采用混酸处理、分子水平法结合行星球磨两步混合工艺制备含0.5%～2%(质量分数)CNTs的Cu基复合粉末,然后通过放电等离子烧结技术制备了Cu-CNTs复合材料,探讨了制备工艺及CNTs含量对Cu-CNTs复合材料的组织、电导率和力学性能的影响规律。结果表明:当CNTs含量小于1.0%时,采用两步混粉工艺制备的Cu-CNTs复合粉体均匀性、分散性良好,经烧结后可获得致密度高、CNTs分布均匀的Cu-CNTs复合材料;当CNTs含量大于1.0%时,复合材料的致密度及CNTs分布均匀性明显降低;随CNTs含量的提高,复合材料的强度先升高后降低,塑性和电导率趋于降低;相对高能球磨、分子水平法等单一混粉工艺而言,两步法制备的Cu-1.0%CNTs复合材料综合性能更优,其电导率为51.7 MS/m(89.1%IACS),维氏硬度为1130 MPa,抗拉强度为279 MPa,断后伸长率为9.8%。     

Preparation and properties of Cu matrix composite reinforced by carbon nanotubes

Cu matrix composites reinforced by carbon nanotubes(CNTs) were prepared. The effect of carbon nanotubes on mechanical and tribological properties of the Cu matrix composites were investigated. The chemical method for coating CNTs was reported. The morphology of the fracture surfaces and worn surface were examined by SEM.The results show that Cu/coated-CNTs composites have higher hardness, much better wear resistance and antifriction properties than those of the reference Cu alloy (Cu-10Sn) and Cu/uncoated-CNTs composite sintered under the same conditions. The optimal mechanical properties of the composites occurred at 2. 25%(mass fraction) of CNTs. The excellent wear resistance and anti-friction properties are attributed to the fiber strengthening effect of CNTs and the effect of the spherical wear debris containing carbon nanotubes on the tribo-surface.     

电流对碳纳米管增强铜基复合材料载流摩擦学性能的影响

采用粉末冶金方法在相同的工艺条件下制备纯铜和碳纳米管含量为10%（体积分数）的铜基复合材料。在一种销盘式载流摩擦磨损试验机上考察了不同电流条件下2种材料的载流摩擦磨损性能。结果表明：纯铜和铜基复合材料的摩擦系数和磨损率均随电流的增大而增大,但是电流对纯铜材料的影响更加显著;纯铜材料的主导磨损机制是电弧烧蚀磨损,而铜基复合材料的主导磨损机制是塑性流动变形;碳纳米管可以改善铜基复合材料的载流摩擦磨损性能。     

Effect of Cu additive on the structure and magnetic properties of （CoPt）1-xCux films

CoPt thin films with various Cu contents varying from 0 vol.% to 21.5 vol.% were deposited on glass substrates by magnetron sputtering. The effects of Cu additive on the structural and magnetic properties and the ordering temperature of CoPt films were investigated in detail. The results show that the Cu in CoPt films plays an important role in promoting the ordering parameter S and reducing the ordering temperature of CoPt films. A nearly perfect (001) texture was obtained in a CoPt film doped with 15.3 vol.% Cu. Besides, the preferred orientation of the CoPt film can be changed by annealing temperature. The perpendicular growth of the CoPt film is favored at a high annealing temperature.     

Cu含量对CNTs/Al-Cu复合材料显微组织和压缩力学性能的影响（英文）

通过热压烧结和热轧制备碳纳米管(CNTs)增强的Al-Cu基复合材料,系统研究Cu含量对Al与CNTs的界面反应、含Cu沉淀物的析出行为及相应复合材料力学性能的影响。研究表明,提高Cu含量不仅能使复合材料制备过程中含Cu析出相的数量和尺寸增加,而且能促进CNTs与Al基体之间的界面反应,加剧CNTs转化为Al₄C₃。由于含有1%Cu(质量分数)的复合材料保持CNTs的原始结构,因此,它在所有复合材料中具有最高的强度、弹性模量和硬度。此外,增加Cu含量还能改变影响复合材料强度的主要强化机制。     

Grain refinement and tensile strength of carbon nanotube-reinforced Cu matrix nanocomposites processed by high-pressure torsion

In recent years, the processing of metallic materials via severe plastic deformation has been widely applied to manufacture bulk specimens of ultrafine grained/nanocrystalline structures. In this study, bulk nanocomposites of carbon nanotube-reinforced Cu were manufactured by consolidation of mixtures of coarse grained Cu powders and CNTs of two volume fractions (5 vol% and 10 vol%) using high-pressure torsion, a typical SPD method. The effects of CNT reinforcements on the microstructural evolution of the Cu matrix were investigated using electron backscatter diffraction and scanning/transmission electron microscopy; the results showed that the Cu matrix grain size was reduced to ～114 nm, and the CNTs were well dispersed in the matrix. Due to the effect of the UFG Cu and CNTs, the tensile strength (350 MPa) of the nanocomposite was higher than that (190 MPa) of Cu processed by the powder HPT process without CNTs. However, the Cu-CNT 10 vol% indicated a decreased tensile strength due to an increased interface area between the matrix and CNTs at high volume fractions of CNTs.     

Effect of Cu additive on the structure and magnetic properties of (CoPt)1-xCux films

CoPt thin films with various Cu contents varying from 0 vol.% to 21.5 vol.% were deposited on glass substrates by magnetron sputtering. The effects of Cu additive on the structural and magnetic properties and the ordering temperature of CoPt films were investigated in detail. The results show that the Cu in CoPt films plays an important role in promoting the ordering parameter S and reducing the ordering tempera-ture of CoPt films. A nearly perfect (001) texture was obtained in a CoPt film doped with 15.3 vol.% Cu. Besides, the preferred orientation of the CoPt film can be changed by annealing temperature. The perpendicular growth of the CoPt film is favored at a high annealing tempera-ture.     

Properties of copper/graphite/carbon nanotubes composite reinforced by carbon nanotubes

Electroless Cu plating was used for flake G powder and CNTs, Cu-G-CNTs (copper/graphite/carbon nanotubes) composites were manufactured by means of powder metallurgical method. The influences of CNTs on the mechanical properties, conductivity properties, friction, and wear performance of the composite were examined. The results indicate that adding a small amount of CNTs can improve comprehensive property of the composites, especially mechanical property. However, excessive CNT, which is easily winding reunion and grain boundary segregation, results in performances degradation.     

Gra./Cu和CNTs/Cu复合材料的截流值与阴极斑点研究

采用粉末冶金方法制备石墨铜复合材料(Gra./Cu)和碳纳米管铜复合材料(CNTs/Cu),研究2种铜基复合材料的真空电弧截流现象和阴极斑点特性。结果表明,与Gra./Cu相比,CNTs/Cu在真空放电过程中电弧更加稳定,且分散性好,截流值小;在正对阳极处CNTs/Cu的真空电弧烧蚀坑明显比Gra./Cu的细小,灼痕直径约为0.1～5μm,分布面积也较小,而Gra./Cu的灼痕直径为10～100μm;两者的相同之处在于,在电击穿过程中阴极斑点的运动呈一种随机的、突变式的跳跃,而且选择性发生在Cu相上,Cu相被消耗。总之,CNTs/Cu比Gra./Cu具有更高的耐电弧烧蚀能力,CNTs的加入可以有效地增加铜基复合材料的电弧稳定性和降低截流值。     

Uniform and Homogeneous Growth of Copper Nanoparticles on Electrophoretically Deposited Carbon Nanotubes Electrode for Nonenzymatic Glucose Sensor

The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper(Cu) nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose detection.The expensive glassy carbon electrode was replaced by fluorine-doped tin oxide glass containing CNTs film to confine the Cu nanoparticles growth by electrodeposition through cyclic voltammetry(CV). The ultraviolet visible and X-ray diffraction analysis revealed the successful deposition of Cu nanoparticles on the CNTs-modified electrode. The atomic force microscopy images confirmed the morphology of electrodeposited Cu on CNTs film as uniformly dispersed particles.The electrocatalytic activity of electrode to the glucose oxidation was investigated in alkaline medium by CV and amperometric measurements. The fabricated sensor exhibited a fast response time of less than 5 s and the sensitivity of 314μA mM~(-1)cm~(-2)with linear concentration range(0.02–3.0 mM) having detection limit 10.0μM. Due to simple preparation of sensor, Cu/CNTs nanocomposite electrodes are a suitable candidate for reliable determination of glucose with good stability.     

Electrocatalytic oxidation of methanol on carbon-nanotubes/graphite electrode modified with platinum and molybdenum oxide nanoparticles

Electrochemical codeposition and electrocatalytic properties of platinum and molybdenum oxide nanoparticles(Pt-MoOx) on carbon-nanotubes/graphite electrode for methanol oxidation were investigated.The micrograph and elemental composition of the resulting Pt-MoOx/CNTs/graphite electrode were characterized by scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS).The results show that the Pt-MoOx particles with the average size of about 50 nm are highly dispersed on the CNTs surface.The Pt-MoOx/CNTs/graphite electrode delivers excellent electrocatalytic properties for methanol oxidation.The highest mass activity(Am)reaches 264.8 A/g at the loading mass of 159.3μg/cm2.This may be attributed to the small particle size and high dispersion of Pt-MoOx catalysts deposited on the CNTs surface.The kinetic analysis from electrochemical impedance spectroscopy(EIS)reveals that the existed MoOx phase can improve the chemisorptive and catalytic properties for methanol oxidation.     

高压酸浸镍钼矿提取钼和镍

研究一项针对镍钼矿用高压酸浸的方法回收镍和钼的全湿法工艺。采用该工艺避免了传统上艺焙烧镍钼矿（15％～25％s）带来的人量S02和As2O3排放,减小了对环境的污染;与现有的湿法碱浸回收钼工艺相比,本工艺存酸浸过程中回收了儿乎全部的镍和人部分的钼。在氧压环境下,几乎全部的镍和大部分的钼都进入溶液,少部分的钼留在酸浸渣中,睃浸渣进一步用碱（NaOH）浸出。在最佳的实验条件下,97％的镍和96％的钼分别被浸出。     

Effects of Growth Parameters on the Morphology of CNTs/Cu Composite Powder Prepared Using Cr/Cu Catalyst by Chemical Vapor Deposition

采用化学共沉淀法制备了Cr/Cu复合粉体催化剂,并用化学气象沉淀法（CVD）原位合成CNTs/Cu复合粉末。利用SEM, TEM和Raman光谱分别对其微观形貌和结构进行表征。结果表明：采用化学气相沉淀法,使用10 wt%Cr/Cu 的催化剂,在混合气体(Ar/H2/C2H4) 流量2450/300 mL/min下,于1073 K 温度生长30 min,可以得到优质、结晶良好的 CNTs/Cu 复合粉末     

Characterization and mechanical testing of alumina-based nanocomposites reinforced with niobium and/or carbon nanotubes fabricated by spark plasma sintering

Alumina-based nanocomposites reinforced with niobium and/or carbon nanotubes (CNT) were fabricated by advanced powder processing techniques and consolidated by spark plasma sintering. Raman spectroscopy revealed that single-walled carbon nanotubes (SWCNT) begin to break down at sintering temperatures >1150 °C. Nuclear magnetic resonance showed that, although thermodynamically unlikely, no Al₄C₃ formed in the CNT-alumina nanocomposites, such that the nanocomposite can be considered as purely a physical mixture with no chemical bond formed between the nanotubes and ceramic matrix. In addition, in situ single-edge notched bend tests were conducted on niobium and/or CNT-reinforced alumina nanocomposites to assess their toughness. Despite the absence of subcritical crack growth, average fracture toughness values of 6.1 and 3.3 MPa m^1/2 were measured for 10 vol.% Nb and 10 vol.% Nb-5 vol.% SWCNT-alumina, respectively. Corresponding tests for the alumina nanocomposites containing 5 vol.% SWCNT, 10 vol.% SWCNT, 5 vol.% double-walled-CNT and 10 vol.% Nb yielded average fracture toughnesses of 3.0, 2.8, 3.3 and 4.0 MPa m^1/2, respectively. It appears that the reason for not observing improvement in fracture toughness of CNT-reinforced samples is because of either damage to CNTs or possibly non-optimal interfacial bonding between CNT-alumina.     

Corrosion and electrochemical evaluation of an Al–Si–Cu aluminum alloy in ethanol solutions

The corrosion of aluminum alloy AlSi8Cu3Fe(Zn) in ethanol and ethanol solutions containing 10 vol.% water and 10 vol.% acetic acid, respectively, was investigated by means of electrochemical impedance spectroscopy (EIS), polarization curve, immersion, optical microscopy, scanning electron microscopy and element mapping. The Al alloy in the ethanol and its solutions exhibited a capacitive loop in the measured Nyquist EIS spectra at high frequencies, which can be attributed to the ethanol’s dielectric response. Addition of 10 vol.% acetic acid increased the ethanol corrosivity more significantly than the same amount of water addition. The Al–Si–Cu–Mg precipitated zones in the alloy were susceptible to corrosion attack due to the micro-galvanic effect by the Cu-containing precipitates.