空心阴极远区等离子体放电结构的优化设计

射频空心阴极远区等离子体放电具有离子浓度高、易于实现大面积处理的优点,正受到越来越多的关注。空心阴极等离子体流的特性与空心阴极的喷嘴结构有很大的关系。如何准确、便捷设计空心阴极喷嘴放电结构,是空心阴极远区等离子体表面处理的关键问题。构建了空心阴极等离子体放电自洽模型,推导了空心阴极等离子体放电电流与空心阴极喷嘴结构之间的关系,应用放电粒子模拟仿真软件,对空心阴极放电结构进行优化设计,实现了快速、准确设计,达到高效等离子体表面改性的目的。     

常压DBD等离子体对高分子纤维材料改性应用

利用常压介质阻挡放电等离子体对超高分子量聚乙烯和聚丙烯纤维进行表面改性，研究了处理前后聚乙烯纤维的力学性能的变化和纤维束与环氧树脂粘合性能的改善情况，以及等离子体处理对聚丙烯纤维吸湿改性的影响。结果表明，纤维束在断裂强度相对较低的情况下，纤维与树脂的层间剪切应力有比较大的提高，此外，等离子体处理后经观察发现，聚丙烯纤维的微观表面出现了明显的凹坑和裂纹，其吸湿性能得到了提高。     

等离子体表面改性对PTFE织物自润滑衬垫综合性能的影响

采用等离子体对PTFE织物进行表面改性,通过接触角测试、顶破强力、剥离强度和摩擦磨损寿命试验研究等离子体表面改性对PTFE织物亲水性、PTFE织物自润滑衬垫整体强度、剥离强度和摩擦磨损性能的影响。试验结果表明：等离子体表面改性后PTFE织物与水的接触角由135.9°降至91.8°,树脂对织物的浸润效果得到了改善;等离子体表面改性后PTFE织物衬垫的平均顶破强力为未处理衬垫的1.59倍;平均剥离强度为未处理衬垫的2.07倍;平均摩擦磨损寿命为未处理衬垫的1.66倍,衬垫的整体强度和耐磨性均得到了提高。     

失效空心阴极发射体的扫描电镜研究

利用场发射扫描电镜(FESEM)及其附带能谱仪研究了失效空心阴极发射体的表面形貌、元素组成.研究了离子源环境参数包括预热温度、环境气体组成等对空心阴极失效的影响.提出在离子束辅助沉积(Ion Beam As-sisted Deposition)系统中影响空心阴极发射体寿命的影响因素包括预热温度,环境气体等.通过控制温度和环境气体参与反应的时间可以提高空心阴极的寿命.     

微球材料作为润滑添加剂的摩擦学性能研究——粒径分布的影响

以未处理空心微球材料为原料制备粒度分布均匀集中的空心微球材料,用硅烷偶联剂对其进行表面改性处理,使其具有良好的亲油性。用HQ-1环块试验机在高速低载荷和低速高载荷2种工况下,测定了所制备的空心微球材料作为500SN基础油添加剂的摩擦磨损性能。结果表明:经处理后的空心微球材料可以显著提高500SN基础油的抗磨减摩性能;经处理后的空心微球材料的抗磨减摩性能好于未处理空心微球材料,表明粒径分布对摩擦学性能有显著影响。     

不同方法表面改性碳纤维增强热塑性聚酰亚胺复合材料的摩擦磨损性能

采用硝酸氧化改性和涂层复合改性法分别对碳纤维(CF)进行了表面处理,并制备了CF增强热塑性聚酰亚胺(TPI)复合材料;对CF的表面形貌进行了观察,研究了表面改性方法对复合材料摩擦磨损性能的影响,并利用扫描电子显微镜观察了磨损表面形貌。结果表明:硝酸氧化改性增大了CF的表面粗糙度,随处理时间的延长粗糙度增大;经涂层复合改性后,CF表面包覆了一层聚酰亚胺(PI),保护了CF并提高了其与基体界面的结合强度;经表面改性后的CF增强TPI复合材料的摩擦磨损性能均得到提高,以涂层复合改性的效果最好;硝酸氧化改性后的CF在摩擦过程中易断裂,复合材料的磨损形貌以磨粒磨损为主,而涂层复合改性后的CF断裂得到抑制,与基体结合更为牢固,磨损表面较为平整。     

无机填料的改性及其在复合材料中的应用

阐述了填料表面改性技术即偶联剂处理技术、表面活性剂处理技术、等离子体处理技术的最新研究进展,介绍了数种典型无机填料在复合材料中的应用现状,以及填料粒径、形状和含量对填充效果的影响。     

表面改性对滑动轴承弹流润滑的影响

考虑滑移边界条件,建立了极限剪应力模型和线接触弹流润滑模型,推导了润滑剂界面滑移速度,并修正了流体润滑Reynolds方程,针对界面改性后滑动轴承的润滑状态进行了探究。首先,分析了对轴瓦和轴颈界面均进行改性处理后,轴承润滑状态在整个弹流润滑接触区的变化;其次,分别研究了仅对轴瓦或者轴颈做改性处理的影响;最后,探究了界面改性对轴承摩擦因数的影响,并讨论了摩擦因数随载荷、速度的变化。结果表明,在弹流润滑的条件下,同时对轴瓦和轴颈进行表面改性处理时,油膜会在入口区形成凹陷,在出口区形成坍塌;仅对轴颈界面进行改性处理时,油膜会在整个接触区形成凹陷,对应的压力也会随之增加;相反,仅对轴瓦界面进行改性处理时,油膜厚度减小,压力降低;表面改性处理后,摩擦因数降低,并随载荷、速度的增大而减小。     

不锈钢方轨形靶PIII处理及流体力学模拟*

对方轨形AISI304不锈钢靶进行了氮的等离子体浸没离子注入(PI II)处理,试验结果表明,表面硬度明显提高,摩擦学特性也得到显著改善。其中上表面的 改 性效果明显优于侧表面。利用二维流体模型对注入过程中等离子体行为进行了模拟研究,结 果表明：最大的注入剂量发生在上表面的中心区,在侧表面附近由于离子受到底面的竞争吸 引,而使注入的剂量明显低于上表面,因而得到不同的改性效果。     

空心阴极等离子烧结工艺

本文提出的空心阴极等离子烧结工艺，其原理是利用空心阴极放电时，正离子对烧结坯料表面的轰击，使坯料得到直接加热而烧结。具有烧结产品质量高、省电节能、无污染、设备无专门加热装置，还可对零件同时进行等离子化学热处理等优点。     

Prediction of permeability of non-woven geotextiles from morphometry analysis

The permeability coefficient of non-woven geotextiles used for soil stabilization, erosion control and earth reinforcement is predicted from a proposed analytical method. A mathematical model is used to depict both fabric's void and soil particles histograms and related them to forecast eventual clogging level. Experimental data indicated a relationship between water permeability and fibre density of a fabric. Lastly a proposed method is presented for the prediction of the filtration performance of multi-layer or composite fabrics.     

Effect of plasma treatment of Kevlar fabric on the tribological behavior of Kevlar fabric/phenolic composites

Pure and plasma-treated Kevlar fabrics were used to prepare Kevlar fabric/phenolic composites by consecutive dipping of the fabric in phenolic adhesive resin. The friction and wear performance of the resulting composites has been evaluated in a pin-on-disk wear tester at various dry-sliding conditions. The surface changes occurring on Kevlar fibers treated with air-plasma were analyzed by using X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscope (FT-IR) and scanning electron microscope (SEM). Moreover, the impact of air-plasma treatment time and power on the friction and wear behavior of Kevlar fabric/phenolic composites composed of the air-plasma-treated Kevlar fabrics was systematically studied. It was found that plasma treatment can significantly improve the tribological performance of the prepared Kevlar fabric/phenolic composites; the best performance was after a plasma treatment at 50 W for 15 min. The plasma treatment generates oxygenic and nitrogenous groups on the surface of the fabric, coupled with an increase of the surface roughness, strengthening the bond between the Kevlar fabric and phenolic adhesive resin and hence improving the tribological properties of the Kevlar fabric/phenolic composites.     

PTFE/芳纶纤维编织衬垫自润滑关节轴承的黏接性能及摩擦学性能

对PTFE/Kevlar纤维混合编织衬垫分别进行超声波处理、稀土CeO2处理后,制备了自润滑关节轴承,利用Instron5944型电子万能材料试验机和自制的高频摆动摩擦磨损试验机对关节轴承进行了剥离强度测试和摩擦磨损性能试验,考察了前处理工艺对关节轴承的黏接性能和摩擦学性能的影响,并采用扫描电镜(SEM)观察分析了衬垫表面的微观形貌变化,以探究轴承的摩擦学性能与衬垫形成PTFE转移膜的成膜性能之间的关系。结果表明,衬垫经改性前处理后,不仅提高了衬垫与基体的黏接性能,而且提高了轴承的摩擦学性能;轴承的摩擦学性能与其在摩擦磨损过程中形成PTFE转移膜的成膜性能之间存在一定的对应关系,即PTFE转移膜的形成越快,耐磨性、均匀连续性越好,在摩擦磨损过程中表现出较优的摩擦诱导成膜性能,其摩擦学性能也越优。     

山梨糖醇类成核剂(TM-3)对PP性能的影响

本文采用山梨糖醇类成核剂(TM-3)对均聚PP作了增透处理,研究了TM-3用量对PP材料透明性、结晶性能以及力学性能的影响。研究结果表明在合适的添加量下,TM-3能明显提高均聚PP的透明性、结晶度以及力学性能。     

表面渗铬渗碳后力学性能的研究

在50钢表面进行等离子渗Cr，然后进行等离子超饱和渗碳、淬火及回火处理，获得表面强化层，并对处理后的材料进行拉伸试验和断口形貌观察。结果表明：50钢经表面强化处理后，表面硬度迭HV1000以上，抗拉强度得到了显著提高，极大地改善了其力学性能。表面强化层均存在解理台阶；而未经过处理的基体表面存在大量韧窝。     

聚丙烯PP注塑化学微发泡过程的研究

本文通过对聚丙烯PP化学微发泡注塑过程进行研究,对微发泡后材料的密度、力学性能、泡孔分布、断口特征进行分析,结果表明在化学微发泡注塑过程中存在有"欠发泡"、"微发泡"以及"过发泡"三种状态,对注塑化学微发泡过程的控制是制备高性能微发泡材料的关键。     

车用聚丙烯及其复合材料的性能与应用

聚丙烯及其复合材料是汽车上常用的塑料材料之一,也是用量最大的塑料材料,约占汽车塑料总用量的21%。研究了PP,PP/弹性体,PP/滑石粉,PP/玻璃纤维,PP/PA,PP/PE等材料的结构和力学性能,分析了它们在汽车零部件领域的应用,为聚丙烯及其复合材料的深入发展与应用提供参考。     

Investigation of air filter properties of nanofiber non-woven fabric manufactured by a modified melt-blowing method along with flash spinning method

Nanofibers are used in various fields and applications, such as medical care, environment protection, apparel, and agriculture; it is believed that they will continue to show substantial growth in the future. In this study, we focused on the filtration application of nanofibers. The filtration performances achieved polymeric nanofiber mass production by a melt-blowing method. First, the filtration performances of the fiber were experimentally tested with different thicknesses. Then, the computational fluid dynamics flow-analyzing software was used to simulate the pressure loss and flow resistivity of the trial-produced filter under the same conditions as those used in the experiment. Then, a three-directional physical model was proposed and used to calculate the fiber's gap size with different diameters under the same filling rate and the assumption that the fibers always exhibit uniform distribution. Consequently, it was confirmed that the trial-produced non-woven filter possessed excellent filtration abilities and that the investigated data can be used as a standard to manufacture non-woven fabric for producing high-performance filters and face masks. However, the manufacturing method of non-woven fabric filters must be investigated to satisfy both high particle filtration efficiency and low pressure loss in order to develop a high-performance filter.     

A proposed method to reconstruct the three‐dimensional dispersion profile of polymeric fibres based on variable wavelength interferometry

In this paper, we suggest a modification to the conventional variable wavelength interferometry. This modification allowed us to calculate the dispersion curve of each point inside polymeric fibres instead of calculating the mean dispersion of these fibres. This modified mathematical treatment was used to calculate the three‐dimensional dispersion profile of isotactic polypropylene fibres suffering from necking deformation. The different steps of calculating the three‐dimensional dispersion profile of the fibre were demonstrated. The application of this modified method revealed the variation of the fibre material dispersion before, inside and after the necking region. In addition, the birefringence profile of the necked isotactic polypropylene was determined using the proposed mathematical treatment. This allowed us to diagnose the interaction of the incident waves with necked polypropylene fibres, which gives extensive information on the orientation of the molecular chains during the formation of the necking phenomenon.     

A study on tribological behaviours of ZDDP in polymer thickened lubricating greases

Zinc Dialkyl Dithiophosphate (ZDDP) is a well‐known multifunctional additive for soap based lubricating greases. Polymers are being studied for their performance as lubricating grease thickeners and rheology modifiers. In this work the tribological study of ZDDP was carried out in polypropylene (PP), maleated polypropylene (mPP) and linear low density polyethylene (PE) thickened lubricating greases. Performance of lithium grease was taken as a reference. The tribological properties were evaluated using a four ball tester for EP properties and Optimol SRV‐III machine for coefficient of friction. The mechanism of action of ZDDP in polymer greases was established through analysis of the worn surface of steel balls with scanning electron microscope (SEM) and energy dispersive x‐ray spectroscopy (EDAX). The results show that the performance of ZDDP depends on the thickener system. The antiwear and EP property exhibited by ZDDP varies from polymer to polymer. Poor performance was observed with PP type thickener whereas performance in PE and lithium grease was comparable. Copyright © 2015 John Wiley & Sons, Ltd.