The Application of Mossbauer Spectroscopy to the Study of Corrosion

The Mossbauer spectroscopic methods that have been used for studying corrosion phenomena include transmission, emission and reflection (scatterimg) techniques. Each of these techniques provides unique capabilities for studying a wide range of applied and fundamental corrosion problems. The various Mossbauer spectroscopic techniques are described and compared, and applications of each method to corrosion studies are reviewed

The Application of Mossbauer Spectroscopy to the Study of Corrosion

The Mossbauer spectroscopic methods that have been used for studying corrosion phenomena include transmission, emission and reflection (scatterimg) techniques. Each of these techniques provides unique capabilities for studying a wide range of applied and fundamental corrosion problems. The various Mossbauer spectroscopic techniques are described and compared, and applications of each method to corrosion studies are reviewed

Characterization of the Surface of High-Area Ni(OH)2 and NiO

The surface propertij:ls of Ni(OH)2, and the mechanism of decomposition of Ni(OH)2 to NiO were investigated by a variety , of experimental approaches including gas adsorption, heats of immersion and diffuse ir reflectance. The N~(OHh samples were prepared by bubbling ammonia gas through a Ni(N03)2 solution at different temperatures. Ni(OHh is relatively hydrophobic while NiO is completely hydrophilic. A relatiQIIlShip was estabhlshed between the specific surface areas of rthe parent Ni(OH)2 and Its decomposition product NiO which supports a mechanism of dehydration at 200 °c involving separation along the hexagona~ planes. This mechanism was confirmed by electron micrographs during decomposmon of Ni(OHh to NiO. Gravimetric studies of the decomposition of Ni(OH)2 at 200 °c iindicated that approximately 14°/o of the hydroxyl groups are not removed. Diffuse ir reflectance studies showed that surface hydroxyls were not removed. Physical adsorption of water vapor on Ni(OHh as a function of surface area supports the hypo·thesis that the basal planes are hydrophobic and the crystal edges are hydrophilic

Inter-layer Adhesion Performance of Steel Packaging Materials for Food Cans Under Retort Conditions

The steel packaging industry faces the dual challenge imposed by legislation to eradicate the use of Chrome(VI) from sub- strate manufacture and the removal of Bisphenol-A (BPA) from the organic lacquer at the point of food contact. The paper reports on an experimental investigation into the quality of adhesion between the coatings and substrates as a result of the retort process, typically the harshest conditions to which the materials will be exposed. In terms of adhesion, the novel Chrome(III) substrates show promise when compared with current Chrome(VI) substrate. There is a significant reduction in the adhesion of the polyester-based Bisphenol-A non-intent lacquers compared to the incumbent epoxy-phenolic lacquers. Adhesion performance is lower with an increase in retort temperature and time of exposure. The adhesion further reduces in mild acidic and saline conditions. The reduction in adhesion post-retort is attributed to the sensitivity of the polyester-based BPANI lacquers to water vapour absorption. The process reversible nature of the adhesion loss indicates that, at short time- scales, the adhesion loss is a result of polyester hydrolysis. Acidic and saline solutions also lead to a reduction in adhesion as a result of metal surface corrosion. The paper has impact on producers, fillers and consumers of steel packaging foodstuff

PROVOCATIVE QUESTIONS IN METAL/SOLUTION REACTIONS TO WHICH MÖSSBAUER SPECTROSCOPY SHOULD BE APPLIED

Eight problems in the field of metal/solution chemistry capable of attack by Mössbauer spectroscopy are outlined. These include : studies of corrosion beneath a coating ; chemical factors associated with the delamination of a coating during corrosion ; the chemical nature of the bond between steel and an organic coating ; the effect of cobalt on the corrosion of galvanized steel ; corrosion inhibition in aqueous solution ; the behavior of inhibitors in organic coatings ; the nature of the inhibition of corrosion by tin ions and the ion exchange properties of iron corrosion products.Huit problèmes concernant la chimie d'interface métal/solution, utilisant la spectroscopie Mössbauer, sont présentés. Ils comprennent des études de corrosion sous un recouvrement dont les propriétés chimiques sont associées à sa séparation en différentes couches durant la corrosion ; la nature chimique de la relation entre l'acier et un recouvrement organique ; l'effet du cobalt sur la corrosion de l'acier galvanisé ; l'inhibition de la corrosion en solution aqueuse ; le comportement des inhibiteurs dans les recouvrements organiques ; la nature de l'inhibition de la corrosion par l'étain sous forme d'ions et les propriétés de l'échange ionique des produits de la corrosion du fer

NACA Technical Notes

Note presenting a study of the chemical action of oils on large single crystals of metals in the presence of various gases, with special emphasis placed on the influence of crystal plane. The studies primarily have been concerned with four metals: silver, copper, lead, and iron and four types of oil: pure hydrocarbons with mineral oil as representative, oiliness agents with stearic acid as representative, chemical polishing agents with tricresyl phosphate as representative, and commercial oils with new and used aviation oils as representatives. The methods used in preparing large single crystals of various metals are briefly discussed