Coating System for Magnesium Diecastings in Class A Surface Quality

Gadow, Rainer; Gammel, F.; Lehnert, F.; Scherer, D.; Skar, Jan Ivar

doi:10.1002/3527607552.ch78

Cited by 7 publications

(1 citation statement)

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“…Commonly, the protective coatings applied on the automotive [17] and aeronautics [18] industries consists of a series of superposed layers of different chemical nature, which typically consists of a chemical/anodic conversion layer, an adhesion primer and an organic paint or finishing. Many surface treatments for magnesium alloys including a sol-gel coating have been studied in combination with conversion layers [19,20], anodic coatings [21,22] or even multilayered sol-gel coatings [23][24][25], in order to provide a complex "architecture" to the protective anticorrosion system.…”

Section: Introductionmentioning

confidence: 99%

Architectural optimization of an epoxy-based hybrid sol–gel coating for the corrosion protection of a cast Elektron21 magnesium alloy

Murillo-Gutiérrez¹,

Ansart²,

Bonino³

et al. 2014

Applied Surface Science

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An epoxy-based hybrid sol-gel coating was prepared in various architectural configurations has been studied for the corrosion protection of a cast Elektron21 magnesium alloy. The creation of a single layer of this coating presents defects consisting of macro-pores and protuberances, which opens access for corrosive species to reach the metallic substrate. These defects are suspected to result from the high reactivity of the substrate, as well as to the irregular topography of the substrate disrupted by the microstructure of the own magnesium alloy. Hence, a sol-gel coating in bilayer architecture is proposed, where the first layer would "inert" the surface of the magnesium substrate, and the second layer would cover the defects of the first layer and also thickening the coating. The morphological characteristics of the sol-gel coatings were analyzed by scanning electron microscopy (SEM), and their corrosion behavior was evaluated by OCP (open circuit potential) monitoring and electrochemical impedance spectroscopy (EIS) in chloride media. It is shown that both the architectural arrangement and the individual thickness of the first and second layers have an important influence on the anticorrosion performances of the protective system, just as much as its global thickness.

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