石墨毡电极与集流体的简单可靠粘接及其在电解中的应用

石墨毡有比表面积大、导电性强、廉价易得等优点,被认为是极具应用前景的三维电极材料。为使电极与集流体良好接触,采用高导电碳黑做导电填料、聚偏氟乙烯做粘接剂制备了导电胶,实现了对石墨毡电极与柔性石墨纸集流体的简单可靠粘接。探究了导电胶配比、涂胶量和固化压力条件对石墨毡-集流体粘接试样导电性能和粘结强度的影响。粘接试样的接触电阻相较于靠压紧的无胶试样降低了50%,拉伸剪切强度达到与石墨毡自身强度接近的25.3×10^-3 MPa。将胶粘石墨毡电极用于印刷电路板酸性氯化铜蚀刻液的电解再生和铜回收,单槽电压降低了0.08 V。这使得以金属铜计的电解再生和铜回收的比能耗降低了80 kW·h·t^-1。     

延伸外摆线齿准双曲面齿轮接触特性有限元分析

针对车辆运行的几种工况（正车、倒车、空挡前行、空挡后退）,在摆线齿准双曲面齿轮三维几何建模基础上,采用有限元方法对准双曲面齿轮动态接触进行仿真,获得了不同运行工况下齿面接触面积、接触力的变化特征。仿真结果表明,小轮轮齿凹面驱动大轮轮齿凸面的驱动方式（正车）下,齿轮接触面积和接触力较稳定,动态啮合性能和传动性能较好,而车辆空挡运行时啮合稳定性较差,对齿轮的损伤将增大。     

某厂地下水除铁锰系统的改造工程

某水厂以地下水为水源,主要以去除地下水中的铁和锰为主要任务。为了满足生活及生产用水量的需求,解决系统设施老化陈旧以及运行成本高等问题,对该厂现有处理工艺进行改造。将压力式滤罐改换为重力式无阀滤罐,新建了回收水池,将原回收水池改为清水池。改造后的水厂处理系统稳定、可靠,节约了高运行成本,且符合节能环保的要求,出水水质满足《生活饮用水卫生标准》GB5749-2006。     

臭氧氧化处理法对聚丙烯表面涂装性的改良 Ⅳ.聚丙烯表面亲水性和涂膜剥离强度的关系

讨论了用臭氧氧化法对聚丙烯表面进行涂装性改良时,丙烯均聚物、乙烯-丙烯嵌段共聚物及无规共聚物表面以接触角表示的亲水性和涂膜剥离强度之间的关系。结果表明,当聚丙烯表面对水的接触角在84°附近时,可反应型涂料的涂膜剥离强度将出现最大值。在此也证明了涂膜的剥离破坏存在着接着破坏和凝集破坏两种机理,当接触角减小到84°及84°以上时,剥离发生在聚丙烯和涂层的界面上产生接着破坏;当接触角减小到84°以下时,剥离发生在聚丙烯的表面氧化层相中,产生凝集破坏。     

Surface properties of polymers treated with tetrafluoromethane plasma

Polymer films of poly(ethylene terephthalate), polypropylene, and cellophane were surface treated with tetrafluoromethane plasma under different time, power, and pressure conditions. Contact angles for water and methylene iodide and surface energy were analyzed with a dynamic contact angle analyzer. The stability of the treated surfaces was investigated by washing them with water or acetone, followed by contact angle measurements. The plasma treatments decreased the surface energies to 2–20 mJ/m² and consequently enhanced the hydrophobicity and oleophobicity of the materials. The treated surfaces were only moderately affected after washing with water and acetone, indicating stable surface treatments. The chemical composition of the material surfaces was analyzed with X-ray photoelectron spectroscopy (XPS) and revealed the incorporation of about 35–60 atomic % fluorine atoms in the surfaces after the treatments. The relative chemical composition of the C ls spectra's showed the incorporation of —CHF— groups and highly nonpolar —CF₂— and —CF₃ groups in the surfaces and also —CH₂—CF₂— groups in the surface of polypropylene. The hydrophobicity and oleophobicity improved with increased content of nonpolar —CF₂—, —CF₃, and —CH₂—CF₂— groups in the surfaces. For polyester and polypropylene, all major changes in chemical composition, advancing contact angle, and surface energy are attained after plasma treatment for one minute, while longer treatment time is required for cellophane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1591–1601, 1997     

胀接压力与初始间隙对换热器胀接质量的影响

为研究换热管-管板胀接压力与初始间隙对换热器胀接质量的影响,采用胀接参数化模拟研究方法对液压胀接进行可靠性研究,建立换热管-管板胀接的弹塑性参数化几何模型,对不同的换热管-管板胀接压力和初始间隙进行研究,得到换热管残余等效应力、残余接触应力大小及分布规律。研究表明：胀接压力相同、间隙不同时,卸载后残余等效应力和残余接触应力值差别较小;初始间隙相同,胀接压力不同时,卸载后残余应力和残余接触应力值差别较大;换热管的残余等效应力和残余接触应力随着胀接压力的增大而增大,其变化趋势一致;当材料为Ti31钛合金、胀接压力为183 MPa时换热管与管板的初始间隙消除。研究结果为换热器最佳胀接性能优化及胀接质量的提高提供了依据。     

Rupture of Wetting Films Formed by Bubbles at a Quartz Surface in Cationic Surfactant Solutions

Experimental studies were performed on the kinetics of the three‐phase contact formation and bubble attachment to a quartz surface in solutions of a cationic surfactant of various concentrations. By tuning the distance between the single‐bubble formation point and the quartz surface immersed in the solution, the influence of the state of the dynamic adsorption layer over a rising bubble on the mechanism of rupture of a wetting film formed was elucidated. Based on the unique methodology, allowing precise control over the initial degree of adsorption coverage at the detaching bubble, new evidence was found confirming the electrostatic character of the wetting film rupture in cationic surfactant solutions of low concentrations.     

Wettability of Surface Oxyfluorinated Polypropylene Fibres and Its Effect on Interfacial Bonding with Cementitious Matrix

The surface of high molecular weight polypropylene monofilament fibre was modified using a oxyfluorination method. The oxyfluorination treatment level was varied and a hydrolysis post-treatment was also applied. Contact angles of oxyfluorinated, hydro-lyzed oxyfluorinated and unmodified polypropylene fibres were obtained by dynamic contact angle (DCA) measurement using three liquids of known dispersion, acid and base surface free energy components. The surface free energies were then calculated according to the acid-base theory developed by Good, van Oss and Chaudhury. Surface oxyfluorination largely increased the acid and base components of the fibres' surface free energy compared with unmodified polypropylene fibres. The oxyfluorinated and unmodified polypropylene fibre surfaces were observed by Scanning Electronic Microscopy and Photoacoustic Infrared Spectroscopy. It was found that the surface oxyfluorination largely increases the roughness of the polypropylene surfaces and the carbonyl group content increases as the treatment level increases. The interfacial shear bond strengths between the cementitious matrix and the polypropylene fibres treated under various conditions were determined by embedded fibre pull-out tests. Results showed that the fibre surface oxyfluorination treatments increase the interfacial bond strengths. The correlations between the shear bond strengths and surface free energy components were established. Results showed that fibre/concrete interfacial bonding was best correlated with the acid component of surface free energy of polypropylene fibres.     

On the importance of some surface and interface characteristics in the formation of the properties of adhesive joints

The importance of some relative surface characteristics which determines the strength of adhesive joints: specific surface of substrate , relative contact area β and specific contact area β in the adhesion interaction process were emphasised. Existing and potential methods of experimental evaluation of these characteristics were shortly analysed. The durability of the adhesive joints in water media significantly increases with growth of specific surface ^* of chemically treated substrate evaluated from the SEM micrographs. Specific surface calculated from the experimental data of hexane adsorption measurements for iron particles (particulate model of steel substrate) is more then ten times greater than respective ^* values. The relative contact area β of the Al₂O₃ particles (in wide range of ) with PE melt was in a roundabout way evaluated by experimental determination of the affect of on kinetic of peel strength formation of adhesive joints: Al₂O₃ filled PE-steel. The speculation was based on the ability of Al₂O₃ to adsorb low-molecular products of contact oxidation of PE which takes place in the process of formation of adhesive joints and determines their strength. The ability of sorption in its turn is proportional to efficient value of β. The availability of the Al₂O₃ surface was evaluated.     

表面改性对滑石粉理化性质的影响

采用钛酸酯对滑石粉进行表面改性,以接触角为评价指标,得到最佳的改性工艺参数为:钛酸酯的添加量为3％,反应温度为65℃,反应时间为1.5h.分别采用粒度分析、XRD分析、红外光谱分析以及热重分析对改性前后滑石粉的结构和表面性质进行表征,结果表明,钛酸酯对滑石粉的改性效果显著,表面改性过程不仅发生了物理吸附,还存在化学键合.