The very thin native oxide film on stainless steel, of the order of 2 nm, is known to be readily modified by immersion in aqueous media. In this paper, XPS and ToF-SIMS are employed to investigate the nature of the air-formed film and modification after water emmersion. The film is described in terms of oxide, hydroxide and water content. The preferential dissolution of iron is shown to occur on immersion. It is shown that a water absorbed layer and a hydroxide layer are present above the oxide-like passive film. The concentrations of water and hydroxide appear to be higher in the case of exposure to water. A secure method for the peak fitting of Fe2p and Cr2p XPS spectra of such films on their metallic substrates is described. The importance of XPS survey spectra is underlined and the feasibility of C60+ SIMS depth profiling of a thin oxide layer is shown.
In the search for improvements in the environmental credentials of the organic coatings industry, several different aspects are currently being addressed, including the reduction of volatile organic compounds, development of UV curable coatings and the reduction of potentially hazardous components in the coatings formulations. The aim of this work was to develop the water based primers for coil coating applications as a substitution for chromate conversion coatings. The performance and durability of three novel water based systems applied on alkali cleaned HDGS has been investigated; XPS and ToF-SIMS have been employed to analyse the failure interfaces generated by various test methods designed to assess the performance and durability of each of the systems. In depth analysis has been carried out using ULAM for sample preparation, and XPS and ToF-SIMS were employed to analyse the buried metal/ primer interface, in order to investigate the interface chemistry. A method of post processing data, obtained by surface analysis techniques, was invented to gain a clear understanding of the possible chemical interactions occurred at the metal/primer interface. Adsorption studies were also carried out to encode the interfacial chemistry. The method was used to understand the role of adhesion promoter in the primer formulation, particularly the manner in which it interacts with the substrate and the topcoat and the way it improves the performance and durability; also to determine the role of anti-corrosive additives, especially the manner in which it prevents the corrosion and therefore its contribution toward the performance and durability. The distribution of these components across the primer layer was also investigated considering the possible opportunities of such components enhancing the primer interaction at either interfaces. The finding has been used for re-adjustment of some of process parameters in coil coating systems and specifically water based primers.
This study investigates the formation of a chromate conversion coating at Al–Cu–Fe–Mn intermetallic sites of an Al2219 alloy and the corrosion initiation at these sites in a 3.5% NaCl solution, using SEM, AES and EDX. Changes in the surface chemistry were monitored after progressive exposures to the solution up to 42 h. The coating was found to be thinner and more defective on the intermetallic. Initially, Al is dissolved and Al(OH)3 deposited on and around the intermetallic. After 42 h of exposure, Al(OH)3, Fe and Mn oxides and small particles of elemental Cu are deposited as corrosion products.
Sandwich panels, polyurethane foam sandwiched between two sheets of steel, form the walls and roofs in the construction of buildings. ArcelorMittal is a manufacturer of the steel as well as these finished panels. For this project they combined with a supplier of the polyurethane foams, Huntsman Polyurethanes, to joint-fund a research project investigating the fundamental mechanisms of adhesion, as well as the causes of failures in the product which manifests primarily in two different ways, blisters appearing on the outer surfaces of the panels in use and voids appearing in the foam during fabrication. There is a fundamental lack of understanding on how precisely these systems adhere together and thus what causes failures in the product, both during construction and also in use. In order to achieve these goals, characteristics of each of the constituent parts were evaluated; supporting, disputing and contributing entirely novel findings to the information available in literature. Following this the manufacturing processes were investigated thoroughly, examining each with reference to the locations of noted failure. The polyurethane foam/coated steel interface was found to be of specific interest. The nanoscopic mechanisms of adhesion through this interface were examined thoroughly using a variety of spectroscopic and imaging techniques. It was found that a number of components in the foam diffused into the polymeric coating. The diffusion was experimentally analysed to understand its role in the overall performance of the product. Finally, forensic analyses were conducted on a failed product displaying the blistering. Using the knowledge gained through the project this failure could be explained, contributing towards making a significantly enhanced product and thus potentially saving the sponsoring companies millions of pounds.
To investigate the role of intermetallic particles in the localised corrosion of AA7075-T6, three particles were monitored over 16 hours immersion in 3.5 wt.% KCl solution. These were examined using Auger electron spectroscopy, energy dispersive x-ray spectroscopy, scanning Kelvin probe force microscopy and focused ion beam-scanning electron microscopy. Despite similar Volta potential measurements, the corrosion microchemistry varied significantly with composition. A Al7Cu2Fe intermetallic resulted in trenching while a (Al,Cu)6(Fe,Cu) intermetallic showed crevice corrosion and sub-surface intergranular corrosion and a Al12Fe3Si intermetallic appeared to be galvanically inactive but showed crevice formation at the matrix interface and sub-surface intergranular corrosion.
Lithium scribed in vacuum and a particle of lithium oxide were analysed by AES and lithium metal exposed to atmosphere for <1 min was analysed by XPS. The oxide particle embedded in the host metal was analysed at low and high take off angles. AES spectra acquired demonstrate the change in the KLL structure with increasing oxygen concentration. Survey spectra as well as high resolution narrow spectra were acquired and are presented. The presence of lithium carbonate, together with the oxide, formed in air, was confirmed by XPS as it is not easily resolvable using AES.
As-received beryllium and beryllium oxide were analysed by X-ray photoelectron spectroscopy and Auger electron spectroscopy. Additionally, beryllium metal was scribed in vacuum and analysed by AES. Survey spectra together with high-resolution spectra were acquired in XPS and AES mode and are presented here. The binding energies of the beryllium and the beryllium oxide Be 1s peaks were found to be 110.5 and 113.4 eV respectively, as collected by XPS, and the kinetic energies of the primary metal and oxide KLL Auger transitions were found to be 103.0 and 93.6 eV respectively, as collected by AES. Three loss peaks are also observed at 87.1, 78.0 and 67.2 eV in the AES spectrum of beryllium oxide
Herein we report the construction of a Wagner chemical state plot for beryllium containing the: metallic, oxide, nitride and carbide forms of beryllium by combining electron beam induced AES and XPS data. AES and XPS values were collected from metallic beryllium mechanically abraded in vacuum, bulk and native beryllium oxide and homogeneous secondary-phase beryllium nitride and beryllium carbide inclusions. XPS data for beryllium nitride and carbide were obtained from the literature.
As-received beryllium, beryllium scribed in vacuum and beryllium oxide were analysed by Auger Electron Spectroscopy. As-received beryllium was analysed at low and high take off angles. Spectra produced demonstrate the change in the KLL structure with increasing oxygen concentration. Survey spectra as well as high resolution Be KLL and O KLL transitions were collected and are presented.
As received beryllium and beryllium oxide, purchased from Goodfellow, were analysed by x-ray photoelectron spectroscopy. Survey spectra, high resolution spectra of elemental peaks and beryllium Auger transitions were collected and are presented. The binding energy of metallic beryllium 1s peak and the beryllium oxide 1s peak were found to be 110.5 and 113.4 eV respectively. The kinetic energy of the main metal and oxide KVV Auger transitions were found to be 103.5 and 95.5 eV respectively.
Secondary phase particles of beryllium nitride and beryllium carbide in beryllium were analysed by Auger Electron Spectroscopy. Survey spectra as well as high resolution Be KLL, N KLL and C KLL transitions were collected and are presented. The primary beryllium KLL Auger transitions for the nitride and carbide were recorded at 96.7 and 100.4 eV respectively. The homogeneity and composition of the secondary phase particles was confirmed by energy dispersive x-ray spectroscopy.
In this work, the feasibility of XPS analysis using locally generated Al K α radiation has been demonstrated. Both photo and Auger-electron signals can be obtained from a single, sub-micrometre, particle, achieving the aim of chemical state identi fi cation by means of the Auger parameter. The results, demonstrated in t his work using copper particles on an aluminium substrate, suggest that the technique, with further development, will be valuable for those concerned with the health hazards of nano-particles in general.
Four samples of well-defined silicon-germanium alloys were used as standards for calibration purposes to allow accurate quantification of silicon-germanium-on-insulator (SGOI) microelectronic devices using Auger electron spectroscopy. Narrow Si KLL and the Ge LMM, high resolution Si KL_2,3L_2,3 and Ge L_3M_4,5M_4,5 together with survey spectra were collected and are presented from each sample. A matrix effect was observed for silicon in germanium and calculated as 0.85 and 0.95 for the Ge77.5Si22.5 Ge52.4Si47.6 alloys respectively.
Beryllium is an important metal in the nuclear industry for which there are no suitable replacements. It undergoes localised corrosion at the site of heterogeneities in the metal surface. Corrosion pits are associated with a range of second phase particles. To investigate the role of these particles in corrosion, a safe experimental protocol was established using an aluminium alloy as a corrosion material analogue. The 7075-T6 alloy had not previously been investigated using the experimental methodology used in this thesis. This work led to the development of the experimental methodology and safe working practices for handling beryllium. The range and composition of the second phase particles present in S-65 beryllium billet were identified using a combination of SEM, AES, EDX and WDX. Following the identification of a range of particles with various compositions, including the AlFeBe4 precipitate which has been previously associated with corrosion, the location of the particles were marked to enable their repeated study. Attention was focused on the microchemistry in the vicinity of second phase particles, as a function of immersion time in pH 7, 0.1 M NaCl solution. The corrosion process associated with different particles was followed by repeatedly relocating the particles to perform analysis by means of SEM, AES and EDX. The use of traditional chlorinated vapour degreasing solvents on beryllium was investigated and compared to two modern commercially available cleaning solutions designed as drop-in replacements. This work expanded the range of solvents suitable for cleaning beryllium and validated the conclusions from previous thermodynamic modelling. Additionally, a new experimental methodology has been developed which enables the acquisition of chemical state information from the surface of micron scale features. This was applied to sub-micron copper and iron particles, as well as a copper intermetallic