Magnesium films

Gault and coworkers have used a specially constructed chamber interfaced to a mass spectrometer to examine the reactions of organic substrates with magnesium films ... 

An unsaturated compound in the course of its isomerization in magnesium-containing films performs two functions (i) it forms a catalyst when the Mg4 cluster is inserted into the activated C-H bond, and (ii) it acts as a reaction substrate. The stages of the synthesis of the catalyst and isomerization can be separated. For example, anthracenyltetramagnesium hydride can be preliminarily obtained in anthracene-magnesium films, and then it can be used as a catalyst. The introduction of this cluster compound into a solution of allylbenzene or methylindene at room temperature ensures high yields of multiple bond migration products. 

Electrodeposition and dissolution of magnesium film were studied from the ionic liquid of [BmimJBF with 1 MMgfCFjSOj) at room temperature by Nuli et al. [176, 177]. It was shown that magnesium can be electrodeposited on Ag substrate and the deposits were dense. They also smdied the electrochemical magnesium deposition and dissolution on metal substrates in organic electrolyte... 

Nuh Y, Yang J, Wang P (2006) Electrodeposition of magnesium film from bmimbf ionic liquids. Appl Surf Sci 252 8086-8090... 

Nitrile rubber/phenolic resin produces one of the most durable and toughest elastomeric materials developed in the adhesive industry. Further, its resistance to water as to organic solvents is excellent. For these reasons, the nitrile rubber/phenolic resin laminates are used in printed circuit board manufacturing, to bond metallic substrates between themselves (aluminium, steel) and to bond rubber to magnesium. Films of nitrile rubber/phenolic blends have also been used in the aircraft industry for bonding metal-to-metal surfaces in both plain and honeycomb sandwich constructions. 

NuLi, Y, Yang, J., and Wang, P. (2(X)6) Elecirodeposition of magnesium film from BM1MBF4 ionic liquid. Appl. Surf. Sci, 252, 8086-8090. 

Metallic magnesium and water [7732-18-5] react. Under normal atmospheric conditions or in pure or chloride-free water of high pH, the reaction is suppressed by the formation of an insoluble magnesium hydroxide [1309-42-8] film. 

If conditions aie such that the film does not form, such as in the case of acids, then the reaction proceeds until all the metal is consumed. The reaction of magnesium with hydrofluoric acid [7664-39-3J is an exception to this rule, because a stable fluoride film forms. 

The magnesium nitride [12057-71 -5] produced does not form a stable film. If sufficient nitrogen is present this reaction can be self-sustaining. The nitride produced can react with water to form ammonia [7664-41 -7]. 

In neutral and alkaline environments, the magnesium hydroxide product can form a surface film which offers considerable protection to the pure metal or its common alloys. Electron diffraction studies of the film formed ia humid air iadicate that it is amorphous, with the oxidation rate reported to be less than 0.01 /rni/yr. If the humidity level is sufficiently high, so that condensation occurs on the surface of the sample, the amorphous film is found to contain at least some crystalline magnesium hydroxide (bmcite). The crystalline magnesium hydroxide is also protective ia deionized water at room temperature. The aeration of the water has Httie or no measurable effect on the corrosion resistance. However, as the water temperature is iacreased to 100°C, the protective capacity of the film begias to erode, particularly ia the presence of certain cathodic contaminants ia either the metal or the water (121,122). 

Corrosion by Various Chemicals and Environments. In general, the rate of corrosion of magnesium ia aqueous solutions is strongly iafluenced by the hydrogen ion [12408-02-5] concentration or pH. In this respect, magnesium is considered to be opposite ia character to aluminum. Aluminum is resistant to weak acids but attacked by strong alkaUes, while magnesium is resistant to alkaUes but is attacked by acids that do not promote the formation of iasoluble films. 

Properties. Uranium metal is a dense, bright silvery, ductile, and malleable metal. Uranium is highly electropositive, resembling magnesium, and tarnishes rapidly on exposure to air. Even a poHshed surface becomes coated with a dark-colored oxide layer in a short time upon exposure to air. At elevated temperatures, uranium metal reacts with most common metals and refractories. Finely divided uranium reacts, even at room temperature, with all components of the atmosphere except the noble gases. The silvery luster of freshly cleaned uranium metal is rapidly converted first to a golden yellow, and then to a black oxide—nitride film within three to four days. Powdered uranium is usually pyrophoric, an important safety consideration in the machining of uranium parts. The corrosion characteristics of uranium have been discussed in detail (28). 

Group IIB ineludes Zn, Cd and Hg. Zine has some resemblanee to magnesium but the other metals in the group have little in eommon. At room temperature mereury is unaffeeted by air, water or non-oxidizing agents whereas zine is more reaetive, albeit tempered by a proteetive hydroxide film, a property utilized in galvanizing. 

CoiTosion prevention is achieved by correct choice of material of construction, by physical means (e.g. paints or metallic, porcelain, plastic or enamel linings or coatings) or by chemical means (e.g. alloying or coating). Some metals, e.g. aluminium, are rendered passive by the formation of an inert protective film. Alternatively a metal to be protected may be linked electrically to a more easily corroded metal, e.g. magnesium, to serve as a sacrificial anode. 

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