Metals industry oxygen corrosion

Oxygen corrosion only occurs on metal surfaces exposed to oxygenated waters. Many commonly used industrial alloys react with dissolved oxygen in water, forming a variety of oxides and hydroxides. However, alloys most seriously affected are cast irons, galvanized steel, and non-stainless steels. Attack occurs in locations where tuberculation also occurs (see Chap. 3). Often, oxygen corrosion is a precursor to tubercle development. 

To prevent the oxygen corrosion in tihe industrial boilers the feed wator is stripped by means of a steam in the so call i deaeration columns. For diis purpose usually special type of plate columns are used. To intensify the process, it was offered [2] to use the Holpack packing of horizontal expamted metal sheets, described in CDlmjptGur 3 ([3 21 >2 >3 X lis lii uid sup rficifll vdooit v3.s chosen equal to 120 m7(m h) (or 33.333 k s) based on experimental data which show that at this condition the maximal liquid superficial velocity is 140... 

Metal-reducing bacteria, such as those that convert ferric to ferrous ion, have been suggested as an accelerant for steel corrosion in oxygenated waters, lb date, evidence of these bacteria influencing corrosion in industrial systems is scarce. 

A clean, solid surface is actually an active center for adsorption from the surroundings (e.g., air or liquid). A perfectly cleaned metal surface, when exposed to air, will adsorb a single layer of oxygen or nitrogen (or water). Or, when a completely dry glass surface is exposed to air (with some moisture), the surface will adsorb a mono-layer of water. In other words, the solid surface is not as inert as it may seem to the naked eye. This has many consequences in industry, such as with corrosion control. Accordingly, solid surfaces should always be exposed to vacuum prior to any kind of adsorption studies. 

Titanium metal is very highly resistant to corrosion. It is unaffected by atmospheric air, moisture and sea water, allowing many of its industrial applications. The metal burns in air at about 1,200°C incandescently forming titanium dioxide Ti02. The metal also burns on contact with liquid oxygen. 

ANODIC OXIDATION. Oxidation is defined not only as reaction with oxygen, but as any chemical reaction attended by removal of electrons. Therefore, when current is applied to a pair of electrodes so as to make them anode and cathode, the former can act as a continuous remover of electrons and hence bring about oxidation (while the latter will favor reduction since it supplies electrons). This anodic oxidation is utilized in industry for various purposes, One of tire earliest to be discovered (H, Kolbe. 1849) was the production of hydrocarbons from aliphatic acids, or more commonly, from their alkali salts. Many other substances may be produced, on a laboratory scale or even, in some cases, on an economically sound production scale, by anodic oxidation. The process is also widely used to impart corrosion-resistant or decorative (colored) films to metal surfaces. For example, in the anodization or Eloxal process, the protection afforded by the oxide film ordinarily present on the surface of aluminum articles is considerably increased by building up this film by anodic oxidation. 

Another industrially important transition metal is titanium, which is used especially to make light but strong industrial parts, such as pipes and airplane propellers. When it is exposed to the air, titanium reacts with oxygen to form a thin layer of titanium dioxide, a compound of titanium and oxygen. The titanium dioxide protects the metal against corrosion, or the gradual breakdown... 

The electrodeposition of aluminum has enormous potential in industrial applications. The main reason for this is that aluminum reacts with oxygen to form dense layers of aluminum oxides, protecting metals from corrosion. By far most of the publications concerning the electrodeposition of metals from tetrachloroaluminate-based ionic liquids focus on aluminum. 

To illustrate the application of the method to the study of the oxidation of metals, some of our recent results on the oxidation of columbium and tantalum (30) will be described here. Their high melting points and their other valuable physical and chemical properties have made these metals useful to both science and industry. Chemically columbium and tantalum are resistant to corrosion by gases and liquids at room temperature. However, at temperatures of 250°C. and higher the metals react readily with oxygen and hydrogen. 

The first of the previous reactions is responsible for a good portion of the acid rain problem troubling the industrialized world. Sulfur, present in small quantities as an impurity in coal and oil, is converted to sulfur dioxide when the coal or oil is burned then the sulfur dioxide reacts with the moisture in the air to produce sulfurous acid. Sulfurous acid can react with the oxygen in air to produce sulfuric acid. These acids are washed from the air by rain (or snow), and the solution can cause some corrosion of concrete and metal in buildings. Acids in the air and in the rain or snow also injure trees and other plants, as well as animals, including humans. In high concentrations, acids and acid anhydrides in the air can make breathing difficult, especially for people who are already in poor health. 

When the sulfur content of the crude oil is low (usually less than one percent by weight), the crude oil is known as a sweet crude, while crude oil with higher concentrations of sulfur is called sour crude. Removal of sulfur and other impurities form part of the treating processes and sulfur itself can form a valuable by-product in a refinery as an input into the chemical industry. Other impurities include nitrogen, oxygen, and salt, as well as small quantities of metals such as vanadium and nickel that are common in certain of the heavier crude oils. As well as extraction processes to purify oil and its products of impurities, specific additives are also used to react with corrosive or odiferous constituents to produce harmless and odorless substances. Such processes are generally termed sweetening processes. 

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