Preparation of electrically conductive polyimide/silver composite fibers via in-situ surface treatment

Polyimide (PI)/silver composite fibers with high electrical conductivity were prepared via an in-situ surface treatment method. The following procedures were included: hydrolyzing the PI fibers in alkali solution, followed by silver ion loading through ion exchange in silver salt solution and finally reducing the silver ion-loaded PI fibers in ascorbic acid solution. The effects of alkali treatment and ion-exchange conditions on the surface morphology, electrical conductivity and mechanical properties of the final composite fibers were studied. Excellent surface electrical conductivity was achieved on PI fiber surface with an electrical resistance of about 10² Ω/cm. The mechanical properties of the PI composite fibers were essentially similar to those of the bare PI fiber.     

Modifying the surface of electrically conductive porous alumina

Electrically conductive porous alumina has been paid great interest due to its excellent properties determined by its unique porous structure and electrical conductivity. In this paper, acid-treatment has been employed to activate the inner-connected graphite pathways along alumina grains, which is responsible for its high conductivity and erosion resistivity. By this method, various oxygen-functional groups can be grafted onto graphite defects, which could be used for a number of potential applications. Field-emission scanning electron microscope (FE-SEM) observation, X-ray diffraction (XRD) analysis and Raman spectroscopy evaluation were employed to characterize the structure and component changes after acid-treatment. Electrochemical measurements carried out in 0.5 M H₂SO₄ electrolyte indicated its possible application as electrode material.     

原位置换法稳定导电胶接触电阻的研究

研究两种水溶性银盐(硝酸银及乙酸银)对银填充导电胶的热行为和体积电阻率的影响,及湿热老化条件下在锡表面接触电阻的稳定作用.DSC测试结果表明,这两种银盐的引入对导电胶固化行为没有影响.导电胶在湿热老化600h后,添加了2%(质量分数)的硝酸银和1.5%(质量分数)乙酸银样品体积电阻率分别下降了48.5%和47.4%,而...     

表面改性自金属化技术制备表面导电热固性聚酰亚胺复合材料

采用碱刻蚀/离子交换的方法对碳纤维增强热固性聚酰亚胺基复合材料进行了表面自金属化,制备了表面覆银导电聚酰亚胺复合材料。表征了聚酰亚胺复合材料表面酰亚胺五元环开环程度随碱液刻蚀条件的变化,研究了碱液刻蚀、酸洗、离子源和离子交换时间对复合材料表面导电性和力学性能的影响。当碱液刻蚀5 h、离子交换9 h时,热固性聚酰亚胺复合材料表面方块电阻可达0.26 Ω·sq?1,且基本力学性能得到保持。      

采用表面凝胶化技术制备超疏水性涂膜

采用表面凝胶化技术制备了超疏水性涂膜.在醇溶性氟化聚合物溶液中,在水量不足的酸性条件下,掺杂聚四氟乙烯(PTFE),得到了杂化复合溶胶.涂敷后,以表面凝胶化技术为手段,在涂层表面形成了微米和纳米相结合的阶层结构膜.TEM和XPS证实了凝胶化只在膜表面发生,SEM和AFM观察到膜表面的形貌与天然荷叶表面极其相似.该方法制备的涂膜对水的接触角高达155°,并具有良好的力学性能,可用于制备超疏水性功能化膜材料.     

包覆沉淀法制备氧化硅改性的纳米二氧化钛及其性质

采用包覆沉淀法,以混晶纳米二氧化钛粉体为载体,硅酸钠为包覆剂,用硫酸调pH值,成功的在纳米二氧化钛表面包覆致密的二氧化硅膜.并用IR、XRD、EDS及TEM进行了表征,同时对包覆改性前后的纳米二氧化钛进行比表面积、光催化活性的测定.IR、EDS表明:该包覆方法可行,氧化硅以化学键合的方式沉积在纳米TiO2的表面,在包覆层和纳米TiO2颗粒之间的界面上形成了Ti-O-Si键.XRD证实氧化硅的添加提高了二氧化钛纳米颗粒的热稳定性能,有效地抑制纳米二氧化钛的晶型转化.TEM照片显示,包覆后的TiO2粒径减小,粒度分布均匀,表面光滑.比表面和光降解实验结果显示,改性后的TiO2具有高的比表面,而且随包SiO2含量的增大而减小.和未改性纳米TiO2相比,具有较高的光催化活性,且在煅烧温度为600℃时催化活性最好.     

Preparation of highly conductive graphene-coated glass fibers by sol-gel and dip-coating method

In order to fabricate highly-conductive glass fibers using graphene as multi-functional coatings, we reported the preparation of graphene-coated glass fibers with high electrical conductivity through sol-gel and dip-coating technique in a simple way. Graphene oxide (GO) was partially reduced to graphene hydrosol, and then glass fibers were dipped and coated with the reduced GO (rGO). After repeated sol-gel and dip-coating treatment, the glass fibers were fully covered with rGO coatings, and consequently exhibited increased hydrophobicity and high electrical conductivity. The graphene-coated fibers exhibited good electrical conductivity of 24.9 S/cm, being higher than that of other nanocarbon-coated fibers and commercial carbon fibers, which is mainly attributed to the high intrinsic electrical conductivity of rGO and full coverage of fiber surfaces. The wettability and electrical conductivity of the coated fibers strongly depended on the dip-coating times and coating thickness, which is closely associated with coverage degree and compact structure of the graphene coatings. By virtue of high conductivity and easy operation, the graphene-coated glass fibers have great potential to be used as flexible conductive wires, highly-sensitive sensors, and multi-functional fibers in many fields.     

Preparation of multiple oxide BaTiO3 fibres by the sol-gel method

Multiple oxide BaTiO₃ gel fibres were prepared by the sol-gel method from Ba(OC₂H₅)₂-Ti(O-isoC₃H₇)₄-H₂O-C₂H₅OH-CH₃COOH and Ba(CH₃COO)₂-Ti(O-isoC₃H₇)₄-H₂O-CH₃COOH solutions. Relatively long gel fibres of 10cm length were obtained from both solutions in the limited composition region. The latter solution in particular showed a spinnability even when it contained no water. Therefore, the occurrence of spinnability of the solution was considered to be due to the formation of linear polymers composed of bridging acetate groups such as TiO-C(CH₃)-O-Ti rather than metalloxane bonding as Ti-O-Ti. Addition of water to the solutions seems to break the bridging acetate bonds and replace some of them by bridging oxygen bonds. The as-drawn gel fibres which were X-ray amorphous crystallized into BaTiO₃ ceramic fibres of 5mm average length upon heating above 600 ° C. However, the gel fibres drawn from the sols without water became powdery on heating because of the lack of Ti-O-Ti metalloxane bonds. The crystallization behaviour of the BaTiO₃ gel fibres is discussed based on the infrared spectroscopy, X-ray diffraction analysis and thermogravimetric-differential thermal analysis.     

Sol-Gel法制备钛酸铅涂层碳纤维工艺研究

用三种不同方案制备了钛酸铅（PT）溶胶,并在碳纤维表面制备了PT溶胶涂层。测试了溶胶黏度和稳定性,对纤维涂层的物相进行了XRD分析。实验表明,加入乙酰丙酮能有效地螯合Ti^4＋和控制水解的程度,合成的溶胶宜于长期放置;增加[Ti]^4＋／[Pb]^2＋比值会使溶胶的稳定性降低;溶胶黏度与浓度有相同的增大趋势,但高浓度的溶胶不宜于涂层制备;将溶胶涂于碳纤维表面,在氮气保护下经热处理,XRD检测结果有PbTiO3相存在,可成功制得连续的阿涂层碳纤维。     

不锈钢表面阴极等离子体液相沉积氧化铝层

使用阴极等离子体液相沉积技术在不锈钢表面生成了厚度达40μm的氧化铝膜层,研究了电流密度对膜层的组成和结构影响,以及膜层的生长规律和形成过程.膜层由α-Al2O3和γ-Al2O3组成,随着电流密度的增大,α-Al2O3的含量逐渐增大,电流密度为8 A/dm2时达到86%.膜层的表面粗糙、多孔,随着电流密度的增大,表面颗粒状明显增多,微孔数减少;基体中的Fe没有进入膜层,从膜层内向外Al和O的含量逐渐下降.     

浸渍-涂布法制备In2O3薄膜

以InCl3@4H2O为原料,采用溶胶-凝胶技术、浸渍-涂布法制备了In2O3薄膜.同时对薄膜厚度与In2O3含量、涂布液粘度以及提拉速度等关系进行研究,发现薄膜厚度与涂布液粘度、提拉速度成对数线性关系.膜厚与提拉速度的关系式为t≈v0.62.XRD、IR测试表明经过400℃煅烧,PVA已经完全排除.SEM照片表明薄膜形貌平整、光亮,从而为该种材料制作实用的气敏元件打下了良好的基础.     

Preparation of homogeneous titania coating on the surface of MWNT

Preparation of homogeneous and stable inorganic coatings on the surface of multi-wall carbon nanotubes (CNTs) was studied. Precursor compounds such as titanium (IV) bromide and titanium (IV) chloride were used to cover the surface of CNTs under either solvent-free or solution conditions. As-prepared titania layers were characterized by transmission, scanning electron microscopy and X-ray diffraction techniques. Results revealed that homogenous coverage can be achieved in a controllable way.     

表面包覆氧化镧的富锂锰基正极材料的制备及性能研究

通过溶液法在富锂锰基0.5Li2MnO3·0.5LiMn1/3Ni1/3Co1/3O2(简称LLO)正极材料前驱体表面包覆了一层稀土氧化物--氧化镧,制备了表面包覆氧化镧的LLO正极材料。采用X射线衍射仪、能量色散谱仪、扫描电子显微镜以及电池测试仪对材料进行表征和电化学性能测试,考察表面包覆氧化镧对LLO正极材料性能的影响。研究结果表明,用摩尔分数1%的氧化镧包覆LLO正极材料,极大地改善了材料的电化学性能。电化学性能的改善归因于包覆氧化镧后有效地稳定了材料的表面结构,避免了材料在循环过程中的分解。     

Preparation and conductive properties of neodymium-doped lanthanum nickelate thin films by chemical solution deposition method

Neodymium-doped lanthanum nickelate (La_1 − xNd_xNiO₃, LNNO) thin films have been prepared on Si substrates by chemical solution deposition method. The effects of annealing temperature and the neodymium concentration on the structural and electrical properties of the thin films have been investigated. X-ray diffraction analysis showed that the LNNO thin films exhibited perovskite structure with (100) preferential orientation. The (100) orientation degree of the thin films changed with neodymium content; however, the resistivity of the thin films was not related to the degree of orientation. Field emission scanning electron microscopy observations confirmed that the films had a smooth surface and uniform thickness. The resistivity of the thin films annealed at 700 °C increased from 1.97 mΩ·cm to 5.35 mΩ·cm, with increasing neodymium doping amount from LaNiO₃ to La_0.6Nd_0.4NiO₃.     

Preparation of transparent conductive indium tin oxide thin films from nanocrystalline indium tin hydroxide by dip-coating method

Indium tin oxide (ITO) thin films with well-controlled layer thickness were produced by dip-coating method. The ITO was synthesized by a sol-gel technique involving the use of aqueous InCl₃, SnCl₄ and NH₃ solutions. To obtain stable sols for thin film preparation, as-prepared Sn-doped indium hydroxide was dialyzed, aged, and dispersed in ethanol. Polyvinylpyrrolidone (PVP) was applied to enhance the stability of the resulting ethanolic sols. The transparent, conductive ITO films on glass substrates were characterized by X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy. The ITO layer thickness increased linearly during the dipping cycles, which permits excellent controllability of the film thickness in the range ~ 40-1160 nm. After calcination at 550 °C, the initial indium tin hydroxide films were transformed completely to nanocrystalline ITO with cubic and rhombohedral structure. The effects of PVP on the optical, morphological and electrical properties of ITO are discussed.     

采用溶胶-凝胶法在刀具表面制备MoS2软涂层的研究

在成功地采用柠檬酸溶胶-凝胶法在硬质合金试样表面制备出MoS2软涂层的基础上,采用扫描电镜形貌观察和摩擦系数测定等实验方法研究了MoS2加入量对涂层表面微观形貌及其摩擦性能的影响规律。结果表明,采用溶胶-凝胶法在1.6mol/L柠檬酸水溶液中分别添加13、20和27g/L MoS2粉末条件下,应用刷涂法均可以在硬质合金试样表面得到与基体结合牢固、表面质量较高的MoS2软涂层。所获得的MoS2软涂层的表面形貌呈片状。MoS2软涂层的存在明显地降低了硬质合金试样的摩擦系数,由硬质合金试样的0.58～0.86降低到软涂层的0.18～0.23。而具有不同MoS2加入量的软涂层间的摩擦系数相差不大。软涂层试样的摩擦系数明显低于硬质合金试样的原因与涂层中存在有摩擦系数低、承载力大等优良性能的MoS2以及软涂层的存在改变了原摩擦副材料间的性质等因素有关。     

磁控溅射金刚石微粉表面镀镍及其在电镀金刚石线锯上的应用

为了增强电镀金刚石线锯对金刚石颗粒的把持力,提高金刚石线锯寿命,使金刚石颗粒与电镀金属更好地结合,通过振动辅助的摇摆式样品台将金刚石微粉充分分散,使用磁控溅射方法在粒径为30~40μm的金刚石微粉表面镀附金属镍,利用其制备电镀金刚石线锯,借助光学显微镜(OM)、扫描电子显微镜(SEM)、能量色散X射线光谱仪(EDX)对制备的镀镍金刚石颗粒和电镀金刚石线锯进行形貌和成分表征,研究不同溅射和电镀条件对实验结果的影响;通过自制切割实验装置对比金属化前后的金刚石微粉制备的金刚石线锯对金刚石的把持力。结果表明:磁控溅射表面镀镍能增强电镀金属与金刚石表面的结合,切割试验后金刚石脱落量相比原始金刚石明显从17.4%减少到4.9%。     

Preparation of a tantalum-based MoSi2-Mo coating resistant to ultra-high-temperature thermal shock by a new two-step process

To develop an ultra-high-temperature resistant coating for a reusable thermal protection system,the preparation of a tantalum-based MoSi2-Mo coating by a new two-step process of multi-arc ion plating and halide activated pack cementation is presented.The coating has a dense structure and is well compatible with the tantalum substrate,which can be thermally shocked from room temperature to 1750℃ for 360 cycles without failure.The mechanism of the coating's excellent resistance to high-temperature thermal shocks is that a strong-binding gradient interface and a dense SiO2 oxide scale with good oxygen resistance are formed by the high-temperature self-diffusion of Si.     

通过仿生法在硅橡胶表面制备磷灰石薄膜的研究

用CaCl2的乙醇溶液和K2HPO4溶液对硅橡胶进行预处理,将处理过的硅橡胶分别浸渍于模拟体液和钙磷饱和溶液中来制备磷灰石薄膜.利用薄膜X射线衍射、红外吸收光谱和扫描电子显微镜对形成的薄膜进行了表征.结果表明,分别在模拟体液中7d和在钙磷饱和溶液中5d后,硅橡胶表面形成了一层磷灰石薄膜;在模拟体液中的薄膜表面呈网状并分布有许多球状晶粒,在钙磷饱和溶液中的薄膜为结晶良好的片状晶体.     

Characterization of SiO2/Ag composite particles synthesized by in situ reduction and its application in electrically conductive adhesives

In the study, SiO₂/Ag composite particles with silver coating onto the surface of silica have been successfully prepared via a novel and facile approach (Oxidation–Reduction Method). In this approach, the SiO₂ particles were first modified with 3-ammoniatriethoxysilane (APTES) and glyoxalic acid (GA) through two-step reaction, the aldehyde group (CHO) were anchored onto the surfaces of silica spheres via electrostatic attraction, these [Ag(TEA)₂]⁺ ions in the solution were then reduced by the CHO and coated onto the surface of silica to obtain SiO₂/Ag composite particles. The effects of the reaction conditions on silver content and synthetic mechanism had also been discussed. The structure, morphology and optical properties of the SiO₂/Ag composite particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis spectroscopy. The results showed the surface of SiO₂ was surrounded by pure silver nanoparticles, and the silver nanoparticles had face-centered-cubic structure, the SiO₂/Ag composite particles with core–shell morphology and special optical properties. And the small content SiO₂/Ag composite particles applied in electrically conductive adhesives (ECAs) improved the electrical bulk resistivity and tensile shear strength.