Encapsulated corrosion inhibitors

Precaution Combustible corrosive to copper Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Uses Epoxy curing agent/hardener intermediate for pharmaceuticals, anthelmintics, surfactants, synthetic fibers, corrosion inhibitors, asphalt additives, emulsion breakers, emulsifiers, textile chems. used for civil engineering, coatings, adhesives, grouts, casting and elec, encapsulation corrosion inhibitor in petrol, prod. solvent Manuf./Distrib. Akzo Nobel http //www.akzonobel.com] Aldrich http //www.sigma-aldrich.com] Alfa Aesar http //www.alfa.com] Alkyl Amines Chems. Ltd http //www.alkylamines.com] BASF AG http //www.basf.de... 

Javierre E., Garda S.J., Mol J.M.C., Vermolen F.J., Vmk C., van der Zwaag S. (2012), TaUoiing the release of encapsulated corrosion inhibitors from damaged coatings controlled release kinetics by overlapping diffusion fronts . Prog. Org. Coat. 75,20-27. 

Uses Epoxy curing agent/hardener intermediate for pharmaceuticals, anthelmintics, surfactants, synthetic fibers, corrosion inhibitors, asphalt additives, emulsion breakers, emulsifiers, textile chems. used for civil engineering, coatings, adhesives, grouts, casting and elec, encapsulation corrosion inhibitor in petrol, prod. solvent Regulatory Canada DSL... 

The addition of various corrosion inhibitors to the epoxy encapsulant formulation to prevent corrosion was also evaluated (8). This procedure basically adds compounds or complexing agents to neutralize or "getter corrosion accelerating impurities or adds hydro-phobic agents to reduce the moisture permeation of the plastic. 

It appeared to us that if we could add aluminium corrosion inhibitors to the encapsulating resin it was possible that diffusing moisture would transport the inhibitor to the chip surface so that the aluminium conductors would experience an inhibited electrolyte rather than an agressive electrolyte and corrosion would thereby be reduced. It should be noted that this mechanism does not operate in the absence of diffusing moisture but that it is not needed in those circumstances because corrosion would not normally occur. For this approach to be successful the following conditions must be met ... 

While attempts have been made to mitigate corrosion of electronics by encapsulating the components in plastics, it is useful to note that polymers are permeable to moisture. Hermetically sealed ceramic packaging is more successful. However, care must be taken to prevent moisture and other contaminants from being sealed in. A useful common approach for mitigating corrosion of circuits housed inside a relatively large-size chassis includes the use of volatile corrosion inhibitors. 

Kartsonakis, 1., Daniilidis, 1., and Kordas, G. Encapsulation of the corrosion inhibitor 8-hydroxyquinoline into ceria nanocontainers. Journal of Sol-Gel Science and Technology, 48(1-2) 24-31 (2008). 

A number of factors have enabled the economies in cost possible with the use of plastic packaged devices to be realised. The development of new grades with freedom from the ionisable impurities that could result in corrosion problems when transported to the chip surface by water permeation, the incorporation of corrosion inhibitors, the careful selection of plastic material (to avoid thermal expansion mismatches with resulting stresses on the chips) and the reduction in life expectancy of current equipment due to the rapid rate of development and outdaring of equipment associated with the new silicon technology has now resulted in plastic encapsulated devices dominating the component field. 

Recently, encapsulation of benzotriazole [283], a corrosion inhibitor in silica-zirconia anticorrosion film on aluminum alloy substrates, has been reported. The benzotriazole could be slowly released from the hybrid film deposit on the substrate and provide long-term corrosion protection. This approach is especially attractive because the dissolution and redeposition of the benzotriazole is pH dependent and increases when local corrosion takes place. This type of self-healing material is likely to play an increasing role in futuristic active smart materials or corrosion protection as well as other applications. 

AhduUayev, E., Lvov, Y., 2010. Clay nanotuhes for corrosion inhibitor encapsulation release control with end stoppers. Journal of Materials Chemistry 20, 6681—6687. 

Khramov A.N., Voevodin N.N., Balbyshev V.N., Donley M.S. (2004), Hybrid otgano-ceramic corrosion protection coatings with encapsulated organic corrosion inhibitors . Thin Solid Films, 447-448, 549-557. 

Corrosion inhibitors are sold in solid or liquid form. Most solids are relatively pure, but sometimes a solid inhibitor is fused with another ingredient or encapsulated where a controlled rate of solubility is required. Liquids are usually preferred because of the ease with which they can be transported, measured, and dispersed. 

Abstract Nanomaterials such as polyelectrolytes, layered clays, sol-gel encapsulants and surface-modified nanoparticles can function as carriers of corrosion inhibitors. Carried in this way, the inhibitors can be released on demand, triggered by change in pH, ion exchange and change in oxidation state. This chapter gives an outline of such carriers with an emphasis on the surface-modified nanoparticle/nanostructure ofboehmites. Subsequently, the chapter provides a detailed account of self-assembled nanofihns on various surfaces such as nickel oxide, copper oxide and iron oxide and their effect on corrosion resistance. 

Various approaches to corrosion inhibitor immobilisation on different nano/ micro-particulated carriers have been discussed above. Another strategy is based on the use of different encapsulation techniques when a protective shell is created around a core containing inhibitor. 

The encapsulation of active healing agents for protective coatings has already been discussed in Section 2.2. A corrosion inhibitor can be encapsulated together with a polymerisable healing agent [12,13]. 

The addition of water soluble corrosion inhibitors to coating systems can be problematic due to the solubilisation of the inhibitors causing osmotic blistering. One approach is to coat inhibitors with a plasma-polymer surface to reduce the release rate of the encapsulated inhibitor. Yang and van Ooij [131] coated triazole particles with an inner layer of (hydrophobic) perfluorohexane plasma polymer and then an outer layer of pyrrole plasma polymer. The resultant particles were then dispersed into a water-based epoxy and it was shown that the release rate of the triazole had been significantly reduced and blistering was not observed. 

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