Corrosion pigments

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Etzrodt, G. (1993) Anti corrosion pigments. In Buxbaum, G. (ed.) Industrial inorganic pigments. VCH Weinheim, 186-206 Evanko, C.R. Dzombak, D.A. (1998) Influence of structural features on sorption of NOM-analogue organic acids to goethite. Environ. Sci.Techn. 32 2846-2855... 

Lead chromate pigments are mainly used as corrosion inhibitive pigments. These pigments are of low opacity and can be combined with higher opacity pigments for use in primers. Zinc chromate, also an anti-corrosion pigment, is used in metal pretreatments such as wash primer, which also promotes adhesion to aluminum and steel. 

Austin, M. J., Inorganic Anti-Corrosive Pigments, ASTM MANUAL 17, American Society for Testing and Materials, Philadelphia, USA, 1995, p. 238... 

Bravo, C. A., Non Toxic Ion-Exchange Anti-Corrosion Pigments, ABRAFATl Congress Proceedings, Sao Paulo, Brasil, 1995, p. 770... 

Liu, WM. 1998. Efficiency of Barrier-Effect and Inhibitive Anti-Corrosion Pigments in Primers. Mater. 

Zinc orthophosphate, Zn3(P04>2-41120 (Hopeite), forms the basis of an important group of dental cements and it is also used as an anti-corrosive pigment (Chapter 12.8). On heating, the tetrahy-drate loses water in two stages ... 

The salts FeH2P30io and CrH2P30io are formed in similar dehydration sequences, and the acid salts of all three metals exist in various isomorphous and polymorphic forms. Both CrH2P30io 2H2O and AIH2P3O10 2H2O find use in anti-corrosive pigment formulations. Both salts can form intercalation compounds (Chapter 12). 

Anti-corrosive pigments may be used in etch primer formulations (see above), or as components of the closely related anti-corrosive paints which are based on alkyd resins or other organic binders. Among the compounds used for the latter are [22]... 

Green CrP04 3H2O is a good long-term inhibitor and is usually employed in connection with other anti-corrosive pigments in order to overcome its poor immediate protective action. 

What are termed multiphase anti-corrosive pigments are based on mixtures of inorganic phosphates and sparingly soluble organic corrosion inhibitors. 

Two-pack etch primers usually contain an anti-corrosive pigment. In traditional formulations, zinc tetroxychromate was used. Current products, however, are mostly chromate-free, in response to environmental pressures. The zinc tetroxychromate has been replaced with a small amount of less toxic anti-corrosive pigments, such as zinc phosphate. Anticorrosive performance may be compromised, to a degree, by such substitutions. 

Primer prl-m9r (1819) n. First complete coat of paint of a painting system apphed to a surface. Such paints are designed to provide adequate adhesion to new surfaces and are formulated to meet the special requirements of the surfaces. The type of primer varies with the surface, it condition, and the total painting system to be used. Thus, primers for new wood and certain other surfaces must provide for exceptional absorption of the medium. Primers for steelwork contain special anti-corrosive pigments, such as red lead, zinc chromate, zinc powder, etc. A coating applied to a surface, prior to the application of an adhesive, to improve the performance of... 

Anti-corrosive action Inorganic All anti-corrosive pigments are inorganic... 

This resin will be partly neutralized with acetic or lactic acid, and co-emulsified with a blocked isocyanate cross-linker (p. 225). This type of resin is now the standard protective primer coating on the majority of the world s motor cars. Pigmentation will include anti-corrosive pigments. 

Ahmed Al-Dulaimi, Ahmed (2010). Evaluation of polyanUine composites and nanostructures as anti-corrosive pigments for carbon steel. Masters thesis, Universiti Teknologi Malaysia, Faculty of Chemical and Natural Resource Engineering. 

These are anti-corrosive pigments enhancers, anti-foams, anti-settling agent, anti-skidding agents, driers and preservatives, which are added in small amount to improve the properties of the paints. Examples of additives are calcite (CaCOs), quartz (SiOz) and kaolin clay (AbfOH) SuOio). A comparison of different types of coatings is shown in Table 7.10. 

Industrial coatings are usually applied to ferrous or non-ferrous metal surfaces. Exposed ferrous surfaces oxidize rapidly forming a non-protective oxide coating. Protective coatings are therefore usually based on primers containing a linseed oil or alkyd binder and anti-corrosion pigments such as red lead, lead chromate, zinc chromate, potassium zinc chromate, and zinc dust. The completed coating system will have a dry thickness of 5 to 10 mils. 

Yamamato, T. A Novel Anti-Corrosion Pigment Containing Vanadate/Phosphate, in Proc. Advances in Corrosion Protection by Organic Coatings, PV 8913, Pennington, NJ, The Eletrochem. Soc., 1989, 476. 

Unfortunately, most of the available information about anti-corrosive pigments, active pigments or self-healing pigments (all terms are synonymously used) cover only certain application conditions and practical examples for the use of the... 

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