Electrochemical Corrosion Studies Research Articles

Evaluation of sodium alendronate drug released from TiO2 nanoparticle doped with hydroxyapatite and silver–strontium for enhancing antibacterial effect and osteoinductivity

Hydroxyapatite (HA) nanocrystalline coatings on implants increase bone/implant joint fusion, but bacteria grow on hydroxyapatite-coated implants and cause infections. To solve this problem, silver (Ag), strontium (Sr), and chitosan were used to modify the surface of the titanium dioxide nanoparticles (TNPs) coated with hydroxyapatite. Ag was used for antimicrobial properties, and Sr was used to control drug release and increase the ossification of titanium implants. Chitosan (Chit) is a natural polymer with good biocompatibility, low toxicity, and strong antibacterial properties. The results show that HA + Sr + Ag + Chit coating causes controlled and long-term release (more than 16 days) of the alendronate sodium drug, an osteoporosis drug, from the implant. Electrochemical corrosion studies reveal that the Sr + Ag + HA + Drug + Chit coating on titanium dioxide nanoparticles has reduced the corrosion penetration rate compared to pure titanium dioxide nanoparticle (TNP). The cytotoxicity analysis results show that the TNP + Sr + Ag + HA + Drug sample has the highest cell viability, equal to 99.3%. Microbial study shows that coated TNPs have more inhibition of Staphylococcus aureus growth than uncoated TNPs. Among the coated TNP samples, TNP samples with HA + Sr + Ag coating had the highest inhibition of bacterial growth.

Electrochemical Corrosion Studies of Low-Alloyed Carbon Steel in Acidic Methylimidazolium Derivate Ionic Liquids with Varying Water Content

The application of ionic liquids (ILs) in a wide range of technologies requires a thorough evaluation of their corrosion behavior to typical structural steels. In this work, the corrosion effects of two acidic-type methylimidazolium derivates (potential catalyst candidates) on low-alloyed carbon steel were studied with electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy [EIS]). The ILs cause moderate corrosion around 0.1 mm/y at water content up to 10‰ and severe corrosion around 1 mm/y at 100‰, which underlines that before industrial applications of ILs systematic corrosion studies should be performed as part of the process design. With both ILs we found that the cathodic process exhibited apparently good linear Tafel slopes in the cathodic polarization range but in the anodic range the IL with the hydrogensulfate anion showed an active-passive transition only at the highest water concentration. In this series at lower water concentrations, under 100‰, a model assuming a potential-independent anodic current rate correctly matched with the polarization data. The EIS measurement data showed chaotic, but reproducible deviations in the low-frequency range, which were interpreted as the effect of the timely variation of distribution parameters and they apparently did not affect the charge transfer parameters essentially.

Electrochemical Corrosion Study on Nickel and Chromium with Different Surface Orientations in Molten MgCl2-KCl

In the present work, the electrochemical corrosion tests were performed on single-crystal nickel and chromium with different surface orientations having (100), (110), and (111) facets, in a MgCl2-KCl eutectic molten salt at 500oC under an argon atmosphere. The corrosion rate of Ni is lower than that of Cr, indicating that Ni is electrochemically more stable than Cr in the molten salt. The anodic corrosion rates of different single crystals increase in the order of (111) < (100) < (110). This observation shows that the degree of electrochemical stability is related to the coordination of surface atoms and lower density surfaces yield higher corrosion rates. In addition, the corrosion rate of a polycrystalline sample is similar to that of the single-crystal (110) sample, which suggests that the corrosion rate of the polycrystalline surface is dominated by the orientation with the lowest surface density.This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science. Keywords: Tafel, Nickel, Chromium, MgCl2-KCl, Single crystal.

Effects of Vermiculariser, Inoculant and Copper Addition on Microstructure and Corrosion Properties of Vermicular Graphite Cast Iron

In this study, the microstructure and corrosion properties of Vermicular Graphite Cast Iron (VGCI) produced via different methods and parameters were investigated. VGCI was produced from a base ductile iron material using different proportions of vermiculariser and inoculant. Copper was added to a group of samples as an alloying element. The microstructures and corrosion properties of samples were investigated in saltwater media. The effects of production parameters on the microstructure and corrosion behavior were determined. It was observed that as the ratio of vermiculariser applied was increased, the vermicular graphite ratio and vermicularity was also increased. The matrix grain size decreased while the inoculant and pearlite phase ratio increased due to the addition of copper. In electrochemical corrosion studies, VGCI was superior in corrosion resistance compared to SGCI and addition of vermiculariser, inoculants and copper was found effective in improving the corrosion resistance of the VGCI material.

Effect of Zr and ZrO2 on aqueous corrosion behaviour of oxide dispersion strengthened 9Cr ferritic-martensitic steels

• All three alloys showed hysteresis loops, suggesting localized corrosion. • The ODS9Cr steels exhibited an improved corrosion resistance compared to NODS. • Higher E BP and R ct ; lower I pass were observed for ODS9Cr-ZrO 2 alloy. • The finer structure and passive layer make ODS9Cr steels more corrosion resistant. • However, ODS9Cr steel has slightly better corrosion resistance. The effect of Zr and ZrO 2 on corrosion behaviour and passive film characteristics of the oxide dispersion strengthened (ODS) steels with 9%Cr (ODS9Cr-Zr and ODS9Cr-ZrO 2 ) and those without the addition of oxide dispersions (NODS) has been studied in 0.6 M NaCl solution using cyclic polarization and electrochemical impedance spectroscopy measurements. Electrochemical corrosion studies indicated that Zr and ZrO 2 addition increases the corrosion resistance of ODS9Cr steels, with the best results obtained for ODS9Cr-ZrO 2 steel. The better corrosion behaviour of ODS9Cr steels is due to its surface morphology and Cr 2 O 3 enriched passive film. Dispersion of Zr and ZrO 2 along with Y 2 O 3 in 9Cr steel considerably improved the corrosion resistance further.

2D MoS2-hBN hybrid coatings for enhanced corrosion resistance of solid lubricant coatings

Molybdenum disulphide (MoS2) is commonly utilized as a solid lubricant due to its outstanding wear resistance properties. However, the application of MoS2 is restricted due to its high tendency of oxidation and corrosion when exposed to oxygen and humid air. Here, in this work, we developed a 2D hybrid structure by incorporating the 2D material, hexagonal boron nitride (hBN), with MoS2 to enhance the corrosion resistance properties. MoS2-hBN 2D hybrid coatings with varying concentrations of hBN nanosheets were deposited onto mild steel specimens to evaluate tribological and corrosion properties. The friction studies were carried out using a high-frequency reciprocating tribometer (HFRR) and found that hybrid coatings showed a slightly higher coefficient of friction (CoF) than pure MoS2 coating due to hBN addition. Electrochemical corrosion studies of the coatings were conducted in 3.5 wt% NaCl solution. Potentiodynamic polarization and electrochemical impedance spectroscopy studies depicted lower corrosion rate and higher corrosion resistance for MoS2-hBN coatings than pure MoS2 coating. The increase in hBN content resulted in an enhanced corrosion resistance. Raman spectroscopy studies of corroded coatings revealed the presence of a high concentration of MoO3 in pure MoS2 coating, while oxide peaks were nearly absent in MoS2-hBN coatings. XPS analysis depicted comparatively lower oxidation and MoO3 concentration in hybrid coating compared to pure MoS2 coating.

Structural and electrochemical corrosion studies of spin coated ZrO2 thin films over stainless steel alloy for bone defect applications.

Sol-Gel-based reaction mixture sols have been long used to fabricate dense and uniform bioactive coatings with superior mechanical stability over metallic implants. On account of precise control over synthesis, fabrication, formed and low temperature of processing, this technology is one of the most feasible routes to produce bio-ceramic coatings. The study aims to develop a physical barrier over metal implants in form of bioinert Zirconia coatings, phase-stabilized using Dysprosium. The metallic substrates were cut into 10 mm × 10 mm samples and diamond polished after being polished with a 1000 grade emery sheet. Novel spin-coated zirconia films were fabricated over 316L Stainless steel substrates and were sintered at 600°C to obtain firm and uniform crack-free coatings. The thickness of the coatings was determined by ELCA-D meter thermal analysis was performed using TGA-DTA. Phase determination was performed using X-Ray diffraction followed by morphological investigations using Scanning electron microscopy. The corrosion resistance was evaluated with Polarization studies and electrokinetic data was derived using Tafel extrapolation. Biocompatibility evaluation was performed against MG-63 cell lines and RBCs along with bone-forming ability in vitro in SBF. Stable crack-free 3 Layer coatings fabricated at 2000 rpm for 3 s with a thickness of around 1 μm were found to be optimal for corrosion resistance behavior of steel implants at a low ICorr value of 0.501 µA/cm2 and adhesion strength of 40.93 MPa when untreated falling down to 39.92 MPa when immersed in SBF. The study concludes that medium rpm coatings sustain enough sol to produce crack-free coatings that form a strong physical barrier between body fluid and implant surface thereby reducing the attack of corrosive ions and protecting the implant surface without participating in any form of bioactivity but supporting native bone regeneration capabilities.

Electrochemical corrosion study on base metals used in nuclear power plants in the HyBRID process for chemical decontamination

Base metal corrosion forms a significant issue during the chemical decontamination of the primary coolant loop in nuclear power plants as it is directly related to the economic and safety viability of decommissioning. In this technical note, potentiodynamic evaluations of several base metals (304 stainless steel, SA106 Grade B carbon steel, and alloy 600) were performed to determine their corrosion behavior during the hydrazine (N2H4)-based reductive ion decontamination (HyBRID) process. The results suggested that N2H4 protected the surface of the base metals in the HyBRID solution, which is primarily composed of H2SO4. The corrosion resistance of the carbon steel was further improved through the addition of CuSO4 to the solution. The corrosion rate of carbon steel in the H2SO4-N2H4-CuSO4 solution was lower than that exhibited in an oxalic acid solution, a commonly used reaction medium during commercial decontamination processes. These results indicate the superiority of the HyBRID process with respect to the base metal stability.

Microstructures and corrosion resistances of hypoeutectic Al-6.5Si-0.45 Mg casting alloy with addition of Sc and Zr

The microstructures and corrosion resistances of hypoeutectic Al-6.5Si-0.45 Mg casting alloys with addition of both Sc and Zr were investigated by using scanning electron microscope, X-ray diffraction, electrochemical measurement techniques and immersion corrosion tests. The results show that the addition of lower content of Sc has some modifying effect on the eutectic Si phases, but doesn't exhibit obvious refining action on the primary α (Al) phases of the alloy. The combined addition of both Sc and Zr can enhance the refining and modifying effects of Sc, and transform the primary α(Al) phases to equiaxed crystal, and the eutectic Si phases to the fine granular shapes. The corrosion resistance of the test alloys is firstly weakened, and then recovered, to some extent, with the increase of the exposure time in the 3.5 wt%NaCl solution. The test alloys with fine eutectic Si have poorer corrosion resistance than the test alloys with coarse eutectic Si. The formation of more galvanic couplings in the test alloys with fine eutectic Si is responsible for the poor corrosion resistance. The immersion corrosion rate of the test alloys with fine eutectic Si is higher than that of the test alloys with coarse eutectic Si. This is consistent with the results of the electrochemical corrosion studies. The corrosion of the alloys mainly occurs in the eutectic region, and the eutectic α(Al) phases are dissolved. It indicates that the Si phase is more noble than the α(Al) phase, and the galvanic couplings can be formed between the eutectic Si and α(Al) phases.

Study of Electrochemical Corrosion in Samples of a Horizontally Solidified AlCuSi Alloy

Study of Electrochemical Corrosion in Samples of a Horizontally Solidified AlCuSi Alloy

Linseed oil derived terpolymer/silica nanocomposite materials for anticorrosive coatings

AbstractFormulation of sustainable resource‐based organic–inorganic hybrid protective coatings have been achieved using Linseed oil‐based silica hybrid with terpolymer (TP) as basic skeletal matrix. The fabrication of TP system was performed by using systematic one pot multi‐facile steps (diol fatty amide–linseed oil‐based polyester amide TP) synthesis route. The conversion of ester amide functional ends of TP to urethane was initiated to enhance adhesiveness, impermeability, and corrosion resistivity of the processed hybrid material. FT‐IR and NMR (1H, 13C, and 29Si) studies help in verifying the chemical structure and progress of the reaction. The formulation of smooth corrosion resistive coating was further analyzed by transmission electron microscopy, scanning electron microscope, and electrochemical corrosion studies. The in‐situ tethering and homogeneous dispersion of inorganic moiety in nanoregime throughout the TP system further enhances the stability, wettability, and corrosion protection ability of the nanohybrid vegetable oil‐based coating under corrosive environment. High phase angle value at higher frequency end indicates the stability of the coating system. Such coating systems composed of sustainable resource with improved mechanical, thermal, and corrosion protective properties have great potential in future applications.

CHARACTERIZATION AND ELECTROCHEMICAL CORROSION ANALYSIS OF HEAT-TREATED REINFORCED HA COATINGS DEPOSITED BY VACUUM PLASMA SPRAY TECHNIQUE

Herein, a biomimetic coating of hydroxyapatite (HA)–Al2O3 and HA–ZrO2 was deposited on Ti–6Al–4V-alloy using vacuum plasma spray (VPS) technique. The bond-coat of ZrO2 has been introduced between the substrate and reinforced HA coatings to study the effect of bond-coat on structural, mechanical properties and electrochemical corrosion performance of the developed coatings. In addition, the impact of thermal treatment of coating was investigated on these properties too. Coating characteristics, such as morphology, porosity, surface roughness, and crystallinity were investigated. The corrosion performance of coatings was tested in Hank’s-based salt solution (HBSS). Significant enhancement in crystallinity and surface-hardness has been witnessed after heat treatment; nevertheless, porosity reduced. The electrochemical corrosion study revealed that the corrosion resistance of heat-treated samples was better than the as-sprayed coatings samples. The intensity of XRD peaks of all coatings increased after 24[Formula: see text]h immersion in HBSS for the electrochemical test in comparison to the intensity of peaks before the corrosion test.

Hard Anodization Film on Carbon Steel Surface by Thermal Spray and Anodization Methods.

In this paper, we used two mass-produced industrial technologies, namely, thermal spraying and anodization methods, to enhance the surface characteristics of AISI 1045 medium carbon steel for use in special environments or products. The anodic film can effectively improve the surface properties of carbon steel. A sequence of treatments of the carbon steel substrate surface that consist of sandblasting, spraying the aluminum film, annealing, hot rolling, cleaning, grinding, and polishing can increase the quality of the anodized film. This paper proposes an anodization process for the surface of carbon steel to increase the corrosion resistance, hardness, color diversification, and electrical resistance. The resulting surface improves the hardness (from 170 HV to 524 HV), surface roughness (from 1.26 to 0.15 μm), coloring (from metal color to various colors), and corrosion resistance (from rusty to corrosion resistant). The electrochemical corrosion studies showed that the AISI 1045 steel surface with a hard anodized film had a lower corrosion current density of 10−5.9 A/cm2 and a higher impedance of 9000 ohm than those of naked AISI 1045 steel (10−4.2 A/cm2 and 150 ohm) in HCl gas.

Electroanalytical and surface studies on the protective action of a coating of PVA@3WGO on mild steel in acidic and saline environment

Corrosion aversion capability of Polyvinyl alcohol (PVA) coatings with different loading levels of Graphene Oxide (GO) nanoparticles on mild steel testing panels has been studied in different aggressive media. The chemical structure of the developed coatings was studied by FTIR, UV–Visible,​ and X-ray diffraction studies. The viability of the coating to offer corrosion resistance and the barrier performance were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology of the material was characterized by FESEM and AFM techniques. The electrochemical and non-electrochemical corrosion study of the coated panels were compared with uncoated mild steel panel and showed that PVA polymer matrix filled with 3.0 weight % of GO (PVA@3WGO) gives better protection in 0.5M HCl and 3.5% NaCl.

Electrochemical behavior of machined Ni55Ti45 alloy by Wire Electro Spark Erosion (WESE) technique

This study aims to understand the electrochemical behavior of the Wire Electro Spark Eroded Ni55Ti45 alloy. The WESE machining process had been performed by considering the spark on time, spark off time and applied voltage as process parameters. The response chosen for the valuation of the machining process is surface quality. The surface properties of machined specimen were studied through the Scanning Electron Microscopy (SEM) and surface roughness meter. Then the maximum and minimum surface roughness samples were exposed to the electrochemical corrosion studies considering NaCl as the electrolyte medium. The outcomes of the corrosion result are projected in form of corrosion rate found from the TAFEL plot. Further, the surface of corroded specimens was studied using the imaging techniques.

Retracted] Electrochemical Studies of WC‐Flyash HVOF Coating Interface on SA209‐T1 Steel under 3.5 NaCl Solution

In this present research, the coatings of SA209‐T1 using high velocity oxygen fuel were employed for the application of boiler tubes. Due to the adaptation of corrosion easy in boiler material, the research of those properties is significant because of its criticality and functionality during the service time. A right coating was found and applied on the SA209‐T1 surface against corrosive environments. Good corrosion resistance is achieved by WC‐flyash coatings applied on SA209‐T1 substrate. The 90% WC‐10% flyash coatings were found to be more protective followed by SA209‐T1 steel. WC‐flyash covering was tracked down so that the covering is compelling to secure the SA209‐T1 steel substrate. It is reasoned that the arrangement of NiO, Cr2O3, CoO, and NiCr2O4 could add to the advancement of consumption opposition in coatings. The steel of uncoated endured erosion as extraordinary stripping and spalling of the scale, which could be because of the development of Fe2O3 oxide scale unprotectively. This paper reveals the performance, applications, and development of 90wt.% WC and 10wt.% fly ash through HVOF coating in SA209‐T1 for electrochemical corrosion studies at room temperature.

Flexible epoxy graphene thermoset with excellent weather and corrosion resistance

The chemical-bonding-dispersed method was used to develop a functional graphene oxide/epoxy nanocomposite coating with multifunctional properties and long-term stability for anticorrosion and weather resistance purposes. This study compared relevant properties before and after ultraviolet (UV) irradiation of the chemical-bonding-dispersed nanocomposite, a physically blended composite, and a neat polymer by using Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, ultraviolet aging, contact angle testing, electrochemical corrosion studies, dynamic mechanical analyzer testing, thermogravimetric analysis, flexibility testing, and an adhesion test. The as-prepared nanocomposite prevented the yellowing of epoxy resin, demonstrating the nanocomposite’s durability under UV light. Furthermore, the nanocomposite exhibited excellent anticorrosion properties. Anticorrosion performance with a corrosion rate of 6.10 × 10−3 mil/year and a corrosion efficiency of 99.99 % was attained with a thin-film coating of approximately 10 μm, and it retained a corrosion rate of 1.50 × 10-2 mil/year with a corrosion efficiency of 99.98 %. The results of the long-term durability tests performed using the electrochemical impedance spectrum indicated that the chemical-bonding-dispersed nanocomposite was superior to the physically blended dispersed composite and pure epoxy coating. The nanocomposite coating retained its high impedance over long-term durability tests, with a charge transfer resistance of 8.73 × 107 Ω·cm2 after 90 days. This study demonstrated the durability of the anticorrosion, mechanical, thermal, and degradation properties of the designed coating material before and after UV irradiation.

Chemical and electrochemical corrosion studies of ricinus communis oil based poly(urethane-ricinoleamide) coatings

In view of the depletion and possible exhaust of fossil fuels in near future, enormous increase in the cost of petroleum products and production of volatile organic compounds (VOC) by synthetic polymers and their application, the proposed article reports the development of sustainable resource based high performance Ricinus communis oil (Castor Oil) [RC] poly(urethane-ricinoleamide) [PUR] corrosion resistant coatings on mild steel. The physico-mechanical properties were investigated using standard methods. The corrosion resistance performance of PUR coatings was evaluated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in acid (3.5 wt% HCl) and alkaline (3.5 wt% NaOH) mediums. The weight loss measurement was also carried out under tap water (Cl- ion 63 mg/l; Conductivity 0.953 mS/A). Salt mist test (5 wt% NaCl) was performed on these coatings. The effect of additional –OH functionality of RC oil on the corrosion resistance performance of PUR coatings was also discussed. These investigations reveal that the PUR coatings provide protection to the mild steel by reducing the corrosion current density by 104 times as compare to bare MS. These coatings also exhibits higher corrosion resistance performance as compared to other reported sustainable resource based coating systems, hence show good potential for their commercial application.

Electrochemical corrosion tests in an environment of low-conductive ethanol-gasoline blends: Part 1 – Testing of supporting electrolytes

Bioethanol is a promising biofuel that can be used in the pure form or in the form of ethanol-gasoline blends (EGBs) as a transportation fuel. The combustion of bioethanol in petrol engines is associated with several problems, with bioethanol corrosion effects on metallic construction engine parts being one of the most serious ones. Electrochemical methods, such as electrochemical impedance spectroscopy, measurement of polarization characteristics (Tafel scan), etc., have been found to be efficient in studying corrosion effects in metal-EGB systems. However, a fuel environment with a low ethanol content (such as E10 and lower) has low conductivity, which can be a limiting factor for electrochemical corrosion studies. Supporting electrolytes can be used to increase the conductivity of such environments. These supporting electrolytes must be inert against the occurring corrosion reactions in order not to negatively affect the obtained corrosion data. In this work, we tested four potential supporting electrolytes (lithium perchlorate, tetrabutylammonium tetrafluoroborate, potassium hexafluorophosphate, and tetrabutylammonium bromide) to be used for the electrochemical corrosion tests on mild steel in the environment of an E85 fuel. In our study, we demonstrated that tetrabutylammonium tetrafluoroborate (TBATFB) can successfully be used for short-term corrosion studies as it exhibited minimum effects on the obtained electrochemical data even at a relatively high concentration of about 500 mg/L. The use of this supporting electrolyte can substantially facilitate electrochemical corrosion studies in less conductive media such as EGBs with a low content of ethanol. • Corrosion behavior of mild steel in the environment of E85 fuel was tested. • Electrochemical impedance spectroscopy and Tafel scan were used as testing methods. • Applicability of four supporting electrolytes for the testing methods was studied. • TBATFB was found to be usable for short-term corrosion studies by the testing methods.

HIGH TEMPERATURE AND ELECTROCHEMICAL CORROSION OF Zn0.5Al ALLOY DOPED WITH CALCIUM IN VARIOUS MEDIA

The article presents the results of a study of high-temperature and electrochemical corrosion of Zn0.5Al alloy doped with calcium in the various media. The thermogravimetric method was used to study the interaction of the Zn0.5Al alloy doped with calcium with atmospheric oxygen in the temperature range 523–623 K in the solid state. The kinetic and energy parameters of the process of high-temperature oxidation of alloys are determined. The process of high-temperature oxidation of Zn-Al-Ca alloys system is characterized by a monotonic decrease in the true oxidation rate and an increase in the effective activation energy when the alloying component in the initial Zn0.5Al alloy is up to 1.0 wt% doping with zinc-aluminum alloy 0.5 and 1.0 wt%. Calcium shows a slight increase in the oxidation rate of alloys. It was revealed that the oxidation process of the studied alloys with oxygen of the gas phase obeys the hyperbolic law. It was found that calcium supplements in the range of 0.01 - 0.1 wt%. The oxidizability of the initial Zn0.5Al alloy is reduced significantly, and the oxidation products of the alloys were ZnO, Al2O3, Al2O3 ∙ ZnO, CaO, Al2O3 ∙ CaO. By potentiostatic methods in the potentiodynamic mode with a potential sweep speed of 2 mV/s, it has been shown that for all samples of the Zn0.5Al-Ca alloys system in the acidic, neutral, and alkaline media, electrochemical potentials of corrosion, pitting formation, and repassivation are shifted to the region of negative values. It was revealed that zinc-aluminum alloys doped with calcium are most resistant to pitting corrosion in all studied media, respectively, in acidic (0.01n.), neutral (0.03-, 0.3-, 3.0 wt%) and alkaline (0.01n.) electrolytes of HCl, NaCl and NaOH. It has been established that calcium additions in the range of 0.01 - 0.1 wt.% reduce the corrosion rate of zinc-aluminum alloy Zn0.5Al by a factor of 2–3. Calcium alloys are recommended as anodic coatings and protectors for corrosion protection of steel products and structures operating at high temperatures.