Department of Chimical Engineering
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Date
2022
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جامعة سبها
Abstract
The use of organic or inorganic coatings for protecting metallic substrates is widely accepted
in various structural engineering applications, such as aerospace, automobiles. In order to
meet the industry requirements, the ability to achieve good corrosion resistance properties
under a wide variety of conditions should be considered. The present work is based upon
the use of Mg-Al sol-gel material to protect mild steel substrates against NaCl media.
Filiform corrosion was employed in this experimental work to identify the possibility of
corrosion on mild steel substrates compared with the commercial epoxy resin. Filiform
corrosion is usually initiated by weak points or discontinuities in the film they never cross
each other, and their growth is independent of light and of the metallurgical structure of the
metal substrate and the driving force of this type of corrosion is controlled by the osmotic
action (pressure) in the growing corrosion cell. The attack of this type of corrosion is usually
affects steel. Visual examination of mild steel samples for both coated system showed the
unstable adhesion property of epoxy resin on mild steel surface compared with that in the
sample coated with sol-gel material. This can be attributed to chemical structure of Mg-Al
sol-gel material play a key role in this behavior. IR spectra showed the two small bands at
3072 and 3049 cm-1 correspond to the C-H stretching vibrational bands. Additional a very
strong bands between 1300 and 1200 cm-1 proves the presence of magnesium into the
structure of the sol-gel materials. Also, the combination bands at 1711 and 1630 cm-1 are
visible in these spectra and are related to the incorporation of aluminum and magnesium into
the sol-gel structure. All these chemical bonds within the structure of sol-gel play a role in
reducing the inter of water molecules within the Mg-Al\sol-gel and develop more adhesion
bonding at the interface of sol-gel material and metal surface.