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Scanning vibrating electrode technique (SVET) analysis of processable polyaniline-HCSA/poly(vinyl acetate-co-butyl acrylate) coated on to aluminium alloy 2024-T3 exhibited strong interaction between the polymer coating and the underlying metal. A scribed defect in the coating surface resulted in rapid oxidation of the exposed metal within a coating defect while the overlying polymer coating underwent both reduction and dedoping. Under the conditions investigated no protective oxide was observed to form. Raman spectroscopy of the polymer surface confirmed that dedoping was the dominant process which was accompanied by a clear reduction of the emeraldine salt form of the coating to the leucoemeraldine base form within the defect. This coating/metal interaction was observed to be dependant of the proximity to an artificial defect, initially yielding a more reduced material in close proximity to the coating defect, providing evidence of an electrochemical interaction between the polyaniline co-polymer system rather than a barrier effect.

The direct electrodeposition of electroactive conducting polymers on active metals such as iron and aluminum is complicated by the concomitant metal oxidation that occurs at the positive potentials required for polymer formation. In the case of aluminum and its alloys, the oxide layer that forms is an insulator that blocks electron transfer and impedes polymer formation and deposition. As a result, only patchy nonuniform polymer films are obtained. Electron transfer mediation is a well-known technique for overcoming kinetic limitations of electron transfer at metal electrodes. In this work, we report the use of electron transfer mediation for the direct electrodeposition of polypyrrole onto aluminum and onto Al 2024-T3 alloy. This report focuses on the use of Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) as the mediator, although catechol appears to function in a similar manner. Depositions were carried out under galvanostatic conditions at current densities of 1 mA/cm2. The mediator reduced the deposition potential by nearly 500 mV compared to deposition performed in the absence of mediator (where Tiron was replaced by p-toluene sulfonic acid sodium salt). Polypyrrole formation and deposition appears to occur with 100% current efficiency and uniform films are obtained. Results of the characterization of these films by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, conductivity measurements, and adhesion measurements are presented.

Electroactive conducting polymers (ECPs) continue to be of considerable interest as components of corrosion-resistant coating systems. ECPs, in addition to being conductive, are redox active materials, typically with potentials that are positive of iron and aluminum. Thus, as with chromate, interesting and potentially beneficial interactions of ECPs with active metal alloys such as steel and aluminum are anticipated. In this work, the scanning vibrating electrode technique (SVET), also known as the current density probe, was used to probe such interactions between a poly(3-octyl pyrrole) coating (POP) and cold-rolled steel and aluminum (Al 2024-T3) substrates. The POP coatings were scribed to simulate a defect through the coating to the metal substrate surface. The SVET was used to map the current flowing in and around the defect while the sample was immersed in either 3% NaCl (steel) or in dilute Harrison solution (aluminum), an aqueous solution consisting of 0.35% (NH4)2SO4, 0.05% NaCl. Although there were significant differences in the behavior of the POP-coated steel and POP-coated aluminum substrates, both exhibited a significant delay before the onset of any observable current compared to uncoated or epoxy-coated samples. Current density maps for the steel clearly indicate that the reduction reaction occurred on the conducting polymer surface, with oxidation confined to the defect. Current density maps for the aluminum alloy never displayed significant oxidation at the defect. Rather, reduction (after a significant delay) occurred at the defect as well as across the polymer surface, with concomitant localized undercoating oxidation of the aluminum substrate.

This research grant focused on electrochemical techniques for the investigation of corrosion protection afforded by organic coatings. The main aim of the work was the study of marine coatings using the electrochemical noise methods (ENM). Skerry et al had ENM to examine organic coatings (mainly primer) on metal., Prepared in cooperation with Sherwin Williams Company.

Dusts were ranked by potential risk, derived from a matrix formula calculation that took into account dose, mine population, and sampling size. The dusts determined to have the highest risk potential were quartz respirable particulates, mine dust, cristobalite respirable particulates, welding fume components, and nuisance respirable dust. Other dusts and fumes not ranked due to small sampling populations, but which show a potential risk, include asbestos, talc, hydrogen cyanide, organic compound dusts, arsenic, metal dusts, and metal and nonmetal fumes., Dusts were ranked by potential risk, derived from a matrix formula calculation that took into account dose, mine population, and sampling size. The dusts determined to have the highest risk potential were quartz respirable particulates, mine dust, cristobalite respirable particulates, welding fume components, and nuisance respirable dust. Other dusts and fumes not ranked due to small sampling populations, but which show a potential risk, include asbestos, talc, hydrogen cyanide, organic compound dusts, arsenic, metal dusts, and metal and nonmetal fumes.