一个自动扫描电子显微镜系统方法

扫描电子显微镜对于材料研究来说是一个很好的工具,该工具在较大扫描尺度上需要在人工操作下探索材料的形貌和组成.当前其发展重点是:通过无需仪器设置的完全自动的仪器操作方法快速地检测出大量的不同性质的样品,例如颗粒样品.技术领域的不断创新与仪器领域关键区域的革新带来一个新层次的操作,其具有的可靠性和准确性开创了一个新的应用领域.     

High Lubricity of Re-Doped Fullerene-Like MoS2 Nanoparticles

The electrostatic effects in tribological systems have been studied in the past, especially with regards to data storage media. Nanoparticles (NP) of WS₂ and MoS₂ with fullerene-like structure (IF) have been studied in the past and showed very good tribological behavior. Being semiconductors, their electrical properties can be controlled by, e.g., substituting the lattice Mo (W) atoms with Re (n-type conductivity) and Nb (p-type conductivity) atoms. In this study doping of IF-MoS₂, and to a lesser degree IF-WS₂, NP with small amounts (< 1 at.%) of rhenium atoms has been studied. For this purpose two new synthetic approaches have been pursued. The doped nanoparticles were characterized by various techniques. In particular, the doping density was determined by ICP-MS technique. The resistivity of the nanoparticles was shown to decrease significantly with increasing doping level. In contrast to the undoped nanoparticles, the doped NP were shown to exhibit reduced agglomeration and produce stable suspensions in PAO-4 and PAO-6 oils. Extensive tribological measurements with these PAO oils formulated with 1 wt % of the doped NP showed friction coefficients as low as 0.01 in mixed lubrication conditions and negligible wear. Microscopy analysis of the tribological surfaces reveal very smooth but discontinuous and dense film of the doped NP on the tribological surfaces. It is proposed that the doped NP are negatively charged at their surface eliciting mutual repulsion, which has a remarkable influence on their rheological properties and their tribological behavior.     

Ultrastructure of Tracheal Surface Liquid: Low-Temperature Scanning Electron Microscopy

A layer of liquid lines the airways in the lung. Previous microscopic studies have suggested that it is in two phases, with a mucous gel lying above a periciliary sol. However, shrinkage artifacts due to chemical fixation, dehydration, and drying have prevented reliable estimates of the depth of these layers. To avoid such problems, we have studied the surface liquid of bovine trachea by low-temperature scanning electron microscopy (LTSEM). A polished copper probe cooled to liquid nitrogen temperature was applied to the mucosal surface of sheets of excised tracheal epithelium to effect rapid freezing of surface liquid. Tissue sheets were then mounted in an LTSEM (AMRay 1000A with Biochamber) which maintains samples at -180°C with a Joule-Thompson refrigerator built into the stage. Tissues were fractured at right angles to the epithelial surface, coated with gold, and viewed, all at 10^?5 to 10^?6 torr without transfer through air. The sample was stable under the electron beam at accelerating voltages up to 20 kV. Epithelial features (nuclei, cilia, microvilli, mucous granules) were well preserved. The mucosal surface of the cells was covered with material on the order of 8 μm in depth. The mucous gel and periciliary sol could be seen as distinct layers and could be distinguished by the size and pattern of ice crystal voids generated by radiant-etching of the fractured surface of the sample.     

Analysis of Fatigue Fracture with Scanning Electron Microscopy of Valve Spring Steel

Valve spring steel for engines, belonging to the class of super clean steel, must be supported due to their application, high numbers of cycles in fatigue and cannot suffer any type of failure, which would be catastrophic for the vehicle. From these considerations, it was tested in axial fatigue, a test that can detect possible internal defects in their structure, caused by inclusions, a class of valve spring steel, where it aimed to discover the values of their fatigue life, followed by an analysis ofmicrostructural fracture surface by SEM （scanning electron microscopy）. It was proved, after testing, the specimens tested broke up a number of cycles always compatible with the life work of a valve spring and that fractures always occurred by surface defects in the specimens.     

Tribometer for In Situ Scanning Electron Microscopy of Microstructured Contacts

Here, we report on a special tribometer built to operate inside an environmental scanning electron microscope enabling charge-free imaging of non-conductive and/or hydrated materials. The device is intended to be used for simultaneous testing and in situ visual inspection of biological and biomimetic patterned surfaces during contact formation, pulling-off, peeling, and shearing modeling the behavior of biological microstructured attachment systems in nature. To demonstrate its performance, a simple array of hexagonal elastomer micropillars is tested. The results obtained show that direct link between precise data on the contact forces and images of the contact elements deformed by these forces indeed allows getting an insight into how contact surface patterns function when in contact.     

Efficient Detection of Secondary Electrons in Low-Voltage Scanning Electron Microscopy

A new detection method is proposed allowing an efficient extraction of the secondary electrons without affecting the scanning spot of the primary beam. The suggested detector arrangements can be regarded as generalized Wien filters whose electric and magnetic fields do not affect the primary electrons with average beam energy, yet strongly influence the paths of the secondary electrons. The new detectors are especially useful in low-voltage scanning electron microscopy.     

扫描电镜低电压显微的实现

介绍了扫描电镜低电压显微的优点和限制及为实现低电压显微而对扫描电镜的改进。     

Scanning Electron Microscopy Study of Charging Phenomena on Insulating Materials

Instruments and Experimental Techniques - Charging phenomena of insulating materials were studied thanks to a scanning electron microscope SEM LEO 440 which allows the injection of electrons doses...     

Methods for Preparing Samples of Track Membranes for Scanning Electron Microscopy

Methods for preparing porous polymer samples to investigate their structure by scanning electron microscopy are described. The technique for cleavages preparation is complemented by preliminary treatment of a polymer with radiation, photo- or thermal-oxidation destruction to render it brittle. The advantages of this technique have been demonstrated with Mylar, polycarbonate, and polypropylene track membranes.     

A new method using Scanning Electron Microscopy (SEM) for preparation of anisopterous odonates

Anisopterous odonate male's secondary genitalia is a complex of several structures, among them the vesica spermalis is the most informative with important specific characters. The observation of those characters, mostly of membranous nature, is difficult in the Scanning Electron Microscope due to dehydration and metallization processes. In this contribution, we discuss a new and low cost procedure for the observation of these characters in the SEM, compatible with the most common agents used for preserving specimens.     

Design and Application of a Quadrupole Detector for Low-Voltage Scanning Electron Microscopy

Scanning electron microscopes operated at low voltages are applied in the inspection and metrology of microstructures as well as in the testing of integrated circuits. The efficiency of a conventional Everhart-Thornley-detector is poor in this application, especially if large samples, e.g. wafers, are inspected or tested at small working distances. In addition, the primary beam is deflected and aberrations are added by the extraction field of this detector. A new type of detector for secondary electron recording in low-voltage scanning electron microscopy was, therefore, designed, built and tested. It utilizes crossed electric and magnetic quadrupoles to compensate for each other in their effect on the primary beam. On the other hand, both fields support the extraction and collection of the secondary electrons. During the test application, the detector showed high efficiency resulting in low-noise images without any negative effect on the resolution.     

Microstructure Evolution and Enhanced Tribological Properties of Cu-Doped WS2 Films

To improve the tribological properties of WS₂ film both in vacuum and in humid air conditions, its microstructure was optimized by doping different concentrations of Cu via radio frequency co-sputtering method. The film microstructure and composition were investigated by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, grazing incidence X-ray diffraction and high-resolution transmission electron microscopy. It was verified that Cu was presented in amorphous phase in the WS₂ matrix and could also induce amorphization and densification of the composite films gradually. The film microstructure changed from coarse columnar platelet structure at low Cu content (0–5.8 at.%) to transition structure with two separate layers at increased Cu content (11.5–16.2 at.%) and to a featureless structure at high Cu content (above 24.4 at.%). The mechanical and tribological properties of films were evaluated using the scratch tester and ball-on-disk tribometer, respectively. It was found that the incorporation of a suitable content of Cu dopant could significantly improve the film toughness, but excess amount of Cu dopant lead to high brittleness. All the composite films exhibited much lower wear rate and longer wear life than those of pure WS₂ film both in vacuum and in humid air conditions. The wear mechanisms were proposed after correlating the mechanical performance with film microstructure.     

Antispalling Effect of WS2 Nanoparticles on the Lubrication of Automotive Gearboxes

The effect of WS₂ nanoparticles used as lubricant additives in the lubrication of automotive gearboxes has been studied. The results suggest that nanoparticles can be used to increase the life span of the mechanical parts of gears. Chemical analyses and observations made after transmission tests have shown that nanoparticles are able to go inside cracks and may have a sealing effect, preventing spalling and further failure of the material. Moreover, the addition of nanoparticles in fully formulated oil reinforces the antispalling properties of the lubricant.     

扫描电镜(SEM)在失效分析中的应用

失效分析是故障分析的重要方法,而扫描电镜为失效分析的重要手段,两者在工程领域有着广泛的应用,尤其是在断口分析中的应用。通过扫描电镜可以确定失效的形式和机理,对于确定故障的原因和制定措施起着关键作用。笔者通过工程具体的实例,结合失效分析理论,应用扫描电镜的分析,针对具体工程问题分析了原因,并制定了措施,着重介绍了扫描电镜在失效分析中的应用。     

趋磁细菌AMB-1磁小体纯化及扫描和透视电镜形态观察

培养并收集趋磁细菌AMB-1,采用超声波破碎菌体的方法提取磁小体,并对磁小体进行洗涤、分离、纯化。对趋磁细菌AMB-1,进行扫描电镜观察,同时对趋磁细菌AMB-1和纯化的磁小体进行透射电镜观察。电镜下见,趋磁细菌AMB-1为螺菌,无规则排列;磁小体位于菌细胞内,沿菌体长轴排列成链状。纯化的磁小体为立方-八面体,均匀分散于悬浮液中,表面有完整外膜包裹。     

The Effect of WS2 Nanoparticles on Friction Reduction in Various Lubrication Regimes

A study of the tribological behavior of nested inorganic fullerene-like (IF) nanoparticles of WS₂, as a potential additive to base oils is presented. Friction measurement results obtained from three different test rigs over a wide range of normal loads and sliding velocities are shown. Stribeck curves are used to reveal the lubrication regimes where the IF are most effective. It is found that the addition of IF-WS₂ nanoparticles to the base oils results in up to 50% reduction in friction coefficient in the mixed lubrication regime. The mechanism of improved friction and wear behavior with the IF additive is discussed.     

Action Mechanism of WS2 Nanoparticles with ZDDP Additive in Boundary Lubrication Regime

The effect in the tribological performance of WS₂ fullerene-like nanoparticles in PAO base oil when adding a ZDDP additive was studied at 100 °C in the boundary lubrication regime. The tribological properties of the dispersion surpass those obtained without one of the two additives. The friction modifier properties of the particles are improved in the presence of ZDDP, while the anti-wear properties of the ZDDP are increased when the particles are added to the dispersion. The composition of the formed tribofilm was investigated. Results show that a 50–60 nm tribofilm is formed on the steel surface composed by WS₂ mixed on the ZDDP chemical tribofilm. A WS₂-rich layer is observed at the top of the tribofilm. A correlation between the chemical composition of the tribofilm and the tribological properties of the “PAO + WS₂ + ZDDP” dispersion was made. Synergy between the two additives was proven.     

The Enhanced Tribological Properties of NiAl Intermetallics: Combined Lubrication of Multilayer Graphene and WS2

In recent years, reducing friction and wear-related adverse impacts on efficiency and durability in moving mechanical systems has gained increased attention. Herein, the search continues for novel materials and lubricants that can potentially reduce friction and wear. As one of the emerging self-lubricating materials, the tribological potential of graphene has been researched deeply. This article was dedicated to explore the combined lubrication of multilayer graphene (MLG) and WS₂. The as-prepared sample of NiAl–1.5 wt% MLG–5 wt% WS₂ (NB) exhibited excellent tribological properties. During the sliding process, a continuous lubricating film was formed to provide the low-strength junctions at the interface, reducing the friction coefficient and wear rate. Moreover, the MLG played the role of reinforcement particles and improved loading carrying ability.     

模块化的保偏近场扫描光学显微镜结构设计

采用模块化的设计思想，制成了高质量且简单易用的音又光纤探针模块、模块化的扫描探头、扫描台等，从而研制出高性能，易操作的模块化的保偏近场扫描光学显微镜。