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Typical cross-cut images for coatings A to F, left (photograph image) and right (optical microscope image magnification of 2.5)
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Hybrid sol–gel materials have been extensively studied as viable alternatives to toxic chromate (VI)-based coatings for the corrosion protection of AA2024-T3 in the aerospace industry, due to the wide range of available chemistries they offer and the tremendous development potential of innovative functional coatings. However, so far, little work ha...
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In this work, the anticorrosion properties of phenyl trimethoxysilane (PTMS) films coated on aluminium 5000 series alloys were studied. PTMS films were deposited at various cathodic potentials. The optimum electrodeposition potential was found to be −0.8 V vs. SCE. The coatings were also modified by different amounts of nano-TiO2. In order to intro...
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Citations
... For anticorrosion application, in addition to the chemical resistance, mechanical strength and adhesion to metal substrates, coatings require hydrophobicity to reduce interactions between the metal surface and corrosive agents, usually entrapped in water [15][16][17]. Amongst the numerous anticorrosion sol-gel coatings reported in the state of the art, a formulation based on the combination of 3-trimethoxysilylpropylmethacrylate and a zirconium complex has been intensively investigated and has shown exceptional performances for the protection of aluminium alloys against corrosion [18][19][20][21][22][23][24][25][26][27]. Different strategies have been employed to improve the anticorrosion barrier properties of this formulation, including varying the ratio of the Si/Zr [18,19], the hydrolysis conditions [20], the nature of the chelating agent [21,22], the incorporation of anticorrosion compounds [23], and silanes such as TEOS [24,26] and diphenylsilanediol [27]. ...
... Amongst the numerous anticorrosion sol-gel coatings reported in the state of the art, a formulation based on the combination of 3-trimethoxysilylpropylmethacrylate and a zirconium complex has been intensively investigated and has shown exceptional performances for the protection of aluminium alloys against corrosion [18][19][20][21][22][23][24][25][26][27]. Different strategies have been employed to improve the anticorrosion barrier properties of this formulation, including varying the ratio of the Si/Zr [18,19], the hydrolysis conditions [20], the nature of the chelating agent [21,22], the incorporation of anticorrosion compounds [23], and silanes such as TEOS [24,26] and diphenylsilanediol [27]. ...
The current study reports on the impact of a series of functional alkoxysilanes on the wettability and structure of a well-established silicon/zirconium hybrid anticorrosion sol–gel coating. The selected functional alkoxysilanes comprise tetra ethylorthosilicate (TEOS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and vinyltriethoxysilane (VTES) and are incorporated at various concentrations (1, 5, 10 and 20%) within the silicon/zirconium sol–gel material. The prepared materials are successfully processed as coatings and cured at different temperatures in the range of 100–150 °C. The characterisation of the structures and surfaces is performed by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), silicon nuclear magnetic resonance spectroscopy (29Si-NMR), atomic force microscopy (AFM) and static water contact angle (WCA). Structural characterisations (DLS, FTIR,29Si-NMR) show that the functional alkoxysilanes effectively bind at the surface of the reference sol–gel material, resulting in the formation of functional core–shell nanoparticles. WCA results show that the hydrophobic properties of all materials decrease with curing temperature, and AFM analysis demonstrated that this behaviour is associated with a decrease in roughness. The physico-chemical processes taking place are critically assigned and discussed.
... 03 precursor MAPTMS (99% in methanol, Aldrich) and the modified organic zirconium complex, prepared from the chelation of Zr 4+n-propoxide (ZPO) (assay 70% in propanol, Sigma Aldrich, Irl.), at a ratio of 80:20, with the theoretical hydrolysis degree being 50% against the total content of reactive alkoxide groups. The synthesis required a three-step process, as demonstrated in ESI 3 as follows (Cullen et al., 2017;Oubaha, 2019): i) pre-hydrolysis of the MAPTMS and complexation of ZPO with the chelating agent, ii) addition of the pre-hydrolysed alkoxysilane within the zirconate complex, and finally iii) hydrolysis of the solution mixture, where MAPTMS is pre-hydrolysed using an aqueous HNO 3 (0.1 M) solution with a 1:0.25 ratio. The hydrolysis is performed in a heterogeneous way within 5 min until methanol production becomes sufficient enough to enable miscibility of all species in solution. ...
... FTIR of the synthesized Sol gel was recorded on a thin coating deposited on a glass slide and dried at 100°C for the complete removal of all solvents. In the FTIR spectrum (Figure 1), the vibration located at 840 cm −1 was assigned to the presence of residual uncondensed silanol species (Si-OH) (Cullen et al., 2017;Oubaha, 2019) and the vibrations located at 950 and in the range 1,000-1,100 cm −1 were assigned to condensed silicon species, including silicon/zirconium oxide (Si-O-Zr) and siloxane (Si-O-Si) groups, respectively, as reported earlier by Oubaha et al. (Cullen et al., 2017;Oubaha, 2019). ...
... FTIR of the synthesized Sol gel was recorded on a thin coating deposited on a glass slide and dried at 100°C for the complete removal of all solvents. In the FTIR spectrum (Figure 1), the vibration located at 840 cm −1 was assigned to the presence of residual uncondensed silanol species (Si-OH) (Cullen et al., 2017;Oubaha, 2019) and the vibrations located at 950 and in the range 1,000-1,100 cm −1 were assigned to condensed silicon species, including silicon/zirconium oxide (Si-O-Zr) and siloxane (Si-O-Si) groups, respectively, as reported earlier by Oubaha et al. (Cullen et al., 2017;Oubaha, 2019). ...
Nanomaterial combined polymeric membranes such as polyurethane foams (PUFs) have garnered enormous attention in the field of water purification due to their ease of management and surface modification, cost-effectiveness, and mechanical, chemical, and thermal properties. Thus, this study reports the use of novel Sol-gel impregnated polyurethane foams (Sol-gel/PUFs) as new dispersive solid phase microextractors (d- µ SPME) for the efficient separation and subsequent spectrophotometric detection of Eosin Y (EY) textile dye in an aqueous solution with a pH of 3–3.8. The Sol gel, PUFs, and Sol gel–impregnated PUFs were characterized using scanning electron microscopy (SEM), goniometry measurements, dynamic light scattering (DLS), energy dispersive spectroscopy (EDS), UV-Visible, and FTIR spectra. Batch experiment results displayed a remarkable removal percentage (96% ± 5.4%) of the EY from the aqueous solution, with the total sorption time not exceeding 60 min. These data indicate rate-limited sorption via diffusion and/or surface complex ion associate formations after the rapid initial sorption steps. A pseudo-second order kinetic model thoroughly explained the sorption kinetics, providing a sorption capacity (qe) of 37.64 mg g⁻¹, a half-life time (t1/2) of 0.8 ± 0.01 min, and intrinsic penetration control dye retention. The thermodynamic results revealed a negative value for ΔG⁰ (−78.07 kJ mol⁻¹ at 293 K), clearly signifying that the dye uptake was spontaneous, as well as a negative value for ΔH⁰ (−69.58 kJ mol⁻¹) and a positive value for ΔS⁰ (147.65 J mol⁻¹ K⁻¹), making clear the exothermic nature of EY adsorption onto the sorbent, with a growth in randomness at the molecular level. A ternary retention mechanism is proposed, involving the “weak base anion exchanger” of {(–CH2–OH⁺ –CH2–) (Dye anion)⁻}Sol-gel/PUF and/or {(–NH2 ⁺ –COO-) (Dye anion)⁻}Sol-gel/PUF via solvent extraction and “surface adsorption” of the dye anion on/in the Sol-gel/PUFs membranes in addition to H-bonding, including surface complexation and electrostatic π-π interaction, between the dye and the silicon/zirconium oxide (Si-O-Zr) and siloxane (Si-O-Si) groups on the sorbent. Complete extraction and recovery (93.65 ± 0.2, −102.28 ± 2.01) of EY dye with NaOH (0.5 M) as a proper eluting agent was achieved using a sorbent-packed mini column. In addition, the established extractor displayed excellent reusability and does not require organic solvents for EY enrichment in water samples, making it a talented nominee as a novel sorbent for EY sorption from wastewater. This study is of great consequence for expanding the applicatio1n of Sol-gel/PUFs in developing innovative spectrophotometric sensing strategies for dye determination. In view of this, it would also be remarkable to perform future studies to explore the analytical implications of this extractor regarding safety and environmental and public health issues associated to the pollutant.
... Thus, DLS analysis after 30 days of the preparation of the sol-gel material was recorded. The DLS analysis revealed the appearance of one band that lays within the range 2-50 nm and is centered between 5 and 20 nm, indicating that the network is composed of a distribution of particles with the most ranging between 5 and 20 nm [41,42]. Thus, the developed sol-gel material can be used as a nanomaterial that can be immobilized onto PUF sorbent. ...
... 7.9, and 0.13, 0.0.25, respectively. These results are much better than the results reported earlier for the chemical modification of chitosan by tetraethylenepentamine [42] and using ethylenediamine-modified chitosan [43]. The CC, i.e., the amount of analyte retained on the column before first detection in the effluent per one gram of the solid sorbent, was further calculated. ...
... 7.9, and 0.13, 0.25, respectively. These results are much better than the results reported earlier for the chemical modification of chitosan by tetraethylenepentamine [42] and using ethylenediamine-modified chitosan [43]. Based on the values of N, HETP, BC, and CC, the analytical utility of sol-ge sorbent-packed mini-column was successfully tested for complete collection, re and spectrophotometric determination of EY dye at trace and ultra-trace levels (0. µg mL −1 ) in deionized water. ...
Textile dyes widely used in industrial products are known as a major threat to human health and water ecological security. On the other hand, sol gel represents a principal driver of the adoption of dispersive solid-phase microextractors (d-µ SPME) for pollutants residues in water. Thus, the current study reports a new and highly rapid and highly efficient hybrid sol-gel-based sponge polyurethane foam as a dispersive solid-phase microextractor (d-µ-SPME) platform packed mini-column for complete preconcentration and subsequent spectrophotometric detection of eosin Y textile dye in wastewater. The unique porous structure of the prepared sol-gel immobilized polyurethane foams (sol-gel/PUF) has suggested its use for the complete removal of eosin Y dye (EY) from water. In the mini-column, the number (N) of plates, the height equivalent to the theoretical plates (HETP), the critical capacity (CC), and the breakthrough capacities (BC) of the hybrid sol-gel-treated polyurethane foams towards EY dye were determined via the breakthrough capacity curve at various flow rates. Under the optimum condition using the matrix match strategy, the linear range of 0.01–5 µg L−1, LODs and LOQs in the range of 0.006 µg L−1, and 0.01 µg L−1 for wastewater were achieved. The intra-day and inter-day precisions were evaluated at two different concentration levels (0.05 and 5 μg L−1 of dye) on the same day and five distinct days, respectively. The analytical utility of the absorbents packed in pulses and mini-columns to extract and recover EY dye was attained by 98.94%. The column could efficiently remove different dyes from real industrial effluents, and hence the sol-gel/PUF is a good competitor for commercial applications. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements. Therefore, this study has provided a convenient pathway for the preparation of compressible and reusable sponge materials from renewable biomass for efficient removal of EY from the water environment.
... The presence of zirconium also affects the coating composition, mechanical (Bae et al., 2011;Gorin et al., 2011) and corrosion properties (Oubaha et al., 2014;Rodič et al., 2014a;Rodič et al., 2014b;Rodič and Milošev, 2015;Rodič et al., 2018a;Rodič et al., 2018b;Varma et al., 2010a;Varma et al., 2010b). In previous work, the coatings were synthesised using silicon precursors tetraethyl orthosilicate (TEOS), organically modified silicon precursor 3-methacryloxypropyltrimethoxysilane (MAPTMS), without or with the addition of zirconium(IV) n-propoxide (ZTP) chelated with methacrylic acid (MAA) (Cullen et al., 2017;Cullen et al., 2018;Cullen et al., 2021;Rodič et al., 2014a;Rodič et al., 2014b;Rodič and Milošev, 2015;Rodič et al., 2018b). The hydrolysis and condensation reactions were characterised using real-time Fourier transform infrared spectroscopy (FTIR) to postulate the mechanism of final sol formation and curing in the form of coating (Rodič et al., 2014a;Rodič et al., 2014b). ...
This study aimed to synthesise and characterise two types of sol-gel acrylic coatings: one based on Si and the other based on Si and Zr. These coatings, which served as a barrier for corrosion protection of aluminium, were synthesised by sol-gel methodology using silicon precursors tetraethyl orthosilicate and organically modified silicon precursor 3-methacryloxypropyltrimethoxysilane, without and with the addition of zirconium(IV) n-propoxide chelated with methacrylic acid. The synthesis process was followed using real-time Fourier transform infrared spectroscopy, which confirmed the condensation reactions of Si–O–Si and Si–O–Zr networks, depending on the sol type. This was reflected in the composition of the coating as well, as shown by X-ray photoelectron spectroscopy. The coating topography, thickness and morphology were analysed using focused ion beam scanning electron microscopy. X-ray photoelectron spectroscopy was employed to follow the degradation of acrylic coatings upon immersion in sodium chloride solution. Corrosion properties, evaluated using electrochemical impedance spectroscopy in 0.1 M NaCl, confirmed high barrier protection of coated aluminium with acrylic coatings based on Si and even better for coating based on Si with Zr. The more durable corrosion protection of the latter was also confirmed by salt spray testing.
... Different methodologies for the deposition of these films have been reported in the literature, including wet methods of hot dipping [22] and sol-gel [23,24], and dry methods of electrodeposition [25] and glow discharge plasmas [26]. Among these, plasma-enhanced chemical vapor deposition (PECVD) stands out as an advantageous approach [27]. ...
We present a review of low-pressure plasma-enhanced chemical vapor deposition (PECVD) with the hexamethyldisiloxane (HMDSO) precursor for production of organosilicon thin films. This topic has been the subject of numerous studies in recent years, and there is a need for a focused review. Low-pressure plasma represents a simple, cost-effective, and environmentally friendly methodology for depositing films. The use of HMDSO as a precursor is justified by the advantages of this compound as the source of high vapor pressure, the high deposition rates that may be imposed, as well as the possibilities of adjustment of the properties and of the chemical nature of the final coating. Thus, the association of PECVD in a low-pressure system with HMDSO leads to a series of favorable implications for the development of new materials and technologies. In this work, before discussing the properties and application possibilities of organosilicon films, we present the concepts involved with low-pressure plasma deposition kinetics. The strict correlation between the plasma excitation parameters (such as pressure, power, and time) with the deposition kinetics and the final film properties is discussed. After that discussion, some specific properties of organosilicon films are presented and illustrated with results reported in the literature. The films produced in the consulted works modified the surface properties of polymeric, metallic, fabric, and membrane substrates. The modifications were evaluated in terms of surface-thermodynamic, anticorrosive, optical, mechanical, and barrier properties, among others. The possible applications for the treated materials in biomedical, energy, optics, sensoring, and separation systems, among others, are presented.
... The elaboration of advanced coatings systems is an object of intensive worldwide research activities. In this sense, among the basic directions of advanced coating system development are (i) optimization of the preliminary surface treatment procedures [173][174][175][176][177][178][179][180]; (ii) substitution of Cr(VI) from conversion coatings by lanthanides [122,[181][182][183][184][185][186][187][188][189][190][191][192]; (iii) elaboration of sol-gel derived hybrid coatings [193][194][195][196][197][198][199][200][201][202][203][204][205][206][207][208][209][210]; (iv) development of reinforced hybrid/nano-composite coating layers [211][212][213][214][215][216][217][218][219][220][221][222][223][224][225], including carbon fiber reinforcement [226][227][228][229][230]; (v) hydrophobic coatings elaboration [231][232][233][234][235][236][237][238][239][240][241][242][243][244]; (vi) UV-curable layers [245][246][247][248][249][250]; (vii) corrosion inhibitor releasing coatings [251][252][253][254][255]; (viii) coatings with encapsulated self-healing agents, [256][257][258][259]; (ix) coatings with chitosan-based biocompatible polymers [260][261][262], (x) alternative polymeric coating matrixes, [263] including natural polymers [264,265], etc. In this sense, an ongoing near future alternative field of research activities for advanced coating elaboration will be based on materials' recycling of various industrial and natural resources. ...
... The effects of curing temperature on bilayer and monolayer hybrid films: mechanical and electrochemical properties. Journal Applied Electrochemistry 44:759-71.Classical and Modern Methods for Corrosion Impact Rate Determination …129[202] Cullen, M., Morshed, M., O'Sullivan, M., MacHugh, E.,Duffy, B., and Oubaha, M. 2017. Correlation between the structure and the anticorrosion barrier properties of hybrid sol-gel coatings: application to the protection of AA2024-T3 alloys. ...
Book description
This handbook is about theory, phenomenon and state-of the-art research results in corrosion science, written by accomplished, internationally revered scientists and engineers on the fields. The numerous illustrations are related to subtle ideas. Furthermore, experimental data are based on original research results. Figures summarise delicate achievements besides well-elaborated examples and case studies. All the representations serve clear and rapid understanding. Discussed material originates partially from international literature of leading groups and advanced proprietary results of the authors.
This handbook is intended for college and university students striving for B.Sc. and M.Sc. degrees. Furthermore, the one is also targeted who plans to pursue further training or post-gradual study and perform high-quality research. This compilation with seven chapters is devoted to young scientists with an interest in making the first move to corrosion science and to acquaint with many of basics and necessary terms. There are many examples of remarkable findings and recognised standard practices followed by engineers in the related industry. Three main topics are covered in this material such as aluminium and titanium alloys, thin films and composite coatings as well as microbially influenced corrosion.
If anyone finds hard to differentiate multiple phenomenon, to understand the general terms, to define reasons for using specific investigation methods and struggles with comprehension of this very multidisciplinary science, then this publication is unanimously a good material to help them. Readers, who are relatively new to corrosion and protection, are anticipated to gain aspiration for further study and to make endeavour in this field, too. When chapters are perused by beginners, then overview on basics and clear insight to precious details will develop in readers’ mind. After careful reading this compilation, the outcome delineates as rapid recognition of many of the corrosion phenomenon in the everyday and professional life, identifying their root-causes, proposing investigation methods to obtain further appropriate knowledge in many aspects and the ability to recommend remedy measures to forgoing integrity failure.
The editor, who worked on various fields of chemistry and authored highly interested, one of the most read and downloaded papers in the subjects of corrosion protection with graphene films and graphene based composite coatings as review papers, as well as zinc-rich paint coatings containing alumina-carrier based core-shell type nano-sized particles combined with either physically modified or chemically functionalised multi-walled carbon nanotubes based on his own research results, wishes all the book readers instructive, useful and enjoyable times whilst reading the chapters.
... In addition, no delamination or peeling occurred on cross- (Fig. 5b), indicating the film adhered excellently to the Al alloy substrate. This result proved that the adhesion of TiO 2 deposit to the Al alloy surface was very high [36]. ...
Anticorrosion deposits were prepared on Al alloy substrate surface by a hydrolysis process. In this paper, a hydrolysis reaction technique was applied to prepare TiO2 deposit on Al alloy surface by formation of Al2O3 particles at home temperature. The prepared deposits were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The amorphous TiO2 was characterized by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods and the anticorrosion performance in 0.1 M NaCl solution was evaluated by electrochemical measurements. The value of the Ecorr can positive shift from − 685 to − 539 mV in 0.1 M NaCl. The results indicated that the TiO2 layer provided good barrier on Al alloy surface with Al2O3 particles, and the amorphous TiO2 deposit decreased Al alloy corrosion rate by self-sacrifice. This amorphous deposit can be applied as a protection layer at the Al alloy surface by simple hydrolysis reaction.
... 1,2 However, due to the new environmental regulations, studies have been conducted to find appropriate eco-friendly replacements for this toxic material. [3][4][5][6][7] In this case, the hybrid organic-inorganic coatings obtained from sol-gel method have gained more attention in recent years. [8][9][10][11][12][13][14][15][16][17] High mechanical, chemical and thermal stabilities together with easy, low temperature and waste-free processing associated with the ability to form strong covalent bonding 18 with metal oxides are the main reasons that can explain the great attention to this potent alternative for traditional chromate based conversion coatings. ...
In this study, combinations of two environmentally friendly compounds including a silane-based organic-inorganic coating and a rare earth (RE) salt have been investigated for mitigation of corrosion activity of mild steel. Bilayer silane coatings based on methyl triethoxy silane (MTES) and tetraethyl orthosilicate (TEOS) were reinforced by different amounts of praseodymium cations (Pr³⁺). The effects of Pr³⁺ loading on the hydrophobicity and surface properties of the coating were studied by contact angle measurements. Fourier Transform Infrared (FT-IR) spectroscopy was done to scrutinize the curing process and possible structural changes of silane network in the presence of inhibitor. Despite the decrease in the hydrophobic nature of silane coating, the Pr³⁺ cations did not change the curing of the coating. Electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) measurements confirmed the high corrosion inhibition power for the mild steel sample immersed in 400 ppm Pr³⁺ containing the saline solution. The results of EIS, polarization and salt spray tests besides the scanning electron microscopy (SEM) images confirmed the silane coating healing ability and corrosion protection properties enhancement in the presence of Pr³⁺ cations.
... In this concern, sol-gel hybrid films are widely used to enhance the corrosion resistance of several metals, such as steel, aluminum and magnesium alloys (Asadi et al., 2014;Cullen et al., 2017) (C ordoba et al., 2015). Furthermore some inorganic oxide fillers can be added both to enhance the coating protective properties and to induce corrosion inhibitory capabilities of silane hybrid film (Palanivel et al., 2003;Montemor and Ferreira, 2007;Zanotto et al., 2011). ...
Purpose
This paper aims to evaluate the efficacy of a zeolite-filled silane sol–gel coating as protective layer on pretreated AZ31 magnesium alloy substrates.
Design/methodology/approach
Anti-corrosion properties of a silane–zeolite composite coating, at various zeolite content, have been investigated on AZ31 magnesium substrates subjected to different surface pretreatment procedures before coating deposition. A short time etching by hydrofluoric acid (HF) and an anodic polarization in NaOH solution were used as surface pretreatments.
Findings
High hydrophobicity and good adhesion performances of coatings have been observed. Corrosion protection performance, during immersion in 3.5 per cent NaCl solution, was evaluated by means of electrochemical impedance spectroscopy tests. All coating formulations evidenced good barrier properties. Better durability properties have been shown by coating obtained on HF pretreated magnesium substrate and with a 60 per cent of zeolite content.
Originality/value
High electrochemical reactivity of magnesium alloys represents the mayor limit of its application in many different fields. In this concern, zeolite-based coatings are emerging as potentially effective environmentally friendly coating for metallic substrates. Despite aluminum and stainless steel substrates, in the literature, only expensive direct synthesis zeolite coating was investigated for its application on magnesium alloys protection. For this reason, this paper fulfills the need to assess the adhesion and anti-corrosion behavior of sol–gel silane–zeolite coating in magnesium alloy substrates.
... Hybrid precursors are used for their effect on mechanical properties and especially for shaping and flexibility [13]. To improve the affinity between sol-gel coating and aluminium alloy, an aluminium alkoxide precursor can be used [14] and for durability and barrier properties, zirconium alkoxide is employed as precursors [15][16][17][18][19]. ...
... Aluminium element allows increasing adhesion of sol-gel coating on substrate with strong chemical bonds [14]. Furthermore, the zirconium contributes to the barrier effect and improves coating durability [15][16][17][18][19]. This positive aspect can be confirmed by GZ coating, which presents a better corrosion resistance than GA coating (respectively around 300 h against 200 h, ( Figure 3B and 3A). ...
The aim of our study is to improve the aluminium alloy corrosion resistance with Organic-Inorganic Hybrid (OIH) sol-gel coating. Coatings are obtained from unusual formulation with precursors mixing: glycidoxypropyltrimethoxysilane (GPTMS), zirconium (IV) propoxide (TPOZ) and aluminium tri-sec-butoxide (ASB). This formulation was characterized and compared with sol formulations GPTMS/TPOZ and GPTMS/ASB. In each formulation, a corrosion inhibitor, cerium (III) nitrate hexahydrate, is employed to improve the corrosion performance. Coatings obtained from sol based on GPTMS/TPOZ/ASB have good anti-corrosion performances with Natural Salt Spray (NSS) resistance of 500 h for a thickness lower than 4 µm. Contact angle measurement showed a coating hydrophobic behaviour. To understand these performances, nuclear magnetic resonance (NMR) analyses were performed, results make sol-gel coating condensation evident and are in very good agreement with previous results.
