Corrosion alloys

Sulfides are directly aggressive to many metals. In particular, copper alloy corrosion is severe (Fig. 4.20). Sulfides are easily detected in the... 

Corrosion of industrial alloys in alkaline waters is not as common or as severe as attack associated with acidic conditions. Caustic solutions produce little corrosion on steel, stainless steel, cast iron, nickel, and nickel alloys under most cooling water conditions. Ammonia produces wastage and cracking mainly on copper and copper alloys. Most other alloys are not attacked at cooling water temperatures. This is at least in part explained by inherent alloy corrosion behavior and the interaction of specific ions on the metal surface. Further, many dissolved minerals have normal pH solubility and thus deposit at faster rates when pH increases. Precipitated minerals such as phosphates, carbonates, and silicates, for example, tend to reduce corrosion on many alloys. 

Copper-alloy corrosion behavior depends on the alloying elements added. Alloying copper with zinc increases corrosion rates in caustic solutions whereas nickel additions decrease corrosion rates. Silicon bronzes containing between 95% and 98% copper have corrosion rates as low as 2 mil/y (0.051 mm/y) at 140°F (60°C) in 30% caustic solutions. Figure 8.2 shows the corrosion rate in a 50% caustic soda evaporator as a function of nickel content. As is obvious, the corrosion rate falls to even lower values as nickel concentration increases. Caustic solutions attack zinc brasses at rates of 2 to 20 mil/y (0.051 to 0.51 mm/y). 

Haynie, F. H. and Ketcham, S. J., Electrochemical Behaviour of A1 Alloys Susceptible to Intergranular Corrosion. Electrode Kinetics of Oxide-covered Al , Corrosion, 19,403t (1963) Ketcham, S. J. and Haynie, F. H., Electrochemical Behaviour of Al Alloys Susceptible to Intergranular Corrosion. Effect of Cooling Rate on Structure and Electrochemical Behaviour in 202A Al Alloy , Corrosion, 19, 242t (1963)... 

Streicher, M. A., Relationship of Heat Treatment and Microstructure to Corrosion Resistance in Wrought Ni-Cr-Mo Alloys , Corrosion, 19, 272t (1963)... 

Coriou, M., Grail, L, Mahieu, C. and Pelas, M., Sensitivity to Stress Corrosion and Intergranular Attack of High-nickel Austenitic Alloys , Corrosion, 22, 280 (1966)... 

Pakhomova, N. A. and Levin, I. A., Effect of Grain Size on the Inter-crystalline Corrosion of Stainless Steel Type 18-8 , Zashch. Metal, 9, 676 (1973) C.A., 80, 86207j Brown, M. H. and Kirchner, R. W., Corrosion of High Alloy Weldments 1. Sensitisation of Wrought High Nickel Alloys , Corrosion, 29, 470 (1973)... 

Hultquist, G. and Her0, H. Surface Enoblement by Dissolution of Cu, Ag and Zn from Single Phase Gold Alloys , Corrosion Science, 24, 789-805 (1984)... 

Compared with ferritic carbon and low-alloy steels, relatively little information is available in the literature concerning stainless steels or nickel-base alloys. From the preceding section concerning low-alloy steels in high temperature aqueous environments, where environmental effects depend critically on water chemistry and dissolution and repassivation kinetics when protective oxide films are ruptured, it can be anticipated that this factor would be of even more importance for more highly alloyed corrosion-resistant materials. 

Locomotive diesels As larger volumes of coolant are required in railway locomotives than in road vehicles, the cost of inhibition is proportionally greater. An additional factor is the possibility of cavitation attack of cylinder liners. These considerations place a restriction on the choice of inhibitors. In the past, chromates have been used at concentrations of up to 0-4%, but their use presents handling and disposal problems. Chromates cannot be used with ethanediol antifreeze solutions. A IS I borate-metasilicate at a concentration of 1 % has been used in the UK. Nitrate is added to this to improve inhibition of aluminium alloy corrosion. Tannins and soluble oils are also used, but probably to a lesser extent than in the past. The benzoate-nitrite formulation (formerly BS 3151) is effective and has been used by continental railways . ... 

Corrosion of metals and alloys. Corrosivity of atmospheres. Methods of measurement of pollution... 

These alloy corrosion products usually originate in the pre-boiler section but deposit in the boiler at points of low flow, such as just beyond bends... 

In certain direct steam-contact process applications (such as in food and beverage processing or pharmaceutical preparations) the use of amine-based products in steam and condensate systems is subject to legal restrictions. Also, the use of ammonia or amines may be dependent on the materials of construction employed or technical limitations (such as the risk of copper alloy corrosion). 

High performance sealants, 22 28 High phosphorus alloys, corrosion performance of, 9 710-711 High pinning Type II superconductors, 23 High pressure apparatus, 13 413 High pressure applications, 13 436-448 in commercial products, 13 436-438 in inorganic chemistry reactions, 13 440—448... 

Asami, K. Hashimoto, K. Shimodaira, S. (1978) XPS determination of composition of alloy surfaces and surface oxides on mechanically polished iron chromium alloys. Corrosion Sci. 18 713-723... 

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