X-ray probe microanalyses and scanning x-ray microscopies

The analytical techniques based on excitation of inner-shell electrons by an incident X-ray photon beam suffer generally from their poor degree of lateral localization. Nevertheless it is possible to perform the microanalysis of a sample in the forms of a thin film by: (i) X-ray photoelectron spectroscopy (XPS or ESCA) and X-ray-induced Auger electron spectroscopy (XAES) for surface analysis; (ii) X-ray absorption spectroscopy (XAS) and X-ray microfluorescence spectroscopy (XMS) for bulk analysis. The corresponding images can also be obtained in the scanning mode: scanning X-ray photoelectron microscopy (SXPM), scanning X-ray-induced Auger electron microscopy (SXAEM) and scanning X-ray microradiography (SXM). The experimental arrangement and the results obtained are described here, together with further improvements and comparisons with other technical solutions.     

纳米陶瓷润滑油添加剂润滑机制研究

研究了纳米陶瓷润滑油添加剂的润滑机制.采用四球试验机考察了纳米陶瓷润滑油的抗磨性能和极压性能,利用NT场致发射扫描式电子显微镜、高分辨率扫描电子显微镜、X射线光电子能谱仪,观察了磨损表面的纳米粒子形貌,分析了磨损表面的形貌及表面元素成分.结果表明,纳米陶瓷润滑油润滑时,摩擦表面的磨斑很光滑,磨斑表面有Si3N4存在;纳米陶瓷添加剂具有很好的抗磨和极压性能;纳米陶瓷粒子具有"滚珠效应".     

Functionalization of Scanning Force Microscopy Cantilevers via Galvanic Displacement Technique

A galvanic displacement technique is used to coat silicon scanning force microscopy cantilevers with copper. The copper coating is characterized using X-ray photoelectron spectroscopy, scanning force microscopy, contact angle measurements, scanning electron microscopy and energy-dispersive X-ray spectroscopy. This coating technique results in uniform, reflective and conformal films and hence, no stress-induced bending of the cantilever is observed. To demonstrate the effectiveness of this approach for tribological studies, the coated cantilevers are chemically modified with alkanethiol monolayers in order to functionalize the cantilevers. The effect of changed surface energy are detected with adhesion measurements in water and ethanol.     

Spectroscopic study of tribooxidation processes in modified PTFE

The effect of layered silicates on the structure and performance characteristics of polytetrafluoroethylene is studied using IR spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy, as well as tribological and physicomechanical testing. It has been shown that the filling of polytetrafluoroethylene with layered silicates leads to a substantial (up to 2500 times) decrease in its mass wear rate, while its strength characteristics remain similar to those of the original polymer. The use of IR spectroscopy and X-ray photoelectron spectroscopy to study structural transformations that occur during the friction of the polymer composite materials with various compositions of fillers has revealed the formation of intermediate products in the course of the oxidative destruction of polytetrafluoroethylene.     

Preparation and tribological properties of tungsten disulfide hollow spheres assisted by methyltrioctylammonium chloride

In the current paper, tungsten disulfide hollow spheres modified by methyltrioctylammonium chloride with diameters of about 200 nm have been successfully prepared through a solvothermal process. The products were characterized by X-ray power diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, scan electron microscopy and high revolution transmission electron microscopy, respectively. The tribological properties of the as-prepared WS₂ in liquid paraffin (LP) were studied and compared with those of commercial colloidal MoS₂ (CC-MoS₂). The worn surfaces were analyzed by XPS and SEM. Results show that the as-prepared WS₂ hollow sphere is a better anti-wear and friction-reducing additive in LP than CC-MoS₂.     

Tribological properties of Mo–S–I nanowires as additive in oil

A new nanowire-like material with the chemical formula Mo₆S_4.5I_4.5 was studied as additive in a synthetic base oil, a polyalphaolefin (PAO). This material presents interesting friction reducing properties, with friction coefficients reaching a value of 0.04 in boundary lubrication. Transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy were used to characterise nanowires before and after friction. The combination of these techniques gave evidence of MoS₂ formation in the contact area during friction tests. This structural evolution of nanowires explains their good friction reducing properties.     

Energy-dispersive X-ray microanalysis of aqueous biologic samples on bulk supports

The present investigation describes a modification of the liquid droplet technique that allows for the quantitative elemental analysis of small volumes (< 100 picoliters) of aqueous biologic samples using a scanning transmission electron microscope (Philips 400 HTG-STEM) equipped with an EDAX energy dispersive detector. Aliquots of samples and standards were micropipetted onto solid beryllium supports under paraffin oil. The oil was washed with organic solvents and the samples frozen and freeze-dried. The samples were excited in a Philips 400-HTG-STEM by scanning a 1-μm, 20-kV electron beam over the surface of the droplets, and the X-ray spectra were collected. Measured X-ray intensities in characteristic peaks were found to be linearly related to the concentration of various elements in the sample. This work demonstrates the feasibility of performing quantitative elemental analysis of minute samples and cells in a scanning transmission electron microscope equipped with an energy dispersive X-ray detector.     

铝掺杂类石墨薄膜的构筑及其摩擦学性能研究

利用磁控溅射技术在硅片表面上制备铝掺杂类石墨(Graphite-like carbon,GLC)薄膜,采用原子力显微镜、场发射扫描电镜、X射线光电子能谱仪、纳米压痕仪等考察铝掺杂对薄膜表面形貌、结构及其机械性能的影响规律;利用旋转的球一盘微摩擦试验机考察薄膜的摩擦行为.结果表明:铝的引入使GLC薄膜表面更加平整、致密;GLC薄膜的硬度和弹性模量随着掺铝量的增加而增加;低载低速时,薄膜摩擦因数随着铝含量的增加而增加,高载高速时,摩擦因数随铝掺入量的增加明显降低且更稳定.     

Sialolith characterization by scanning electron microscopy and X-ray photoelectron spectroscopy

The objective of this study has been to characterize sialolith, a calcium phosphate deposit that develops in the human oral cavity, by high-resolution field emission scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The morphological and chemical data obtained helped in the determination of their formation mechanism in salivary glands. Sialoliths in the submandibular salivary glands may arise secondary to sialodenitis, but not via a luminal organic nidus. We believe this is the first study that characterizes a sialolith by XPS.     

Coaxial arrangement of a scanning probe and an X-ray microscope as a novel tool for nanoscience

We report on the design and first tests of a novel instrument aimed at combining the benefits of scanning force microscopy with those of X-ray spectroscopy. For this we built an instrument combining a scanning transmission X-ray microscope with a beam-deflection atomic force microscope in a coaxial geometry. This allows to combine X-ray absorption spectroscopy and high resolution topography in-situ. When replacing the conventional scanning probe tip by a coaxially shielded tip the instrument will allow detection of the photoelectrons produced by resonant X-ray absorption. This could yield spectroscopic information with a spatial resolution approaching the values achievable with atomic force microscopy.     

Synthesis,characterization and tribological properties of Cu/reduced graphene oxide composites

In this paper, nano-copper/reduced graphene oxide (Cu/rGO) composites were synthesized by the facile one step in-situ reduction method. The as-prepared Cu/rGO composites were characterized by means of transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD) and Raman. Mechanism of reduction and growth of Cu/rGO composites were also discussed. The friction and wear properties of oleic acid (OA) modified composites as additives in poly-alpha-olefin (PAO) were investigated using four-ball wear tester.     

摩擦化学反应对环氧复合材料摩擦性能的影响

碳纤维和纳米粒子混杂填充环氧复合材料对其减摩耐磨性能的提高具有协同效用。为了研究其协同作用机制,用X射线光电子能谱仪(XPS)对材料摩擦前后磨损面进行分析;用与扫描电镜联用的X射线能谱仪(EDS)对摩擦后的对偶面进行分析;用纳米闪光导热仪对材料的导热系数进行分析;用热分析仪对材料磨损面热性能进行分析。结果表明,复合材料中碳纤维增加了基体的导热性,纳米粒子增强了基体的力学性能,减弱了分子链的氧化降解反应,混杂填料兼备两方面的因素且互相促进,在提高复合材料的减摩耐磨性中表现出协同效应。     

固体润滑剂对碳纤维增强尼龙复合材料摩擦学性能的影响

分别制备了PTFE／碳纤维、MoS2／碳纤维混杂增强的尼龙66复合材料,用MM-2000型摩擦磨损试验机评价其摩擦磨损性能,用SEM和XPS分析了磨损表面。结果表明：PTFE／碳纤维混杂增强可以明显改善尼龙复合材料摩擦学性能;MoS2／碳纤维混杂增强没有改善复合材料的摩擦学性能;MoS2在摩擦过程中氧化生成的MoO3充当了摩擦副之间的磨粒,其磨损机理推测为粘着和磨粒磨损的综合作用。     

司班-80/二聚酸作为润滑油添加剂的摩擦聚合机制研究

采用盘-销式摩擦试验机,以司班-80/二聚酸体系作润滑油添加剂,在陶瓷-陶瓷(A l2O3-A l2O3)表面进行摩擦磨损实验。采用差示扫描量热法(DSC)探讨了单体在陶瓷表面的吸附类型;采用扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)、傅立叶红外光谱仪(IR)对盘上磨痕进行表面分析。结果表明添加剂在磨痕处生成了保护性体型聚酯膜。其摩擦聚合机制为:在摩擦过程中,二聚酸以物理吸附的方式吸附在陶瓷表面;由于二聚酸的羧基与司班-80的羟基发生摩擦聚合反应,在陶瓷表面生成体型聚酯膜,从而降低陶瓷表面的磨损。     

Soft X-ray microscopy with a cryo scanning transmission X-ray microscope: II. Tomography

Using a cryo scanning transmission X-ray microscope ( Maser, et al . (2000 ) Soft X-ray microscopy with a cryo scanning transmission X-ray microscope: I. Instrumentation, imaging and spectroscopy. J. Microsc . 197, 68–79), we have obtained tomographic data-sets of frozen hydrated mouse 3T3 fibroblasts. The ice thickess was several micrometres throughout the reconstruction volume, precluding cryo electron tomography. Projections were acquired within the depth of focus of the focusing optics, and the three-dimensional reconstruction was obtained using an algebraic reconstruction technique. In this first demonstration, 100 nm lateral and 250 nm longitudinal resolution was obtained in images of unlabelled cells, with potential for substantial further gains in resolution. Future efforts towards tomography of spectroscopically highlighted subcellular components in whole cells are discussed.     

Cavitation erosion of metals and alloys

Several high purity metals (aluminium, cobalt, chromium, copper, iron, magnesium, molybdenum, nickel, tungsten and zinc) and some commercial copper-, iron-, nickel- and cobalt-base alloys were investigated by weight loss measurements and by surface analysis with scanning electron microscopy and X-ray photoelectron spectroscopy. The results lead to the conclusion that the cavitation erosion resistance (CER) is decisively determined by the binding energy and the crystal structure of the base metal. The ability of alloys made of base metals with a high CER to deform and to transform allotropically is the second important factor.     

Determination of oxygen in acid-treated high-purity niobium by X-ray photoelectron spectroscopy

High-purity niobium was immersed in nitric acid and hydrofluoric acid for two minutes and the resulting product was characterized. Scanning electron microscopy was employed to characterize the morphology of the acid treated product. Inert gas fusion was used for determination of oxygen in the high-purity niobium. X-ray photoelectron spectroscopy was employed to characterize the surface ratio of oxygen to niobium. The oxygen concentration was 30 ppm in the acid-treated material and 70 ppm in the untreated material. X-ray photoelectron spectroscopy was employed to characterize the reduction of oxygen at the surface. The ratio of oxygen to niobium decreased from 9.75 to 2.60 without treatment compared to acid treatment for two minutes. The concentrations of adsorbed water and niobium oxide decreased following etching. The acid-treated high-purity niobium was characterized by argon ion bombardment; adsorbed water molecules and niobium oxides were not present but non-lattice oxygen was observed.     

Si3N4-hBN陶瓷复合材料与Fe-B合金配副的摩擦学特性研究

利用MMU-5G销-盘式端面磨损试验机考察Si3N4-hBN陶瓷复合材料与Fe-B合金配副分别在干摩擦和水润滑条件下的摩擦磨损性能,分别采用扫描电子显微镜( SEM)、激光扫描显微镜(LSM)、X光电子能谱(XPS)、X射线能谱(EDS)和X射线衍射(XRD)分析摩擦面及磨屑的形貌与物质组成.结果表明,hBN的加入未能有效地改善Si3N4-hBN/Fe-B合金摩擦副的摩擦学性能,干摩擦条件下,Si3N4-hBN摩擦表面微凸体与Fe-B合金中的硬质相Fe2B发生碰撞而导致脆性断裂和剥落,发生磨粒磨损,摩擦因数均高于0.9,磨损率均高于10-5 mm3/ (N·m)数量级;水润滑条件下,由于水流带走了磨屑,避免磨粒磨损的发生,为Si3N4-hBN摩擦表面发生化学抛光提供条件,化学抛光使销、盘试样的摩擦表面变得光滑,从而获得较为优异的摩擦学性能.     

Mechanical and Tribological Properties of TiTaBN Graded-Composite Coatings Deposited Using the CFUBMS Technique

In this study, TiTaBN graded-composite coatings were deposited utilizing different process parameters on D2 steel and glass substrates using pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS). The morphology and structure of the coatings were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The hardness and critical load values of the coatings were determined using a microhardness tester and scratch tester, respectively. The tribological properties of the coatings were analyzed in different testing environments using a pin-on-disc tribometer. The properties of the coatings were found to be strongly affected by the coating parameters. The maximum thickness and hardness were obtained at the lowest nitrogen flow rate and highest frequency. Critical load values of coatings were increased with increased nitrogen flow rate. The low nitrogen flow rate and high frequency across the coatings resulted in enhanced tribological properties.     

新型硼氮型润滑油添加剂的合成及摩擦学性能

以植物油为原料合成了一种新型硼氮型润滑油添加剂,采用摩擦磨损试验机考察了它在加氢基础油和成品油中的摩擦学性能,结果表明此添加剂具有良好的抗磨减摩效果.用扫描电子显微镜和X射线光电子能谱仪观察分析了磨痕表面的形貌及元素,发现磨损表面含有大量的硼元素,表明在摩擦过程中,通过物理吸附和化学反应在摩擦表面生成了含硼润滑膜,起减摩和抗磨作用.