Inorganic salts, aqueous corrosion

The Mechanism of Corrosion.—An attractive theory of the mechanism of corrosion has been outlined by Aitchison.2 Compact iron, when examined under the microscope (see Part III.), is seen to consist of crystals of ferrite separated from each other by an amorphous cement. It is reasonable to suppose that the solution pressure of this cement differs from that of the ferrite, for differences of this kind invariably occur between amorphous and crystalline varieties of substances. Upon immersion in an electrolyte, therefore, such as ordinary tap water or aqueous solutions of inorganic salts, a difference of potential exists leading to corrosion. If the cement is positive to the ferrite, it is the cement that will oxidise away and vice versa. In a perfectly annealed specimen, in which there is but little mechanical strain, the action will, in the main, be confined to that between the cement and ferrite. If, however, there is any appreciable potential difference between the crystals of ferrite themselves, this will increase the effect, the total observed corrosion being the sum of the two actions. 

An interesting case arises when iron is immersed in alkaline solutions containing inorganic salts. For example, iron will remain bright in a 1 per cent, solution of caustic potash for an indefinite time, but upon addition of potassium chloride corrosion readily takes place. It is possible, however, to increase the alkali to such an extent that corrosion is entirely prevented, no matter how concentrated the solution of chloride. The minimum amount of alkali required rises with the percentage of chloride until saturation of the latter is arrived at. This is indicated in fig. 4. AK represents the solubility curve of potassium chloride in aqueous solutions of potassium hydroxide, and CE the maximum concentration of the chloride that may be present in the... 

Brines designate liquids used as heat transport agents between a remote heat source and the refrigeration systems. Salt brines are water solutions of inorganic salts. For example, NaCl solutions could be used down to -10 °C, but these are corrosive. Instead aqueous CaClz solutions (concentration of maximum 25%) are preferable down to -20 °C. Salt brines have low purchase cost but are expensive in operation. Antifreezes described below are preferable. 

Mineral-Salt Medium A corrosive medium such as aqueous solution, containing mineral or inorganic salt such as sodium chloride (NaCl). Used in material testing, especially of anticorrosive properties. 

Post-combustion capture using chemical absorption by aqueous alkaline amine solutions has been used for C02 and H2S removal from gas-treating plants for decades [6]. Amines react rapidly, selectively and reversibly with C02 and can be applied at low C02 partial pressure conditions. Amines are volatile, cheap and safe in handling. They show several disadvantages as they are also corrosive and require the use of resistant materials. Furthermore, amines form stable salts in the presence of O2, SOx and other impurities such as particles, HC1, HF and organic and inorganic Fig trace compounds that extremely constrain the content of those compounds in the treated gas. 

SULFURIC ACID, ALUMINUM SALT (10043-01-3) A1j(S04)3 Noncombustible solid. Forms sulfuric acid with water. Aqueous solution has a violent reaction with bases, amines, amides, inorganic hydroxides, and many other materials. See also sulfuric acid. Dry material is weakly corrosive to carbon steel aqueous solution attacks... 

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