Scott A. Furman

Multispectral and hyperspectral image analysis of elemental and micro-Raman maps of cross-sections from a 16th century painting

Spectroscopic imaging is well suited to the study of micro-samples from artworks, where the sample material is limited and the maximum amount of information needs to be obtained. In this study, a new approach to imaging elemental data from energy dispersive X-ray analysis maps was used in conjunction with micro-Raman spectroscopic imaging to characterise the paint layers within micro-samples. Cross-sections from the 16th century painting Portrait of a Youth were found to contain vermilion, lead-tin yellow type 1 and a blue-green pigment consistent with terre-verte. The mid-preparatory layer (imprimatura) contains a high proportion of elements and mineral inclusions that indicates a clay-type composition. The ground layer was identified as anhydrite with large gypsum inclusions. The pigments and composition of the preparatory layers are consistent with those used by Italian Renaissance artist Dosso Dossi.

Holistic model for atmospheric corrosion: Part 2 - Experimental measurement of deposition of marine salts in a number of long range studies

Abstract This paper is the second in a series looking at understanding the factors controlling and predicting marine aerosol concentration on land. It looks at results from three transects across the Australian continent. In each transect, the airborne salinity was measured, using the wet candle method at distances from 10 m to 40-300 km from the coast. The positions of the transects were selected to give a significant variation in the factors controlling salt production and transport. For example, one transect in South Australia was established where both high whitecap activity is likely to promote salt production and flat terrain and prevailing winds are likely to favour transport. Another, in Queensland, was established where calm seas will limit salt production and very seasonal winds and high relative humidity and rainfall will limit transport. On the basis of this experimental study, the general validity of the fundamental concepts put forward in Part 1 is assessed. Further, the feasibility of building a mathematical model to predict salinity is determined and the main factors causing variations in salinity on land are outlined. The results are then used to assist in the interpretation of previous work in the literature.

Controlled synthesis of a large fraction of metallic single-walled carbon nanotube and semiconducting carbon nanowire networks

Controlled synthesis of both single-walled carbon nanotube and carbon nanowire networks using the same CVD reactor and Fe/Al(2)O(3) catalyst by slightly altering the hydrogenation and temperature conditions is demonstrated. Structural, bonding and electrical characterization using SEM, TEM, Raman spectroscopy, and temperature-dependent resistivity measurements suggest that the nanotubes are of a high quality and a large fraction (well above the common 33% and possibly up to 75%) of them are metallic. On the other hand, the carbon nanowires are amorphous and semiconducting and feature a controlled sp(2)/sp(3) ratio. The growth mechanism which is based on the catalyst nanoisland analysis by AFM and takes into account the hydrogenation and temperature control effects explains the observed switch-over of the nanostructure growth modes. These results are important to achieve the ultimate control of chirality, structure, and conductivity of one-dimensional all-carbon networks.

Products Formed during the Interaction of Seawater Droplets with Zinc Surfaces: I. Results from 1- and 2.5-Day Exposures

This paper reports on a study in which fine seawater droplets were placed on zinc surfaces for periods up to 2.5 days. At the end of each exposure, the droplets were either extracted from the specimens or allowed to evaporate in laboratory conditions. Scanning electron microscope-energy-dispersive spectroscopy, X-ray diffraction studies (including mapping), and Fourier transform infrared and Raman spectroscopy were carried out on the specimens after exposure and on the dried extractions. It was observed that soon after the droplets were placed on the surface, a thin moisture layer (termed the secondary spreading film) spread out from the central droplet. X-ray analysis indicated the presence of gordaite and simonkolleite in the center of the drop when the droplet volume was maintained. However, during droplet evaporation a wider range of species was detected, including boyleite, zinc chlorate hydrate, and sodium zinc chloride hydrate. In the secondary spread region, an amorphous phase with a composition and morphology consistent with zinc hydroxy carbonate was present. The phase analysis is supported by electrochemical data and by analysis of changes in droplet chemistry with time. A synthesis of the data permits a description of the processes leading to the phase development. The implications to atmospheric corrosion are discussed.

Pitting Corrosion of Zn and Zn-Al Coated Steels in pH 2 to 12 NaCl Solutions

Corrosion behavior of hard zinc, Zn-5% Al (Galfan), and Zn-55% Al alloy (Zincalume or Galvalume) coated steels was studied using cyclic voltammetry and potential scan/hold technique in the presence of 0.10-0.90 mol L -1 NaCl over a pH range of 2 to 12. Influence of chloride concentration and electrolyte pH on pitting potential values of the above three types of specimens were examined. On the basis of the electrochemical, scanning electron microscopy with energy dispersive X-ray spectroscopy, and chemical equilibria data obtained from hard zinc, a pitting corrosion mechanism involving a series of processes from anion competitive adsorption to penetration to nucleation and growth was proposed.

Fast, energy-efficient synthesis of luminescent carbon quantum dots

A simple, fast, energy and labour efficient, carbon dot synthesis method involving only the mixing of a saccharide and base is presented. Uniform, green luminescent carbon dots with an average size of 3.5 nm were obtained, without the need for additional energy input or external heating. Detection of formation moment for fructose–NaOH-produced carbon dots is also presented.

The use of macroscopic modelling of intermetallic phases in aluminium alloys in the study of ferricyanide accelerated chromate conversion coatings

Intermetallic (IM) second phases of FeAl3, Cu2FeAl7, and CuAl2, were coupled to aluminium for the macroscopic study of the deposition of chromate conversion coatings. Characterisation of the coating deposition was done using X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, Auger electron spectroscopy, scanning electron microscopy with X-ray analysis, and Fourier transform infrared spectroscopy. The coatings covering the IM phases were only one-tenth the thickness of the matrix, and contained higher levels of F, Al, and O. Cr, O, Fe, and N, indicative of a chromate conversion coating, were detected over the matrix. Over IM phases, decomposition of [Fe(CN)6]3−/4−, and fluoride ion attack were found to be responsible for reduced rates of deposition.

Microstructure of a Paint Primer - a Data-Constrained Modeling Analysis

Metallic aerospace components are commonly painted with a primer to improve their corrosion resistance. The primer contains a polymer matrix with embedded corrosion inhibitor and filler particles. Its performance is determined by the microscopic distributions of the particles. Various techniques have been used to quantify such distributions, including X-ray micro-computed tomography (CT). However, its success is sometimes limited by factors such as different particles having similar X-ray CT absorption properties and their size being smaller than the resolution of micro-CT. In this paper, we have performed two X-ray CT measurements on a paint primer sample consisting of SrCrO4 corrosion inhibitor particles and UV-absorbing TiO2 filler particles. Fe and Ti targets were used as X-ray sources with different spectral distributions. The measured CT data sets were used as constraints for a data-constrained microstructure modeling (DCM) prediction of the sample’s microscopic structures. DCM model predictions were compared with experimental elemental surface maps and showed reasonable degree of agreement, suggesting X-ray micro-CT combined with DCM modeling would be a powerful technique for detailing the dynamics of chromate-inhibited primers and other multiphase systems where the components are sensitive to incident X-ray energy.

Interaction of Ce(dbp)3 with surface of aluminium alloy 2024-T3 using macroscopic models of intermetallic phases

Abstract The mechanism of corrosion inhibition by cerium(III) dibutylphosphate [Ce(dbp)3] on aluminium alloy 2024-T3 (AA2024-T3) has been investigated using macroscopic models of the intermetallic (IM) phases in the alloy. Polished specimens of pure Al (99·999%) and the macroscopic IM phases Al2CuMg, Al7Cu2Fe and Al3Fe were each coupled to a large surface area of AA2024-T3 to simulate the interaction they experience in the alloy. Samples were immersed in 0·1M NaCl with 200 ppm Ce(dbp)3 for 24 h, and the resulting surfaces characterised by scanning electron microscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy and Raman spectroscopy. Ce(dbp)3 was found to interact differently with each of the different phases examined, providing evidence for a multifunctional corrosion inhibition mechanism.

TENSOR LEED ANALYSES FOR THREE CHEMISORBED STRUCTURES FORMED BY IODINE ON A Pt(111) SURFACE

Three distinct ordered iodine structures on a Pt(111) surface have been studied with LEED crystallography in the coverage range 0.33–0.44 monolayers. These surfaces have translational symmetries of the , and (3×3) types, and they all involve overlayer adsorption on the basically unreconstructed metal structures. The surface phase is indicated to have essentially all I atoms adsorbed at the regular threefold sites of the fcc type (i.e. 3f sites), with no significant involvement by the corresponding sites of the hcp type (i.e. 3h sites). The structure has one I on an atop Pt site, and one each at 3f and 3h sites per unit mesh, while the (3×3) surface has one I on an atop site and three on bridge sites per unit mesh. The I corrugation is about 0.5 A for the structure, but is reduced to around 0.1 A at the (3×3) surface. The surface I–Pt bond lengths from these analyses show a general tendency to follow trends expected with the varying I coordination numbers. A preliminary discussion is given for uncertainties associated with some relaxations indicated in the metallic structures.