A Comparison of the Corrosion Response of Zinc-Rich Coatings with and Without Presence of Carbon Nanotubes Under Erosion and Corrosion Conditions

CORROSION ◽  
10.5006/2743 ◽  
2018 ◽  
Vol 74 (11) ◽  
pp. 1203-1213 ◽  
Author(s):  
Dailin Wang ◽  
Elzbieta Sikora ◽  
Barbara Shaw
Keyword(s):  
Carbon Nanotubes ◽  
Elevated Temperature ◽  
Aqueous Electrolyte ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Chloride Concentration ◽  
Synergic Effect ◽  
Corrosive Environment ◽  
Degradation Mechanisms ◽  
Galvanic Couples

Electrochemical impedance spectroscopy tests were conducted on carbon nanotubes (CNTs) enriched zinc-rich epoxy coating and a commercial zinc-rich coating. Coating performances were examined after exposure to a corrosive environment (a CO2 saturated aqueous electrolyte with 2,000 ppm chloride concentration and pH 3.5 to 5.3) at an elevated temperature of 60°C. The coatings’ response after solid particle impingement erosion was also studied. Equivalent circuit models were proposed to elucidate the degradation mechanisms of the zinc-rich coatings under the synergic effect of corrosion and erosion. Results showed that the addition of CNTs into zinc-rich coatings provided better barrier protection for the steel substrate than traditional zinc-rich coatings in the noneroding environment. However, the CNT-filled zinc-rich epoxy coatings did not provide adequate protection when the coated specimens were exposed to an erosive and corrosive environment. CNTs could help with maintaining continuous electrical paths within zinc-rich coatings; however, the conductivity of the coating decreased significantly when zinc particles were partially oxidized. When defects caused by erosion are present in the coatings, CNTs may form galvanic couples with the steel and thus increase the corrosion rate of steel substrate.

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

scholarly journals Sacrificial Dissolution of Zinc Electroplated and Cold Galvanized Coated Steel in Saline and Soil Environments: A Comparison

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 744
Author(s):  
Ameeq Farooq ◽  
Umer Masood Chaudry ◽  
Ahsan Saleem ◽  
Kashif Mairaj Deen ◽  
Kotiba Hamad ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Electrochemical Impedance ◽  
Saline Soil ◽  
Steel Substrate ◽  
Salt Spray ◽  
Steel Structures ◽  
Open Circuit ◽  
Cyclic Polarization ◽  
Transfer Resistance ◽  
Soil Solutions

To protect steel structures, zinc coatings are mostly used as a sacrificial barrier. This research aims to estimate the dissolution tendency of the electroplated and zinc-rich cold galvanized (ZRCG) coatings of a controlled thickness (35 ± 1 μm) applied via brush and dip coating methods on the mild steel. To assess the corrosion behavior of these coated samples in 3.5% NaCl and 10% NaCl containing soil solutions, open circuit potential (OCP), cyclic polarization (CP), and electrochemical impedance spectroscopy (EIS) tests were performed. The more negative OCP and appreciably large corrosion rate of the electroplated and ZRCG coated samples in 3.5% NaCl solution highlighted the preferential dissolution of Zn coatings. However, in saline soil solution, the relatively positive OCP (>−850 mV vs. Cu/CuSO4) and lower corrosion rate of the electroplated and ZRCG coatings compared to the uncoated steel sample indicated their incapacity to protect the steel substrate. The CP scans of the zinc electroplated samples showed a positive hysteresis loop after 24 h of exposure in 3.5% NaCl and saline soil solutions attributing to the localized dissolution of the coating. Similarly, the appreciable decrease in the charge transfer resistance of the electroplated samples after 24 h of exposure corresponded to their accelerated dissolution. Compared to the localized dissolution of the electroplated and brush-coated samples, the dip-coated ZRCG samples exhibited uniform dissolution during the extended exposure (500 h) salt spray test.

Low velocity oxy fuel spraying of hydroxyapatite coating on a multifunctional UNS S31254 austenitic stainless steel

2021 ◽  
pp. 095441192110157
Author(s):  
Srikant Tiwari ◽  
Suryanarayan B Mishra
Keyword(s):  
Stainless Steel ◽  
Calcium Phosphate ◽  
Austenitic Stainless Steel ◽  
Bacterial Adhesion ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Steel Substrate ◽  
The Body ◽  
Low Velocity ◽  
Uncoated Steel

Artificial material such as stainless steel (SS) is widely used for orthopaedic applications owing to its superior properties, ease of fabrication and lower cost. However, in the body environment, stainless steel can leach toxic elements such as nickel and chromium. To prevent this, a hydroxyapatite (HAp) coating having chemical characteristics very similar to the human bone was deposited on a medical-grade UNS S31254 austenitic stainless steel by a Low-velocity oxy-fuel spray gun (LVOF). The coating was characterised by using a field emission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and Fourier transform infrared spectroscope (FTIR). The adhesion strength, microhardness and corrosion behaviour were studied using the Tensometre, Vickers microhardness tester and potentiodynamic polarisation with electrochemical impedance spectroscope. The bacterial adhesion and bioactivity of the coating were also evaluated. The LVOF sprayed HAp coating has shown better corrosion resistance, higher bioactivity and higher hardness than the uncoated steel. The presence of tricalcium phosphate, octa-calcium phosphate (OCP) and tetra-calcium phosphate (TTCP) was found in the coating. LVOF sprayed HAp coating is also found suitable in lowering the bacterial adhesion on the steel substrate.

Effect of coating composition on the anticorrosion performance of a silane sol–gel layer on mild steel

RSC Advances ◽  
2015 ◽  
Vol 5 (129) ◽  
pp. 106485-106491 ◽  
Author(s):  
A. Foroozan E. ◽  
R. Naderi
Keyword(s):  
Mild Steel ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Sol Gel ◽  
Gel Layer ◽  
Gel Film ◽  
Coating Composition ◽  
Anticorrosion Performance ◽  
Protective Performance ◽  
Mild Steel Substrate

In this study, the effect of coating composition on the protective performance of an eco-friendly silane sol–gel film applied on a mild steel substrate was investigated using electrochemical impedance spectroscopy and surface analysis methods.

scholarly journals Structure and Properties of TiO2/nanoTiO2 Bimodal Coatings Obtained by a Hybrid PVD/ALD Method on 316L Steel Substrate

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4369
Author(s):  
Marcin Staszuk ◽  
Daniel Pakuła ◽  
Łukasz Reimann ◽  
Anna Kloc-Ptaszna ◽  
Mirosława Pawlyta ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Electrochemical Properties ◽  
Surface Engineering ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Atomic Layer ◽  
Scanning Transmission Electron Microscope ◽  
Structural Defects ◽  
Structure And Properties ◽  
316L Steel

This paper presents the synergy of the effect of two surface engineering technologies—magnetron sputtering (MS-PVD) and atomic layer deposition (ALD) on the structure and properties of 316L steel. Recent studies indicate that PVD coatings, despite their thickness of a few micrometers, have many discontinuities and structural defects, which may lead to pitting corrosion after time. Applying an ALD layer to a PVD coating seals its structure and contributes to extending the service life of the coating. Investigations of the structure and morphology of the produced layers were carried out using a scanning electron microscope (SEM) and atomic force microscope (AFM). In addition, the structure of the coatings was investigated on the cross-section using a scanning-transmission electron microscope S/TEM. The tribological properties of the materials studied were determined by the ball-on-disc method. The corrosion resistance of the tested materials was determined by the electrochemical potentiodynamic method by recording the polarization curves of the anodes. Additional information about the electrochemical properties of the tested samples, including the quality, their tightness, and their resistivity, was obtained by electrochemical impedance spectroscopy (EIS). In addition, the main mechanisms of corrosion and tribological wear were determined by SEM observations after corrosion tests and after tribological tests. The study showed that the fabrication of hybrid layers by MS-PVD and ALD techniques allows obtaining coatings with electrochemical properties superior to those of layers fabricated by only one method.

UNUSUAL ELECTROCHEMICAL RESPONSE OF ELECTROCHEMICAL ETCHING ON MULTIWALLED CARBON NANOTUBES

NANO ◽  
2008 ◽  
Vol 03 (06) ◽  
pp. 461-467 ◽  
Author(s):  
JIAN-SHAN YE ◽  
GUANGQUAN MO ◽  
WEI DE ZHANG ◽  
XIAO LIU ◽  
FWU-SHAN SHEU
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Electrochemical Impedance ◽  
Electrochemical Etching ◽  
Current Response ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Oxidation Of Glucose ◽  
Total Disappearance ◽  
Electrocatalytic Effects

Multiwalled carbon nanotubes (MWNTs) can be etched at potentials more positive than 1.7 V versus Ag / AgCl (3 M KCl ) in 0.2 M HNO 3. The electrochemically etched MWNTs show an increase in electrochemical impedance and sluggish electron transfer kinetics, and lose the electrocatalytic effects toward the oxidation of glucose, H 2 O 2, uric acid (UA) and L-ascorbic acid (L-AA). Transmission electron microscope (TEM) images reveal that the nanotube tips are cut off by electrochemical oxidation. This may lead to the degradation of electrocatalytic ability in the MWNTs. Furthermore, the current response after different electrochemically etched cycles shows that the electrocatalytic ability of the MWNTs toward different molecules can be tuned by etched cycles. For example, five etched cycles leads to the total disappearance of the oxidative response to L-AA, with the remaining over 50% of the UA current response in the L-AA and UA mixture. Thus, electrochemical etching is a simple yet novel way to tune the electrocatalytic reactivity and improve the selectivity of the MWNTs.

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