Steels and copper

The most serious form of galvanic corrosion occurs in cooling systems that contain both copper and steel alloys. It results when dissolved copper plates onto a steel surface and induces rapid galvanic attack of the steel. The amount of dissolved copper required to produce this effect is small and the increased corrosion is difficult to inhibit once it occurs. A copper corrosion inhibitor is needed to prevent copper dissolution. 

Hirayaina et al. [22] have shown that polyhydrogenmethylsiloxane can bind to aluminum, copper and steel surfaces via activation with a suitable platinum complex. The attached polymer promotes the adhesion of silicone materials whose cure involves SiH/SiVinyl hydrosilylation. Presumably, it would also be effective with other unsaturated organic polymer phases. 

A tabulated form as in Table 19.3. This shows flows versus pipe length and diameter for both copper and steel. Such tables are included in British Gas lM/16 and British Standard BS 6891. Note that Table 19.3 includes allowances for elbows, tees and bends. Allowances, equivalent to numbers of pipe diameters, must be made for all pipe fittings, which cause an additional pressure loss. Further details for allowances to be made for pipefittings, including valves and nonreturn valves, are given in Table 19.4. 

Substantial quantities of aluminum, copper, and steel are reused as scrap. The challenge is to purify the scrap metal sufficiently to process it for reuse. There is opportunity for new processes that can remove unwanted elements—either alloyed or piece contaminants—more effectively and at lower cost than current processes. 

Plant 36030 enamels both copper and steel. It uses 0.042 m3 water/m2 product in all coating operations. Process wastewater flow is 0.466 m3/h for metal preparation and 1.69 m3/h for coating... 

The roller atomization process has been applied to the atomization of many metals and alloys, such as lead, tin, aluminum, copper and steel. The production rate is potentially high, and the energy requirement is much lower than in commercial gas and water... 

A good data fit is also obtained for copper. It confirms that the complex chloride deposition rate-rain regime is important for determining mass loss of copper and steel. In this model TOW-ISO has not been used and a good fitness has been obtained. 

A large number of structural materials were evaluated for possible attack by run-off from a sulfur-asphalt pavement. Of the ten materials studied, copper and steel appeared to indicate a vulnerability. The former or its alloys should never be used in equipment or structures which could bring them in contact with sulfur due to the high probability of producing the sulfates of copper. Steel reinforcing rods would be susceptible to attack by H SO produced by moisture on contact. 

Gasket materials are chosen primarily on the basis of their internal friction or extrusion resistance under pressure, compressibilities, thermal stabilities, chemical inertness, and ease of fabrication. Often several materials comprise the gaskets of a particular apparatus. Suitable materials include certain kinds of slightly porous natural stone (e.g., pyrophyllite, or various ceramic materials, and some metals such as copper and steel). Usually slippery or organic materials are unsatisfactory because they tend to fail catastrophically in shear and thereby allow violent extrusion of the gasket and part of the chamber contents. 

Anodization is also important for titanium, copper, and steel and in the fabrication of electrolytic and non-electrolytic capacitors from aluminium, niobium, and tantalum. 

An interesting exercise is to try to generate Evans diagrams for the copper and steel (mostly Fe) from theoretical data (i.e., reversible potentials, exchange current densities, Tafel slopes, expected limiting currents, etc.) and compare to the experimental data obtained. 

Figure 5 Sample polarization curves for copper and steel samples.

Platinum is attacked only slowly by fluorine. Copper and steel can be used as containers lor the gas they are attacked by it, but become coated with a thin layer of copper fluoride or iron fluoride which then protects them against further attack. Fluorine was first made in 1886 by the French chemist Henri Moissan (1852-1907), by the electrolysis of a solution of potassium fluoride, KF, m liquid hydrogen fluoride, HF. In recent years methods for its commercial production and transport (in steel tanks) have been developed, and it is now used in chemical industry in moderate quantities. 

Properties Colorless solid. D 1.48, mp 20C, bp 167C (10 mm Hg). Slightly soluble in benzene almost insoluble in other organic solvents. Attacks iron, copper, and steel. 

NO in combination with SOp has a synergistic corrosion effect especially indoors on electrical contact materials, copper and steel. The influence of acid precipitation may differ for different metals and depends also on the pollution level. The atmospheric corrosion of metals due to acid deposition is in most regions mainly a local problem restricted to areas close to the pollution source. 

ILs as lubricants exhibit generally good tribological properties, not only for steel/ steel contacts but also for steel/aluminum, steel/copper, and steel/SiOj, among others. 

A variety of bench tests exist which attempt to evaluate the oxidative stability and/or the corrosion protection of a particular formulation. These invariably involve subjecting a coupon of one or more metals (chiefly copper and steel) to wet conditions for a fixed period at an elevated temperature. The assessment is carried out on the basis of weight loss and surface discolouration of the coupon. 

Cobratec . [PMC Specialdes] Benzo-triazoles and tolyltriazoles chelating agent and sequestrant copper and steel corrosion inhibita metalworking fluids. 

Table 1.1 illustrates the growth in production of polymers compared with the static state of production of some important metals. When it is remembered that aluminium has a density roughly twice, and copper and steel have densities of order six times, those of even the denser polymeric materials, table 1.1 also illustrates that the volume production of some of the commoner polymers roughly equals or exceeds that of aluminium and copper, and that the total volume production of all the polymers listed is about 60% of the volume production of steel. 

Anodizing is the process of forming a surface oxide film by electrochemical oxidation. It is used as a surface finishing technique particularly for aluminium but also for titanium, copper and steel, and for the manufacture of electrolytic capacitors based on aluminium, tantalum and niobium. 

Table 12.2 Corrosion potentials of substrates of copper and steel, plated and unplated in same plating solutions. Deposition potential is accompanied by current density (A/m ) in parentheses the plated substrate s coating thickness was 2 5 ftm. The final column gives the potential below which hydrogen evolution is possible only in the cuprocyanide is it observed...

Copper is extremely resistant to atmospheric corrosion as it rapidly forms a complex green hydrated copper(I) oxide/carbonate film that prevents further corrosion. Copper is very suitable for underground services as it is extremely resistant to attack. Corrosion troubles occur when copper and steel pipes are joined together, because copper induces corrosion in steel objects joined to it by electrochemical action. 

Carbon dioxide is often ignored in steam systems. However, when absorbed in water, it forms carbonic acid, which can be corrosive to all parts of the steam and condensate system. Its potential presence is frequently overlooked in the design of heat exchangers, steam traps, condensate systems, deaerators, and water-treating systems. Most steam systems require continual addition of makeup water to replace losses. Makeup water must be adequately treated, by demineralization or distillation, to remove carbonates and bicarbonates. If these are not removed, they can be thermally decomposed to carbon dioxide gas and carbonate and hydroxide ions. The ions will normally remain in the boiler water, but the caron dioxide will pass off with the steam as a gas. When the steam is condensed, the carbon dioxide will accumulate since is is noncondensable) be passed as a gas by the steam trap or if the condensate and carbon dioxide are not freely passed by the steam trap, become dissolved in the condensate and form carbonic acid. If carbonic acid is formed it can have a pH approaching 4 and be very corrosive to copper and steel. Even if both the gas and condensate are passed freely by the steam trap, the gas will become soluble in the condensate when subcooling occurs. If oxygen is present, the corrosion rate Is accelerated. 

Fig. 2.12 Atmospheric corrosion rate of zinc, copper, and steel related pollution in rainwater precipitation rain average, I m year duration of 0.25-0.32 pH values of rain on small surfaces (Van Eijnsbergen).

Grabener, K.-H. Melting and recycling of contaminated (a, p and y) aluminium, copper and steel. Proc. CEC 3. Internat. Conf. on Decommissioning of Nuclear Installations, Luxembourg, 1994, p. 433 -445... 

Schwartz and co-workers [52, 63] applied a silica layer on the inner surfaces of polymeric, copper, and steel capillaries of 4-400 m length and =0.5 mm inside diameter. The authors [62] ran into difficulties in using a suspension containing micron-size particles and therefore they decided in favor of true colloidal silica solutions. They used [52] 22% silica sol in [water-2-propanol] system commercially available under the trade mark Nal-coag 1092. Such colloidal silica sols are produced for preparing adsorption and antistatic impregnated systems. They have a low viscosity and therefore can readily pass through a capillary to form a thin... 

---