Publications

XPS analysis of different forms of copper sulfate, including antlerite, brochantite, posnjakite, chalcanthite and anhydrous copper sulfate, as well as pure copper and its oxides cuprite and tenorite, was carried out. These products most often occur when dealing with atmospheric corrosion of copper and bronze in sulfur‐bearing environments. These compounds were minerals, commercial products, or grown on pure copper by artificial weathering. Spectral features such as peak energy and line shape for Cu 2p, Cu LMM, O 1s and S 2p bands were examined. Comparison of the measurements obtained proves the efficiency of XPS in differentiating the various compounds. Copyright © 2004 John Wiley & Sons, Ltd.

The bonding properties of zirconium- and titanium-based conversion coatings were evaluated using model conversion solutions of H2ZrF6 and H2TiF6 with addition of various organic additives (PAA, PVA, PVP). Macroscopic testing techniques such as contact angle and pull-off adhesion measurements were performed on galvanized steel sheets. Complementary to this, molecular studies were performed on model zinc substrates using ATR-FTIR in the Kretschmann configuration. The macroscopic and molecular approaches showed a good correlation demonstrating ATR-FTIR in the Kretschmann configuration to be a valuable tool to gain fundamental insights in metal oxide-polymer interfacial phenomena. Zirconium-treated galvanized steel substrates were shown to have a higher bonding affinity for the polyester coil coat primer than titanium-treated galvanized steel substrates. The presence of organic additives did not further improve the bonding properties. Yet, organic additives initially improved the interfacial stability of titanium-treated substrates. However, on the long term, organic additives are shown to be detrimental for polyester coil coat adhesion. This adverse effect of organic additives on the long term was assigned to its selective dissolution during immersion and was most pronounced for titanium-treatments. The limited effect of organic additives in case of zirconium-treatments was attributed to the higher portion of chemical interfacial bonds, as well as its tendency for crosslinking reactions causing entanglement of polymeric compounds in the zirconium oxide structure.

The main purpose of this publication is to define sensing parameters by means of optical spectroscopy to study and characterize ancient glass. Because during different times different flux agents were used, a chemical individuation of these elements provides a first dating classification. Normally, X‐ray‐based chemical methods are applied to this kind of investigation. On the basis of the Ligand‐field theory , the absorption band positions of a transition metal ion undergo a change when the ion is placed in different chemical environments. A total of 25 cobalt coloured Roman, post‐medieval and industrial glasses were analyzed by means of SEM–energy dispersive X‐ray spectroscopy to group them according to their chemical composition. Optical spectroscopy was applied to build a method to study glass with this low‐cost and non‐destructive technique. It is proved that the cobalt absorption band situated around 535.5 nm for sodium‐rich glasses (Roman and industrial material) is shifted towards 526.5 nm for calcium–potassium‐rich glasses (post‐medieval window glass). This feature was employed as a marker in the case study of the Renaissance window of the Church Wardens from the Church of Our Lady in Bruges, Belgium to distinguish the post‐medieval material from the 19th and 20th century restoration material. Copyright © 2011 John Wiley & Sons, Ltd.

Lithium salts were investigated as leachable corrosion inhibitor and potential replacement for hexavalent chromium in organic coatings. Coatings loaded with lithium carbonate or lithium oxalate demonstrated active corrosion inhibition by the formation of a protective layer in a damaged area. The present paper provides more insight into the formation and composition of the protective layer in a damaged area generated from the lithium salt loaded coatings when exposed to neutral salt spray testing conditions (ASTM B-117). Lithium-ion leaching from the coating matrix was demonstrated with atomic absorption spectroscopy and the pH conditions in the damaged area were determined with a scanning ion-selective electrode technique. Additionally, the formation of the protective layer was studied with microscopic and surface analytical techniques. Scanning electron micrographs and Auger electron spectroscopy depth profiles revealed the process of coverage and growth of the protective layer in the damaged area. Furthermore, X-ray photoelectron spectroscopy analysis indicated that the protective layer likely consists of a hydrated oxide in the form of a (pseudo) boehmite with lithium distributed in its matrix.

Window glass fragments from four Belgian sites were studied and for a set of eighty-five samples the UV-VIS-NIR transmission spectra were analyzed. This collection contains historical and archaeological finds originating from religious buildings namely the Basilica of Our Lady of Hanswijk in Mechelen (17^th-20^thc) and the Church of Our Lady in Bruges (16^th-20^thc) as well as from secular buildings as a private house/Antwerp (18^th-1948) and the castle of Middelburg-in-Flanders (1448-17thc). All sites contain material on the hinge point between the medieval and the industrial tradition. The variation in composition of the analyzed samples can be explained by the use of different glassmaking recipes, more specifically the use of different raw materials. The composition of window glass differs essentially in the type of flux, using a potash rich fluxing agent until the post-medieval times and industrial soda from the 19^th century onwards. A second difference concerns the iron impurities in the glass. For all fragments a clear compositional classification could be made based on the iron concentration. These conclusions were based on archaeological research and drawn after submitting samples to expensive, complex, time-consuming and destructive chemical analyzing methods. Our study indicates that similar conclusions could be made applying the proposed optical based methodology for plain window glass. As a whole, the obtained results make it possible to cluster the fragments for a particular site based on three different sensing parameters: the UV absorption edge, the color and the presence of characteristic absorption bands. This information helps in identifying trends to date window glass collections and indicating the use of different raw materials, production technologies and/or provenance.

In this paper, the behaviour of the industrial applied Ti/Zr conversion coating (CC) pretreatment on rolled automotive aluminium samples (AA5182) is analysed. Due to its nanometre lateral and depth resolution, Auger electron spectroscopy (AES) is used to analyse the CC distribution at surface cathodic intermetallic particles. As a result of its high surface sensitivity, the AES technique is very susceptible to differences in the top contamination layer thickness. It is demonstrated that AES point measurements performed on aluminium model samples coated with 1.5 and 3 nm of Ti (oxide) layer cannot differentiate the two‐layer thicknesses if a difference in the top contamination thickness is not taken into account. A data analysis methodology is introduced, based on the ratio of normalized peak areas (enrichment ratios), to eliminate the effect of the contamination layer thickness. The experimental validation of the methodology is performed on the model samples, demonstrating errors of 2% on the enrichment ratios on similar samples with different contamination layer thicknesses, while the conventional spectra quantification results in errors of 49%. The methodology is also theoretically substantiated within certain constraints. By the use of the AES methodology, an enriched Ti and Zr deposition is confirmed at the cathodic intermetallic particles at the surface of the industrial no‐rinse CC sprayed automotive aluminium sheet samples.

The process of electropolishing aluminium and its influence on the visual appearance are studied. Angle‐resolved scattering (ARS) and total integrated scattering (TIS) are used to investigate the influence of electropolishing on surface roughness. The ARS apparatus is built similar to the ASTM E430‐97A standard. This standard test method is used for measurement of distinctness of image and haze by goniophotometry. These visual appearance parameters, together with TIS, reflect the changes in surface roughness. Total reflectance is correlated to the composition of the aluminium as well as the composition and thickness of the layer formed on the aluminium. Copyright © 2003 John Wiley & Sons, Ltd.

Plasma density influences the chemistry and the morphology of deposited plasma polymers even under the same energy to monomer ratio.

By immersing polycrystalline Cu in a solution of 0.1M NaCl and 0.5M Na2SO4 the grain dependent electrochemical behavior is studied. In order to exclude possible compositional effects, high purity Cu was used. With the use of Atomic Force Microscopy (AFM) and Electron Backscatter Diffraction (EBSD) it was possible to link the dissolution behavior of a polycrystalline material to specific crystallographic features. The results suggest that the grain orientation has no major influence on the corrosion kinetics. On the other hand, the orientation of the neighboring grains seems to play a decisive role in the dissolution rate.

Obtaining chemical information from the buried interface of an organic coating is not straightforward. In this paper, for the first time, atomic force microscopy-based infrared spectroscopy (AFM-IR) is used to probe the chemical interactions at the metal oxide/polymer interface. AFM-IR is a novel technique that provides chemical spectra with spatial resolution below the optical diffraction limits. Poly(acrylic acid) (PAA) on aluminum oxide was chosen as a model system. Two different approaches were used: a thin-layer approach and a cross-section approach. The thin layer confirmed the validity of the AFM-IR to look at the buried interface by comparison with results from the literature. Additionally, with a line scan, the exposed interfaces obtained from cross sections of thick coatings on aluminum substrates were analyzed. A semiquantitative analysis of the spectra from the line scan allowed to identify the chemical contribution coming from the polymer/metal oxide interfaces.

No abstract is provided for this article.

No abstract is provided for this article.