Bright metal surfaces

The corrosion behavior of plutonium metal has been summarized (60,61). a-Plutonium oxidizes very slowly in dry air, typically <10 mm/yr. The rate is accelerated by water vapor. Thus, a bright metal surface tarnishes rapidly in normal environments and a powdery surface soon forms. Eventually green PUO2 [12059-95-9] covers the surface. Plutonium is similar to uranium with respect to corrosion characteristics. The stabilization of 5-Pu confers substantial corrosion resistance to Pu in the same way that stabilization of y-U yields a more corrosion-resistant metal. The reaction of Pu metal with Hquid water produces both oxides and oxide-hydrides (62). The reaction with water vapor above 100°C also produces oxides and hydride (63). 

On introducing 15 cc. of ether into a dry, glass-stoppered flask with a freshly-cut piece of sodium the size of a pea, only a very slight evolution of gas should take place, and the bright metallic surfaces of the sodium should not completely lose their luster within six hours. 

Nanostructural Analysis of Bright Metal Surfaces in Relation to their Reflectivities... 

Figure 38. Schematic presentation of the different metal surfaces a) mirror bright metal surfaces, b) semi-bright metal surfaces, c) a surface which would show a small degree of mirror reflection. (Reprinted from Ref.12 with permission from Elsevier.)...

Finally, the different preferred orientations of copper coatings, as well as the copper surface polished both mechanically and electrochemically, which are characterized as mirror bright metal surfaces, clearly indicate that mirror brightness of a surface is not associated with a preferred orientation. Also, the preferred orientations of the copper coatings did not depend on type of electrodes used.21... 

A materials - science aspect of metal electrodes is treated in chapter 5, by Nicolid and RadoCevid Nanostructural Analysis of Bright Metal Surfaces in Relation to Their Reflectivity. This is an area of practical importance in electrochemistry applied, e.g., to metal finishing. Details of how reflectivity and electron microscopy can be usefully applied in this field are given with reference to many examples. 

The reaction between iron and oxygen tends to be relatively slow, but other metals, such as the alkali and alkaline earth metals, react quickly upon exposure to air. FIGURE 4.12 shows how the bright metallic surface of calcium tarnishes as CaO forms in the reaction... 

In recent years, plastics have been used to replace some metal products. They have lighter weight, low corrosion, and are electrically non-conductive. Plastics are easy to color and offer design flexibility. Metal components have been replaced by amorphous plastics like polyvinyl chloride and by crystalline plastics such as polypropylene and polyethylene [12]. Processes for plating on plastics to give a bright metallic surface (example automobile grill) have been developed too. 

The reflection of light from a silver mirror surface is mostly mirror reflection and the degree of diffuse reflection is very small (up to 2 %). The degree of mirror reflection from this surface is also very close to the ideal reflectance of silver [87,91,92], The silver mirror surface consists of parts parallel to the base and flat on the atomic level with low-step heights between them, as is shown in Fig. 2.28. It is clear that bright metal surfaces must be similar to the surface of the mirror. 

Nikolid ND, Rakocevlc Z, Popov KI (2005) Nanostmctural analysis of bright metal surfaces in relation to their reflectivities. In Conway BE, Vayenas CG, White RE, Gamboa-Adelco M (eds) Modem aspects of electrochemistry, vol 38. Kluwer Academic/Plenum Publishers, New York, pp 425 74... 

The term oxidation is used because the first reactions of this sort to be studied thoroughly were reactions with oxygen. Many metals react directly wifli O2 in air to form metal oxides. In these reactions the metal loses electrons to oxygen, forming an ionic compound of the metal ion and oxide ion. For example, when calcium metal is exposed to air, the bright metallic surface of the metal tarnishes as CaO forms ... 

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