Influence of curing temperature, silica nanoparticles- and cerium on surface morphology and corrosion behaviour of hybrid silane coatings on mild steel
TL;DR: In this paper, a silane-based organic-inorganic hybrid coatings possessing unique properties can be used to improve the performance of steel structures subjected to marine corrosion, and the effect of change in the temperature and composition on the microstructural properties of the coatings was determined using optical microscopy, scanning electron microscopy and atom force microscopy.
Abstract: This work is aimed at developing and investigating silane based organic–inorganic hybrid coatings possessing unique properties, which can be used to improve the performance of steel structures subjected to marine corrosion. These silane based sol–gel coatings were prepared by dip coating planar samples of mild steel in solution of an organically modified silica sol made from hydrolysis and polycondensation of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) in acid catalysis condition. Crack-free coatings were obtained on curing at 200 °C. On increasing the curing temperature to 400 °C, however, cracks developed in the plain organic–inorganic hybrid coatings. This observation was consistent with the visual observations where appearance of the coated specimen changed from colourless metallic to brownish grey on curing from 200 °C to 400 °C temperature. The coatings were further modified using SiO 2 nanoparticles and cerium. The effect of change in the – temperature as well as – composition on the microstructural properties of the coatings was determined using optical microscopy, scanning electron microscopy and atom force microscopy. Additionally, Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy (ATR/FTIR) was carried out to show the formation of the Si–O–Si structural backbone of the hybrid material with the organic CH 3 group incorporated into the silica network. The corrosion protection performance of these coatings was examined using potentiodynamic polarisation technique and electrochemical impedance spectroscopy in aerated 3.5 wt.% NaCl solution. The polarization curves and corrosion resistance as measured by the bode plots suggested that the plain hybrid coatings offer good protection against corrosion. However, the SiO 2 and cerium modified nano hybrid coatings exhibited superior performance to that displayed by plain hybrid coatings.
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TL;DR: A review of the most recent and relevant achievements on the development of organic-inorganic hybrid (OIH) coatings produced by sol-gel-derived methods to improve resistance to oxidation/corrosion of different metallic substrates and their alloys is presented in this paper.
Abstract: This paper is a review of the most recent and relevant achievements (from 2001 to 2013) on the development of organic–inorganic hybrid (OIH) coatings produced by sol–gel-derived methods to improve resistance to oxidation/corrosion of different metallic substrates and their alloys. This review is focused on the research of OIH coatings based on siloxanes using the sol–gel process conducted at an academic level and aims to summarize the materials developed and identify perspectives for further research. The fundamentals of sol–gel are described, including OIH classification, the interaction with the substrate, their advantages, and limitations. The main precursors used in the synthesis of OIH sol–gel coatings for corrosion protection are also discussed, according to the metallic substrate used. Finally, a multilayer system to improve the resistance to corrosion is proposed, based on OIH coatings produced by the sol–gel process, and the future research challenges are debated.
290 citations
TL;DR: In this paper, a sol-gel based silane film filled with functionalized graphene oxide nanosheets (fGO) was developed to enhance the epoxy coating resistance against corrosion and cathodic delamination over the steel substrate.
287 citations
TL;DR: In this paper, the effect of graphene oxide (GO) nano-fillers embedded in the sol-gel based silane coating on the corrosion protection and adhesion properties of the epoxy coating applied on the steel substrate pre-treated by silane coatings was investigated.
156 citations
TL;DR: In this paper, a new nano-filler based on graphene oxide is recommended for this type of coating and the results obtained from different characterizations showed successful silanization and dispersion of graphene oxide in the silane hybrid coating.
Abstract: Silane coating has been used as a steel surface treatment for the promotion of adhesion between a substrate and an organic coating. However, the corrosion protection properties of this coating are not sufficient. Incorporation of various additives and nano-fillers into the coating is a promising way to improve the coating barrier action. In this paper a new nano-filler based on graphene oxide is recommended for this type of coating. The graphene oxide is silanized in the first step through a sol–gel route by using aminopropyl triethoxysilane (ATPES). Then, it is employed in a hybrid silane coating based on the mixture of aminopropyl triethoxysilane and tetraethyl orthosilicate (TEOS). The graphene oxide functionalization was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The silane coatings filled with silanized and untreated graphene oxide were also characterized by FT-IR, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained from different characterizations showed successful silanization and dispersion of graphene oxide in the silane hybrid coating. The silane coating containing silanized graphene oxide showed superior corrosion protective performance compared to the unfilled silane coating in electrochemical impedance spectroscopy (EIS) and polarization measurements, indicating the considerable corrosion barrier effect of this nano-filler.
107 citations
TL;DR: In this paper, the results of electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), and pull-off tests indicated that the presence of the 8-Hydroxyquinoline (8-HQ) organic inhibitor provides the optimal performance for coating systems.
91 citations
References
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TL;DR: In this article, the structural phases and the growth of self-assembled monolayers (SAMs) are reviewed from a surface science perspective, with emphasis on simple model systems, and a summary of the techniques used for the study of SAMs is given.
2,374 citations
PARC1
TL;DR: In this article, the dominant Raman peak is assigned to a singular matrix element rather than a peak in the density of vibrational states, and simple expressions are developed which yield useful values of the vibrational force constants and intertetrahedral angles for vitreous Si, Ge, and Be.
Abstract: The primary features of the Raman and infrared spectra of $A{X}_{2}$ tetrahedral glasses are associated with the edges of the vibrational bands calculated by Sen and Thorpe. The dominant Raman peak is assigned to a singular matrix element rather than a peak in the density of vibrational states. Simple expressions are developed which yield useful values of the vibrational force constants and intertetrahedral angles for vitreous Si${\mathrm{O}}_{2}$, Ge${\mathrm{O}}_{2}$, and Be${\mathrm{F}}_{2}$.
652 citations
TL;DR: In this paper, a nanostructured hybrid sol-gel coatings doped with cerium ions were investigated as pre-treatments for the AA2024-T3 alloy.
483 citations
TL;DR: In this article, Fourier transform infrared absorption spectroscopy has been used to characterize the structure of porous silica gel films, both deposited on c-Si substrates and free standing.
Abstract: Fourier transform infrared absorption spectroscopy has been utilized to characterize the structure of porous silica gel films, both deposited on c‐Si substrates and free standing. The films were either dried at room temperature or subjected to partial densification at 400–450 °C. The spectra of the gel films are compared to those of thermal SiO2 grown on c‐Si and to Kramers–Kronig analysis of the reflection spectra of bulk SiO2 gels and v‐SiO2. The gel films show small frequency shifts compared to the latter spectra and they also exhibit new bands due to the presence of OH groups, although very little molecular water or residual organic species were found. The results are interpreted in terms of the gel structure. Compared to the thermal oxide, the sharp peak near 1070 cm−1 is narrower for the gels and the spread in intertetrahedral angles is estimated at 24° and 27° for room temperature dried and partially densified gels, respectively, compared to 33° for the thermal oxide. This is in agreement with a st...
410 citations
TL;DR: In this paper, the development and state of the art in the application of certain organosilicon compounds known as trialkoxysilanes (or simply silanes) to the problems of the metal finishing industry is reviewed.
316 citations