Development of new high transparent hybrid organic–inorganic monoliths with surface engraved diffraction pattern

Moreira, Sandra D. F. C.; Silva, Carlos J. R.; Prado, L.A.S.A.; Costa, Manuel F. M.; Boev, V. I.; Martín‐Sánchez, Javier; Gomes, M. J. M.

doi:10.1002/polb.23028

Cited by 25 publications

(33 citation statements)

References 25 publications

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“…36 Table III shows the average values of the logarithm of resistivity (log ρ) and normalized capacitance from five samples of each OIH film (uncertainty is expressed for 95% confidence). Table III demonstrates that for all analyzed OIH film samples, ρ is between 10 6 and 10 8 cm.…”

Section: Resultsmentioning

confidence: 99%

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Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Cementitious Media

Figueira

Silva

Pereira

et al. 2013

J. Electrochem. Soc.

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This study is focused on the electrochemical behavior and surface analysis of an eco-friendly organic-inorganic hybrid (OIH) coating for hot dip galvanized steel (HDGS) in contact with cementitious media. This treatment is a proposed alternative to replace toxic Cr(VI)-based pre-treatments used to control reactions between the zinc and wet concrete. HDGS samples were coated with two different sets of OIH gels obtained by a sol-gel process using a dip-coating method. Five distinct OIH matrices were obtained by reaction of functionalized metal-alkoxide (3-isocyanatopropyltriethoxysilane) with five different molecular weight diaminealkylethers. One set of HDGS samples was coated with each of the five pure OIH matrices and another was coated with similar matrices doped with Cr(III). The morphology of OIH coatings over HDGS surface was characterized by SEM/EDS. Similar films were prepared separately and the respective resistivity was measured by electrochemical impedance spectroscopy. Polarization resistance and macrocell current density were used to evaluate the corrosion protection properties of the HDGS coated samples in contact with cementitious media for a period of 74 days. Results showed that the produced coatings provide barrier properties that withstand the high pH of the electrolyte, protecting the HDGS when it first contacts cementitious media.The corrosion of steel in concrete is one of the major causes of structures degradation, requiring expensive rehabilitation. The use of hot dip galvanized steel (HDGS) has been recognized as an effective measure to increase the service life of reinforced concrete structures exposed to carbonation or to chloride ions. 1-3 The galvanized coating is a physical barrier that hinders the contact of aggressive agents with the steel substrate and the zinc layer acts as a sacrificial anode, protecting the steel against corrosion. 4,5 Immediately after the HDGS is embedded in fresh concrete, a highly alkaline environment, the zinc coating corrodes for a limited period (from several hours to a few days) until passivating surface layers are formed and concrete hardens. This initial corrosion process may lead to zinc consumption between 5 to 10 μm. 2 At the same time hydrogen is produced which may lead to the loss of adhesion between steel and concrete.Several corrosion studies reported the behavior of HDGS in contact with concrete media and in alkaline solutions. 2-21 However, uncertainties concerning the initial corrosion behavior of the galvanized coating when embedded in concrete still remains. The main literature about corrosion and passivation mechanisms of zinc in concrete environments, suggest that the formation of the protective layer due to zinc oxidation takes place with water reduction and subsequent hydrogen evolution. 9-11 Other authors claim that the formation of protective layer is related to the presence of oxygen at the concrete/rebar interface. 12,14,18 Andrade and co-workers, 11,22,23 found that at pH ≥ 12.5 zinc dissolution and hydrogen evolution takes place p...

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Section: Resultsmentioning

confidence: 99%

“…[34][35][36][37][38][39][40] Several studies have demonstrated 41-44 that the mechanical and electrical properties of these materials make them suitable pre-treatments to improve the corrosion resistance of several metals and alloys.…”

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confidence: 99%

Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Cementitious Media

Figueira

Silva

Pereira

et al. 2013

J. Electrochem. Soc.

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“…If the drying of the gel occurs in wet supercritical conditions, the shrinkage will be minimal, and the resulting product is porous and is known as an aerogel [1,111,161]. The material is known as a monolith if the dimensions of the gel are greater than scarcely millimeters [1,[162][163][164]. In case of the gelation, it takes place by quick evaporation of the solvents; the materials obtained are coatings (Figure 3), films and fibers [14,154,165].…”

Section: -Methacryloxypropyltrimethoxysilane Maptsmentioning

confidence: 99%

“…The organic groups, through the combination of suitable monomers, may allow the formation of bridges between the silicate groups [175]. Examples of these types of products were reported by different authors [16,17,162,164]. In the last fifteen years, several review articles have been published in the design and application of OIH materials, and mostly were approached from the point of view of materials [2,3,12,27,36,112,148,[178][179][180][181][182].…”

Section: Hybrid Sol-gel Coatings For Corrosion Mitigationmentioning

confidence: 99%

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Figueira

2020

Polymers

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The corrosion process is a major source of metallic material degradation, particularly in aggressive environments, such as marine ones. Corrosion progression affects the service life of a given metallic structure, which may end in structural failure, leakage, product loss and environmental pollution linked to large financial costs. According to NACE, the annual cost of corrosion worldwide was estimated, in 2016, to be around 3%-4% of the world's gross domestic product. Therefore, the use of methodologies for corrosion mitigation are extremely important. The approaches used can be passive or active. A passive approach is preventive and may be achieved by emplacing a barrier layer, such as a coating that hinders the contact of the metallic substrate with the aggressive environment. An active approach is generally employed when the corrosion is set in. That seeks to reduce the corrosion rate when the protective barrier is already damaged and the aggressive species (i.e., corrosive agents) are in contact with the metallic substrate. In this case, this is more a remediation methodology than a preventive action, such as the use of coatings. The sol-gel synthesis process, over the past few decades, gained remarkable importance in diverse areas of application. Sol-gel allows the combination of inorganic and organic materials in a single-phase and has led to the development of organic-inorganic hybrid (OIH) coatings for several applications, including for corrosion mitigation. This manuscript succinctly reviews the fundamentals of sol-gel concepts and the parameters that influence the processing techniques. The state-of-the-art of the OIH sol-gel coatings reported in the last few years for corrosion protection, are also assessed. Lastly, a brief perspective on the limitations, standing challenges and future perspectives of the field are critically discussed.Polymers 2020, 12, 689 The development of OIH sol-gel coatings, based on siloxanes, for corrosion mitigation, has been widely studied in the last few years [2,31,[36][37][38]. Numerous studies have been conducted since the early 1990s [39,40]. The studies performed showed that siloxanes were effective in mitigating the corrosion processes of different metallic substrates. This development was mainly due to the need for alternative environmentally friend materials and processes to replace the traditional chromium-based pre-treatments. Hexavalent chromium (Cr (VI)) is carcinogenic and shows high environmental toxicity and its use has been forbidden since 2006. However, Cr(VI) based pre-treatments improve the coating adherence to the substrate and are effective corrosion inhibitors [41][42][43] which make its replacement challenging. The use of the sol-gel method to produce OIH coatings for corrosion mitigation suits the main requirements of what should be an environmentally friendly process (i.e., excludes washing stages; it is a waste-free method) and allows one to obtain coatings with high purity and specific pore volumes and surface areas. Since it is a mild synthesis...

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“…The OIH gel matrices were prepared following a well-established methodology described elsewhere [28][29][30]. Two sets of four different structural types of ureasilicate OIH gel matrices were prepared by a reaction between the isocyanate group of the derived siloxane (ICPTES) with four different di-amino functionalized polyether (Jeffamine® D-400, Jeffamine® ED-600, ED-900 and ED-2000, hereafter generically referred as Jeffamines) with different molecular weights, with and without incorporated Cr(III) ions, obtained by adding the correspondent salt aqueous solutions with a concentration of 0.01M.…”

Section: Reagentsmentioning

confidence: 99%

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

Figueira¹,

Pereira²,

Silva³

et al. 2013

Port. Electrochim. Acta

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Corrosion of steel in concrete is one of the major causes of structure degradation, requiring expensive maintenance. The using of hot dip galvanized steel (HDGS) has been recognized as one effective measure to increase the service life of reinforced concrete structures in marine environmental. However, HDGS corrodes in contact with high alkaline environment of fresh concrete. Although this initial corrosion process allows the formation of a protecting layer barrier, the corrosion that occurs initially is harmful and chromate conversion layers are usually used to prevent it. Due to toxicity of Cr(VI), these kinds of pre-treatments have been forbidden and hybrid coatings have been proposed as alternatives [1][2][3]. To evaluate the performance of these coatings, beyond the laboratory characterization, in situ tests in real conditions should be performed. An electrochemical system to measure the macrocell current density (i gal ) was designed to evaluate the degradation of HDGS coated samples with different organic-inorganic hybrid films, embedded in mortar during 70 days, using an automatic data acquisition system. This system revealed to be feasible and highly sensitive to coatings degradation. Also, allow distinguishing different hybrid coatings with different thicknesses.

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Development of new high transparent hybrid organic–inorganic monoliths with surface engraved diffraction pattern

Cited by 25 publications

References 25 publications

Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Cementitious Media

Ureasilicate Hybrid Coatings for Corrosion Protection of Galvanized Steel in Cementitious Media

Hybrid Sol–gel Coatings for Corrosion Mitigation: A Critical Review

Corrosion Protection of Hot Dip Galvanized Steel in Mortar

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