Steel, corrosion protection

Corrosion Protection of Iron and Steel Corrosion Protection of Aluminum and Its Alloys Corrosion Protection of Other Metals... 

Atik M, Luna F, Messaddeq S, Aegerler M (1997) Ormocer (Zr02-PMMA) films for stainless steel corrosion protection. J Sol Gel Sci Technol 8(l-3) 517-522... 

Monitors potential copper corrosion reducing steel corrosion protection if concentration >0.1 mg/L. Monitors potential copper corrosion. Acceptable level <0.05 mg/L. 

Hosseini M.G., Sabouri, M., Shahrabi, T. ( 2006). Comparison between polyaniline -phosphate and polypyrrole- phosphate composite coatings for mild steel corrosion protection, Material and Corrosion, Vol. 57, pp. 447 - 453, ISSN 0947-5117... 

Atik M., Luna F. R, Messaddeq S. H. and Aegerter M. A. (1997), Ormocer (Zr02 -PMMA) Films for Stainless Steel Corrosion Protection , J. Sol-Gel Sci. TechnoL, 8, 517-22. 

The corrosion rate of steel in carbonic acid is faster than in hydrochloric acid Correlations are available to predict the rate of steel corrosion for different partial pressures of CO2 and different temperatures. At high temperatures the iron carbonate forms a film of protective scale on the steel s surface, but this is easily washed away at lower temperatures (again a corrosion nomogram is available to predict the impact of the scale on the corrosion rate at various CO2 partial pressures and temperatures). 

It is reported that mild carbon steels may be effectively protected by as little as 55 ppm of KTc04 in aerated distilled water at temperatures up to 250oC. This corrosion protection is limited to closed systems, since technetium is radioative and must be confined. 9sTc has a specific activity of 6.2 X lOs Bq/g. Activity of this level must not be allowed to spread. 99Tc is a contamination hazard and should be handled in a glove box. 

Fiber-reiaforced panels covered with PVF have been used for greenhouses. Transparent PVF film is used as the cover for flat-plate solar collectors (114) and photovoltaic cells (qv) (115). White PVF pigmented film is used as the bottom surface of photovoltaic cells. Nonadhering film is used as a release sheet ia plastics processiag, particularly ia high temperature pressing of epoxy resias for circuit boards (116—118) and aerospace parts. Dispersions of PVF are coated on the exterior of steel hydrauHc brake tubes and fuel lines for corrosion protection. 

A similar coating, containing 4 wt % tin, is appUed to copper sheet and is used primarily for huilding flashings. Other lead—tin aUoys, usuaUy with 50 wt % tin, ate appUed as coatings to steel and copper electronic components for corrosion protection, appearance, and ease of soldering. Lead—tin aUoys can... 

Under severe conditions and at high temperatures, noble metal films may fail by oxidation of the substrate base metal through pores in the film. Improved life may be achieved by first imposing a harder noble metal film, eg, rhodium or platinum—iridium, on the substrate metal. For maximum adhesion, the metal of the intermediate film should ahoy both with the substrate metal and the soft noble-metal lubricating film. This sometimes requires more than one intermediate layer. For example, silver does not ahoy to steel and tends to lack adhesion. A flash of hard nickel bonds weh to the steel but the nickel tends to oxidize and should be coated with rhodium before applying shver of 1—5 p.m thickness. This triplex film then provides better adhesion and gready increased corrosion protection. 

Boiler Water Treatment. Alkanolamines, in general, provide excellent corrosion protection to steel in many appHcations. When used in boiler water treatment, AMP provides excellent protection to steel and copper in steam lines through efficient absorption of CO2, effectual distribution ratio for... 

Feedwater treatment is designed to protect the feedwater system and, to some extent, the boiler. Most systems contain carbon steel piping. Carbon steel corrosion (Fig. 23a) is considerably slower at a pH between 9.0 and 11.0. In aH-ferrous feedwater systems, the preferred pH range is therefore 9.2 to 9.6, although some systems are operated at a pH as high as 10. In systems where copper alloys are present, high concentrations of ammonia accelerate corrosion of the copper alloys. In those systems the preferred pH is 8.8—9.2. 

Galvanic corrosion can be controlled by the use of sacrificial anodes. This is a common method of controlling corrosion in heat exchangers with Admiralty tube bundles and carbon steel tube sheets and channel heads. The anodes are bolted direcdy to the steel and protect a limited area around the anode. Proper placement of sacrificial anodes is a precise science. 

A range of acetoacetylated lesins has been intioduced (68,69). The acetoacetoxy functionahty can be cioss-linked with melamine—formaldehyde resins, isocyanates, polyacrylates, and polyamines. There is particular interest for possible corrosion protection on steel because the acetoacetoxy group can form coordination compounds (qv) with iron, perhaps enhancing the adhesion to steel surfaces (see Chelating agents). 

An important function of many coatings is to protect metals, especially steel, against corrosion. Corrosion protection is required ia two different situations ia one case, the steel is protected against corrosion with iatact coating films ia the other case, the objective is to protect the steel against corrosion even when the film has been mptured. 

The second class of anodic inhibitors contains ions which need oxygen to passivate a metal. Tungstate and molybdate, for example, requke the presence of oxygen to passivate a steel. The concentration of the anodic inhibitor is critical for corrosion protection. Insufficient concentrations can lead to pitting corrosion or an increase in the corrosion rate. The use of anodic inhibitors is more difficult at higher salt concentrations, higher temperatures, lower pH values, and in some cases, at lower oxygen concentrations (37). 

Cadmium, being anodic to steel, behaves quite similarly to zinc in providing corrosion protection when apphea as a coating on steel. Tests of zinc and cadmium coatings should be conducted when it becomes necessaiy to determine the most economical selection for a particular environment. 

When alloy steels do not give adequate corrosion protection— particularly from sulfidic attack—steel with an aluminized surface coating can be used. A spray coating of aluminum on a steel is not likely to spall or flake, but the coating is usually not continuous and... 

Acidic pH helps break down protective oxides on stainless steels. Corrosion usually develops faster and is more severe as pH decreases. At very low pH, however, attack inside crevices may be no more severe than on regions outside the crevice. 

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