等离子体表面处理技术的应用

作为表面处理技术之一的等离子体表面处理技术已经获得广泛的应用。等离子体表面处理方法的优点是利用其处理后的表面化学活性状态增快反应速度。在较低温度下,这类反应也能进行。在这种处理方法中,使置放在等离子体中的固体表面产生新的化合物,改变固体表面的性质。等离子体表面氧化是使半导体表面经过辉光放电处理形成表面氧化膜。若把试样放在等离子体中进行表面处理,试样会直接受到带电粒子的冲击。为了弥补这个缺点,可以在半导体上加盖保护膜,使其产生界面氧化。这个方法叫做界面氧化。作为保     

玻璃纤维表面化学处理对其浸润性能的影响

本文应用单丝接触角测定仪测定了不同偶联剂处理的玻璃纤维临界表面张力。结果表明:由于固体临界表面张力是描述固体表面性质的物化数据,因此它仅与表面复盖物的性质有关,而与内部的玻璃纤维的成份无关。不同偶联剂处理的玻璃纤维具有不同的表面张力,依次为7114>KH550>A151。沉积在玻璃纤维表面的偶联剂各级分对浸润性能的贡献是不相同的。     

碳纤维的电聚合处理及其对复合材料性能的影响

一、引言 碳纤维电聚合表面处理是近年发展起来的一项新技术。所谓电聚合处理,就是在电场引发下使单体在碳纤维表面聚合,从而在碳纤维表面生成聚合物涂层。在电聚合中可以通过选用不同的单体和聚合条件来改变聚合物涂层的性质,以改善碳纤维复合材料(CFRP)的性能。电聚合处理有可能在碳纤维表面生成聚合物接枝,使聚合物涂层和碳纤维产生化学键接。同时,聚合物涂层内一些活性基团能与基体树脂中的官能团发生化学反应,这样就可大大提高碳纤维与树脂间的粘结强度。     

氧离子注入对铝膜导电性能的影响

众所周知,离子注入能够的改变固体表面的物理、化学、机械等性质。例如,改变金属的导电及摩擦性质,改变光学材料的折射率。我们把离子注入技术和真空镀膜技术结合起来,在蒸发薄膜中,注入各种不同的离子,来改变薄膜组分、结构和性质,以期制取各种不同性质的薄膜。一、实验步骤     

用低温等离子体对高分子材料进行表面加工

用等离子体对高分子材料进行表面处理.改变其表面性质是一个值得推广的方法.在第一部分介绍了高温等离子体和低温等离子体的特性;在第二部分介绍了荷电粒子与高分子材料表面的相互作用;第三部分介绍了低温等离子体在改善纺织品表面性能中的应用.其中的一类主要是表面变性.即改善纺织品的亲水性或润湿性.提高表面染色粘附性:另一类主要的表面处理是乙烯系不饱和单体.不饱和聚合物、丙睛、丙烯酸等的接枝.可以根据不同的单体与要达到的目的来确定使用什么单体和什么工艺.经过接枝处理的纤维性能将会发生较大的改变.     

硅烷偶联剂对玻璃纤维表面性能的影响

固体的表面自由能是影响到吸收,浸润,粘附等表面性能的一个特征因子,但测定固体表面能的直接方法尚未建立。在本研究中,我们采用电子天秤法对未处理玻璃纤维及各种硅烷偶联剂处理后玻纤的表面自由能及其分量作了测定,其基础是通过测定液体L₁在另一液体L₂之下对固体S接触角,间接地求得固体的表面能。结果表明,玻纤的表面自由能因硅烷偶联剂的处理而降低,并与偶联剂的结构密切有关。若硅烷中带有极性基团,则处理后玻纤的表面能较高;反之若硅烷中不含有极性基,则处理后玻纤的表面能较低。用带双键硅烷处理的玻纤有中等的表面自由能。      

等离子化学在高分子材料中的应用

等离子体是一种由离子、电子和中性粒子组成的部分电离气体。与普通气体相比,等离子体处于高度激发的不稳定状态,利用这一性质进行化学反应,即为等离子化学或等离子处理。等离子化学反应的主要特征是只在固体材料表面发生反应,而在材料内部基本不发生反应。因此,将这一特性用于高分子材料的表面改性,具有重要的     

纳米TiO2电泳粒子表面电荷的可控制备

分别以阴、阳离子表面活性剂和聚合物作为表面修饰剂,以四氯乙烯、十二烷基苯和Isopar H作为分散介质,研究纳米TiO2电泳粒子表面荷电性质及其荷电量的可控制备.研究结果表明,阳离子表面活性剂修饰的TiO2粒子的ξ电位在四氯乙烯中呈负性,在十二烷基苯和Isopar H中呈正性;阴离子表面活性剂的修饰产物则相反.进一步研究了十二烷基苯磺酸钠、十六烷基三甲基溴化铵和苯乙烯/二乙烯苯修饰的TiO2粒子体系中电荷控制剂的浓度对TiO2粒子荷电量的影响.结果表明TiO2电泳粒子的ξ电位在电荷控制剂的临界胶束浓度附近存在极小值,并随着浓度的增加而有规律地变化,但荷电性质不改变.根据这一规律可实现对粒子表面电荷的可控制备.     

微观结构表面接触角模型及其润湿性

润湿性是固体表面的重要性质之一,固液界面润湿性与表面微观结构、界面能等有关.研究了微观结构固体表面固液界面润湿性以及界面能、液滴重力、微观结构参数对润湿性的影响.分析表明,Young、Wenzel、Cassie、Cassie-Baxter等4种接触角模型分别把固体表面看成光滑、粗糙(液滴完全填满)、粗糙(液滴不填充)以及粗糙(液滴部分填充),后3种模型可用于实际固体表面,并可在3种状态下实现转换.设计了方柱凹坑、圆柱凹坑等微观结构表面,调控横径比、纵径比、深径比等微观结构参数,可以改变固液界面润湿性.研究发现,液滴重力对表面接触角存在稍许影响,界面能的大小决定着材料表面的疏/亲水性.     

轮缘固体润滑剂对轮轨减摩及损伤性能影响

用MMS-2A滚动摩擦磨损试验机完成试验工作,对比干态和3种不同固体润滑剂作用工况,分析干态和3种不同固体润滑剂作用后的轮轨摩擦性能和固体润滑剂的有效作用时间,探究固体润滑剂对轮轨摩擦性能的影响;分析不同工况下轮轨表面磨损量和表面裂纹,同时对裂纹的长度、角度、深度进行统计,分析固体润滑剂作用对轮轨损伤性能影响。结果表明:固体润滑剂具备减摩润滑作用,其中1号效果最佳,将干态下的摩擦系数0.5降低到0.2左右;固体润滑剂通过降低接触界面的摩擦系数减小轮轨界面的切向摩擦力,降低轮轨表面的磨损量,其中固体润滑剂1降低车轮和钢轨的磨损量最大,分别降低95.3%和97.1%;固体润滑剂主要通过抑制疲劳裂纹的长度来抑制轮轨疲劳裂纹的生长和扩展,通过正应力挤压作用使轮轨表面疲劳裂纹开口紧闭,缓解裂纹根部分支现象,有效抑制轮轨疲劳裂纹生长与扩展行为.     

Curvature‐Controlled Wrinkling Surfaces for Friction

Topographical patterns endow material surfaces with unique and intriguing physical and chemical properties. Spontaneously formed wrinkling has been harnessed to generate surface topography for various functionalities. Despite promising applications in biomedical devices and robot engineering, the friction behavior of wrinkling on curved surfaces remains unclear. Herein, wrinkled surfaces are induced by sputtering metals on soft polymer microspheres. The wrinkle morphologies and length scales can be controlled precisely by tailoring the microsphere radius (substrate curvature) and film thickness. The wrinkled surfaces exhibit controlled friction property, depending on the wrinkling patterns and length scales. An increase in friction force with increasing surface roughness is generally found for dimple patterns and labyrinth patterns. The dimple patterns show the lowest friction due to strong curvature constraint. The herringbone patterns exhibit apparent friction anisotropy with respect to topographic orientation. These results will guide future design of wrinkled surfaces for friction by harnessing substrate curvature.     

Friction and Wetting Transitions of Magnetic Droplets on Micropillared Superhydrophobic Surfaces

Reliable characterization of wetting properties is essential for the development and optimization of superhydrophobic surfaces. Here, the dynamics of superhydrophobicity is studied including droplet friction and wetting transitions by using droplet oscillations on micropillared surfaces. Analyzing droplet oscillations by high‐speed camera makes it possible to obtain energy dissipation parameters such as contact angle hysteresis force and viscous damping coefficients, which indicate pinning and viscous losses, respectively. It is shown that the dissipative forces increase with increasing solid fraction and magnetic force. For 10 µm diameter pillars, the solid fraction range within which droplet oscillations are possible is between 0.97% and 2.18%. Beyond the upper limit, the oscillations become heavily damped due to high friction force. Below the lower limit, the droplet is no longer supported by the pillar tops and undergoes a Cassie–Wenzel transition. This transition is found to occur at lower pressure for a moving droplet than for a static droplet. The findings can help to optimize micropillared surfaces for low‐friction droplet transport.     

考虑离心作用的螺杆挤出机固体输送理论模型

在固体输送段,物料由散粒体逐渐被压缩,形成压力梯度。离心力对固体输送有较大的影响,由于离心力的作用,物料与机筒之间的径向作用力大于物料与螺杆之间的径向作用力。在固体输送段压力沿螺杆轴向逐渐增大,输送角逐渐减小。文中根据实验现象,考虑离心力,建立了可压缩体的固体输送物理模型,并求出数学模型的解析解。理论计算表明,即使机筒与固相的摩擦系数小于螺杆与固相的摩擦系数,仍会有固体输送。     

石墨烯基薄膜作为固体润滑材料的研究现状及展望

近年来,微型机械系统对摩擦接触表面和界面性能的要求越来越高,表界面设计与改性问题亟待解决.石墨烯自发现以来,由于具有高机械强度、超薄的厚度、原子级光滑表面及低的层间剪切力和高的化学稳定性,作为表面固体润滑材料在摩擦学领域成为研究热点.本文主要介绍了石墨烯及其衍生物薄膜材料的制备方法,作为固体润滑材料在摩擦学方面的研究现...     

Analysis of abnormal wear on a certain type of CRH380 high-speed railway grounding brush

This paper investigated the causes of premature wear of grounding brushes in high-speed train which was less than 40 % of design service life. The grounding brushes were analyzed from the material composition, microstructure and mechanical property under different wear conditions. The results indicated that their material composition and microstructure were basically identical, and the phase compositions of the four samples were mainly copper (Cu) and carbon (C). There were no obvious defects in the structure. The load differences will give rise to vibration of the friction pairs and lead to electrical erosion on the worn surface. The electrical erosion produced oxides and fused hard particles as well as caused abrasive wear. The test results also indicated that the spring-induced gap across the contact surfaces resulted in electrical erosion.     

有机硅高沸物水解物作为塑料填料的应用

水解有机硅高沸物制盐酸的过程会产生大量高度交联的聚硅氧烷固体残渣,利用该残渣与塑料的相容性,将其作为填料加入其中,达到增量与降低成本的目的。文中以低密度聚乙烯(LDPE)为例,对有机硅高沸物水解物/LDPE复合材料的力学、燃烧与耐候性能进行了研究。结果表明,有机硅高沸物水解物填料在基材LDPE中的填充量为20%时,复合材料性能较优。此时,材料的拉伸强度与断裂伸长率分别降低14.05%和34.00%,燃烧速率略有降低;而硬度提高9.03%,弯曲强度提高16.82%,热稳定性与耐候性也有所提高。     

Using hierarchical memory to calculate friction force between fractal rough solid surface and elastomer with arbitrary linear rheological properties

An algorithm for calculating the force of friction between a fractal rough solid surface and a model elastomer with arbitrary linear rheological properties has been developed based on the method of dimensionality reduction with application of a hierarchically organized memory. Using this method, it is possible to calculate the friction force between an elastomer and a solid surface with experimentally determined topography, taking into account both the broad spectrum of wave vectors (ranging from nanometers to centimeters) for real surfaces and the wide range of relaxation times (from nanoseconds to seconds).     

多纤维增强重型汽车制动器摩擦材料的摩擦磨损性能研究

采用芳纶浆粕、玻璃纤维、硅灰石纤维和钛酸钾晶须多纤维混杂增强制备重型汽车制动器摩擦材料.利用XD-MSM型定速摩擦试验机,考察了摩擦材料的摩擦系数和磨损率随温度变化的情况,并且通过扫描电镜观察了摩擦材料在不同温度下磨损后的表面形貌,分析其摩擦磨损机理.研究结果表明,所研制的摩擦材料具有足够的机械性能和优异的摩擦磨损性能,热衰退小、恢复性能好、耐磨损,可满足重型汽车制动性能的要求.材料在中高温下主要是磨粒磨损和热疲劳磨损,同时伴随着粘着磨损.     

Analytical study of energy-force parameters in the upsetting-torsion of cylindrical semifinished products made of a highly ductile material

The upper-bound method is used to solve a problem concerning the upsetting of a solid circular cylinder made of a linear strain-hardening material. The cylinder is upset with the use of flat rotating dies. Total power consumed in the operation is minimized on the basis of a parameter that characterizes slip between the dies and the ends of the semifinished product. Analytic expressions are obtained to determine the upsetting force and turning moment. It is found that a decrease in the upsetting force increases the friction coefficient on the contact surfaces, the rotational velocity of the dies, and strain in the height direction.Translated from Problemy Prochnosti, No. 6, pp. 68–71, June, 1994.