W-C-S-Mo复合薄膜的制备及力学和摩擦学性能

利用磁控溅射与磁过滤阴极真空电弧（MS/FCVA）复合沉积法，在不同偏压下在单晶Si基体上制备W-C-S-Mo四元复合薄膜；分析沉积偏压对薄膜纳米硬度、弹性模量和膜基结合力等力学性能的影响；在潮湿大气、真空环境下研究偏压对薄膜摩擦学性能的影响。结果表明，薄膜硬度、弹性模量和附着力随着沉积负偏压的增大呈现先增大后减小的趋势，在偏压-100 V时薄膜力学性能最好；负偏压-100 V下制备的W-C-S-Mo四元复合薄膜样品在潮湿大气和真空环境下均具有较好的摩擦学性能，拉曼测试发现，W-C-S-Mo复合薄膜在潮湿大气环境中的润滑作用主要由DLC提供，而在真空环境中薄膜中的软质相MoS2晶粒起润滑作用。     

一种介电型电活性聚合物材料的非线性超弹性模型

介电型电活性聚合物(Electroactive polymer,EAP)材料的应力应变本构模型是进行EAP驱动器设计和优化的基础。提出一种由非线性弹簧组成的、具有空间网状结构的EAP膜超弹性模型,基于能量法推导出其应力变形关系式,并揭示该模型与Ogden模型之间的关系。采用单轴、等双轴拉伸试验分别对相关模型参数进行拟合,利用该结果对等双轴、单轴拉伸的受力进行预测和对比分析。根据不同条件拟合出的材料参数进行试验预测时,其结果与实际值存在一定差异,提出对单轴、等双轴拉伸试验数据进行综合拟合的方法。采用综合拟合方法后模型分析精度得到很大提高。分析结果表明,3参数的非线性超弹性模型能较准确描述两种试验条件下的EAP膜应力变形关系,模型参数的拟合数据宜选与其工作条件相近的试验方法获取。     

Investigation of the Tribological Behaviors of Polymer Molecular Deposition Films by Tribometer Based on Interferometer

The polymer molecular deposition films including polyelectrolyte molecular deposition (PEMD) film and nanoparticles composite molecular deposition (NPs/MD) film have been prepared using the molecular deposition method and the in situ synthesize method. The polymer molecular deposition films were characterized by atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The tribological behaviors of the substrate and polymer molecular deposition films were investigated by a tribometer based on interferometer. It is found that the NPs/MD film has a lower friction force and a better anti-wear property than the PEMD film under the dry friction. The poly alpha olefin (PAO2) and water films confined between samples and steel ball surfaces have been investigated using thin film interferometry. The friction force of substrate was lower than the polymer molecular deposition films under PAO2 lubrication. The friction forces alteration of PEMD film and NPs/MD film were similar and consistent, and lower than that for substrate under water lubrication.     

Strain shielding and confined plasticity in thin polymer films: Impacts on thermomechanical data storage

Substrate constraints and interfacial boundary layers in thin polystyrene films are explored with high strain rate indentations characteristic of thermomechanical terabit data storage operations. Under these impact-like conditions, the coupling of strain-rate and inertial effects leads to large plastic deformations relative to quasi-static indentations. Strain shielding is present when the plastic deformation radius exceeds 65% of the film thickness. Thereafter, deformation is restricted by the rigid substrate, giving rise to elevated rim heights and interfacial shearing. The shielding effects were alleviated with use of a modulus-matched buffer layer between the polymer film and the substrate. A non-monotonic rheological gradient in the polymer films leads to the distribution of contact pressures between two asymptotic scenarios: (i) a compliant surface with a rigid sub-surface and (ii) a rigid surface with a compliant sub-surface.     

超磁致伸缩薄膜磁致伸缩耦合机理的有限元分析

从微观能量角度分析了超磁致伸缩薄膜的磁致伸缩机理,建立了超磁致伸缩薄膜的非线性强磁—机械耦合模型。设计了简支梁式超磁致伸缩薄膜的驱动磁场并对其进行实验研究。通过Ansys有限元分析软件对简支梁式超磁致伸缩薄膜驱动模型进行了模拟分析,最终得到的薄膜的内部磁场分布结构及固有频率。结果表明,采用椭圆积分法得到薄膜内部磁场分布的数学模拟计算结果与有限元仿真结果基本一致。     

The tribological behaviour of glass filled polytetrafluoroethylene

Polymers and polymer composites are steadily gaining ground over metals in the field of engineering applications in tribology. Laboratory wear tests were carried out under ambient temperatures with no lubricant as well as in distilled water at an average sliding velocity of 0.2 m/s and contact pressures of 2.6–6.4 MPa. Three forms of glass viz. glass fibres, glass beads and glass flakes, each with a content of 25% weight were used in this study. Both hollow and solid glass beads were used. The sliding wear of the different glass filled PTFE composites was dependent on their ability to form transfer films on the counterface. The glass bead filled PTFE showed comparatively thicker films and higher wear rates than other forms of glass filled grades. The glass fibres and solid glass beads showed the lowest wear whilst hollow beads showed the highest under both low and high pressures due to crumbling and crushing of the beads during the sliding process. The glass flake filled PTFE showed relatively high but stable wear results up to 4.5 MPa above which the wear rate increased dramatically. A marginal increase in wear was achieved by using high aspect ratio glass fibres to the PTFE matrix. No correlation between the size of glass reinforcement and wear rate was established. The addition of a lamellar solid lubricant to the glass fibres reduced both the wear and friction of PTFE. The study of the transfer film growth by means of an optical microscope revealed that it was due to the mechanical interlocking of the polymer fragments into the metal asperity valleys. The compositional changes in the transfer film were studied by XPS which, among other things, showed presence of metal fluoride on the metal counterface.     

FeGa 膜 / AT 切石英晶片双面复合蝶形谐振磁场传感器

蝶形磁致伸缩膜由于磁汇聚,其中心区域的磁致伸缩应变增强,但是和矩形 AT 切石英晶片复合时,磁膜耦合至矩形晶 片电极区的应变会向周围无磁膜区域扩散,降低应变对晶片厚度剪切振动的作用,降低磁场传感器灵敏度。 提出 AT 切石英晶 片和 FeGa 膜形状一样的蝶形谐振磁场传感器,蝶形晶片可以将蝶形磁膜增强的晶片应变汇聚至晶片电极区,以提高传感器灵 敏度。 仿真结果预测,在 23. 8~ 118. 9 Oe 的磁场范围内,蝶形结构的灵敏度为蝶形磁膜/ 矩形晶片结构的 3. 73 倍。 通过微机械 加工,制作了蝶形器件,对实际器件测试的结果表明,在 76. 4~ 117 Oe 的线性区间内,蝶形传感器的灵敏度可达-29. 08 Hz/ Oe。     

Nanoparticle embedded chitosan film for agglomeration free TEM images

Transmission electron microscopy (TEM) is a very useful and commonly used microscopy technique, used especially for the characterization of nanoparticles. However, the identification of the magnetic nanoparticle could be thought problematic in TEM analysis, due to the fact that the magnetic nanoparticles are usually form aggregates on the TEM grid to form bigger particles generating higher stability. This prevents to see exact shape and size of each nanoparticle. In order to overcome this problem, a simple process for the formation of well‐dispersed nanoparticles was conducted, by covering chitosan film on the unmodified copper grid, it was said to result in aggregation‐free TEM images. It is also important to fix the magnetic nanoparticles on the TEM grids, due to possible contamination of TEM filament which is operated under high vacuum conditions. The chitosan film matrix also helps to protect the TEM filament from contact with magnetic nanoparticles during the imaging process. The proposed procedure offers a quick method to fix the nanoparticles in a conventional copper TEM grid and chitosan matrix prevents agglomeration of nanoparticles, and thus getting TEM images showing well‐dispersed individual nanoparticles.     

Mechanical and bending properties of a conductive thin single layer composite consisting of carbon nanofibers and polypyrrole

A new conductive composite material with conductive polymer and carbon nanofibers (CNF) was developed to improve some problems such as a slow response and a low actuating force. The disadvantage has been improved in this study by means of using a single layer thin film of PPy (polypyrrole) and conductive composites consisting of CNF and PPy. The composite films were successfully fabricated by the electrophoretic and polymerization method newly developed. The tension tests results show that the strain of CNF/PPy decreases as CNF weight ratio increases. The bending actuation occurs for both pure PPy and CNF/PPy single layer films when an electric current was applied. The tip deflections of the films varied in the range 0.5mm to 2mm. Tension tests were performed with 0%, 3%, 5%, and 7% weight ratios of CNF’s. Specimens with a higher CNF ratio showed larger moduli.     

轴向磁化双环嵌套磁场的解析模型及其应用

以在线式全流量可视铁谱仪为背景,对静磁场的磁路进行设计,采用轴向充磁,双环异极嵌套的安装方式,两环间隙用不导磁材料做成的圆环作为衬套,并从磁荷模型出发,利用标量磁位法,并引入广义二项式定理分别对同心双环嵌套磁体、偏心双环嵌套磁体产生的磁感应强度进行解析计算,通过对比磁感应强度的理论值和实际测量值发现解析表达式很好地反映出静磁场的磁感应强度分布规律,并对误差进行分析。同时,通过对比这两种磁体的磁感应强度的分布,选择合适的静磁场以满足在线式全流量可视铁谱仪在润滑油高流速条件下有效吸附铁磁颗粒的要求。在此基础上,将所设计的静磁场应用到某新型涡喷航空发动机性能监测中,对监测到的磨粒进行分析,分析结果间接验证所设计的静磁场在润滑油高流速条件下吸附铁磁颗粒的有效性。     

Development of a magnetic quartz crystal microbalance

A new technique for measurement of magnetic properties of materials is demonstrated. It can be used for the measurement of thin magnetic films during their chemical modification. The resonance frequency of a quartz crystal microbalance (QCM) with conducting polymer (polyaniline) suspension in poly(ethylene glycol) was observed to increase with increasing the externally applied uniform dc magnetic field. Slowly sweeping the magnetic field between 0 and 3.1 T results in a frequency-field response curve. Chemical doping was done by exposing the polyaniline-emeraldine base film to HCl vapor. The change in population of free spins is reflected in increased frequency-field curve magnitude after HCl doping. Two working hypotheses explaining this observation are offered to explain how frequency of QCM with deposited magnetic film shifts with increasing intensity of the magnetic field.     

Friction and Wear of Epoxy Composites Containing Surface Modified SiC Nanoparticles

The authors of the present paper evaluated the sliding wear behaviors of epoxy and its composites filled with untreated and treated SiC nanoparticles. The experimental results indicate that the nanoparticles pretreated by graft polymerization of polyacrylamide effectively improved the overall performance of the matrix epoxy. In comparison with the untreated SiC nanoparticles, the grafted SiC nanoparticles led to more significant reduction in frictional coefficient and wear rate of epoxy. Even under high contact pressure, the composites with grafted SiC nanoparticles possessed the highest wear resistance. The strong interfacial bonding between the grafted SiC nanoparticles and the matrix should account for the properties enhancement. Accordingly, a feasible way of efficiently applying SiC nanoparticles to the preparation of wear resisting nanocomposites has been developed.     

Using magnetoresistive films with unidirectional anisotropy to register elastic deformations

The magnetoresistive properties of FeMn/Fe₁₀Ni₉₀ films with unidirectional anisotropy have been studied under controlled elastic deformation. It has been shown that linear strain or compression significantly affects the magnetic anisotropy of the films and, as a consequence, leads to major changes in magnetoresistance curves. The dependences of the magnetoresistance on the relative deformation have been determined for varied external magnetic field, magnetic biasing, film thickness, and sample geometry. An optimum combination of the listed parameters has been found that corresponds to the maximum sensitivity and nearly anhysteretic type of the tensomagnetoresistive effect.     

Factors Influencing the Abrasion Resistance of Thin-Film Magnetic Media

Abrasion testing was performed on DC sputtered hydrogenated carbon films on commercial thin-film disks processed under several conditions. Four film characteristics were found to influence the abrasion resistance of the disk, i.e., roughness, film adhesion, carbon toughness, and coefficient of friction. It was found that both fine-scale surface topography from the sputtered layer and substrate texture degraded abrasion resistance. Excellent abrasion resistance was observed for carbon films as thin as 10 nm on polished substrates when the magnetic film topography was minimized. Film adhesion was degraded by exposure to temperature and humidity. Hydrogen incorporation into the carbon films reduced film hardness which degraded abrasion resistance.     

Near-field optical microscope observation of dye-containing nano-domains

A novel method for forming dye‐containing nano‐domains in thin films using a polymer alloy system has been developed. The polymer alloy system (PS‐b‐PMMA), which consists of polystyrene (PS) and polymethyl methacrylate (PMMA), forms microphase separation in thin films. The film was treated using a previously reported technique under vacuum conditions, and an organic dye was selectively dispersed into the PS. Selective association of the dye (diarylethene; cis‐1, 2‐dicyano‐1, 2‐bis (2,4,5‐trimethyl‐3‐thienyl) ethene) with the PS nano‐domains was then observed, with both transmission electron microscopy and scanning near‐field optical microscopy with an absorption spectrum.     

偏置磁场对磁致伸缩液位传感器检测电压的影响

为了提高磁致伸缩液位传感器的检测精度,研究了磁致伸缩液位传感器中产生偏置磁场的浮子磁铁的放置方式及其对检测电压的影响。利用ANSYS软件对浮子磁铁不同放置方式下形成的偏置磁场进行了有限元分析,分析显示:采用3块磁铁互成120°N极N极S极(NNS)放置或者采用圆环磁铁作为偏置磁场时检测效果比较理想。实验研究了磁致伸缩液位传感器的偏置磁场对检测电压的影响,并在浮子磁铁不同放置方式下进行多次实验。结果表明:偏置磁铁为3块磁铁互成120°NNS放置时或者为圆环磁铁时,检测电压的幅值达到50mV,比其它放置方式提高了近30mV。研究表明:磁致伸缩液位传感器应选择3块磁铁NNS放置或者选择圆环磁铁作为偏置磁场。     

镀镍石墨磁性纳米粒子对ZL109微弧氧化反应过程及膜层耐磨性能影响

为进一步探索微弧氧化反应过程中微弧氧化陶瓷层表面形貌、孔隙率等基本特征的受控机制,创新地提出向微弧氧化电解液中引入磁性粒子,即镀镍石墨磁性纳米粒子,探索磁性添加剂粒子对微弧氧化反应过程及膜层耐磨性能的影响.从膜层表面形貌、横截面形貌、孔隙率、平均孔径、厚度、表面粗糙度、反应能耗及物相组成等方面对微弧氧化反应过程进行了分...     

Preparation of magnetic fluid having active-gas resistance and ultra-low vapor pressure for magnetic fluid vacuum seals

The magnetic fluid, having an ultra-low vapor pressure property of 7·0×10⁻¹⁰ Pa at 293 K, was prepared. Hexafluoropropylene oxide polymer oil having high molecular weight was used as base oil. Magnetic particles were dispersed by using two types of new designed and synthesized hexafluoropropylene oxide acid derivative surfactants. The obtained magnetic fluid had a saturation magnetization of 35·0 mT, its magnetite particles were dispersed stably and showed a superior resistance to active gasses. It was ascertained that the magnetic fluid vacuum seal using the prepared fluid had the ultra high vacuum performance.     

Studies of the microstructure of polymer-modified bitumen emulsions using confocal laser scanning microscopy

Polymer-modified bitumen emulsions present a safer and more environmentally friendly binder for enhancing the properties of roads. Cationic bitumen emulsion binders containing polymer latex were investigated using confocal laser scanning microscopy. The latex was incorporated into the bitumen emulsion by using four different addition methods and all emulsions were processed with a conventional colloid mill. The emulsion binder films were studied after evaporation of the emulsion aqueous phase. We show how the microstructure and distribution of the polymer varies within the bitumen binder depending on latex addition method, and that the microstructure of the binder remains intact when exposed to elevated temperature. It was found that a distinctly fine dispersion of polymer results when the polymer is blended into the bitumen before the emulsifying process (a monophase emulsion). In contrast, bi-phase emulsion binders produced by either post-adding the latex to the bitumen emulsion, or by adding the latex into the emulsifier solution phase before processing, or by comilling the latex with the bitumen, water and emulsifier all resulted in a network formation of bitumen particles surrounded by a continuous polymer film. The use of emulsified binders appears to result in a more evenly distributed polymer network compared to the use of hot polymer-modified binders, and they therefore have greater potential for consistent binder cohesion strength, stone retention and therefore improved pavement performance.     

Nanoscale characterization of gold nanoparticles created by in situ reduction at a polymeric surface

Transmission Electron Microscopy is used as a quantitative method to measure the shapes, sizes and volumes of gold nanoparticles created at a polymeric surface by three different in situ synthesis methods. The atomic number contrast (Z‐contrast) imaging technique reveals nanoparticles which are formed on the surface of the polymer. However, with certain reducing agents, the gold nanoparticles are additionally found up to 20 nm below the polymer surface. In addition, plan‐view high‐angle annular dark‐field scanning transmission electron microscopy images were statistically analyzed on one sample to measure the volume, height and effective diameter of the gold nanoparticles and their size distributions. Depth analysis from high‐angle annular dark‐field scanning transmission electron microscopy micrographs also gives information on the dominant shape of the nanoparticles.