The determination of coating performance with impedance measurements-I. Coating polymer properties

Westing, E.P.M. van; Ferrari, G.; Wit, J.H.W. de

doi:10.1016/0010-938x(93)90245-c

Cited by 183 publications

(59 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is generally assumed that the elements of the equivalent circuits are correlated to the corrosion properties of the system [15,[21][22][23][24][25][26]. Although it is necessary in order to fit correctly the equivalent circuit to all impedance spectra versus frequency, this study is only related to the characterization of the hydrolysis degradation of the sol-gel coating, and for this reason we will focus our attention to those results obtained at the high frequency where the response of the coating to its exposition to electrolyte (parameters of the equivalent circuit R po and C c ) is located.…”

Section: Equivalent Circuit Interpretationmentioning

confidence: 99%

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

Hernández-Escolano

Juan-Díaz

Martínez‐Ibáñez

et al. 2012

J Sol-Gel Sci Technol

View full text Add to dashboard Cite

The controlled release of active agents from a matrix has become increasingly important for oral, trans-dermal or implantable therapeutic systems, due to the advantages of safety, efficacy and patient convenience. Controlled-release hybrid (organicinorganic) sol-gel coating synthesis has been performed to create a sol with an active molecule included (procaine). Synthesis proce-dures included acid-catalysed hydrolysis, sol preparation, the addition of a procaine solution to the sol, and the subsequent gelation and drying. The alkoxide precursors used were triethoxyvinylsilane and tetraethyl-orthosilicate (TEOS) in molar ratios of 1:0, 9:1, 8:2 and 7:3. After the determination of the optimal synthesis parameters, the material was physicochemically characterised by silicon-29 nuclear magnetic resonance ( 29 Si-NMR) and Fourier transform infrared spectroscopy, contact angle analysis and electrochemical impedance spectroscopy tests. Finally, the materials were assayed in vitro for their ability to degrade by hydrolysis and to release procaine in a controlled manner. The sustained release of procaine over a 3-day period was demonstrated. A close correlation between release and degradation rates suggests that film degradation is the main mechanism underlying the control of release. Electrochemical analysis reveals the formation of pores and water uptake during the degradation. The quantity of TEOS is one of the principal parameters used to determine the kinetics of degradation and procaine release.

show abstract

Section: Equivalent Circuit Interpretationmentioning

confidence: 99%

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

Hernández-Escolano

Juan-Díaz

Martínez‐Ibáñez

et al. 2012

J Sol-Gel Sci Technol

View full text Add to dashboard Cite

show abstract

“…The elements C dl and C ad were substituted by constant phase elements (CPE). The impedance of a CPE is given by the equation Z CPE ¼ Y À1 0 (jx) Àn , where Y 0 is the admittance constant of the CPE (in s n /X), x is the angular frequency (rad/s) and n is the CPE exponent, n ¼ a/(p/2) (a is the constant phase angle of the CPE) [16]. The capacitance of the double layer was estimated using the equation C ¼ Y 1=n 0 R (1Àn)/n , where R is the resistance parallel to the CPE [17].…”

Section: Impedance Measurementsmentioning

confidence: 99%

Influence of drying temperature on the corrosion performance of chromate coatings on galvanized steel

Zhang¹,

Böhm

Bosch

et al. 2004

Materials & Corrosion

View full text Add to dashboard Cite

The influence of drying temperature on the corrosion performance of chromate coatings on electro-galvanized (EG) steel has been investigated using electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements in 3.5% NaCl solutions. The chromate coatings were applied to the EG steel in a solution (pH 1.2) containing sodium dichromate and sulfuric acid at room temperature. The coatings were dried in an oven at three different temperatures: 60, 110 and 210 8C. The surface of the chromate coatings was analyzed using atomic force microscopy (AFM) and scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS). The results show that the drying temperature significantly affects the morphology of the chromate coatings and consequently affects their corrosion behavior. The chromate coatings dried at 110 8C had few cracks and the lowest corrosion current. The chromate coatings dried at 60 8C showed passivity. The EIS results show that the chromate coatings dried at 60 8C has the largest impedance in a neutral 3.5% NaCl solution. Drying at higher temperature (210 8C) degrades the chromate coatings by widening the cracks and reducing soluble Cr(VI) in the chromate layer. The favorable drying temperature for the chromate coatings on the EG steel is between 60 and 110 8C.

show abstract

“…4 However all polymeric coatings are permeable to corrosive species such as oxygen, water and ions to some extent. [5][6][7][8] Water molecules at the metal/coating interface may reduce the coating adhesion, thus favoring corrosion of the metal underneath the film.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Investigation into the Effect of Nano-Titania on the Protective Properties of Epoxy Coatings on Mild Steel in Natural Seawater

Raj¹

2017

IPCSE

View full text Add to dashboard Cite

The effect of introducing nano-tinania (TiO 2 ) particles to the epoxy coatings on mild steel in natural seawater was analyzed using Scanning Electrochemical Microscopy (SECM) and Electrochemical Impedance Spectroscopy (EIS). Line profile and topographic image analysis were measured by applying -0.70 V and +0.60 V as the tip potential for the cathodic and anodic reactions, respectively. The tip current at -0.70 V for the epoxy coated sample with TiO 2 nanoparticles decreased rapidly due to cathodic reduction of dissolved oxygen. The EIS measurements were conducted in natural seawater after wet and dry cyclic corrosion test. The EIS measured the film resistance (R f ) and charge transfer resistance (R ct ) values which were increased by the addition of TiO 2 nanoparticles in the epoxy coating. SEM/EDX and FIB-TEM analysis showed that complex oxides of titania were enriched in corrosion products at the scratched area of the coated steel and confirmed the presence of the nanoscale oxide layers of titania in the rust of the steel. The formation of complex oxides of titania had a beneficial effect on the corrosion resistance of coated steel. Keywords Electrochemical investigation into the effect of nano-titania on the protective properties of epoxy coatings on mild steel in natural seawater 144Copyright: ©2017 Raj et al. Nanoparticles, owing to high specific surface area and small particle size, can enhance the corrosion resistance of the organic coatings by increasing the electrolyte pathways length. Inclusion of metal nanoparticles to the organic coating provides cathodic protection to the underlying substrate. They also provide barrier and passive protection by generating oxides at a later stage. The importance of nanomaterials compared to conventional micro sized pigments is mainly due to their small size and large specific surface area. The decrease in size of the particles causes mechanical properties enhancement of the coating. There are a large number of reports indicating that the anticorrosion properties of the polyurethane coatings can be markedly improved in the presence of nanoparticles. Citation9-16 Titanium oxide is highly corrosion resistant and provides a barrier protection which is stable over a wide pH range. It is not classified as dangerous for human health and for environment. This has shown interest in using titanium oxide in organic coatings in the corrosion protection of steel. SECM has been introduced to evaluate the localized corrosion process, since it provides electrochemical activity and topographic information about the surface reactions at the micrometer scale in aqueous environments. [17][18][19][20][21] The application of SECM has facilitated experiments on the solid/liquid interface because of its high spatial resolution and electrochemical sensitivity.In this study, SECM was used primarily to evaluate the effect of TiO 2 nanoparticles on the corrosion protection performance of an epoxy coating over mild steel in natural seawater. The tip current was detected during the cor...

show abstract

The determination of coating performance with impedance measurements-I. Coating polymer properties

Cited by 183 publications

References 10 publications

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

The design and characterisation of sol–gel coatings for the controlled-release of active molecules

Influence of drying temperature on the corrosion performance of chromate coatings on galvanized steel

Electrochemical Investigation into the Effect of Nano-Titania on the Protective Properties of Epoxy Coatings on Mild Steel in Natural Seawater

Contact Info

Product

Resources

About