Synthesis of Hybrid Organic-Inorganic Sol-Gel Coatings for Corrosion Resistance

1999 ◽  
Vol 576 ◽  
Author(s):  
T. L. Metroke ◽  
R. L. Parkhill ◽  
E. T. Knobbe
Keyword(s):  
Corrosion Resistance ◽  
Salt Spray ◽  
Sol Gel ◽  
Organic Content ◽  
Film Structure ◽  
Mas Nmr ◽  
Silica Network ◽  
Nmr Data ◽  
Acid Catalyzed ◽  
Cp Mas Nmr

ABSTRACT1H-13C and 1H- 29Si CP/MAS NMR spectroscopy has been used to characterize the structure of sol-gel derived hybrid materials prepared from 3-glycidoxypropyltrimethoxysilane (GLYMO) and tetraethylorthosilicate (TEOS) as a function of hydrolysis water ratio and organic content. 1H-13C CP/MAS NMR data indicate that the concentration of hydrolysis water (R value) has a fundamental effect on the nature of the acid-catalyzed hydrolysis and ring opening products. 1H-29Si CP/MAS NMR data suggest that for low R values, the ormosils are composed of a silica network with epoxide groups randomly dispersed throughout. At high R values, epoxide functionalities were found to coat the surfaces of dense silica particles. Salt spray analysis indicates that the corrosion resistance behavior of thin films derived from GLYMOTEOS ormosils decreases as the concentration of hydrolysis water increases and improves as the organic content in the film increases. These observations can be related to the underlying thin film structure.

Hydrocarbon-Bridged Polysiloxane and Polysilsesquioxane Network Materials.

1994 ◽  
Vol 346 ◽  
Author(s):  
Gregory M. Jamison ◽  
Douglas A. Loy ◽  
Roger A. Assinkt ◽  
Kenneth J. Shea
Keyword(s):  
Sol Gel ◽  
Mas Nmr ◽  
Degree Of Hydrolysis ◽  
Network Polymers ◽  
Surface Areas ◽  
Hydrolysis And Condensation ◽  
Acid Catalyzed ◽  
High Degree ◽  
Hydrolysis And Polycondensation ◽  
Cp Mas Nmr

ABSTRACTHexylene-and phenylene-bridged polymethylsiloxane xerogels X-2 and X-4, respectively, were prepared by the sol-gel hydrolysis and condensation of 1, 6-bis(diethoxymethyl-silyl)hexane 1 and 1, 4-bis(diethoxymethysilyl)benzene 2 under acidic and basic conditions. These polymerizations afforded network polymers in the form of wet gels within several hours. The gels were processed to afford xerogels whose characteristics (determined by solid state 13C and 29Si CP MAS NMR spectroscopy and nitrogen sorption porosimetry) were compared and contrasted with those of their analogous polysilsesquioxanes. 29Si CP MAS NMR indicates a high, degree of hydrolysis and polycondensation; porosimetry measurements reveal that the materials have significant surface areas, save for the acid-catalyzed hexylene gels X-2.

Effect of Sol-Gel Film on the Corrosion Resistance of Low Carbon Steel Plate

2020 ◽  
Vol 984 ◽  
pp. 43-50
Author(s):  
Hua Yuan Zhang ◽  
Can Wang ◽  
Bing Xue ◽  
Jing Luo
Keyword(s):  
Corrosion Resistance ◽  
Carbon Steel ◽  
Steel Plate ◽  
Salt Spray ◽  
Sol Gel ◽  
Low Carbon Steel ◽  
Corrosion Current ◽  
Neutral Salt ◽  
Low Carbon ◽  
Gel Film

To improve the corrosion resistance on Q235 low carbon steel, in this paper, tetraethyl orthosilicate (TEOS), N-dodecyl trimethoxysilane and γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH560) were used to make organic-inorganic hybrid sol-gel film. Cross cut test adhesion method, neutral salt spray test, electrochemical test and film protective efficiency were taken to value the corrosion resistance property. The corrosion topography was studied by optical microscope. In addition, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) curves and equivalent electric circuit fitting were used to analyze the corrosion mechanism. The cross cut adhesion of sol-gel film can reach 1 class and the protection class can attain 5 class after 72 hours neutral salt spray test. According to the potentiodynamic polarization curve analysis, the corrosion potential of sol-gel film coating sample after 0.5 hours immersion was -0.46 V (vs. SCE) on the 0.1 Hz, and its corrosion current density was 4.74×10-7 A·cm-2. The corrosion potential of bare Q235 low carbon steel plate after 0.5 hours immersion was -0.78 V (vs. SCE) on the 0.1 Hz, and its corrosion current density was 4.75×10-6 A·cm-2. The impedance value on 0.1 Hz (|Z|0.1Hz) (1.27×106 Ω·cm2) of sol-gel film coating sample was more than three orders of magnitude higher than the value of the low carbon steel plate. Even dipping in 3.5 wt. % NaCl for 72 hours, the |Z|0.1Hz value of sol-gel coating sample was still one order of magnitude higher than the low carbon steel plate with 0.5 hours immersion. Sol-gel film with excellent adhesion can significantly improve the corrosion resistance of low carbon steel plate. Sol-gel film can increase the protection efficiency of low carbon steel plate by 90%.

Preparation of SiO2 Antireflective Film by a Base/Acid Two-Step Catalyzed Sol-Gel Process

2013 ◽  
Vol 860-863 ◽  
pp. 845-848 ◽  
Author(s):  
De Yi Li ◽  
Kun Peng ◽  
Ling Ping Zhou ◽  
Jia Jun Zhu
Keyword(s):  
Raw Materials ◽  
Salt Spray ◽  
Sol Gel ◽  
Acid Base ◽  
Gel Method ◽  
Antireflective Film ◽  
Sol Gel Process ◽  
Acid Catalyzed ◽  
Antireflective Films ◽  
Silica Sols

SiO2 antireflective films were prepared by two-step catalyzed sol-gel method with TEOS as the raw materials, acid and ammonia as catalyst. Effects of the ratio of acid-catalyzed and base-catalyzed silica sols on the transmittance and stability of SiO2 film were investigated. The transmittance can be adjusted by change the ratio of base-catalyzed sols, and a higher transmittance can be obtained in the higher ratio of base-catalyzed coatings. A higher stability of SiO2 film in salt spray can be obtained in higher ratio of acid-catalyzed AR coatings. AR coatings with excellent transmittance and stability can be obtained by adjusting the ratio of acid/base catalyzed silica sols.

Silsesquioxane Materials as Sun Protection Factor Ingredients and as Films for Greenhouse Covers

2009 ◽  
Vol 610-613 ◽  
pp. 104-108 ◽  
Author(s):  
Ping Chen ◽  
Tao Liu ◽  
Di Wang ◽  
Yu Liu ◽  
Li Jiang Hu
Keyword(s):  
Near Infrared ◽  
Sol Gel ◽  
Film Structure ◽  
Ultraviolet B ◽  
Process Efficiency ◽  
Polyhedral Oligomeric Silsesquioxanes ◽  
Protection Factor ◽  
Silica Network ◽  
Covalently Bonded ◽  
Growth Energy

Using polyhedral oligomeric silsesquioxanes (POSS) derived from the hydrolytic condensation of (3–methacryloxypropyl)trimethoxysilane (MPMS), vinyltrimethoxysilane (VMS), and (3-glycidoxypropyl)trimethoxysilane (GPMS), three hybrid nanofilms, f-MP (film-MPMS-POSS), f-GP and f-VP, were prepared using sol-gel and crosslinking processes. The average transparency (AT) and absorption coefficents (AC) of the films were measured in the ranges of 280-2500 nm. Two film transparency applications are described in this work: 1) The AT values of the POSS films in the range of the ultraviolet B (UV-B) spectrum (280–320 nm) (a skin cancer-causing agent) and 2) the AT values in the visible light (VIS) region (400-750 nm) and the near infrared (NIR) region (750-2500 nm) (providing crops growth energy and the improvement of the photosynthetic process efficiency). The AT values of the POSS films in the UV-B range are only about 13%, indicating these films can provide a physical barrier to block UV-B absorption by the skin, and therefore are possible POSS materials for sunscreen ingredients. The AT values in the VIS region are 95.13%, 89.16% and 91.60%, respectively, and the AT values in the near infrared (NIR) region (750-2500 nm) are 95.39%, 93.11% and 90.50%, respectively. These high AT films are good candidates for greenhouse covers. The AT values among the three films in the 280-2500nm region are different and exhibit varied selectivity for absorbed spectra due to the dissimilar sizes of organic branches covalently bonded to the silica network in the film structure.

Effect of nano ZnO containing sol-gel coating on galvanised iron sheet

2015 ◽  
Vol 44 (4) ◽  
pp. 239-249 ◽  
Author(s):  
Akshya Kumar Guin ◽  
Manish Bhadu ◽  
Mohua Sinhababu ◽  
Tapan Kumar Rout ◽  
G. Udayabhanu
Keyword(s):  
Corrosion Resistance ◽  
Water Permeability ◽  
Steel Sheet ◽  
Salt Spray ◽  
Sol Gel ◽  
Nano Zno ◽  
Content Type ◽  
Galvanised Steel ◽  
Passivation Treatment ◽  
Hexavalent Chrome

Purpose – This paper aims to investigate the potential of sol-gel coating as replacement for hazardous hexavalent chrome passivation treatment for galvanised iron (GI) sheet. Generally, corrosion resistance properties of the GI sheet are increased by hexavalent chrome passivation treatment. But hexavalent chrome is hazardous and not environment friendly. Design/methodology/approach – The aim of this study was to understand the effect of nano zinc oxide (ZnO) on corrosion behaviour of sol-gel coating prepared by hydrolysis of the 3-(Glycidoxy propyl) methyl diethoxy silane (GPTMS) and tetra-ethyl-orthosilicate (TEOS). The morphology of the film was characterised by a scanning electron microscope (SEM). The corrosion resistance of the coated samples was evaluated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarisation curve and salt spray test. Findings – From a different corrosion resistance study, it has been observed that sol-gel coating doped with 1 per cent nano ZnO rendered maximum corrosion protection. Beyond 1 per cent of nano ZnO, corrosion resistance property of coated galvanised steel sheet decreased drastically which may be due to agglomeration of nano ZnO and high water permeability of coated galvanised steel sheet. Research limitations/implications – The anti-corrosive property of the coating can be tested by means of atmospheric exposure which produces a real-time evaluation of the anti-corrosive nature of the coating under natural conditions rather than using an accelerated laboratory test. Practical implications – It may be useful for other metal industry like aluminium. The work can be used as a guiding chemistry for development of chrome-free passivation for aluminium. Social implications – It has the potential to replace hexavalent chrome passivation. Originality/value – The use of nano ZnO in sol-gel polymer matrix for the development of corrosion resistant chrome-free polymer coating for galvanised steel sheet and its corrosion resistance study (EIS curve fitting, capacitance value and water permeability) is a novel approach in this research.

Sol-gel synthesis of ternary phosphate-ZrO2-SiO2 catalysts for alcohol dehydration

2001 ◽  
Vol 79 (8) ◽  
pp. 1224-1228 ◽  
Author(s):  
Quan Zhuang ◽  
Jack M Miller
Keyword(s):  
Key Words ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Tetraethyl Orthosilicate ◽  
Mas Nmr ◽  
Alcohol Dehydration ◽  
Zirconium Propoxide ◽  
P Content ◽  
Sol Gel Synthesis ◽  
Cp Mas Nmr

Phosphate–ZrO2–Si2O catalysts were synthesized by sol-gel method using tributyl phosphite, zirconium propoxide, and tetraethyl orthosilicate as precursors. They were characterized by N2 adsorption, 31P CP MAS NMR, and DRIFTS. At lower P content, monomeric phosphates were formed on the surface of the catalysts, which were mainly responsible for the isopropanol dehydration activity. At higher P content, polyphosphates were formed, and thus, the dehydration activity decreased. An optimum P content for dehydration activity was found to be at 10 mol%.Key words: sol-gel synthesis, ternary oxides, phosphate, acid catalyst, alcohol dehydration, 31P CP MAS NMR, N2 adsorption, DRIFTS.

scholarly journals Improving the Corrosion Resistance of Tin-bronze by Surface Modification

2021 ◽  
Vol 23 (09) ◽  
pp. 1270-1281
Author(s):  
Mahmoud Abbas ◽  
◽  
Rehab M. El-Maghraby ◽  
Esraa Hassan ◽  
Reda F. M. Elshaarawy ◽  
...  
Keyword(s):  
Contact Angle ◽  
Corrosion Resistance ◽  
Surface Modification ◽  
Water Solution ◽  
Salt Spray ◽  
Sol Gel ◽  
Distilled Water ◽  
Adhesion Test ◽  
X Ray ◽  
Tin Bronze

Bronze alloys are made of copper-based materials with another metal, usually tin. Many surface modification techniques such as chemical etching, oxidation, electro deposition and sol-gel could be employed to improve surface properties. The organic compound that was used in this study was extracted from chili peppers. FT-IR (Fourier-transform infrared) spectroscopy and UV (Ultraviolet) spectroscopy investigations were applied on the extracted compound and results showed that this compound is mainly capsaicin [N-(4-hydroxy-3-methoxybenzyl)-8-methylnon-trans-6-enamide) (HMMTE)]. Electrochemical deposition was employed under cell voltage equal to 30 volts in a two-electrodes cell where bronze was the anode and stainless steel was the cathode in a solution of 10 ml/L (HMMTE)/distilled-water. Modification of tin-bronze for 1 hr. in 10 ml/L HMMTE/ distilled water solution increased the contact angle from 48° to 132˚. Attension Biolin device (Model: Theta Optical Tensiometers) was used to measure the contact angle at ambient temperature. Electrochemical measurements revealed that a significant improvement in corrosion resistance of tin-bronze in 3.5% NaCl had been achieved. The corrosion rate of tin-bronze decreased from 10.22 mpy to 1.39 mpy. Surface morphology of the samples was investigated with scanning electron microscopy (SEN) and energy-dispersive X-ray (EDX). X-ray diffraction was employed to determined present phases. Surface investigations results confirmed that a layer of red cuprous oxide (Cu2O) was formed on the surface layer after modification which led to the improvement in corrosion resistance. Salt spray test was carried out using Alpha+ Salt Spray Testing Equipment for 13 days on the base and surface modified samples according to ASTM B117. A green layer from [CuCl2 and Cu46Cl24(OH)68-(H2O)4] was observed on the nonmodified specimen (could be patina and bronze disease) while the red layer [Cu2O] is still observed on the modified specimen. Adhesion test (using X-Cut Tape Adhesion test according to ASTM D3359) was also investigated.

Preparation of a Silicon Oximide Gel via a Non-Aqueous Sol-Gel Route

2002 ◽  
Vol 726 ◽  
Author(s):  
Fei Cheng ◽  
John S. Bradley
Keyword(s):  
Amorphous Silicon ◽  
Surface Area ◽  
Sol Gel ◽  
Total Surface Area ◽  
Mas Nmr ◽  
Bet Surface Area ◽  
Molar Ratio ◽  
Microporous Structure ◽  
Silicon Oxycarbonitride ◽  
Cp Mas Nmr

AbstractA silicon oximide gel was prepared by a reaction in N,N-dimethylformamide between tris(dimethylamino)silylamine (Me2N)3SiNH2 (TDSA) and formamide in a 1:2 molar ratio at 50C. The 29Si, 13C CP-MAS NMR and IR analyses indicated that the gel mainly comprised oximino silicon networks [SiOC(H)=NSi]x. The gel exhibited a microporous structure and had a total surface area of 339 m2/g. A microporous structure with a BET surface area of 195 m2/g was also obtained after pyrolysis of the gel at 1000°C for 2 h. Pyrolysis of the gel under N2 up to 1485°C gave an amorphous silicon oxycarbonitride glass.

Effects of Catalyst on the Transmittance and Stability of SiO2 Antireflective Film Prepared by Sol-Gel Method

2013 ◽  
Vol 834-836 ◽  
pp. 462-465
Author(s):  
Kun Peng ◽  
E. Chen ◽  
Ling Ping Zhou ◽  
Jia Jun Zhu ◽  
De Yi Li
Keyword(s):  
Raw Materials ◽  
Salt Spray ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Antireflective Film ◽  
Average Transmittance ◽  
Acid Catalyzed ◽  
The Stability ◽  
Better Than

SiO2 antireflective films were prepared by sol-gel method with TEOS as the raw materials and acid or ammonia as catalyst. The effects of different catalysts on the transmittance and the stability of film were investigated. The prepared base catalyzed SiO2 film has better antireflective effects than that of film acid catalyzed film, but the corrosion-resistance of SiO2 film catalyzed by acid was better than that of film catalyzed by base, the average transmittance in the range of 400-900nm of acid-catalyzed film after 50h salt spray test was about 93.8%, which was higher than that of base-catalyzed film.

Crosslinked Organic-Inorganic Hybrid Thin Films for Corrosion Resistance: Spectroscopic and Salt Spray Characterization

2000 ◽  
Vol 628 ◽  
Author(s):  
Tammy L. Metrokeand ◽  
Edward T. Knobbe
Keyword(s):  
Thin Films ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Salt Spray ◽  
Crosslinking Agent ◽  
Film Structure ◽  
Organic Polymer ◽  
Paint Systems ◽  
Filiform Corrosion ◽  
Cure Time

ABSTRACTSpray-coated, R-Si (OR')3 / TMOS (R = epoxide), thin films are being investigated as room temperature curing corrosion resistant coatings for 2024-T3 aluminum alloy. Solid state 1H-13C CP/MAS NMR indicates that primary aliphatic amines and super acids are effective crosslinkers for epoxide groups in aqueous ormosil systems. Incorporation of a crosslinking agent into the coating was found to reduce the cure time of the deposited film from >7 days to approximately 30 min. Accelerated salt spray and filiform corrosion resistance tests were conducted to determine the effects of crosslinking on the corrosion resistance behavior of ormosil thin films. The choice of curing agent was found to influence film structure and corrosion resistance properties. Amine cured thin films were hard and highly adherent to the aluminum alloy substrates, exhibiting excellent bare and filiform corrosion resistance, in addition to good compatibility with organic polymer paint systems. In contrast, the adhesion and corrosion resistance of super acid cured thin films to aluminum alloy substrates was significantly less, producing films which readily delaminated from the substrate. These observations can be related to the film structure.

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