Alternate Immersion Research Articles

Corrosion Behavior of Corrosion-Resistant Spring Steel Used in High Speed Railway

Corrosion behavior of 60Si2Mn-A and 60Si2Mn-B in simulated industrial atmospheric environment was investigated by alternate immersion corrosion test and electrochemical method. The phase, morphology, characteristics of corrosion products, and the distribution of Cr, Cu, and Ni in the corrosion products of experimental steel were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalyzer (EPMA). The results show that the phase of rust layer is Fe3O4 and γ-FeOOH in the early stage and then changes to α-FeOOH and γ-FeOOH in the later stage; the size of the rust layer with corrosion resistance of 60Si2Mn is less than 60Si2Mn; the Cr element accumulates in the rust layer of the experimental steel in the early stage of corrosion resistance; and Cu, Ni, and Cr in the corrosion resistance 60Si2Mn are concentrated in the rust layer near the substrate In the later stage of corrosion. As the corrosion cycle is prolonged, the corrosion potential and the resistance of the rust layer of the experimental steel increases, and the corrosion current decreases; in the same corrosion cycle, the corrosion potential and corrosion resistance of 60Si2Mn-B are greater than 60Si2Mn, and the corrosion current is less than 60Si2Mn.

Stress corrosion cracking of A517 steel in marine environments

PurposeThe purpose of this study is to develop the existence and mechanism of stress corrosion cracking (SCC) for A517 steel in marine environments.Design/methodology/approachSlow strain rate test (SSRT) and constant load tests were used to investigate the SCC susceptibility of A517 steel. In addition, the additive stresses caused by the corrosion film and hydrogen entering into steel were applied to reveal the fundamental mechanism of the SCC.FindingsThe SCC susceptibility increased due to anodic dissolution and additive stress caused by the corrosion-produced film under anode polarization. Furthermore, the SCC susceptibility increased with increasing cathodic polarization, which is due to the increased additional stress caused by hydrogen entering into the steel. However, when the cathode polarization further increased, the additional stress remained due to the constant hydrogen content, thus the SCC susceptibility did not vary. Moreover, the SCC susceptibility of A517 steel under an alternate immersion environment (AIE) was lower than that under a full immersion environment and the steel under the AIE with 0.5 W/D had the lowest SCC susceptibility.Originality/valueThe stress corrosion behaviors of A517 in marine environments under various conditions were systematically analyzed.

Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish

Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish

Alternate Immersion in Glucose to Produce Prolonged Hyperglycemia in Zebrafish.

Zebrafish (Danio rerio) are an excellent model to investigate the effects of chronic hyperglycemia, a hallmark of Type II Diabetes Mellitus (T2DM). This alternate immersion protocol is a noninvasive, step-wise method of inducing hyperglycemia for up to eight weeks. Adult zebrafish are alternately exposed to sugar (glucose) and water for 24 hours each. The zebrafish begin treatment in a 1% glucose solution for 2 weeks, then a 2% solution for 2 weeks, and finally a 3% solution for the remaining 4 weeks. Compared to water-treated (stress) and mannitol-treated (osmotic) controls, glucose-treated zebrafish have significantly higher blood sugar levels. The glucose-treated zebrafish show blood sugar levels of 3-times that of controls, suggesting that after both four and eight weeks hyperglycemia can be achieved. Sustained hyperglycemia was associated with increased Glial Fibrillary Acidic Protein (GFAP) and increased nuclear factor Kappa B (NF-kB)levels in retina and decreased physiological responses, as well as cognitive deficits suggesting this protocol can be used to model disease complications.

Corrosion behaviour of X65 carbon steel under the intermittent oil/water wetting: A synergic effect of flow velocity and alternate immersion period

The effect of flow on corrosion behaviour of carbon steel under intermittent oil/water wetting was investigated by a newly-modified “alternate wetting cell”, combining with the use of potentiostatic polarisation, in-situ visualisation, contact angle measurements and scanning electron microscopy (SEM). The oil/water wetting time was determined by the formation of a thin oil/water film on the electrode surface after the transition of immersion state. A short alternate oil/water immersion period and low flow velocity can increase the ratio (oil to water wetting time) and efficiently mitigate the corrosion, proposing a logistic regression tendency between corrosion mitigation efficiency and oil/water wetting time.

The corrosion behavior of marine aluminum alloy MIG welded joints in a simulated tropical marine atmosphere

Abstract The influence of metal inert-gas arc welding (MIG) on the corrosion behavior of 6061-T6 aluminum alloy in a simulated tropical marine atmospheric environment (related to high temperature, high humidity and high salt spray) were examined by dry-wet alternate immersion corrosion tests. The equivalent conversion was used to design the accelerated test time. The results show that in the initial stage, the intermetallic compound, rich in Fe, Si and Cu, had little influence on corrosion resistance in the heat-affected zone. For a corrosion time of 3 days in a tropical marine atmospheric environment, the corrosion rate of the welded joint increased rapidly, even reaching 3.5 times that of the base metal. Though the corrosion products had significant impact on slowing down the corrosion rate, as with the base metal, the corrosion rate of the welded joint was nearly double that of the base metal during the longest cycle period involving alternate immersion corrosion tests for 20 days.

A solvent-responsive robust superwetting titanium dioxide-based metal rubber for oil-water separation and dye degradation

The sewage treatment technology of oil-water separation based on superwetting materials has been widely employed. However, the stability of substrates was rarely considered in the past few years, which greatly limited the application of superwetting materials in engineering field. As a new robust, three-dimensional porous material, metal rubber (MR) has attracted significant attention for solving this problem. To treat the wastewater containing insoluble heavy/light oil and soluble dyes, herein, MR capable of degrading organic dyes with switchable wettability and high oil-water separation efficiency was prepared. Firstly, the superhydrophilic MR was obtained by anodizing. Then, the wettability of MR surface was reversibly switched between superhydrophilic and superhydrophobic via alternate immersion in stearic acid ethanol solution and tetrahydrofuran (THF) solvent to achieve switchable oil-water separation of MR. The superwetting MR displayed excellent abrasion resistance and retained outstanding oil-water separation performance after 100 times of sandpaper abrasion. Besides, the surface of pure titanium MR was rich in titanium dioxide (TiO2) after anodic oxidation, which could effectively degrade the organic dyes under ultraviolet light. Therefore, the as-prepared superwetting MR possesses the ability to treat complex wastewater and have applications prospects in controllable oil-water separation and self-cleaning surfaces.

Justification and calculation of design features of drum-type hydroponics

The purpose of the article is to evaluate the design features of rotary hydroponics and then obtain a method for calculating the main technical characteristics. Drum (rotary) hydroponics is a promising method of growing on artificial media. The planting surface in this method is located on the inner cylindrical surface of the rotor rotating around the lamp. The design of the rotary hydroponics has a number of advantages such as: smaller installation area due to planting in the cylinder area; energy savings due to rational use of the light source; liquid saving for the formation of a nutrient solution due to the alternate immersion of the roots in a more compact bath. In this paper, a number of theoretical aspects for the calculation of drum (rotary) hydroponic machines is considered to ensure the highest productivity. As a result, a method for calculating the following characteristics was derived: determination of the required radius of the rotor depending on plant height; number of planting spots with a known radius and width of the rotor; minimum amount of necessary nutrient solution; electricity consumed when using LED lamps.

Simulation of steel rod atmospheric corrosion by alternate immersion in salt solution

Corroded B235 reinforcing steel rods, which were exposed to an open air environment for 25 years, with a certain specific mass loss, were studied. Test pieces were prepared from them by lathe machining. The test pieces were subjected to accelerated corrosion through an alternate immersion in NaCl solution. The same specific mass loss as on the initial corroded rods was achieved for 52 days. Further the test pieces were cleaned, observed, photographed and tensile tested. The cleaned surfaces and the stress-strain curves of the test pieces were compared with results, obtained from the initial corroded rods. It was found out about the tested steel rods that alternate immersion in salt solution for 52 days is a good simulation of twenty-five-year atmospheric corrosion.

Methods for Determining Resistance Indices of Structural Steels under Various Atmospheric Conditions

Corrosion testing determines the resistance of materials to corrosion under certain environmental conditions including temperature, humidity, and salt water. There are many methods to measure or access corrosion resistance or materials. The study reviews the main methods for assessing the corrosion resistance of structural steels in aquatic environments and moist atmosphere conditions. The method of alternate immersion in a 3.5% NaCl solution has been established as the most complete and reliable method for determining the corrosion resistance of auto-plate steels under atmospheric conditions. There are many standardized corrosion test methods used to assess the corrosion resistance of structural steels in seawater (ASTM G52, ISO 11306, ISO 20340, ISO 2812-2, and GOST 9.909). However, in the Russian Federation, it is nowadays necessary to update the existing standards and develop a new set of standards for testing materials in different zones of exposure to seawater with different corrosion activities.

Corrosion Resistance Properties of a Nickel–Chromium Steel Bar in Marine Atmosphere

The corrosion behaviors of Ni–Cr and 20MnSi steel bars in a simulated marine atmosphere are compared using alternate immersion corrosion tests and electrochemical techniques. The microstructure features are characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical measurements and alternate immersion corrosion tests demonstrate that the Ni–Cr steel bar has a more positive potential (– 0.397 V), lower corrosion current density (28.19 μA/cm2), and better corrosion resistance at a corrosion rate of 3.81 g/(m2· h) and corrosion depth of 4.27 mm/g. There are inner and outer rust layers on the Ni–Cr steel bar, the inner layer being dense and bonded to the steel substrate. The α -FeO(OH)/γ -FeO(OH) ratio of the rust layer on the Ni–Cr steel bar is greater, which contributes to a more denser rust layer enhancing corrosion resistance.

Research on Corrosion Damage Evolution of Aluminum Alloy for Aviation

Based on the real annual average value of atmospheric environmental data in the Wanning area of Hainan Province in China by selecting 7075 ultra-high-strength aluminum alloy specimens for aviation, a new corrosion solution was designed and the traditional alternate immersion corrosion method of using the alternate immersion corrosion test box was improved to simulate the environment of the internal structure of the aircraft. On this basis, two kinds of corrosion damage parameters, the depth of corrosion pits and corrosion rate, were quickly and accurately obtained by the three-dimensional profile of the specimen and binarization images’ method. The optimal linear regression equation combination of pitting depth and corrosion rate was established, and the dynamic evolution equation of the depth of corrosion pits and corrosion rate was obtained. The results showed that: The depth of corrosion pits in the early stage of corrosion (8 h and 24 h) obeyed the Gumbel distribution and Weibull distribution, respectively, and the later stage (48 h, 72 h, 96 h, and 120 h) conformed to the normal distribution; the depth of corrosion pits’ evolution law was in the form of double straight lines and the corrosion rate evolution law was in the power function form (y = a × xb); and the depth of corrosion pits changed rapidly in the early stage and gradually slowed down in the later stage, while the corrosion rate was just the opposite.

Effect of Sn on the corrosion behavior of weathering steel in a simulated tropical marine atmosphere

PurposeThis study aims to study the effect of Sn on the corrosion behavior of weathering steel (WS) in a simulated tropical marine atmosphere.Design/methodology/approachIndoor alternate immersion tests, electrochemical measurements and real-time current-monitoring technology based on the galvanic corrosion principle were used and the scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and electron probe microanalyzer were used to analyze the morphology and component of the rust layer.FindingsThe results indicated that Sn has a positive influence on the corrosion process. Sn participated in the composition of the rust layer in the form of SnO2 and is enriched in the inner rust layer. SnO2 participated in the coprecipitation process with iron oxides and oxyhydroxides, which promoted further transformation of γ-FeOOH to α-FeOOH. As a result, the rust layer of Sn-containing steel was continuous, compact and effectively blocked the invasion of aggressive Cl−. Therefore, the additive of Sn enhanced the corrosion resistance of WS in a simulated tropical marine atmosphere.Originality/valueThe corrosion behaviors of WS were researched by the real-time current-monitoring technology which was rarely used.

Multistep Instead of One-Step: A Versatile and Multifunctional Coating Platform for Biocompatible Corrosion Protection.

Magnesium alloys have potential application in cardiovascular stents and orthopedic implants. However, the rapid corrosion rate of magnesium limits their clinical application. In order to improve the corrosion resistance and biocompatibility of the substrate, a protective coating is constructed by alternate immersing of MgZnMn alloy in epigallocatechin gallate (EGCG) and polyethyleneimine (PEI) solution. The conventional method is immersing magnesium alloy into a conversion solution by simple one-step immersion. In the present work, the EGCG/PEI coating is prepared by a novel alternate immersion method. The number of alternate immersions resulted in a different density of phenolic hydroxyl groups and amino groups on the surface. The corrosion resistance and bonding strength of the coating also varied with alternating immersion times. As the corrosion resistance and density of the functional groups varies, endothelial cells (ECs), smooth muscle cells (SMCs), osteoblasts, and macrophages showed a different growth state on EGCG/PEI coatings. In summary, this EGCG/PEI coating addressed the rapid corrosion rate of the magnesium alloy and can adjust its function by controlling the number of alternate immersions. The EGCG/PEI coating exhibited multifunctions: improved corrosion resistance, good compatibility with ECs and osteoblasts, and inhibition of SMC growth and inflammation, and the effective groups on the coating make it possible for further modification by grafting biomolecules. This is an effective method for preparing a multifunctional platform on biomedical magnesium alloys.

Machine for accelerated cyclic corrosion tests through alternate immersion in salt solution

Metal structures corrosion is a problem of global economic importance. Typically, the corrosion process runs slowly, which requires accelerated methods for corrosion behaviour examination. The conditions when accelerated methods are used differ from the real ones, which affects the results obtained. One of the methods that relatively successfully reproduces corrosion in a natural atmosphere is included in the standard EN ISO 11130:2018 – Alternate immersion test in salt solution. Unlike other widespread methods, uneven corrosion occurs here, including spots and pits, which greatly affect the mechanical behaviour of the material. The commercial devices for such tests are quite expensive. This justifies the development and production of one’s own equipment as the one presented in this paper. The design, construction and production of a low-cost device are hereby described. The first results of the tests performed with this machine are also given. The corrosion rate of rods, 6 mm in diameter, from widely used steel grades – S235JR and S235JRC – was determined. The duration of the test was 42 days. The results were compared with those from another corrosion test method with the same duration – immersion in a solution of 3.5% NaCl.

Development of new criteria for evaluating the effectiveness of Zn-rich primers in protecting Al-Mg alloys

One inorganic and three organic Zn-rich primers (ZRPs) without a pretreatment or a topcoat were evaluated on highly sensitized aluminum alloy 5456-H116 in 0.6 M NaCl for their ability to suppress intergranular corrosion (IGC) and intergranular stress corrosion cracking (IG-SCC) based on the achievement and maintenance of protective potentials under simulated galvanic coupling conditions. These evaluations utilized a combination of existing criteria (e.g., the need to establish an intermediate cathodic potential) and additional new criteria based on fast anodic response and low polarizability. Ethyl silicate, epoxy, epoxy polyamide, and polyurethane resins were considered. Accelerated electrochemical cycle testing in full 0.6 M NaCl immersion demonstrated that anodic charge usage in the candidate ZRPs had a greater dependence on the pore resistance than on theoretical anodic charge capacity. Electrochemical impedance spectroscopy modeling of cycle testing data demonstrated that the ZRPs with low pore resistance also had the fastest anodic response time. Galvanostatic pulse testing demonstrated that the ZRPs with the highest anodic charge usage and low pore resistance were also the least polarizable. These analyses propose relevant metrics to evaluate the effectiveness of Zn-rich primers in a complex challenge heretofore not considered: suppressing IGC/IG-SCC on highly sensitized 5456-H116 in aggressive alternate immersion environments.

Effect of laser repairing on corrosion behaviour of metal–inert gas welding joint of 7N01 aluminium alloy

AbstractThe heat affected zone (HAZ) on the metal–inert gas (MIG) welding joint of 7N01 aluminium alloy was repaired by multipass narrow gap laser welding. The Y–X direction precracked three‐point bending sample was used in the alternate immersion test. The morphology of specimen surfaces demonstrated that the exfoliation corrosion in the HAZ after laser repair (HAZa) was more serious than that before laser repair (HAZb). The electrochemical impedance spectroscopy after different immersion corrosion time indicated that the HAZa and HAZb had similar corrosion potentials. However, the pitting corrosion resistance of HAZa was lower than that of HAZb at the beginning of exfoliation corrosion. The stress corrosion crack (SCC) of 7N01P‐T4 aluminium alloy displayed a multicrack source and an intergranular crack propagated along the rolling grain boundary under the test condition. An unusual method was taken to measure the length of SCC. The results showed that laser repairing did not weaken the stress corrosion resistance of the original joint.

AgCl/Ag functionalized cotton fabric: An effective plasmonic hybrid material for water disinfection under sunlight

Hybrid Cotton-AgCl were prepared and found to be efficient antimicrobial agents for water disinfection under sunlight irradiation. AgCl was grafted on cotton by alternate immersion in AgNO3/KCl solutions, followed by a mild hydrothermal treatment. The as-prepared samples were characterized using a field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman, FTIRS and UV–vis ground state diffusion reflection (GSDR) spectroscopy, TGA, ICP and XRF. The microbial inactivation efficiency was tested using Escherichia coli (E. colis) and Staphylococcus aureus (S. aureus) as model strains of Gram negative and Gram positive bacteria, respectively. The as-prepared composites exhibit stronger antibacterial activity against both strains, with complete inactivation (107 cfu mL−1) of Escherichia coli within 15 min. The preparation method is environmentally friendly, facile to scale up and the AgCl/Ag junction is effectively bonded to the cotton fabric materials. These results show that cotton-AgCl is a promising plasmonic biocidal material for water disinfection under sunlight illumination as well as under indoor illumination.

Advanced chemical stability diagrams to predict the formation of complex zinc compounds in a chloride environment.

A chemical stability map is advanced by incorporating ion complexation, solubility, and chemical trajectories to predict ZnO, Zn(OH)2, ZnCO3, ZnCl2, Zn5(CO3)2(OH)6, and Zn5(OH)8Cl2·H2O precipitation as a function of the total Zn content and pH of an NaCl solution. These calculations demonstrate equilibrium stability of solid Zn products often not considered while tracking the consumed and produced aqueous Zn ion species concentrations through chemical trajectories. The effect of Cl-based ligand formation is incorporated into these stability predictions, enabling enhanced appreciation for the local corrosion conditions experienced at the Zn surface in chloride-containing environments. Additionally, the complexation of Cl− with Zn2+ is demonstrated to compete with the formation of solid phases, making precipitation more difficult. The present work also extends the chemical stability diagram derivations by incorporating a Gibbs–Thompson curvature relation to predict the effect of nanoscale precipitate phase formation on species solubility. These thermodynamic predictions correlate well with experimental results for Zn corrosion in full and alternate NaCl immersion, and have far-reaching utility in a variety of fields requiring nanoscale, semiconductor, and/or structural materials.

Effect of static mechanical load on intergranular stress-corrosion cracking of 7050-T7451 C-Ring specimens

ABSTRACTIn this paper, 7050-T7451 C-Ring stress-corrosion alternate immersion test in neutral 3.5% NaCl solution was conducted to investigate the mechanism of stress-corrosion cracking (SCC). The SCC sequence was proved to comprise dealloying, pitting, micro-cracks, and intergranular (IG) cracks. Besides, anodic dissolution characterised by reticular IG cracks within pitting zones and IG Dimple Rupture is suggested to be the main operative mechanism during this static stress-corrosion process. Since pitting originates from coarse constituents whose number can be reduced by optimised solution treatment, the formation of pitting can, therefore, be delayed by adopting more effective solution treatment before artificial aging to enhance the SCC resistance.