Auger Emission Spectroscopy Research Articles

Examination of wear mechanisms in automotive camshafts

Two worn camshafts from a taxi fleet test were examined by scanning electron microscopy, energy-dispersive analysis by X-rays, Auger emission spectroscopy and secondary ion mass spectrometry. The cam lobes were selected to represent the extremes of cam wear. The two different lubricant formulations used in the engines differed in the VI improver, the dispersant, the antioxidant and the antiwear additive. This investigation showed that surface deformation and fatigue are the primary wear mechanisms on the cam lobe surfaces in the absence of catastrophic wear by scuffing. The fatigue pits were larger and more numerous on the cam lobe with the larger amount of wear. It was also found that lubricant additive components penetrate along the microcracks and the graphite flakes to a great depth. It is suggested that the penetrated lubricant components may cause accelerated fatigue crack growth by stress corrosion cracking.

Pretreatment procedures for corrosion studies of cupro-nickel alloys in sea-water

The effects of surface roughness, degreasing, acid pickling, annealing and sample storage of 70/30 and 90/10 cupro-nickel alloys (CDA 715 and CDA 706, respectively) prior to sea-water exposure were studied. The short term (< 1 day) corrosion behavior of each alloy was monitored by scanning Auger emission spectroscopy (AES) to determine which pretreatment parameters had the most influence. Surface roughness and acid pickling had the greatest effect on the tarnishing behavior, whereas the other parameters had little or no influence. A recommended pretreatment procedure has been given for each alloy, which effectively removes surface history and assures tarnishing behavior is only a function of the alloy composition.

A Study of Inclusions in Indium Phosphide

A detailed examination of unusual inclusions in substrates has been undertaken. Techniques employed have included optical microscopy, scanning electron microscopy, reflection and transmission x‐ray topography, conventional and high voltage electron microscopy, electron diffraction, energy dispersive x‐ray analysis, and Auger emission spectroscopy. Inclusions have been detected in many, but not all, undoped, Fe‐, Sn‐, and Ge‐doped ingots, at densities from ∼103 to 104 cm−2. Larger inclusions consist essentially of a central core of densely tangled dislocations, surrounded by dislocation loops predominantly on {110} planes and extending 10–20 μm outwards from the core. The entire complex of core plus surrounding loops results in a characteristically pitted appearance after etching, or as a region of strong contrast by x‐ray topography. Smaller inclusions (∼1 μm size) have been examined in electron microscope specimens foils. Some inclusions have been found at line dislocations, and it is probable that this is where the majority of inclusions originate, by a nucleation process. Attempts to determine the structure and chemical composition of the inclusions are presented and discussed.

Electronic structure of clean and oxygen-exposed Na and Cs monolayers on Cu (111)

The electronic structure of adsorbed Na and Cs monolayers and these alkalies coadsorbed with oxygen is studied via electron-energy-loss spectroscopy (EELS), work-function changes, Auger emission, and ultraviolet photoelectron spectroscopy. Interest is focused on the changes of the electronic structure due to a change of alkali coverage or to oxygen adsorption. Even at low coverage, when work-function values and core-level binding energies suggest that most of the alkali valence charge is transferred to the substrate, the EEL spectra show a peak due to alkali valence electron excitations. During continued alkali deposition the energy loss after an initial decrease passes a minimum and increases at high monolayer coverage. At high coverage the peak is ascribed to plasma oscillations in the monolayer. For Cs the monolayer plasmon energy loss can be varied in a continuous manner and over a wide range by changing the amount of adsorbed oxygen. We ascribe the energy-loss change to a dilution of the electron gas in the layer. The effect is observed for coverages above a critical value corresponding to around 60% of a close-packed monolayer.

Influence of electronic structure on the friction in vacuum of 3d transition metals in contact with copper

Fundamental mechanisms of the friction in vacuum of 3d transition metals in contact with copper were investigated by Auger emission spectroscopy. The electronic structure of the metals was shown to be a better indication of frictional behaviour than compatibility ratings previously obtained

Glass surface analysis by Auger electron spectroscopy

Specimens of glass with compositions corresponding to (a) modern bottle glass and (b) mediaeval window glass have been examined by Auger emission spectroscopy. The chemically cleaned surfaces initially show the presence of carbon, which decreases with irradiation time. Calcium signals increase to a steady value as the attenuating effect of the carbon decreases. Alkali metal signals generally increase and then subsequently decrease steadily, indicating a loss mechanism for these ions from the surface regions. The results indicate the limitations of AES as a method for glass studies.

Friction and Transfer Behavior of Pyrolytic Boron Nitride in Contact with Various Metals

Sliding friction experiments were conducted with pyrolytic boron nitride in sliding contact with itself and various metals. Auger emission spectroscopy was used to monitor transfer of pyrolytic boron nitride to metals and metals to pyrolytic boron nitride. Results indicate that the friction coefficient for pyrolytic boron nitride in contact with metals can be related to the chemical activity of the metals and more particularly to the d valence bond character of the metal. Transfer was found to occur to all metals except silver and gold and the amount of transfer was less in the presence than in the absence of metal oxide. Friction was less for pyrolytic boron nitride in contact with a metal in air than in vacuum.

The use of analytical surface tools in the fundamental study of wear

This paper reviews the various techniques and surface tools available for the study of the atomic nature of the wear of materials. These include chemical etching, X-ray diffraction, electron diffraction, scanning electron microscopy, low energy electron diffraction, Auger emission spectroscopy analysis, electron spectroscopy for chemical analysis, field ion microscopy and the atom probe. Properties of the surface and wear surface regions which affect wear such as surface energy, crystal structure, crystallographic orientation, mode of dislocation behavior and cohesive binding are discussed. A number of mechanisms involved in the generation of wear particles are identified with the aid of the aforementioned tools.

The metal-to-metal interface and its effect on adhesion and friction

The interface established by two metal surfaces brought into solid state contact is much more rigidly predetermined than is the interface for the other states of matter contacting themselves or solids. Thus, solid state structural factors at the surface such as orientation, lattice registry, crystal lattice defects, and structure are shown to have an effect on the character of the resulting interface established for two metals in contact. The interfacial structural character affects the adhesion or bonding forces of one solid to another. This in turn influences the forces necessary for tangential displacements of one solid surface relative to the other. Because the nature of the metal-to-metal interface is determined to an extent by the solid surficial layers' surface tools such as LEED, Auger emission spectroscopy and field ion microscopy are used to characterize the solid surfaces prior to contacts and after the established of an interface. In addition to the foregoing structural considerations, many of the properties of matter which influence the nature of the interface of the various states of matter with metals are shown to effect the metal-to-metal interface. These include metal surface chemistry and the influence of alloying on surface chemistry and bulk chemical behavior. The nature of the interface, adhesion and friction properties of noble metals, platinum metals, Group IVB metals, and transition metals are considered. Surface chemical activity of the noble and platinum metals are shown to effect metal-to-metal interfaces as docs valence bonding in the transition metals. With the Group IVB metals the degree of metallic nature of the elements is shown to effect interfacial behavior. The effect of surface segregation of alloy constituents such as silicon in iron and its influence on the metal-to-metal interface is discussed. In addition, the effect of alloy constituents on changes in bulk properties such as transformations in tin is shown to effect interfacial adhesion and friction behavior.

Wear and interfacial transport of material

Bonding across the interface for two solids in contact and the subsequent transfer of material from one surface to another is a direct result of the interfacial bonds being stronger than the cohesive bonds in either of the two solids. Surface tools such as LEED, Auger emission spectroscopy, field‐ion microscopy, and the atom probe are used to examine adhesive contacts and to determine the direction, nature, quantity of material transfer, and properties of the solids which effect transfer and wear. The electronic nature, cohesive binding energies, surface structure, lattice disregistry, and distribution of species in surface layers are all found to effect adhesion and transfer or transport for clean surfaces in solid state contact. The influence of adsorbed and reacted surface films from fractions of a monolayer to multilayer reactive films are considered. It is shown that even fractions of a monolayer of surface‐active species such as oxygen and sulfur can markedly inhibit adhesion and transport.

Crystal Surfaces (Alkali-Halides) and Thin Film Growth Observed by LEED and Auger Emission Spectroscopy

Crystal Surfaces (Alkali-Halides) and Thin Film Growth Observed by LEED and Auger Emission Spectroscopy

Analysis profiles of oxide films on chrome steel by auger emission and x-ray photoelectron spectroscopies

Abstract Samples of steel from two different sources were examined. The materials had nominally the same bulk composition but different samples from each batch had been hardened under two slightly different conditions. The surface oxide films were analysed by both Auger emission spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) after a number of ion bombardments, and the variation in composition with depth was established. In general the outermost oxide layers were chromium deficient and XPS results suggested the presence of Fe 2 O 3 at the surface, together with atmospheric contamination. After ion bombardment the proportion of chromium oxide increased and both iron metal and oxide (Fe 3 O 4 ) were present. The amount of chromium oxide reached a maximum at the steel oxide interface and on further bombardment was replaced by chromium metal. AES and XPS results were in agreement qualitatively and also quantitatively after measurement with a curve analyser of the areas under the peaks of certain elements. The present investigation has shown that AES and XPS can give very similar analyses provided some simple corrections are applied. However, the use of the higher resolution of XPS can provide additional information which cannot be obtained by AES. Thus, using expanded XPS scans, together with suitable curve analysis techniques, it is relatively simple to separate signals from oxide and from free metal regions of the sample, and to study in detail the changes in composition of the oxide from the oxide-air to the oxide-metal interfaces. The study of the four steel samples in this manner has shown that there is a thin region rich in chromium oxide adjacent to the metal. The high level of chromium falls off fairly rapidly nearer the surface and appears to stabilize at a very low level. This is particularly obvious in the thicker oxides (PH), where there is a thick surface layer which is principally iron oxide. It would appear that under the conditions of the heat treatment given to the present samples the thickening of the oxide is due almost entirely to iron oxide. Other work has shown that the low temperature air-formed oxide on these steels is chromium rich and it is suggested that the thickening is due to diffusion of iron through the original film with little movement of the chromium. In view of the high chromium deficiency in the outer layers of the oxides examined it is apparent that the supposedly protective chromium oxide film on chrome steel is situated at the oxide-metal interface and not on the outer surface. The present investigation has shown the existence of two unreported iron satellites. One would appear to be associated with the mixed valence oxide Fe 3 O 4 and another with the purely trivalent oxide Fe 2 O 3 . The satellites could be associated with a strong plasma loss mechanism, or be due to shake-up phenomena as in the case of copper and nickel oxides 14 As might be expected from the normal oxidation behaviour of iron, the present oxide films appear to consist of a thin layer of Fe 2 O 3 overlying the main Fe 3 O 4 oxide. The removal of this outermost Fe 2 O 3 layer is rapid and is accompanied by the changes in the satellites mentioned above, together with changes in the position of the Fe 2p 3 2 oxide peak. In conclusion, it is clear that a detailed XPS examination can not only provide information on overall compositional changes, as can be obtained by AES, but can also provide a comprehensive picture of changes in oxide composition, including those due to oxides of one metal in different valency states.

Concentration Change of Sn in the Surface Layers of Cu–Sn Alloy System due to Friction

Changes in the composition and structure of Cu-5w%Sn alloy system due to friction or heating were examined with X-ray technique, electron probe microanalysis and Auger emission spectroscopy. It was found that the intensities of Auger spectra of Sn on the surface increased rapidly with friction process or heating temperature, and that after heating at 500°C for 30 min their maximum was about 40% of that from pure Sn. The structural changes of the surface of polycrystalline ε-Cu3Sn and η-Cu6Sn5 due to friction were examined. The results obtained were as follows: (1) the structure of ε-Cu3Sn remained unaffected by the friction and (2) η-Cu6Sn5 decomposed partially into ε-Cu3Sn during the friction process, and a thin film of Sn arose from its decomposition at the surface.

KCl(100) Surfaces and Epitaxial Grow h of Ag on KCl Studied by LEED and Auger Emission Spectroscopy

Argon ion bombarded KCl(100) surfaces are compared with air and vacuum cleaved surfaces by LEED and AES experiment. When Ag was evaporated on both argon ion bombarded and air cleaved KCl surfaces, the former showed better epitaxial growth. From these surfaces, Cl signals were always observed from AES curve. Therefore, a great probability of K and Cl diffusion into Ag film can be expected. When a total secondary electron curve was taken from KCl surface, elastic peak heights at higher voltages (up to 1 KeV) were very small. They are probably due to dissociation of the KCl surface. This is clearly related to LEED observable voltage regions. Alkali halides are materials from whose surfaces LEED patterns are observable up to several hundred voltages. However, Ta and MgO samples can be observed by LEED up to 1 KeV.

Adhesion and friction of PTFE in contact with metals as studied by Auger spectroscopy, field ion and scanning electron microscopy

The adhesion between PTFE and metals was studied by field ion microscopy, Auger emission spectroscopy and scanning electron microscopy. Strong adhesion between PTFE and all metals, both clean and oxidized, was observed with these techniques for both static and dynamic contact. The bonding is sufficiently strong so that for soft metals such as aluminum, pieces of metal can be pulled out of the bulk and embed in the PTFE subsequently causing severe scoring of the metal surfaces.

Adhesion of metals to a clean iron surface studied with leed and auger emission spectroscopy

Adhesion experiments were conducted with various metals contacting a clean iron (011) surface. The metals included copper, gold, silver, nickel, platinum, lead, tantalum, aluminum, and cobalt. Some of the metals were examined with oxygen present on their surface as well as in the clean state. LEED and Auger emission spectrometer analyses were used to determine the nature of surface changes that took place as a result of adhesive contact. All experiments were conducted at 20°C and 10 −10 torr. Results indicate that, with the various metals contacting iron, the cohesively weaker will adhere and transfer to the cohesively stronger. The chemical activity of the metal also influenced adhesive forces measured. The more reactive metals gave higher adhesion values. With oxygen present on the metal surface, where the metal to oxygen chemical bond was weaker than the metal cohesive bonds, the adhesive forces measured could be correlated with the binding energy of the metal to oxygen.

Low-energy electron diffraction and Auger emission spectroscopy studies of lithium hydride (100) surface

The (100) surface of a lithium hydride (LiH) crystal was investigated by low-energy electron diffraction (LEED) and Auger emission spectroscopy (AES). The LEED measurements indicated an expansion of the two-dimensional unit mesh. Electrical surface charging was observed below 120°C. Exposure of the LiH crystal to H 2, O 2 and CO 2 at 430°C caused no change in the LEED pattern. The AES study of the crystal under the same conditions as in the LEED investigation revealed that heating the crystal to 580°C in vacuum followed by exposure to 1 × 10 −5 torr hydrogen at 350°C minimized the contaminants originally on the surface (S, C and O). Several Auger lines having energies below 60 V were observed and are apparently associated with the band and defect structures of LiH. The experimental observations were consistent with a high lithium metal concentration near the LiH surface.

A Review of Surface Segregation, Adhesion and Friction Studies Performed on Copper-Aluminum, Copper-Tin and Iron-Aluminum Alloys

Auger emission spectroscopy, low energy electron diffraction, sputtering studies, and adhesion and friction experiments on single crystals of Cu-Sn, Cu-Al, and Fe-Al alloys

Surface segregation in boron-doped iron observed by Auger emission spectroscopy

Specimens of iron doped with 0.090 and 0.018 wt.% boron, respectively, were examined by Auger emission spectroscopy after each of a succession of treatments, viz. ion bombardment, heat treatment at increments of 100°C from 500°C to 900°C, inclusive, and then at 1050°C, and finally gas reaction in oxygen and in hydrogen at 750°C. Boron was observed as a trace on the surface at 500°C and 600°C, was measurable at 700°C, and saturated quickly at 800°C and above. There was no difference in the behaviour or the saturation level between the two concentrations. Other elements, and in particular sulphur, were also observed to segregate, sulphur so much so that it dominated the surface concentrations at 1050°C. Nitrogen was observed to behave in a manner identical to that of boron, even to the doubling in concentration seen after the gas reactions with oxygen, and then with hydrogen, had removed some of the sulphur.

The (100) surfaces of alkali halides: I. The air and vacuum cleaved surfaces

This paper is the first of a series of three which report the results of studies on the (100) surfaces of LiF, NaF and KCl. The air cleaved and vacuum cleaved surfaces were examined by LEED and Auger emission spectroscopy and the partial pressures of the constituent elements were measured on cleavage of the specimen. Auger analysis of the air cleaved surfaces of LiF and NaF showed the presence of carbon and oxygen, and oxygen was detected on the air cleaved surface of KCl. These impurities could not be detected on the vacuum cleaved surfaces of NaF and KCl but were still observed on the vacuum cleaved surface of LiF. Mass spectrometer studies showed dissociation occurred on cleavage for all three alkali halides although different in character in each case. The form of the partial pressure curves suggests that this dissociation may be non-stoichiometric. LEED patterns obtained from the vacuum cleaved surfaces were of much better quality than those from the air cleaved surfaces except for the case of KCl which gave a poor LEED pattern directly after cleavage but which improved with time.