Contact corrosion buildings

Niimberger, U. (1986). Corrosion behavior of galvanized steel in contact with building materials. Werkst. Korros., 37, 302-309 (in German). 

The two main uses for gold are in settling international debts and in the manufacture of jewellery, but other important uses are in dentistry, the electronics industry (corrosion-free contacts), and the aerospace industry (brazing alloys and heat reflection), while in office buildings it has... 

Common packaging materials are a potential source of aggressive substance s, and careful selection is recommended to avoid surface deterioration. Where paper is in contact with aluminium, the chloride content should be below 0-05 7o, sulphate content below 0-25 7o, copper content below 0-01% and the pH of aqueous extracts in the range pH 5-5-7-5, in order to avoid corrosion in damp conditions. Papers and felts used in building applications should also conform to this specification as a minimum requirement and be of the highest quality, since metallic copper found in materials of inferior origin can result in severe local galvanic attack of aluminium. 

Where the component is wholly or partly embedded in other building materials, the growth of corrosion products on the face of the metal may cause distortion or cracking of these materials trouble may also arise when the metal is in contact with, although not embedded in, other building materials. 

Many details in building construction may permit rain water to enter and this may be retained in crevices in metal surfaces, or between a metallic and some other surface. Water may drip on to metal surfaces. These conditions, which can involve a greater risk of corrosion than exists where a metal is exposed to the normal action of the weather, are more severe when the water contains dissolved acids, alkalis or salts derived from the atmosphere or from materials with which the water comes into contact. Normal supply waters can also cause corrosion. 

Partial blocking effect was first identified for pure iron in contact with aerated sulphuric acid medium [55]. Corrosion of carbon steel in sodium chloride media clearly showed the porous layer effect (see Section 5.2) [74]. The same effect was found for zinc corrosion in sodium sulphate [75] and the properties of the layer which was demonstrated to be formed of an oxide/hydroxide mixture were further used for building a general kinetic model of anodic dissolution [76], usable for measurement of the corrosion rate from impedance data. 

A problem of obtaining zirconium with lowest possible contents of hafnium comes from construction requirements when using zirconium and its alloys in building nuclear reactors. The construction material must have good mechanical properties and must be resistant to corrosion in contact with heat carriers. Since reactor power is proportional to the quantity of neutrons, their absorption into construction materials should be as small as possible. Zirconium and its alloys are unique materials that satisfy these requirements. However, hafnium has approximately the same chemical characteristics as zirconium but it absorbs neutrons strongly. 

For similar reasons, it is desirable to build process systems out of the same materials. In systems where contact of dissimilar metals cannot be avoided, it is helpful to have the less noble material possess the largest surface area. By doing so, the corrosion current that is generated is distributed over a much greater area and slows the overall rate of penetration. In many such systems, it is also possible to electrically insulate one alloy network from the other. 

Obviously when we deliberately add sulfuric acid to cooling water, we reduce alkalinity and also depress pH. This increases corrosivity of the circulating water, which is saturated with dissolved oxygen, contacts many dissimilar metals, and is elevated in temperature. In the process of acidification to prevent scale deposition so heat transfer equipment will function efficiently, we knowingly build in added corrosion factors and increase corrosion control difficulty. Now we need to find corrosion inhibitor combinations which will be practical for use in industrial systems can be tolerated from the viewpoints of toxicity and pollution controls and will effectively protect these multimetal circuits during their normal service life of 20 to 30 years. 

J. A. Gonzales, An initial effort to use the corrosion rate measurements for estimating rebar durability . Symposium on Corrosion Rate of Reinforcement in Concrete, ASTM, Baltimore, USA, 29, 1988. CEB, Durable Concrete Structures, Bulletin d information No.183,1992. U. Ntirnberger, Corrosion of metals in contact with mineral building materials , European Federation of Corrosion, Riva del Garda,... 

The development and building of large concrete structures for offshore oil and gas production in the 1970s called for increased attention to corrosion of steel reinforcement, and of seawater-exposed steel parts in metallic contact with the reinforcement. Research projects were estabhshed at various laboratories, e.g. as dealt with in References [8.20, 8.21]. 

Wood is usually used as a building material and not as a cladding of metallic materials however, sometime wood parts are used in contact with metallic materials, for storage and packaging, and furthermore, metallic components are used as joints for wood parts. Wood contains ceUnlose, hani-cellulose, lignin, and water in equilibrium with atmospheric humidity, and also complex substances such as acetylated polysaccharides. Some of these substances, by hydrolysis, generate acetic acid, and others release formic acid, propionic acid, and butyric acid, all volatile substances that can dramatically affect the behavior of the atmosphere, especially in indoor environments. On one hand, wood contains tannins, which combine with the metals and may give rise to protective corrosion... 

---