51315-5554-New Coatings for Corrosion Protection Using Nanoparticles or Nanocapsules

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Product Number: 51315-5554-SG

ISBN: 5554 2015 CP

Author: Wolfram Fuerbeth

Publication Date: 2015

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In recent years coatings based on nanotechnological methods have gained increasing importance. Nanoparticles from sol-gel systems or from commercial dispersions as well as different kinds of nanocapsules may be used to produce new coating systems or to increase the corrosion protective properties of conventional coating systems. In this paper an overview of different ways of using nanoparticles for the production or modification of coating systems on metals as followed in the author's research group will shortly be shown.On the one hand nanoparticles may be used as a coating material to obtain inorganic coatings at moderate treatment temperatures due to the high sintering activity of nanoparticles. Such coatings have been obtained on magnesium alloys using different strategies however a sufficient densification of the coating turned out difficult at low temperatures. On the other hand a combination of nanoparticulate layers with a chemical conversion treatment lead to quite promising results. Moreover nanoparticle-based glass-like coatings may also be used to avoid the intense oxidation of steels during a hot-stamping process.Furthermore nanoparticles can be incorporated into conventional coating systems in order to modify their properties. This has been investigated especially for anodising layers on Al and Mg alloys. For Al a modified phosphoric acid anodising process has been developed including an impregnation step in a nanoparticle dispersion thus leading to a sufficient corrosion protection as well as good adhesion properties.On Mg alloys new inorganic coatings have been developed that are based on the anodising at comparably low voltages in an alkaline bath. In parallel to the oxide growth mesoporous nanoparticles can be deposited electrophoretically to be incorporated into the oxide layer. After a suitable surface modification these particles may be loaded by rare earth metal cations as corrosion inhibitors in order to provide self-healing properties of the coating system.