Corrosion Behavior Of Zinc Research Articles

Effect of Soil Moisture on Corrosion Behavior of Zinc in Simulated Soil Environment

Effect of Soil Moisture on Corrosion Behavior of Zinc in Simulated Soil Environment

Role of Al and Mg alloying elements on corrosion behavior of zinc alloy‐coated steel substrates in 0.1 M NaCl solution

AbstractThe corrosion behavior and corrosion products of three zinc alloy‐coated steel substrates with different Al and Mg contents such as hot‐dip galvanized steel (HDG), Zn–Al‐coated steel (ZA), and Zn–Al–Mg‐coated steel (ZM) substrates were investigated during 168 h of immersion in 0.1 M NaCl solution. The characteristics and morphology of corrosion products on all the substrates formed during exposure to electrolyte solution were observed by X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy. Their electrochemical behavior was investigated by open‐circuit potential, polarization curves, and electrochemical impedance spectroscopy. The addition of Al and Mg alloying elements affected the corrosion mechanism as well as the anticorrosion properties. The main crystalline corrosion products on the HDG surface were simonkolleite and zincite, while the ZnAl hydrotalcite was identified as the main corrosion product on ZA and ZM surfaces. The corrosion resistance of ZA and ZM substrates was improved compared to the HDG substrate due to the enhanced adhesion of the corrosion product layer.

Corrosion behavior of zinc and copper coated structural steels in soil environments

AbstractCorrosion behavior of structural carbon steels grade SS400 coated with copper and zinc exposed to soil sample extracted from the central part of Thailand is studied using weight loss analyses and electrochemical methods, including open circuit potential monitoring for 3600 seconds, electrochemical impedance spectroscopic analyses and potentiodynamic polarization measurements. Bare carbon steels are also examined as a reference. Open circuit potential and polarization resistance of all samples are measured on (1, 2, 3, 4, 7, 10, 15, 30, 45, 60, 77 and 91) days of exposure. Corrosion potential is monitored only on the first and last days. After 91 days, corrosion rate in millimeter per year is calculated from weight loss and corrosion product is characterized. Effects of coating material, thickness and process on corrosion resistance of carbon steel subjected to soil environment are reported and discussed.

Effects of Surface Preparation on the Corrosion Behavior of Mild Steel

Surface preparation of engineering materials is necessary for preventing corrosion and subsequent failure of materials in service. There are different methods of surface preparations that can affect engineering materials in different ways. This study investigated the effect of surface preparation on the corrosion behavior of zinc sprayed and unsprayed mild steel. Quantitative analysis and potentiodynamic polarization techniques were used to evaluate the immersed samples of different surface preparations. The results indicated that the least corrosion rate was observed for the uncoated sample prepared with CC1200 grit paper at 0.041 mpy and successive samples in the order of CC220 grit paper at 0.047 mpy < P60 grit paper at 0.052 mpy < filing at 0.064 mpy and grinding at 0.074 mpy after 42-days of immersion. The prepared samples that were further coated with zinc spray demonstrated a similar trend. The sample prepared with CC1200 grit paper and further coated with zinc spray exhibited the lowest corrosion rate of 1.35 x 10-9 mpy. Potentiodynamic polarization results further suggested that the same behavior was observed in the quantitative analysis.

Corrosion Behavior of Zinc Covered with Native Oxides Under Thin Solution Films

This study clarified the influence of native oxides on the atmospheric corrosion of Zn. The electrochemical impedance spectroscopy (EIS) values of native-oxide-covered Zn were measured under thin solution films of 10 μm to 500 μm in thickness. The native oxides were formed by exposing pure Zn plates to humidified air at two different temperatures, 25°C and 60°C, for the duration of one week. EIS was applied to the native-oxide-covered Zn for measurement under thin solution films; the results were analyzed using a transmission line equivalent circuit to determine the charge-transfer resistance (Rct). The native oxide formed at 25°C strongly suppressed the corrosion rate (1/Rct) of Zn, which was independent of the solution film thickness (Xf). However, the 1/Rct was not reduced by the native oxides formed at 60°C, as it was dependent on Xf. This paper discusses the different behaviors of the native oxides in the context of corrosion protection.

Al2O3 Coatings on Zinc for Anti-Corrosion in Alkaline Solution by Electrospinning

The severe corrosion accompanied with hydrogen evolution reaction has become the main obstacle restricting the utilization of zinc as an electrode in alkaline batteries. Al2O3 coating helps control the corrosion of zinc in alkaline solution. Herein, a stable Al2O3 coating is fabricated through facile electrospinning from Al(NO3)3 as an efficient anti-corrosion film on zinc. The electrospinning technique facilitates uniform dispersion of Al2O3 particles, therefore the corrosion inhibition efficiency could be up to 88.5% in this work. The Al2O3 coating prevents direct contact between zinc and the alkaline solution and minimize hydrogen evolution. Further, the effects of the thickness of Al2O3 coating on corrosion behavior of zinc are investigated through hydrogen evolution reaction, Tafel polarization, and impedance test. The results show that the thicker Al2O3 coating possessed better corrosion inhibition efficiency due to the higher corrosion resistance and lower porosity. The 18 μm Al2O3 coating on zinc provides corrosion current density of 60.6 mA/cm2, while the bare zinc substrate delivers as much as 526.3 mA/cm2.This study presents a promising approach for fabricating Al2O3 coating for corrosion-resistant applications.

Electrochemical Characterization of Corrosion Behavior of Zinc in Different Sodium Chloride Solution by comparing Two Electrode and Three Electrode Setups

Electrochemical Characterization of Corrosion Behavior of Zinc in Different Sodium Chloride Solution by comparing Two Electrode and Three Electrode Setups

The Effect of Vinyl-Siloxane Nanolayers on the Corrosion Behavior of Zinc

The effect of surface siloxane nanolayers on the electrochemical and corrosion behavior of zinc is studied. It is found that surface self-organizing siloxane nanolayers inhibit anodic dissolution of zinc and its corrosion in chloride-containing electrolytes and under atmospheric conditions and can also cause a decrease in the pitting rate on the metal surface. It is established that the inhibiting effect of the vinyl-siloxane nanolayer depends on its thickness. Thus, the surface siloxane monolayer is insufficient for suppressing corrosion processes. Siloxane layers with a thickness above two or three molecular layers most efficiently inhibit corrosion and local dissolution of zinc. At this thickness, the most ordered surface structures are apparently formed. The FTIR method is used to show that the formed surface self-organizing vinyl-siloxane nanolayers on zinc are stable under exposure to sodium chloride solution and preserve strong bonds with the metal surface despite the occurring corrosion processes.

EIS of Zinc Under Thin Solution Films with Various Thicknesses Analyzed By a Transmission Line Equivalent Circuit

In this research, an influence of corrosion products on corrosion behavior of zinc under thin solution films with various thicknesses was studied by electrochemical impedance spectroscopy (EIS). The corrosion products evaluated in this work were formed during periods of exposure corresponding to 1, 3, 6, and 12 months in a natural environment (Japan Weathering Testing Center, Japan) compared with the non-exposed (polished zinc). A solution of 0.2 M NaCl was used as the thin film under conditions varying thickness from 5 to 800 µm. For the films thicker than 50 μm, the solution was directly placed whole electrode cell surface with a micropipette. However, For the films thinner than 25 μm, the solution was prepared by mixing with ethanol on the cell surface. The EIS was carried out to monitor impedance behavior at an open circuit potential (OCP) from the frequency range 10 kHz to 10 mHz. The impedance for the interface of metal and electrolyte (Z total) was obtained by dividing the measured impedance with the two-electrode cell by two. A transmission line model equivalent circuit (TML model) as shown in figure 1 was employed to describe the electrochemical impedance behavior. The EIS bode plots show different behaviors when the thickness of thin solution film changes. From the θ vs. log f plot in exposed zinc, all the shapes show two-time constants, one at high frequencies (HFL) and another at low frequency (LFL) where the phase shift does not exceed -45o. It means current distribution remains non-uniform even in a whole range of frequency in all cases. All electrochemical parameters were successfully obtained from the fitting method by applying the TML equivalent circuit of a metal-thin electrolyte layer interface. The appropriate initial values were optimized before input into the fitting software with the two-time constant. Some parameters of corrosion products such as resistance Rf* and capacitance CPEf* at thickness 800 μm were fixed for all thickness in the same exposure periods, where residual parameters in TML circuit were free. Charge transfer resistance R ct obtained from the fitting results (TML model) was used to study the corrosion behavior. The corrosion current density (i corr) can be calculated from the Stern-Geary equation, k= 13 mV and 4 mV for polished and exposed zinc respectively. For polished zinc, the results of polished zinc show that its corrosion behavior was dependent on a varying of the thin solution films. The i corr tends to increase while the thickness was reduced approximately to 25 µm. This behavior can be described by the diffusion limited current density (i lim) is the important parameter affected by the electrolyte layer thickness in cathodic reaction, i.e., an enhancement of diffusion process of O2 through the water layer. Then, the corrosion behavior is cathodically control. Further reduce of the thickness decreased the i corr due to a lack of amount of water needed for hydration of dissolved metal ions. Therefore, in a transition area, the corrosion rate is anodically control. On the other hand, the i corr of the exposed zinc have the approximate value and the corrosion behavior was independent of the thin solution films for whole thickness range. From these results, they might not be controlled by mass transport (O2 diffusion) but they must be controlled by the charge transfer process for both cathodic and anodic reaction. The cathodic and anodic polarization of the exposed and polished zinc were also measured in 0.2 M NaCl bulk solution. Before measurement, open circuit potential (E ocp) was monitored. The polarization curves show the deviation of Tafel slope for exposed zinc (1, 3, 6 and 12 months) compared to non-exposed one (polished zinc). E ocp of exposed zinc approaches to the positive values. It can be preliminary implied that the charge transfer process of both cathodic and anodic reaction was suppressed by zinc corrosion products which were identified as Zincite (ZnO) and Simonkolleite (Zn5(OH)8Cl2.H2O) whereas the charge transfer process of anodic reaction was more suppressed. Figure 1

Corrosion Behavior of Zinc under Thin Solution Films of Different Thicknesses

Zinc corrosion under 0.2 M NaCl solution films 5–800 μm in thickness was studied by electrochemical impedance spectroscopy (EIS). As-polished and rusted zinc plates obtained by exposure to a natural atmospheric environment for 1, 3, 6, and 12 months were used as working electrodes. The obtained EIS results were analyzed using a transmission line equivalent circuit to determine the charge transfer resistance (Rct), the reciprocal of which is proportional to the corrosion current density. For the as-polished zinc, the corrosion behavior is divided into three regions by the solution film thickness (Xf). In Region I (Xf: 800–200 μm), Rct−1 is independent of Xf and is approximately ten times smaller than that for carbon steel. In Region II (Xf: 200–25 μm), however, Rct−1 increases with decreasing solution thickness down to approximately 25 μm due to an enhancement of the oxygen diffusion (cathodic process) through the solution film. In Region III (Xf < 25 μm), further decreases in thickness reduce Rct−1 because the zinc dissolution (anodic process) is suppressed. In contrast, Rct−1 of the rusted zinc is independent of Xf because the charge transfer process is strongly suppressed by the zinc corrosion products, which were identified as simonkolleite and zinc oxide.

Effect of Mg2+ on the Corrosion Behavior of Zinc

Zinc-coated steels have been widely used in various industrial fields such as automobiles and construction since they have excellent corrosion protection in atmospheric corrosion environments. To improve corrosion resistance of the coating, zinc-alloy coatings containing Mg have been develped and they have demonstrated superior corrosion resistance in terms of duration to appearance of red rusts on steel compared with zinc coatings. However, the effect of Mg on the improvement of corrosion resistance of the zinc-alloy coatings is still unclear. In this study, the effect of Mg2+on the corrosion behavior of zinc in Cl-containing aqueous environmnts is investigated by electrochemical measurments and surface analysis. A pure zinc plate (purity: 99.5%) was used as a sample. The zinc plate was grounded with SiC papers up down to JIS #2000 grit and then rinsed in EtOH for several minutes. Test solutions used in this study were aqueous solutions of 1 M MgCl2and 2 M NaCl. Corrosion potential and polarization resistance for zinc were monitored during the immersion in the test solutions. The reciprocal of polarization resistance was used as a measure to evaluate corrosion rate. After the immersion, the surface of zinc was investigated by SEM-EDX, XRD and FE-AES. From the results of the reciprocal of polarization resistances measured in the test solutions, it was confirmed that corrosion rate of zinc in MgCl2 is lower than that in NaCl during the immersion. Furthermore, it was also found that the corrosion rate in MgCl2 decreases obviously ca. 4 h after immersion in the solution. At this time, corrosion potential for zinc in MgCl2 shifted in the noble direction. These results indicate that corrosion rate of zinc is decreased due to the inhibition of anodic dissolution of zinc. From the results of surface observation and anaysis of zinc after the immersion, it was found that finer corrosion products of zinc were formed in the case of MgCl2 compared with that of NaCl. This result suggests that the differenrce in the morphology of zinc corrosion products can be related to the difference in the corrosion resistances in both solutions.

Effects of Additives on Performance of Zinc Air Battery

Appropriate energy storage plays a very important role in a wide range of applications, including frequency regulation of renewable energy sources, peak-shaving of electrical grid, emergency power, and portable power. Metal-air batteries have long been a subject of research since they can be used in many applications, such as small batteries for watches, acoustical devices, and as large batteries for electric vehicles. There is a wide variety of applications for zinc metal as high capacity anodic material in the secondary alkaline batteries due to its high specific energy, good reversibility, environmental friendliness, low equilibrium potential, low cost, and no-toxicity. During battery charging, formation of zinc dendritic deposits in alkaline electrolytes severely decreases the cycle life of zinc rechargeable batteries. Uneven current density distribution, local concentration gradient variation, preferential crystalline growth of zinc causes the formation of dendrites. In order to suppress the dendritic growth, many inorganic additives such as CdO, PbO, Pb3O4, In2O3, and Bi2O3 have been tested. To decrease the hydrogen production potential, organic materials also have been studied, such as, poly vinyl alcohol (PVA), triethanolamine (TEA), ethylene-diamine-tetra-acetic acid (EDTA), poly-oxye-thylene sorbitan mono-laurate (Tween 20) and tartaric acid. In this study, the electrochemical behavior of zinc deposition in electrolyte with various additives is investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The corrosion behavior of zinc in alkaline solution with different additives is also studied. The morphologies and crystalline structures of various Zn deposits are examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. We found that zinc dendrite was eliminated by addition of EDTA and Tween 20. Same components can also improve the stability of zinc in alkaline solution. This work was supported by Bureau of Energy, Ministry of Economic Affairs. Key word: zinc dendrite, corrosion, solution additives

Anticorrosion potential of a pharmaceutical intermediate Floctafenine for zinc in 0.1 M HCl solution

Corrosion inhibition of Floctafenine for zinc in 0.1 M HCl solution was studied using empirical and theoretical methods. Quantum studies have been utilized for studying the interaction between metal and inhibitor. Empirical methods like potentiodynamic polarization and electrochemical impedance spectroscopy were adopted to verify the inhibition efficiency of the inhibitor. Adsorption of the inhibitor follows the Langmuir isotherm. Thermodynamic values show the physical adsorption mechanism of the inhibitor. Activation and thermodynamic parameters explain the corrosion mechanism. The effect of temperature on the corrosion behavior of zinc in the given temperature range 303–333 K was studied and discussed.

Inhibition Effect of an Anti-HIV Drug on the Corrosion of Zinc in Acidic Medium

Corrosion inhibition of zinc in 0.1 M HCl by Tenofovir Disproxil Fumarate (TDF) an anti-HIV drug has been investigated by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy. The experimental results suggested the inhibition efficiency increases with the increase in inhibitor concentration up to 10 ppm. Polarization results revealed that TDF acts as a mixed type inhibitor. The effect of temperature on the corrosion behavior of zinc in the given temperature range from 303–333 K was studied. Adsorption of the inhibitor followed the Langmuir isotherm. Activation and thermodynamic adsorption parameters were calculated and discussed.

Inhibition Effect of Azadirachta indica, a Natural Product, on the Corrosion of Zinc in Hydrochloric Acid Solution

The corrosion behavior of zinc in 0.2 M hydrochloric acid solution by Azadirachta indica (AI-Neem) was investigated using mass loss, electrochemical polarization and impedance methods. Inhibition efficiency depends on the concentration of AI-Neem and it reaches maximum value at 1,000 ppm. The shape of polarization profile indicated that AI-Neem is a mixed type inhibitor with predominant cathodic effect. Adsorption of AI-Neem on the zinc surface follows Temkin adsorption isotherm. The surface morphology of zinc was studied by using scanning electron microscope images.

The Corrosion Behavior of Cold Sprayed Zinc Coatings on Mild Steel Substrate

Zinc and its alloy coatings have been used extensively for the cathodic protection of steel. Zinc coating corrodes in preference to the steel substrate due to its negative corrosion potential. Numerous studies have been conducted on the corrosion behavior of zinc and its alloy coatings deposited using several techniques viz., hot dip galvanizing, electrodeposition, metalizing or thermal spray etc. Cold spray is an emerging low temperature variant of thermal spray family which enables deposition of thick, dense, and pure coatings at a rapid rate with an added advantage of on-site coating of steel structures. In the present study, the corrosion characteristics of cold sprayed zinc coatings have been investigated for the first time. In addition, the influence of heat treatment of zinc coating at a temperature of 150 °C on its corrosion behavior has also been addressed.

Corrosion Behavior of Zinc under the Combined Layer of Electrolyte

By constructing a novel electrochemical cell, the corrosion behavior of pure zinc under the combined layer of 3 wt% sodium chloride electrolyte consisting of an open layer connected with a confined one was studied. The results show that a galvanic corrosion cell is formed once the zinc being covered by the combined layer of electrolyte, where the zinc under the open layer (named as open-Zn) plays as the cathode but the zinc under the confined layer (named as confined-Zn) as the anode, therefore the latter presents the higher corrosion rate. Furthermore, because ions transfer between the open layer and confined layer become difficult, the hydrolysis of excessive zinc ions in the confined electrolyte results the acidification of electrolyte and thus also accelerates the corrosion of confined-Zn. The critical thickness for corrosion of zinc under the combined layer is 105 μm where corrosion rate for both of the open-Zn and confined-Zn reach the maximum.

Effects of Oxygen and Sulfate Concentrations on the Corrosion Behavior of Zinc in NaCl Solutions

Abstract Galvanized steel is one of the most common materials used in the construction industry for its relatively low cost paired with an acceptable corrosion resistance. Nevertheless, the early failure of a number of structures around the world that use galvanized steel as reinforcement has raised some controversy on the understanding of the corrosion behavior of zinc. The purpose of this paper was to study the effect of variable oxygen concentration on the corrosion performance of zinc. High-purity zinc was immersed in solutions with varied concentrations of sodium sulfate (Na2SO4, 1 wt% to 4 wt%), a fixed concentration of sodium chloride (NaCl, 3.5 wt%), and different concentrations of oxygen to simulate the conditions found in soils and groundwater. Differential oxygen access can promote corrosion macrocells that will compromise the performance of the protected structure. The electrochemical corrosion behavior of zinc was studied using potentiodynamic polarization testing and electrochemical impedanc...

Corrosion behavior of pure zinc and its alloy under thin electrolyte layer

The corrosion behavior of zinc and its alloy under thin electrolyte layers (TEL) in 0.1M NaCl solution was investigated by cathodic polarization curves and EIS. There was only one phase in pure zinc while zinc alloy consisted of eutectic phase and primary phase. Corrosion rate of zinc alloy was faster than that of pure zinc due to the effect of the micro-galvanic couples between the primary phase and the eutectic phase. The results indicated that corrosion rate of zinc alloy was greatly enhanced under TEL than that in bulk solution. Pure zinc exhibited minimum corrosion resistance as TEL decreased to 198 mu m. Zinc and its alloy exhibited localized corrosion under TEL while it was more uniform in bulk solution. There were two capacitive loops in high frequency (HF) and middle frequency (MF) respectively, with finite length diffusion in low frequency (LF) presented in EIS. For pure zinc under TEL below 300 mu m an additional inductive loop presented in MF-LF. The corrosion products and morphology were respectively examined by X-ray diffraction (XRD), FTIR (Fourier Transform Infra Red) and SEM-EDS. FTIR micro spectroscopy results indicated that the component of the corrosion products was similar at different section of the specimen surface but different in content.

Effect of minor nickel alloying with zinc on the electrochemical and corrosion behavior of zinc in alkaline solution

The electrochemical and corrosion behavior of pure zinc and Zn–0.5Ni alloy in strong alkaline solution (7 M KOH) was investigated by Tafel plot, potentiodynamic, potentiostatic and electrochemical impedance spectroscopy (EIS) methods, and characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Measurements were conducted under different experimental conditions. The results of both Tafel plot extrapolation and the electrochemical impedance spectroscopy (EIS) measurements exhibited the same trend, which the cathodic and anodic processes on the alloy surface are less significant compared with those on the pure zinc. The results revealed that, the shift in steady state of open-circuit potential ( E corr) to more negative potential in the case of the studied alloy compared with that of pure zinc has a positive effect on both charge efficiency and self-discharge. The anodic potentiodynamic measurements demonstrated that the polarization curves exhibited active/passive transition. The active dissolution of both pure zinc and its alloy increases with increasing temperature and scan rate. The activation energy ( E a) value of active region and peak current ( I AI) of the two studied electrodes in the investigated alkaline solution is calculated and compared. In the case of alloy, the results obtained at certain positive potential (+425 mV vs. SCE), exhibited high current density indicating that the most passive layer was destroyed. This indicates that the addition of small amount from Ni to Zn promotes the electrochemical reaction (in the passive region), acting as so-called self catalysis. Accordingly, one can conclude that, the electrochemical behavior of the investigated alloy in strong alkaline solution contributes to suppression of hydrogen gas evolution and increases the corrosion resistance. In addition, reactivation of the alloy surface takes place in the passive region.