Electronic core level microanalyses and microscopies in multipurpose apparatus

Using an instrument equipped with two electron guns, an electron analyzer, and a Si(Li) diode detector, we developed microanalytical techniques based on inner-shell electron excitations by incident electrons and X-rays, that is, electron energy-loss spectroscopy (EELS) in the reflection mode; electron probe microanalysis (EPMA) and X-ray appearance potential spectroscopy (XAPS); electron-induced Auger electron spectroscopy (e-AES); X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS); X-ray induced AES (XAES), X-ray fluorescence analysis (XRF), and scanning X-ray radiography (SXR). The corresponding characteristic images (including X-ray microradiography and X-ray photoelectron microscopy) were obtained in the scanning mode. The principle of the apparatus is described. Each spectroscopy and microscopy is illustrated by an example. Their performance and limits are discussed.     

X射线诱导俄歇电子能谱(XAES)的应用

简要介绍X射线诱导俄歇电子能谱(XAES)用于化学分析的一般性理论。XAES可与X射线光电子能谱(XPS)一起用于元素化学态分析。但是XAES分析有其优势,(1)俄歇参数与荷电位移无关,结果无需荷电校准就可用于价态分析;(2)在一些涉及过渡元素和重元素物质的价态分析时,XAES峰化学位移大于XPS峰;(3)对于分析一些轻元素(如K、Mg、Al等),XAES峰比某些XPS峰有更高的灵敏度。因而,XAES可弥补XPS分析的某些不足,可方便、有效地表征元素价态。通过实例,介绍XAES在这3个方面的实际应用。     

The use of surface analysis techniques in the study of wear

Surface science has a wide range of instrumentation for analysis of the first few atomic layers in a surface. Some of these techniques are finding increasing use in the study of wear. They include scanning Auger spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering, Raman spectroscopy and ellipsometry. A technique which shows great potential involves in situ wear experiments in a scanning Auger chamber. The initial surface roughening and subsequent prow formation and shear-off have been studied in this manner.     

An approach to improve the load-carrying capacity of zinc dithiophosphate

By mixing 0.5wt.% silver complex with 2-ethylhexyl phosphonic acid mono 2-ethylhexylester (AgL·HL) into a conventional zinc dithiophosphate (ZDTP), a new compounded extreme-pressure and antiwear as well as antiseizure additive was obtained. The antiseizure and load-carrying performance of the mixture (Zn-AgDTP) was significantly improved in comparison with ZDTP and AgL·HL. The synergistic action and tribochemical mechanism is proposed on the basis of the worn surface analysis by scanning Auger microprobe (SAM), X-ray photoelectron spectroscopy (XPS) and X-ray micro-diffraction (XRD).     

Analysis of ceramic materials by electron spectroscopy

The basic principles of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy are described and their relative advantages as analysis methods for ceramic materials are reviewed. Their application in ceramics technology is illustrated by examples taken from the fields of catalysis and mineralogy. In particular, attention is drawn to recent developments of XPS which make it especially attractive for the study of ceramic materials. These include quantitative application of the X-ray photoelectron diffraction effect to layered, single crystal minerals; the development of higher energy X-ray sources for XPS, and the attendant study of the Sils–KLL Auger parameter as a probe of molecular and crystalline structure; and the analysis of small (?250 μm) surface features by XPS.     

The tribological behaviour and tribochemical mechanism of action of oxovanadium (IV)-dithiophosphate

Vanadium (IV)-oxo-dicyclodithiophosphate (VDTP) was prepared and its additive properties evaluated using a four-ball machine. The results show that VDTP exhibits better extremepressure performance, but lower antiwear activity, when compared with ZDTP. The reaction film composition, characterised by scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS) and diffractometer surface techniques, reveals that the antiwear and friction layer containing vanadium oxide, phosphate/phosphide, and sulphide, prevent the rubbing pairs from contacting directly, resulting in better extreme-pressure and antiwear behaviour.     

The Influence of Copper-Containing Additives on Oil Oxidation and Corrosion

The effects of transition metals in either catalyzing or inhibiting oil oxidation in the liquid phase have been extensively reported in the literature. However, little attention has been paid to the surface films formed as by-products of these reactions. In this paper, the authors investigated surface films for the important case of copper-containing additives influencing the oxidation of oil that contacts a steel surface. Copper naphthenate in solution was found to inhibit oil oxidation and to form copper-containing precipitates and deposits on the steel surface. The surface films formed were characterized by X-ray photoelectron spectroscopy, Auger spectroscopy and scanning electron microscopy. The precipitates showed a unique morphology of spherical particles several microns in diameter. A high level of copper naphthenate was found to prevent corrosion of the steel surface.     

Electron spectroscopy in the scanning electron microscope

The combination of ultra high vacuum scanning electron microscopy with spectroscopy of the emitted electrons gives new possibilities for surface analysis. The paper surveys recent results in secondary, Auger, ionization loss, and elastic peak electron spectroscopy.     

A STEM/X-ray microanalytical study of the equilibrium segregation of bismuth in copper

Combined scanning transmission electron microscopy (STEM) and X-ray microanalysis have been used to detect the equilibrium segregation of bismuth to grain boundaries in copper. Quantification of the X-ray data gives grain boundary bismuth concentrations close to those reported previously by Auger electron spectroscopy (AES). Samples tempered at low temperatures (773,873 K) had detectable bismuth concentrations at more boundaries than those samples tempered at high temperature (1073 K). There is evidence that the degree of segregation varies strongly from boundary to boundary.     

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.     

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.     

Surface studies in UHV SEM and STEM

Some recent advances in surface analyses with scanning electron microscopy techniques are reviewed. It is shown that secondary electron microscopy can image monatomic steps, emergent dislocations and the early growth of thin films and oxide nuclei. The chemical composition of inhomogeneous surfaces can, in some cases, be determined with nanometre resolution with Auger signals. Overlayer coverages can occasionally be monitored with the secondary electron signal if the change of work function with coverage has been determined previously. The interpretation of these secondary and Auger signals is discussed. The combination of angular electron spectroscopy with electron microscopy is potentially a powerful technique for determining atomic positions of surface atoms and one method for obtaining the experimental data is described. Several substrate/overlayer systems are used to illustrate the amount of information that can be obtained about surface processes with scanning electron microscopy.     

Tribological performance and action mechanism of certain S,N heterocyclic compounds as potential lubricating oil additives

The tribological performance of 2-(N-alkylcarbamoylmethyl)thiobenzo-thiazole as an additive to liquid paraffin has been evaluated. The novel compound possesses higher load capacity and better lubricating characteristics. The tribochemical reaction of the additive with a metal surface was investigated by X-ray photoelectron spectroscopy and scanning Auger microprobe techniques. An action mechanism is also proposed.     

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。     

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".     

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.     

Effect of phosphorus-containing additives on the wear of aluminum in the lubricated aluminum-on-steel contact

To investigate the effects of phosphorus-containing additives not only on steel but also on aluminum surfaces comprising tribocouples, the effect of phosphates and phosphites on the wear of aluminum was evaluated under boundary lubrication conditions. The chemical reactivity of additives was investigated by differential thermal analysis. X-ray photoelectron spectroscopy and Auger electron spectroscopy were used to determine the tribochemical reaction between additives and aluminum. The active lubrication mechanism of P-containing additives with aluminum is proposed.     

A new experimental technique for the study of the surface reactions of extreme pressure additives at elevated temperatures

A single-pulse heating method for studying chemical surface reactions of extreme pressure additives is described. The method uses a single high intensity pulse of short duration in conjunction with highly sensitive surface analytical tools such as Auger electron spectroscopy and X-ray photoelectron spectroscopy for monitoring reaction products. The method was applied to the study of the reaction of dibenzyl disulphide with iron.     

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.     

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.