Metal dissolution process

Metal Dissolution Processes/Counter Electrode Reactions... 

While the subject of this chapter may seem counter to the title of the book, metal dissolution is vital in numerous aspects of metal deposition, counter electrode processes, pre-treatment protocols and electropolishing. This chapter outlines the current state of understanding of metal dissolution processes and discusses in some detail an electropolishing process that has now been commercialised using a Type III ionic liquid. 

This subchapter has shown that metal dissolution processes are important to numerous aspects of metal plating, however, very few concerted studies have been made in this area. An understanding of dissolution rates and processes, together with information on the stability of oxide films in ionic liquids, is essential for the development of successful metal finishing processes. 

Investigated examples include film formation on lead electrodes, various metal dissolution processes, redox electrochemistry of electrochromic films of IrOa [272] and various intrinsically conducting polymers [273-276]. A review covering experimental aspects and results pertaining to ion adsorption, hydride and oxide film formation and hydrophilicity of metals has been provided elsewhere as well as further reports [277-284],... 

Reaction (4) is of vital importance since the ions produced may enhance the metal dissolution process (Sect. 3.1.2.2.3). When oxidants, such as nitrogen dioxide or ozone, dissolve into the aqueous phase, the bisulfite ion oxidizes to bisulfate (HS04 ), for example,... 

Anodic Inhibitors Inhibitors that directly affect the anodic reaction, that is, the metal dissolution process, are termed anodic inhibitors. Addition of an anodic inhibitor to the corrosion system (dashed and dashed-dotted lines in Fig. 1) can either lower the rate (i.e. the exchange current density) of the anodic process... 

Important for the metal dissolution process are the hydrogen evolution, and the oxygen-reduction reaction as cathodic processes of the anodic corrosion reaction. 

Inhibitors which operate mainly on the metal dissolution process would include aromatic and aliphatic amines, various sulphur compounds and carbonyl molecules phosphorus, arsenic and antimony compounds have a greater effect on the hydrogen evolution reaction. Additions to the metal can have a similar effect for example phosphorus is added to some steels to inhibit H2 evolution. 

Landolt, D. (1987) "Experimental Study and Theoretical Modeling of Electrochemical Metal Dissolution Processes Involving a Shape Change of the Anode , 172nd Meeting of the Electrochemical Society, Honolulu, Abstract No. 544. 

The formation of corrosion products, the solubility of corrosion products in the surface electrolyte, and the formation of passive films affect the overall rate of the anodic metal dissolution process and cause deviations from simple rate equations. Passive films distinguish themselves from corrosion products, in the sense that these films tend to be more tightly adherent, are of lower thickness, and provide a higher degree of protection from corrosive attack. Atmospheric corrosive attack on a surface protected by a passive film tends to be of a localized nature. Surface pitting and stress corrosion cracking in aluminum and stainless alloys are examples of such attack. 

Multiple choice When a metal is corroding in a deaerated acidic solution, the equilibrium electrode potential for the metal dissolution process... 

EC-STM monitoring has been nsed to stndy the dissolntion of metal surfaces and the formation of passivating oxide films— both areas of critical importance to corrosion-related fields. Significant metal dissolution processes characterized with EC-STM using single-crystal snbstrates inclnde... 

However, generally speaking, even in the case of Li electrodes, intensive active metal dissolution processes lead to the breakdown and repair of the surface films. The non-uniformity of the surface films leads to non-uniform secondary current distribution, which leads to a very non-uniform electrochemical process. Hence, when metal is dissolved selectively at certain locations, the surface films are broken down and fresh active metal is exposed to solutions species, with which it reacts immediately (which leads to the "repair" of the surface films and increases further non-uniformity). The expected non-uniform structure of the surface films leads to the dendritic deposition of lithium in a large variety of electrolyte solutions, as illustrated in Figure If. 

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