Corrosion Protection Of Steel Substrates Research Articles

The performance of a self‐adherent foil system for the corrosion protection of steel substrates for offshore wind tower structures

AbstractThe application of multilayer organic protective coating systems with conventional liquid spray methods is complex, time‐ and energy‐consuming, and it requires extensive technical equipment. An alternative to these methods is the application of thin, self‐adherent foil systems directly to the steel substrate. The corrosion protection performance of newly developed foil systems was tested for various combinations of foil materials and pressure‐sensitive adhesives (with and without corrosion inhibitors) and different surface preparation parameters by means of accelerated cyclic laboratory tests with simulated offshore conditions. The adhesion properties were determined by means of peel tests. The tests were designed, by means of statistical methods (design of experiments, analysis of variance). A foil system with the following factor combination was found to provide an optimum performance: Surface preparation grade: Sa 2½; roughness: Rz = 50–75 µm; abrasive material: high‐carbon steel grit; adhesive layer thickness: 200 g/m2; inhibitor material: calcium aluminum polyphosphate silicate hydrate; foil material: polyvinylchloride (160 µm) + poly(methyl methacrylate) (40 µm).

Designing a novel GO@AAP reinforced epoxy coating for achieving the long-term corrosion protection of steel substrate

In this study, 4-amino-antipyrine (AAP) was grafted on graphene oxide (GO) via the hydrothermal strategy (GO@AAP) to improve the corrosion resistant property of epoxy coating. Transmission electron microscope (TEM), scanning probe microscope (SPM) and Raman techniques were employed to investigate the morphology and structure of GO@AAP nanohybrid, which also effectively confirmed the successful AAP grafted on GO surface. Electrochemical and salt spray results indicated that incorporating as-synthesized GO@AAP into epoxy coating powerfully enhanced the anti-corrosion property, which was greatly consistent with the mild steel morphology after corrosion experiment. Besides, after 60 days of immersion, the |Z|0.01 Hz was 3.7 × 108 Ω·cm2, which was two order of magnitude higher than that of pure epoxy coating. Local electrochemical impedance spectroscopy (LEIS) was visually demonstrated the synergistic effect of physical shielding and corrosion inhibition of GO@AAP in 3.5 wt% NaCl solution. This work provides a new method to achieve the barrier and inhibition activities of epoxy coatings, which are suitable for heavy corrosion resistant application in harsh environment.

A layered superhydrophobic coating with excellent mechanical robustness and anti-corrosion performances

Lotus-like superhydrophobic coatings play an essential role for the corrosion protection of steel substrates exposed to harsh environments. Thus, improving the mechanical robustness and corrosion resistance of superhydrophobic coatings through macroscopic material matching and microscopic structure manipulation is an important task. In this study, a layered superhydrophobic coating with a “1 + 1” structural mode was successfully prepared using the spinning and spraying techniques. In order to prevent the interface debonding of upper and lower layers, the epoxy resin was introduced as bonding transition zones, and its three-dimensional cross-linking characteristic was used to realize the super stable “welding”. Then, the structure-function design, surface wetting behavior, mechanical robustness and corrosion resistance were systematically investigated. The results showed that the superhydrophobic coating was successfully constructed by designing micro-/nano-scale hierarchical structure and reducing surface energy, achieving a desirable static contact angle of 172.5° and a roll-off angle of 3.4°. Through high-pressure water anti-jetting, high-height sand impacting, and loaded sandpaper shear abrasion tests, the as-prepared coating still showed obvious superhydrophobicity and the shapes of water droplets on the coating surface continued to be nearly spherical. After immersion in 5 wt% NaCl solution for 28 days, an increase of polarization current density was negligible (∼0.0035 μA/cm2), and the impedance values (107 Ω•cm2) of the superhydrophobic coating were approximately three orders of magnitude higher than the control coating in the low-frequency region. This was because the corrosive species (H2O and Cl−) were restricted from entering the coating interior owing to the extreme water-repellence. In addition, the electron-carrying capacity of the superhydrophobic coating was vastly weakened, which impeded the formation of the corrosive conductive circuit and improved the anti-corrosion properties, prolonging the service life of the polymer coating system.

Durable superhydrophobic silica/epoxy resin coating for the enhanced corrosion protection of steel substrates in high salt and H2S environments

A superhydrophobic coating composed of epoxy on the bottom and siloxane-modified silica on the top was prepared by employing the scraping and spraying methods. The superhydrophobic coating possesses excellent mechanical properties, is superhydrophobic (water contact angle, WCA = 164.3°), and has low adhesion. The long-term corrosion resistance of the epoxy coating and the superhydrophobic coating in a 3.5 % NaCl solution and hydrogen sulfide environment was assessed using electrochemical impedance spectroscopy (EIS), polarization curve analysis, immersion testing, and X-ray diffraction (XRD). Test results indicate that the superhydrophobic coating has excellent anti-corrosion capability in an H2S environment for 50 days and in a 3.5 % NaCl solution for 60 days. This is of great significance for developing the potential applications of superhydrophobic coatings in H2S environments.

Self- replenishing superhydrophobic durable polymeric nanocomposite coatings for heat exchanger channels in thermal management applications

We developed two-coat polymeric nanocomposite coatings for the protection of steel structures from the thermal and corrosive environment. To protect the steel structures, the coating selectivity is crucial; we have chosen the coating such way, the coated surface has low surface energy polymer which has low surface polarity. The polymer nanocomposite coatings were prepared using polydimethylsiloxane with an optimal amount of zirconia nanoparticle. The incorporation of zirconia nanoparticle has extended the thermal stability and efficient corrosion protection of steel substrates. The formulated coatings exhibited a superhydrophobic characteristic with CA-165° and low contact angle hysteresis (<5°). The present study focuses more on the robust superhydrophobic behaviour, were studied using the effectiveness of underwater stability over 30 days in static immersion and water impingement analysis with a velocity of 7.302 m/s at continuous exposure. PDMS-ZrO2 composite films showed excellent resistance to different pH stress without loss of coating. The chemical composition and microstructure of the coatings were studied using EDX and SEM, respectively. The predictive life of the coating performance has been further evaluated by pool boiling test, Thermal shock test, and Electrochemical Impedance Spectroscopy.

Moving boundary simulation and mechanistic studies of the electrochemical corrosion protection by a damaged zinc coating

The mechanism of corrosion protection of steel substrate by a 96 wt% zinc primer that was damaged by scratch was simulated. The primer was approximated to pure zinc layer due to high percentage of zinc. Results show that while the middle of scratch is protected by sacrificial protection, at the corners of scratch a local cathodic inhibition results in barrier protection due to variations in the dissolved oxygen concentration. Moving boundary simulation allowed to predict the changes to the geometry of the corroding electrodes. Finally, taking into account zinc electrodes consumption, the period of sacrificial protection was predicted by simulations.

Corrosion protection of steel substrates by magnetron sputtered TiMgN hard coatings: Influence of surface morphology and Mg content on Mg release in NaCl solutions

TiMgN coatings with three different Mg contents (10, 20 and 35 at.%) were prepared by reactive magnetron co-sputtering. Three different coating microstructures have been studied by using i) polished and ii) sand-blasted sample surfaces and iii) by employing the Glancing angle deposition (GLAD) technique on polished substrates. The chemical composition was analyzed by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry or by glow discharge optical emission spectrometry and coating morphology was characterized by SEM on focused ion beam sliced samples. To determine the Mg release from the TiMgN samples two techniques measuring the open circuit potential were employed: a) an in-situ technique by using a scanning flow cell coupled to an inductively coupled plasma mass spectrometer and b) an ex-situ technique, namely inductively coupled plasma optical emission spectroscopy. The results (measured Mg release) from these two analysis techniques are compared and discussed with respect to results obtained from corrosion studies performed in neutral salt spray tests. It was found that the lowest Mg release has been determined for polished and the highest for GLAD samples. A correlation between the amount and duration of Mg release with the corrosion behavior of the samples could be established and formerly proposed corrosion protection mechanisms could be confirmed.

Corrosion protection of steel substrates by magnetron sputtered TiMgN hard coatings: Structure, mechanical properties and growth defect related salt spray test results

Hard and wear resistant coatings deposited by PVD techniques have been characterized for decades for their capabilities to protect steel substrates from corrosion. In the present work the effect of Mg incorporated into TiN coatings is described in terms of the corrosion behavior as well as the mechanical and structural properties.TiN and TiMgN films with Mg contents between 10 and 35 at.% were deposited onto mirror polished 100Cr6 (1.3505) steel samples with 2.5 and 5 μm thickness by using DC magnetron sputtering. The corrosion protection capabilities of the coatings were characterized by neutral salt spray (NSS) test, considering the amounts and sizes of growth defects inherent in each coated sample as determined by a recently developed optical scan method (Large Area High Resolution mapping). The defect data were statistically analyzed for improved interpretation of NSS test results. Chosen growth defects were additionally analyzed by focused ion beam technique. Furthermore the coating composition and morphology, the hardness and the tribological behavior were characterized.Polished steel samples coated with 2.5 μm TiMgN containing about 35 at.% Mg were in the plane free of corrosion after 24 h in a NSS test. TiMgN with 10 or 20 at.% Mg only provided a slightly improved corrosion protection in relation to pure TiN coatings, which was limited to certain types of growth defects. The highest Mg containing coatings exhibited a decreased hardness down to 1200 or 1800 HV depending on type of deposition (HV 1200: Ti- and Mg-target with rotating substrate holder, 1800: Mg-plugged Ti-target with static substrate holder), but also showed a strongly improved wear resistance against Al2O3 related to pure TiN.By analyzing the NSS test results it was found that the corrosion behavior of the coated samples did not only depend strongly on the Mg content, but also on the sample individual defect concentrations. Therefore this subject is extensively discussed.

Theoretical and experimental studies of dried marjoram leaves extract as green inhibitor for corrosion protection of steel substrate in acidic solution

ABSTRACTDried marjoram leaves (DML) aqueous extract solution was prepared and characterized by Fourier transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV). The effect of DML solution concentration on corrosion protection of mild steel in 0.5 M H2SO4 at different temperatures was studied using anodic and cathodic polarization and electrochemical impedance spectroscopy (EIS) measurements. It was determined from the polariazation curves that the DML acts as a mixed type inhibitor since, both the cathodic and anodic reactions of mild steel corrosion were inhibited. The protection efficiency increases with increasing concentration of DML and decreasing temperatures. The surface morphology was investigated before and after adsorption of DML molecules on the steel surface using scanning electron microscope (SEM). The activation and adsorption parameters were calculated and discussed. The results were supported using density functional theory (DFT), and the quantum chemical parameters were estimated. These parameters reveal the effect of the electronic structure of Thymol, the main component of DML, on its electron donating ability at the B3LYP/6-311 + G (d, p) level.

Testing of the New Chemical Pre-treatments Types Applied on the Steel Substrate

This article deals with the analysis of the chemical pre-treatment influence on the corrosion resistance of the low carbon unalloyed steel material after cold forming. These are the pre-treatments nanotechnology based. The layer is created by sol-gel technology. Except two used types of nano chemical pre-treatments is also used classical ferric phosphate. The six variants of chemical pre-treatments were prepared and these variants were then compared in terms of corrosion resistance and the way of exclusion and surface morphology using SEM and EDS analysis. The experimental samples were prepared for each variant. They were observed macroscopically and using SEM before corrosion load. These analysis shows the differences between each variant. Using SEM and EDS analysis was searched the typical elements for each variant and was observed the excluded layer and potential defects. The experimental samples were placed in the corrosion chamber and loaded according to the standard CSN EN ISO 9227 after this analyses. The surface of the experimental samples were without any other protection thus there was observed changes on the surface of the samples after one hour. The corrosion loading was finished after 24 hours. Experimental samples were evaluated macroscopically and were compared. The result of the experiment is the best variant of chemical pre-treatment in terms of corrosion protection of steel substrate concluded after all analyses and observations.

Electrophoretic deposition of nano-ceramics for the photo-generated cathodic corrosion protection of steel substrates

Electrophoretic deposition (EPD) was employed to deposit crystalline TiO2/WO3 nanoparticles onto stainless steel to fabricate a photo-generated cathodic protection layer. The electrophoretic mobility of the colloidal particles was determined by measuring the zeta-potential of the particles in the suspension. The surface morphology of the EPD layers was observed using scanning electron microscopy (SEM), and the composition of the EPD layer was determined from the peak intensity using an X-ray diffractometer (XRD). Furthermore, the open circuit potential (OCP) of the TiO2–WO3-deposited sample was measured under UV irradiation to evaluate the photo-generated cathodic protection ability of the EPD layers on stainless steel. Through the zeta-potential measurement, it was verified that the TiO2 particle was effectively charged by phosphoric acid di-butyl ester in iso-propanol, but the WO3 particle was slightly negatively charged because of the different zero point of charge. However, TiO2 and WO3 particles were deposited simultaneously via an EPD process at the same rate despite their different electrophoretic mobilities in the suspension. The TiO2–WO3 co-deposited layer was uniformly deposited, and no noticeable homo-aggregation of the same type of particle was observed. Using the OCP measurement, it was also found that stainless steel was cathodically protected from corrosion by UV light irradiation because the potential of the photo-stimulated EPD layers was more negative than the corrosion potential of stainless steel. Because the WO3 contents in the EPD layer were increased, the time of potential recovery was gradually delayed. Moreover, the addition of binders enhanced the adhesion strength between the metal and the layer that hindered the delamination and improved the cathodic protection performance. The potential recovery time of the EPD sample containing 40% TiO2–60% WO3 was approximately 6h after 3h of light irradiation, which implied that the steel was cathodically protected for 6h in dark conditions.

Surface analysis of PECVD organosilicon films for corrosion protection of steel substrates

AbstractThis study deals with the surface and electrochemical characterization of mild steel surfaces after plasma‐enhanced chemical vapour deposition of organosilicon films, performed in order to increase corrosion resistance. Coating deposition was performed in a home‐made reactor with hexamethyldisiloxane–oxygen–argon mixtures of different compositions and at different input power values on as‐received specimens and after a pretreatment step in oxygen‐containing plasma. Surface and morphological characterization of coatings was performed by x‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. To evaluate the protective effectiveness, electrochemical characterization of the coatings was carried out in sulphate‐containing solutions by electrochemical impedance spectroscopy.Notwithstanding their low thickness of ∼1000 nm, the organosilicon films show protective effectiveness properties against corrosion. An increase of the impedance values, related to an increase in the protective effectiveness, has been observed on films obtained at increasing input power and after O2 plasma pretreatment of the substrate. As shown by FTIR data, the positive effect of increasing input power may be related to the progressive increase of the inorganic nature of the deposited coatings, i.e. increase in SiOx groups and decrease of sylanol groups. Furthermore, as shown by XPS analysis, the good corrosion behaviour of mild steels coated after O2 plasma pretreatment may be attributed to removal of the surface contamination, which improves adhesion of the SiOx film, and to enhancement of the surface oxidation degree. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Plasma treatment of cold-rolled steel: actual state, problems to overcome and future

The corrosion protection of steel substrates is an important industrial process for many industries such as the automotive industry, the packaging industry etc. The most common methods of corrosion protection of steel surfaces are actually hot-dipping and electrodeposition. However, these methods suffer from several drawbacks: weak variety of coatings, multilayer deposition nearly impossible, important disposal and recycling costs. It is known that plasma deposition (including sputtering) of thin films can give a very dense structure with uniform deposition, low number of pinholes and adequate long-term corrosion performances. Most of the work in the plasma deposition has been restricted to small objects. Plasma processing for larger objects has been used preliminarily for plastic and glass substrates, but rarely on metallic substrates. In this paper, we shall discuss some of the literature and personal work related not only to surface cleaning and corrosion protection of steel but also to interface engineering for the improvement of paint adhesion. Type of coating, properties achieved will be discussed bearing in mind the industrial application. In addition, some technological aspects related to a continuous in-vacuum coating line will also be addressed. Finally, a few guidelines will be drawn for the implementation of vacuum technology in industry.