scholarly journals Aggressiveness of Different Ageing Conditions for Three Thick Marine Epoxy Systems

2021 ◽  
Vol 2 (4) ◽  
pp. 721-742
Author(s):  
Alexis Renaud ◽  
Victor Pommier ◽  
Jérémy Garnier ◽  
Simon Frappart ◽  
Laure Florimond ◽  
...  
Keyword(s):  
Salt Spray ◽  
Immersion Test ◽  
Organic Coating ◽  
Artificial Seawater ◽  
Galvanized Steel ◽  
Natural Seawater ◽  
Neutral Salt ◽  
Coating System ◽  
Coated Steel ◽  
Artificial Defect

Three different coated steel systems were aged in natural or artificial seawater, in neutral salt spray (NSS), and using alternate immersion tests in order to evaluate the aggressiveness of the different ageing conditions. Commercial epoxy coatings were applied onto steel (S355NL), hot-galvanized steel (HDG), and Zn-Al15 thermal spraying coated steel. The defect-free systems were immersed in artificial seawater at 35 °C for 1085 days and in natural seawater for 1200 days and were characterized by electrochemical impedance spectroscopy (EIS). Panels with artificial defects were immersed for 180 days in artificial seawater and, regarding adhesion, were evaluated according to ISO 16276-2. In parallel, the three coated systems were submitted to cyclic neutral salt spray (NSS) for 1440 h: defect-free panels were regularly evaluated by EIS, while the degree or corrosion was measured onto panels with artificial defect. After NSS, defect-free panels were immersed in artificial seawater at 35 °C for further EIS investigations. Finally, alternate immersion tests were performed for 860 days for the three defect-free coated systems and for 84 days for panels with a defect. The results showed that, for defect-free panels, immersions in natural or artificial seawater and NSS did not allowed us to distinguish the three different systems that show excellent anticorrosion properties. However, during the alternate immersion test, the organic coating system applied onto HDG presented blisters, showing a greater sensitivity to this test than the two other systems. For panels with a defect, NSS allowed to age the coatings more rapidly than monotone conditions, and the coating system applied onto steel presented the highest degree of corrosion. Meanwhile, the coating systems applied onto HDG and the thermal spray metallic coating showed similar behavior. During the alternate immersion test, the three coated systems with a defect showed clearly different behaviors, therefore it was possible to rank the three systems. Finally, it appeared that the alternate immersion test was the most aggressive condition. It was then proposed that a realistic thermal cycling and an artificial defect are needed when performing ageing tests of thick marine organic coating systems in order to properly rank/evaluate the different systems.

Characterization of a Chromium-Free Passivation Coating on Hot Dip Al-Zn Allay Coated Steel Sheets

2013 ◽  
Vol 634-638 ◽  
pp. 2931-2934
Author(s):  
Ping Yuan
Keyword(s):  
Salt Spray ◽  
Optical Emission ◽  
Acrylic Resin ◽  
Organic Coating ◽  
Neutral Salt ◽  
Coated Steel ◽  
Corrosion Performance ◽  
Steel Sheets ◽  
Coated Steel Sheet ◽  
Passivation Coating

The hot dip Al-Zn alloy coated steel sheet was passivated with chromium-free passivation solution which adopted the molybdate and acrylic resin as the main film-forming substances. The surface morphology and corrosion performance of the coating were studied experimentally by using glow discharge optical emission spectroscopy(GD-OES), scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDS), polarization curves and the neutral salt spray test. The GD-OES and SEM results show that the molybdate-containing thin organic coating is deposited on the substrate compactly and homogeneously without obvious tiny cracks. The test results of corrosion performance show that the corrosion potential and current density of the passive films decrease obviously in comparison with those of the substrate, and the corrosion resistance of the coating is comparable with that of the chromate passivation coating.

The corrosion protection of AA2024-T3 aluminium alloy by leaching of lithium-containing salts from organic coatings

2015 ◽  
Vol 180 ◽  
pp. 511-526 ◽  
Author(s):  
Peter Visser ◽  
Yanwen Liu ◽  
Xiaorong Zhou ◽  
Teruo Hashimoto ◽  
George E. Thompson ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Salt Spray ◽  
Protective Layer ◽  
Middle Layer ◽  
Organic Coating ◽  
Organic Coatings ◽  
Inhibition Mechanism ◽  
Dense Layer ◽  
Neutral Salt ◽  
Protective Layers

Lithium carbonate and lithium oxalate were incorporated as leachable corrosion inhibitors in model organic coatings for the protection of AA2024-T3. The coated samples were artificially damaged with a scribe. It was found that the lithium-salts are able to leach from the organic coating and form a protective layer in the scribe on AA2024-T3 under neutral salt spray conditions. The present paper shows the first observation and analysis of these corrosion protective layers, generated from lithium-salt loaded organic coatings. The scribed areas were examined by scanning and transmission electron microscopy before and after neutral salt spray exposure (ASTM-B117). The protective layers typically consist of three different layered regions, including a relatively dense layer near the alloy substrate, a porous middle layer and a flake-shaped outer layer, with lithium uniformly distributed throughout all three layers. Scanning electron microscopy and white light interferometry surface roughness measurements demonstrate that the formation of the layer occurs rapidly and, therefore provides an effective inhibition mechanism. Based on the observation of this work, a mechanism is proposed for the formation of these protective layers.

scholarly journals Effect of Inorganic Filler Addition on Non-Combustible and Mechanical Properties of Color Coated Steel Sheets

2020 ◽  
Vol 58 (11) ◽  
pp. 768-775
Author(s):  
Moon-Hi Hong ◽  
In-kyu Kim ◽  
Hye-Jeong Yun
Keyword(s):  
Mechanical Properties ◽  
Large Scale ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Inorganic Filler ◽  
Coated Steel ◽  
Coating Materials ◽  
Steel Sheets ◽  
Glow Discharge Spectroscopy ◽  
Coated Layer

Recent large-scale fires in buildings and logistic warehouses have become a major social issue, involving both property loss and multiple casualties. To make color coated steel sheets non-combustible and/or have anti-fire properties, various ways of optimizing manufacturing parameters have been investigated for outer, inner, roof and ceiling panels. In the present study, the effect of inorganic filler content and size on the non-combustible and mechanical properties of color coated steel sheets has been investigated using samples prepared as pre-painted coating materials. Both salt spray corrosion and chemical resistance tests were also carried out. Filler distribution and size were measured by optical microscopy, scanning electron microscopy and glow discharge spectroscopy, and found to be critical factors affecting non-combustible performance. As the amount of added filler increased, the non-combustible property of the color coated steel sheets improved, while mechanical properties, corrosion resistance by salt spray and chemical resistances deteriorated. During 3t-bending tests, the adhesive strength at the interface between coated layer and hot dip galvanized steel sheets was rather strong, although the filler-added upper coated layer was mostly peeled off. The mechanical properties of 30% filler addition samples were compared to samples with less than 20% filler addition. The main reason for the poorer performance was clarified in terms of filler size and crack propagation in the 3t-bended color coated layer.

Study of Corrosion Behaviour of Molybdenum Series Coatings on Galvanized Steel

2011 ◽  
Vol 399-401 ◽  
pp. 1972-1975 ◽  
Author(s):  
Hui Min Zhang ◽  
Lin Wu ◽  
Zhao Hui Ouyang ◽  
De Lian Yi ◽  
Qiao Hua ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Acrylic Resin ◽  
Galvanized Steel ◽  
Coupling Agents ◽  
Neutral Salt ◽  
Tafel Polarization ◽  
Chromate Coating

In this paper, an organic/inorganic molybdenum series Cr-free coating was formed on galvanized steel by simple immersion and its corrosion behavior was compared to that of a typical chromate coating. Molybdate and 1-Hydroxy-ethylidene-1, 1-diphosphonic acid (HEDP) were used as corrosion inhibitor, as well as acrylic resin and silane were used as film-former and coupling agents, respectively. The corrosion behavior of the coatings was evaluated by Neutral salt spray (NSS), Electrochemical impedance spectroscopy (EIS) and Tafel polarization. The surface topography of the samples was observed by Scanning Electron Microscopy (SEM). The results indicated that the corroded area of the Mo-HEDP treatment was only corroded 2% after 72 h spraying, while the corrosion behaviour of Mo-HEDP was closed to that of Cr pretreatment due to the synergistic reaction of molybdate and HEDP. Compared with the film of Cr treatment, Mo-HEDP passivating coating was more environmentally friendly.

Passivation Effect of Rare Earth Lanthanum on Galvanized Steel

2014 ◽  
Vol 525 ◽  
pp. 31-34
Author(s):  
Xiao Feng Liu
Keyword(s):  
Corrosion Resistance ◽  
Rare Earth ◽  
Electrochemical Impedance ◽  
Orthogonal Experiment ◽  
Salt Spray ◽  
Conversion Coating ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
White Rust ◽  
Order Of Magnitude

By way of chemical marinate method, carrying out rare earth lanthanum to corrosion protect galvanized steel. The process of rare earth lanthanum conversion coating for galvanized steel was studied by using orthogonal experiment to get the optimized passivation parameters when the concentration of La (NO3) is 30g/L, H2O2is 20ml/L, pH=4 and was passivated at 40°C for 30s. The corrosion resistance was examined by weight loss tests, neutral salt spray tests (NSS) and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion impedance of the pretreated sample was significantly improved, the corrosion rate was decreased by one order of magnitude, and the anti-white rust time was 54h.

Paintability of Traditional and Chromium(VI)-Free Conversion Layers on Galvanized Steels

2008 ◽  
Vol 589 ◽  
pp. 415-420
Author(s):  
Szilvia Kőszegi ◽  
Éva Dénes
Keyword(s):  
Electrochemical Impedance ◽  
Salt Spray ◽  
Earth Metal ◽  
Organic Coating ◽  
Galvanized Steel ◽  
Cerium Chloride ◽  
Corrosion Properties ◽  
Chromium Vi ◽  
Pre Treatment ◽  
Duplex Systems

Continuous hot dip galvanized steel samples have been treated with traditional chromium(VI)-containing passivator and environment friendly rare-earth metal containing ceriumsalt and lanthanum-salt based solutions using different immersion times. The treated surfaces have been examined by scanning electron microscope equipped with an energy dispersive X-ray analyser. After the pre-treatment the samples have been spray-painted with epoxy-based organic paint. The adhesion was tested with bending and cross-cut test. Thereafter salt spray test was performed on duplex systems. After 48 hours samples have been taken out from the corrosion chamber in order to perform electrochemical impedance measurements for 24 hours. Based on the results the most promising passivation among the chromium(VI)-free solutions has been found to be the cerium-salt based treatment. The adhesion of the organic coating was better on cerium-chloride treated substrate than on chromated one, while the anti corrosion properties of the two duplex systems were comparable.

The Evaluation of Organic Coating with Artificial Defect Degradation with EIS Measurement: Phase Angle at High Frequencies

2011 ◽  
Vol 194-196 ◽  
pp. 2027-2030
Author(s):  
Jie Liu ◽  
Xiang Bo Li ◽  
Jia Wang ◽  
Shou Biao Li
Keyword(s):  
Phase Angle ◽  
Electrochemical Impedance ◽  
Organic Coating ◽  
Natural Seawater ◽  
Impedance Spectra ◽  
Electrochemical Impedance Spectra ◽  
Artificial Defect ◽  
High Frequencies ◽  
Damage Rate ◽  
Phase Angles

Electrochemical impedance spectra (EIS) of two kinds of damage rate samples in natural seawater were measured and the relations between coating resistances and phase angles at high frequencies were analyzed. The results indicated that for the coating systems studied, the variation of phase angles at 14 kHz with immersion time was very close to the variation of coating resistance, hence may qualitatively reflect the coating with artificial defect degradation. This approach contains no error in calculation and the special phase angle parameters could be extracted easily from the EIS measured data. These phase angle parameters may be used as quick measurements to evaluate coating with artificial defect performance.

scholarly journals A Novel Accelerated Corrosion Test for Supporting Devices in a Floating Photovoltaic System

2021 ◽  
Vol 11 (8) ◽  
pp. 3308
Author(s):  
Chun-Kuo Liu ◽  
Zhong-Ri Kong ◽  
Ming-Je Kao ◽  
Teng-Chun Wu
Keyword(s):  
Corrosion Test ◽  
Salt Spray ◽  
Protective Layer ◽  
Photovoltaic System ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
Accelerated Corrosion ◽  
Accelerated Corrosion Test ◽  
Type 304

Recently, countries from around the globe have been actively developing a new solar power system, namely, the floating photovoltaic (FPV) system. FPV is advantageous in terms of efficiency and cost effectiveness; however, environmental conditions on the surface of water are harsher than on the ground, and the regulations and standards for the long-term durability of supporting devices are insufficient. As a result, this study aims to investigate the durability of supporting devices through a novel type of accelerated corrosion test, copper-accelerated acetic acid salt spray (CASS). After an eight-day CASS test, the results demonstrated that only a small area of white protective layer on the SUPERDYMA shape steel was fully corroded and rusted. Moreover, five types of screw, fastened solidly on the SUPERDYMA shape steel, namely a galvanized steel screw capped with a type 316 stainless steel (SS) nut, a type 304 SS screw, a type 410 SS screw, a chromate-passivated galvanized steel screw, and a XP zinc–tin alloy coated steel screw, achieved varying degrees of rust. In general, the corrosion degree of the eight-day CASS test was more serious than that of the 136-day neutral salt spray (NSS) test. Therefore, the CASS test is faster and more efficient for the evaluation of the durability of supporting devices.

Corrosion Behavior of Tungsten Copper Alloy Produced by Infiltration Sintering

2015 ◽  
Vol 816 ◽  
pp. 699-704
Author(s):  
Bo Lv ◽  
Da Tong Zhang
Keyword(s):  
Corrosion Behavior ◽  
Corrosion Potential ◽  
Salt Spray ◽  
Electrochemical Measurement ◽  
Corrosion Current ◽  
Immersion Test ◽  
Cold Isostatic Pressing ◽  
Neutral Salt ◽  
Bonding Phase ◽  
Superior Corrosion Resistance

In this paper, W80CuNi0.3 alloy was prepared by cold isostatic pressing (CIP) and infiltration sintering, and its corrosion behavior was investigated by neutral salt spray accelerated test, immersion test and electrochemical measurement. It turned out that in the neutral salt spray and immersion test,the mass loss and corrosion rate of W80CuNi0.3 were far lower than those of 45 steel. The corrosion mainly occurs in the bonding phase of Cu, and the initial corrosion form of W80CuNi0.3 was pitting, the main reason of W80CuNi0.3 corrosion was Cl- erosion. The polarization curves analysis showed that compared with 45 steel, W80CuNi0.3 alloy had higher corrosion potential and lower corrosion current. Therefore, W80CuNi0.3 alloy are prone to stable passivation, so it has superior corrosion resistance.

scholarly journals Accelerated Corrosion Tests in Quality Labels for Powder Coatings on Galvanized Steel—Comparison of Requirements and Experimental Evaluation

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6547
Author(s):  
Izabela Kunce ◽  
Agnieszka Królikowska ◽  
Leszek Komorowski
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Protection ◽  
Experimental Evaluation ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Neutral Salt ◽  
Powder Coatings ◽  
Accelerated Corrosion ◽  
Corrosion Tests ◽  
Accelerated Corrosion Tests

Powder coatings are widely applied for corrosion protection of steel, aluminum, and hot dip galvanized steel in a variety of corrosive environments. Powder coatings are subjected to a number of strict laboratory tests to determine their mechanical properties, corrosion resistance, and color stability. Among European quality certificates for powder coatings applied to galvanized steel, the most commonly recognized are GSB-ST and Qualisteelcoat certificates, which also refer to the EN 13438 standard. Certificates of quality for powder coatings are constantly updated according to the latest research results and experience of specialists operating in the field of corrosion protection. This paper presents an experimental evaluation of how the required length of selected accelerated corrosion tests can affect the final assessment of powder coatings. On the example of two powder painting systems: polyester as well as based on epoxy and polyester resins, the paper presents the influence of the time of accelerated corrosion tests: ISO 6270, ISO 9227 (Neutral Salt Spray and Acetic Acid Salt Spray), and ISO 3231 on the protective properties of the coatings. The results of damage assessment according to ISO 4628 have been correlated with the requirements of particular quality specifications. Additionally, based on FTIR (Fourier Transform Infrared Spectroscopy) and EIS (Electrochemical Impedance Spectroscopy) analyses, the influence of the applied corrosion tests on the degradation degree of the coatings studied has been presented. The paper aims to present a tests for those powder coating systems applied to facilities for which the main requirement is corrosion resistance rather than aesthetics.

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