Intrinsically corrosion protection mechanisms

Mechanism of Corrosion Protection by Intrinsically Conducting Polymers... 

This chapter provides an overview of the corrosion mechanisms of typical Mg alloys, most of which contain two or more phases. Magnesium (Mg) is a reactive metal and corrosion protection is an issue of importance [1] particularly for the automobile industry. The rapid increase in Mg use is due to its lightweight and good casting capabilities, particularly its ability to be diecast into large, thin sections. Typical examples are automobile seats, instrument panels, computer cases, etc. Reviews [1-4] and our early research [5-9] have indicated that the poor corrosion resistance of Mg alloys results from (a) the high intrinsic dissolution tendency of magnesium, which... 

Another potential application of Mg alloys is in the medical field where Mg alloys may be used as a biodegradable implant material. The biocompatibility of Mg was first known in the early twentieth century. However, the intrinsic rapid corrosion and hydrogen evolution phenomena associated with Mg forced researchers to give up the first clinical trials. Recently, a greater understanding of corrosion mechanisms and development of innovative corrosion protection techniques are reviving the research interest in biodegradable Mg alloys. 

The excellent properties of the diamond like materials combined with the low deposition temperature and high deposition rate, make these coatings very promising materials for the future. They have many potential applications as protective coatings for industrial products. Of course the properties of diamond like films never match those of diamond. The films are intrinsically smooth and amorphous, and can be used in coating applications where a plane, mechanically hard and wear/corrosion resistant surface is desirable. 

Figure 16.6 Galvanic coupling between iron disc (0.25 mm diameter) and PPy-coated iron ring (5 mm outer diameter) immersed in 0.1 M K2SO4 solution (pH 4). The gap between the disc and the ring is 75 pm. (Reprinted with permission from Journal of Electroanalytical Chemistry, Mechanism for protection of iron corrosion by an intrinsically electronic conducting polymer by T.D. Nguyen, T.A. Nguyen, M.C. Pham etai, 572, 2, 225-234. Copyright (2004) Elsevier Ltd)...

Nguyen, T.D., et al. 2004. Mechanism for protection of iron corrosion by an intrinsically electronic conducting polymer. / Electroanal Chem 572 (2) 225. 

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