Tailoring the release of encapsulated corrosion inhibitors from damaged coatings: Controlled release kinetics by overlapping diffusion fronts

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• 作者：E. Javierre^a ; ^b ; ^{etelvina.javierre@unizar.es} ; S.J. Garcí ; a^c ; J.M.C. Mol^d ; F.J. Vermolen^e ; C. Vuik^e ; S. van der Zwaag^c
• 关键词：Pigment release ; Corrosion inhibition ; Fickian ; Non-Fickian ; Leaching ; Organic coating ; Mathematical modelling
• 刊名：Progress in Organic Coatings
• 出版年：2012
• 期刊代码：70_03009440
• 类别：ce
• 出版时间：September-October, 2012
• 卷：75
• 期：1-2
• 页码：20-27
• 文件大小：985 K

摘要

The goal of this work is to model the release of corrosion inhibitors from damaged organic coatings. In the present study, the healing response (i.e. the active corrosion protection) is triggered by the ingress of moisture in the coating through the walls of a damaged site, followed by the transport of the corrosion inhibitors to the exposed metal substrate by diffusion through the moisture present in the polymeric coating. We propose a mathematical-analytical model for each step of the healing response in order to determine, through computer simulation, the particle configurations that lead to desired regimes of inhibitors release into the damaged site. The used methodology is based on overlapping Fickian leaching kinetics of the individual corrosion inhibitor particles present in the coating. With the proposed model we analyze different release behaviors proportional to t^伪 with 0.25 < 伪 鈮?#xA0;1 reported in the literature. We study in detail the conditions yielding a linear release of corrosion inhibitors and determine the range of release rates that can be achieved as a function of the particle size distribution within the coating, the moisture diffusion through the coating and the capsule dissolution kinetics. In particular, we clearly demarcate the systems in which the linear release behavior cannot be obtained. Furthermore, we find that our model cannot predict the experimentally observed t^0.25 kinetics for any configuration and condition considered, which indicates that the release of inhibitor compounds from particle dissolution in these systems may not follow a Fickian behavior.