Noble Direction Research Articles

The effect of three types of heat treatment on the hardness and corrosion resistance of Al 2014 alloy

AbstractAl 2014 is a high‐strength aluminum alloy widely used in the aerospace and automotive industries for its mechanical strength. This research examines the effects of three heat treatment processes—retrogression and re‐aging (RRA), T6 standard aging, and a modified RRA with high‐temperature pre‐aging—on the hardness and corrosion resistance of Al 2014. Polarization studies using potentiodynamic electrochemical methods in a 3.5 wt% sodium chloride solution were conducted to evaluate the corrosion resistance. The results showed that heat treatment, which causes precipitation hardening, shifted the corrosion potential (E) toward a more noble direction. The formation of Al2Cu precipitates is associated with improved corrosion resistance. Additionally, samples treated with the T6 process exhibited a higher corrosion current density compared to untreated Al 2014 alloy samples, indicating superior corrosion resistance. Analysis of corroded surfaces using scanning electron microscopy (SEM) with energy‐dispersive X‐ray spectroscopy (EDS) showed evidence of general and pitting corrosion, with distinct patterns among the three heat treatment processes. A comparison of the results revealed that the T6 standard aging process provided the best combination of hardness and corrosion resistance. This was likely due to the formation of stable precipitates during aging. The results also indicated that the RRA process showed good performance, suggesting it is a viable alternative when a balance between hardness and toughness is required. The modified RRA with high‐temperature pre‐aging resulted in lower performance, likely due to overaging, which reduced hardness and corrosion resistance. These findings highlight the significance of heat treatment in improving the corrosion resistance of Al 2014 alloy. This suggests that particular processes can enhance the alloy's durability in corrosive environments, potentially leading to a longer lifespan and reduced maintenance costs. The T6 standard aging process offers the best balance of enhanced hardness and corrosion resistance for Al 2014 alloy, making it ideal for extending lifespan and reducing maintenance costs in corrosive environments. Careful selection of heat treatment is crucial based on specific alloy performance requirements.

Corrosion Initiation on Reinforcing Steel with Mill Scale in Mortar

Corrosion of reinforcing steel rebar is the main cause of loss of the long-term reliability of concrete structures. When the rebar is corroded, the rust induces cracks and detachment of the cover concrete. The mill scale, a thick oxide film, is formed on the rebars when the rebar is hot rolled. The role of mill scale on the corrosion resistance of rebars in concrete has not been clarified, yet. This study studied the corrosion behavior of rebars with mill scale in mortar.The samples are commercial rebars with 19 mm diameter, which have a mill scale of several tens of micrometers in thickness. The rebars without mill scale prepared by the electrolytic polishing were used as the comparison samples. A Hyperbaric-oxygen accelerated corrosion test (HOACT) [1] was carried out using the rebars embedded in the mortar with a 5.5 mm cover thickness. To prompt the breakdown of passive film on the rebars, 2.1 M NaCl solution was mixed with the mortar. In the HOACT, pressurized oxygen gas is supplied to the sample, and the oxygen reduction reaction on the steel surface is enhanced, leading to the steel's corrosion acceleration. The oxygen pressure was 0.6 MPa and the test period was 14 days. The corrosion of the rebar with a mill scale was more significant than that without a mill scale. This result shows that the mill scale reduces the corrosion resistance of the steel rebar in concrete [2].To investigate the effect of the mill scale on the corrosion resistance of the rebar, anodic polarization measurements of the rebars with and without the mill scale were carried out in a saturated Ca(OH)2 solution containing Cl-. The pitting potential of the rebar with mill scale was more noble than that of the sample without mill scale. However, when the mill scale was scratched, the pitting potential was significantly shifted to the less noble direction, and it was below that of the rebar without the mill scale. These results show that the mill scale improves the corrosion resistance of the rebar in concrete, in contrast, the corrosion resistance of the rebar with a defective mill scale becomes even worse than that of the rebar without the mill scale [2].[1] K. Doi, S. Hiromoto, H. Katayama, E. Akiyama, J. Electrochem. Soc., 165(9), C582-C589 (2018).[2] K. Doi, S. Hiromoto, T. Shinohara, K. Tsuchiya, H. Katayama, E. Akiyama, Corrosion Science, 177, 108995 (2020).

Facile route for processing natural polymers for the formulation of new low-cost hydrophobic protective hybrid coatings for carbon steel in petroleum industry

This research helps with the creation, assessment, and characterization of a new hybrid protective coating for carbon steel alloy in acid conditions. The findings of this study will be useful for both chemical and petrochemical companies as well as scientists. This study aims to protect C-steel in acid pickling solution 1.0M HCl and formulate new hydrophobic protective hybrid organic–inorganic coatings from biopolymers chitosan and plant resin guar gum. Eight coating samples of chitosan in the absence and the presence of guar gum, silica and two heterocyclic compounds are prepared at feasible operational conditions using hot melt method. The aiding additives improved compatibility between coating constituents as confirmed by using different methods of analysis. This new processing approach has addressed the problems of using chitosan in corrosion control such as solubility in acid media and low mechanical strength. Coating samples of chitosan and its composites with the heterocyclic compounds (2-Hydrazinyl-6-methyl-4, 5-dihydro pyrimidine-4-on) or (2-Hydrazinyl-6-phenyl-4, 5-dihydro pyrimidine-4-on) are potent biocides. Coating shifts corrosion potential of carbon steel by 30 mV to more noble direction relative to the active potential 520 mV of bare carbon steel surface. Impedance and polarization measurements indicate that coating samples protect metal surface as mixed-type inhibitor by adsorption mechanism. There is a good agreement between percentages protection %P of coating calculated using the values of charge transfer resistance, Rct, and corrosion current density, icorr. All %P values are above 99% for all coating samples. Guar gum plant resin increases gloss of the coating film. Silica fills the pores in the polymeric film and increases the stuffiness of the polymeric coating film by modifying the particle size. All coated samples have high contact angle ranging from 150° to 165° indicating low wettability and high hydrophobicity of coating film on the metal surface.

Investigation of the Electrochemical Corrosion Property of 2xxx Series Cast Aluminium Alloy in 0.3 M, 0.6 M NaCl, and Seawater Environments

The electrochemical corrosion activities of 2xxx series Al alloys were investigated in NaCl of 0.3 M, and 0.6 M concentrations and seawater environments. Both Tafel polarization and electrochemical impedance spectroscopy (EIS) methods were followed to analyze the corrosion behavior. These results implied that corrosive attack is more aggressive in sodium chloride solution compared to seawater, as additional elements present in seawater are involved in forming various protective layers. Again, a higher concentration of NaCl solution damaged the alloy surface more drastically. The open circuit potential moved towards the nobler direction in the case of seawater environment, and 0.3 M solution for NaCl. The corrosion rate and corrosion current showed higher values in NaCl solution than in seawater. The surface morphologies of the alloys were characterized not only with an optical microscope but with a scanning electron microscope also. The scratch marks from polishing were removed after corrosion. Extensive damage to the surface was found in the NaCl environment, where 0.6 M solution created the most damage, which is evident by both optical and scanning electron micrography. A higher level of pitting corrosion occurred in NaCl than in seawater, identified by SEM images.

Green hydrogen generation in alkaline solution using electrodeposited Ni-Co-nano-graphene thin film cathode

Green hydrogen generation technologies are currently the most pressing worldwide issues, offering promising alternatives to existing fossil fuels that endanger the globe with growing global warming. The current research focuses on the creation of green hydrogen in alkaline electrolytes utilizing a Ni-Co-nano-graphene thin film cathode with a low overvoltage. The recommended conditions for creating the target cathode were studied by electrodepositing a thin Ni-Co-nano-graphene film in a glycinate bath over an iron surface coated with a thin copper interlayer. Using a scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) mapping analysis, the obtained electrode is physically and chemically characterized. These tests confirm that Ni, Co, and nano-graphene are homogeneously dispersed, resulting in a lower electrolysis voltage in green hydrogen generation. Tafel plots obtained to analyze electrode stability revealed that the Ni-Co-nano-graphene cathode was directed to the noble direction, with the lowest corrosion rate. The Ni-Co-nano-graphene generated was used to generate green hydrogen in a 25% KOH solution. For the production of 1 kg of green hydrogen utilizing Ni-Co-nano-graphene electrode, the electrolysis efficiency was 95.6% with a power consumption of 52 kwt h−1, whereas it was 56.212. kwt h−1 for pure nickel thin film cathode and 54. kwt h−1 for nickel cobalt thin film cathode, respectively.

Exploring cinnamon extract’s potential as a green corrosion inhibitor for X65 carbon steel in sulfuric acid: a comprehensive investigation

The effectiveness of cinnamon extract as an environmentally friendly corrosion inhibitor for X65 carbon steel (X65CSt) in a 1 mol/L H2SO4 solution was examined using electrochemical, chemical, and computational techniques. This inhibitor has many advantages, it is safe, environmentally friendly, harmless to human health, and economically feasible. The anticorrosion efficacy rises with rising the concentration of the cinnamon extract and reducing temperature and reaches 95.83% at 450 mg l−1 of cinnamon extract using potentiodynamic polarization. All the investigated methods confirm the anticorrosion ability of cinnamon extract as indicated by the reduced the corrosion current density values and mass loss as well as the greater charge transfer resistance. In addition, the values of the pitting potentials were also transformed in a more noble direction implying the resistance of pitting attack. The polarization technique categorized the cinnamon extract as a mixed inhibitor. The mechanism of inhibition was demonstrated in terms of adsorption of the main components of cinnamon extract onto the surface of X65CSt. of the adsorption of the main components of the cinnamon extract on the surface of the X65CSt and this adsorption is of combined type between both physical and chemical modes, as determined by the computed values of free energy of adsorption, which range between −46.96 and −37.42 kJ. mol−1. The adsorption is exposed to Langmuir isotherm. The four components of cinnamon extract were investigated through density functional theory, Monte Carlo, and Molecular dynamic simulation. The quantum parameters and the adsorption of these components on the Fe(110) reveals that cinnamaldehyde and cinnamic acid inhibitors are more effective as corrosion inhibitors.

Biodegradation performance of ball burnished magnesium alloy in stimulated body fluids for bioresorbable implant applications

Magnesium alloys are found to be potential bioresorbable materials. However, the application range of these alloys as bioresorbable materials has been limited due to rapid degradation in physiological fluids. The current study deals with the enhancement of degradation behavior of Mg Ze41A alloy in SBF solution by ball burnishing. Further, the influence of burnishing parameters on biodegradation rate has been investigated by Tafel plots, polarization resistance, electrochemical impedance spectroscopy and surface morphology analysis of degraded samples. Additionally, the biodegradation rate has been estimated by ANFIS modeling. The biodegradation rate of Mg Ze41A has been reduced from 1.106 mm/yr to 0.367 mm/yr with an improvement of 68.82% at optimum burnishing condition of burnishing force 50 N, burnishing speed 1400 RPM, burnishing feed 125 mm/min and 2 passes. ANOVA analysis has revealed that burnishing force and feed have contributed the most for the enhancement. The shift in degradation potential towards noble direction and reduction in degradation current density in potentiodynamic polarization curves and the highest charge transfer resistance in electrochemical impedance spectroscopy of the burnished samples are observed for burnished samples. The results reveal that ball burnishing process is a potential surface modification method in reducing the biodegradation rate of Mg Ze41A alloy. The ball burnishing has resulted in lowest biodegradation rate at a degradation current density of 5.743 μA/cm2 and degradation potential of −1.513 V. The ANFIS model developed with 81 fuzzy rules and triangular membership function estimated the biodegradation rate with an accuracy of 95.03%. The decrease in biodegradation rate of ball burnished magnesium substrate in SBF is essentially due to cumulative effect of compressive residual stress, microhardness, surface finish, work hardening and grain refinement.

Inhibiting general and pitting corrosion of Ni in dilute sulfuric acid solutions with some tetrazole derivatives

5-(Benzylthio)− 1H-tetrazole (BST), ethyl-1H-tetrazole-5-acetate (ETA), and 5-(ethylthio)− 1H-tetrazole (EST) were utilized to inhibit the pitting and general corrosion of nickel in dilute sulfuric acid solutions. The galvanostatic anodic polarization under a constant current and mass loss measurement complemented by a scanning electron microscope is utilized. The tetrazole inhibitors retard the pitting corrosion by shifting the pitting potential, Ep into the more noble direction while lowering the amount of electricity, Qinh, needed to attain Ep. The protection efficiency, η, increased with increasing the amount of tetrazole in the solution to follow the order EST < ETA < BST. The protection influence of such inhibitors is accompanied by the blocking of the investigated metal surface by their molecules through an adsorption process that follows Langmuir's model. The computed -∆G⸰ads values are 37.17, 36.82, and 36.57 kJ/mol for BST, ETA, and ETA, successively, at 298 K. Such values are harmonious with a mixed chemo-, physisorption mechanism. A coordinate link is supposed to originate between the tetrazole compound and the investigated nickel surface.

Investigation of the electrochemical behavior of a newly designed TiMg dental implant

This study is aimed to evaluate the galvanic corrosion of a newly designed TiMg dental implant. The TiMg composite was tested in two forms: (1) cylinders (TiMg cyl) and (2) dental implants (TiMg DI). Surface roughness was measured using a confocal microscope. The electrochemical behavior was determined in a Hank’s balanced salt solution (HBSS) by the open-circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) measurements. Surfaces after corrosion were examined by a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS). OCP of TiMg cyl and TiMg DI increased in the noble direction, indicating the formation and growth of a base film on their surfaces. After 2-h immersion, TiMg cyl had higher values of iCorr and RCorr compared with those of TiMg DI. After 24-h immersion, a prominent reduction in the values of iCorr and RCorr was observed, and ECorr shifted positively. The Nyquist plots of TiMg cyl and TiMg DI show capacitive loops that tended to close after 2-h exposure. As the time extended, TiMg DI showed higher corrosion resistance compared with that of TiMg cyl, and the linear diffusion response arose from the formation and dissolution of chemically non-stable by-products caused by the hydrogen evolution. In such a case, the involved reaction was controlled by charge transfer and diffusion processes. The formation of a film composed of stable CAp species that attached directly to the surface and chemically non-stable by-products that included (Mg3(PO4)2) and Mg(OH)2 was demonstrated. To conclude, the obtained results revealed that TiMg DI of a complicated threaded design had a more stable passive film and higher corrosion resistance in HBSS compared with those of TiMg cyl of a cylindrical design. These findings have the utmost importance for the fabrication of dental implants.Graphical abstract

Random crystal orientation and tensile strength of nanocrystalline dumbbell-shaped copper thick films electrodeposited from acidic aqueous solutions containing polyethylene glycol

Nanocrystalline thick copper films with the thickness of ∼250 μm were electrochemically synthesized from an acidic aqueous solution containing polyethylene glycol (PEG) with the average molecular weight of 3,000 to investigate the preferential crystal orientation and mechanical properties such as microhardness and tensile strength. By addition of PEG to the electrolytic bath, the cathode potential was shifted to a less noble direction during the electrodeposition and the average crystallite size of electrodeposited copper thick films was decreased. The copper thick films electrodeposited from the solution without PEG exhibited a preferentially orientation in (220) texture while that obtained from the solution containing PEG was composed of nanocrystals with random crystal orientation that containing (111) and (200) textures. The micro-Vickers hardness, tensile strength, and elongation of the electrodeposited copper thick films reached up to 133 HV, 234 MPa, and 13.1%, respectively. These improvements in mechanical properties can be explained by the grain refinement effect and the random crystal orientation effect.

Effect of varying weight fraction of silicon carbide (SiCp) particles on the corrosion resistance of Al–Zn–Mg–Cu/SiCp composite

ABSTRACT Metal corrosion is a significant economic issue, affecting 4–5% of GDP. Aluminium and its alloys are moderately resistant to corrosion but become vulnerable in chloride ion environments. Ceramic particles can be incorporated to reduce corrosion, as ceramics are inactive in the corrosive medium. So, the present work investigates the effect of ceramic particle (SiCp) variation in the Al–Zn–Mg–Cu alloy on corrosion resistance. Experimental data reveals that incorporating silicon carbide particles would enhance the corrosion resistance over monolithic alloys. Open circuit potential (OCP) shows that changes in OCP values from −0.8134 V (Al7075S00) to −0.7484 V (Al7075S20) towards the noble direction with increasing the weight per cent of SiCp. The potentiodynamic polarisation (PDP) curve discloses the lowest I corr values for Al7075S20. In the Nyquist plot, the diameter of the capacitive loop increases with increasing the SiCp content; Al7075S20 shows a higher capacitive loop. Overall, the outcomes of the Nyquist, Bode and Tafel plots show good agreement regarding the findings.

Corrosion behavior and microstructure of Al–10Zn alloy with nano CuO addition

The present study explores the preparation of Al–10wt.%Zn alloy by the casting process. Nano CuO was prepared by the Co-precipitation method. The effect of adding nanostructure of (1wt.% CuO) to Al–10Zn alloy was studied the corrosion effects as-cast and with different aging temperatures (423, 443, and 463 K) for 2 h in 3.5% NaCl aqueous solution after homogenized for 2 h at 500 K at room temperature. Electrochemical measurements (OCP, Tafel, and EIS) were performed to determine the corrosion rate (C.R.) and corrosion current density (Icorr.) to find out corrosion behavior. In addition, microstructures of Al–10Zn and Al–10Zn–1CuO were observed using a scanning electron microscope, EDX mapping, and the optical microscope to investigate the effect of the nanoparticle’s addition before and after aging and the corrosion test. The average crystal size and the dislocation density were calculated from the XRD pattern. The results show that the appropriate addition of CuO nanoparticles can refine the Al–10Zn alloy and shift the Al–10Zn alloy to a more noble direction.

Comparative Studies on the Anti‐Corrosive Action of Waterproofing Agent and Plant Extract to Steel Rebar

AbstractReinforcement of steel rebar in concrete infrastructure practices for a long time, mostly to improve tensile strength as well their service time. However, shortcomings related to damage of reinforced concrete (RfC) infrastructures becomes the business of corrosion researchers over the past few years, primarily from a safety and economic perspective. In general, the steel‐reinforced concrete (SRC) infrastructures are porous, and thence water as well different atmospheric pollutant gases penetrate it, causing the corrosion damages of the rebar, which shorten the prolonged existence of the RfC structures. The research aims to differentiate the efficacy and prosperity of waterproofing chemicals and methanol extract of Mangifera indica plant leaves for controlling the RfC susceptibility using a half‐cell corrosion potential measurement method following ASTM standard. The methanolic extract of M. indica leaves and waterproofing agents show high anti‐corrosion characteristics and can prescribe for the protection of the RfC infrastructures. The corrosion controlling performance level of 1000 and 2000 ppm M. indica extracts on the steel rebars in concrete has higher than the additions of alike concentration of both the water‐repellents depend on open‐circuit corrosion potential (CoP) shifting values to a noble direction.

Microstructure, mechanical, and electrochemical properties of Si/DLC coating deposited on 2024-T3 Al alloy

This work evaluated the microstructure, mechanical, and electrochemical properties of Si/DLC coatings deposited using ‎ the plasma-enhanced chemical vapor deposition (PECVD) technique. Tetramethylsilane and acetylene were used as precursor gases in the deposition process. The characteristics of the coating were estimated using different techniques. The corrosion performance was evaluated using various electrochemical methods in 3.5 wt% NaCl solution. The XPS analysis revealed that the film consists of Si and (a-C: H). The results revealed that as the deposition time increased, the hardness and Young's modulus decreased from 15.83 to 14.21 GPa and 125.8–114.9 GPa, respectively, while the thickness and adhesion strength increased. Moreover, the anti-corrosion ability of the DLC has been improved. It was found the corrosion potential moved to more noble direction (−618 to −562 mVAg/AgCl) while the corrosion rate decreased from 0.012 to 0.001 mmy−1. This trend can be attributed to growing coating thickness and fewer film defects which operated as a protective barrier against the corrosive solution. A failure mechanism of Si/DLC film has been suggested.

Electrochemical behavior and electro-crystallization mechanism of Cu-Ni/Nano-Al2O3 coating with a deposition current density dependence

In this work, preparation of Cu-Ni/Nano-Al2O3 composite coating with (111)-preferred orientation on the surface of the H64 brass via electrodeposition technique. Variation of the deposition current density was found to play a key role in the control of the microstructure and strongly influence the corrosion resistance of the composite coating. Electrochemical impedance spectroscopy results indicated that the increase of nano-alumina content in composite coating is caused by the change of polarization mode. Under different current densities, the Ni (111) plane is only preferred orientation and the relative texture coefficient reaches the highest value of 54.36% at 5 A•dm−2. The crystallite size of these coatings is about 10–55 nm dependent on current density, and high current density could refine the size. The microstructure of the coating changed from cauliflower to spherical with increasing deposition current density. Moreover, the Cu-Ni/Nano-Al2O3 composite coating obtained at 5 A•dm−2 increased the polarization resistance and coating resistance of the H64 brass by about 50% and 83%, respectively. The corrosion potential (Ecorr) of Cu-Ni/Nano-Al2O3 composite coating is shifted towards the nobler direction from − 1.191 V to − 0.063 V(Ag/AgCl) with the current density increases. The corrosion mechanism of Cu-Ni/Nano-Al2O3 composite coating has gone through two stages corresponding to two-time and three-time constant of EEC models, respectively. The Cu-Ni/Nano-Al2O3 has large potential merits in field of corrosion.

Experimental Study and Quantum Calculations for Spiramycin and Isosorbide Dinitrate as Corrosion Inhibitors

The investigation of the efficiency of two expired drugs, including Spiramycin and Isosorbide dinitrate, was done as corrosion inhibitors for aluminum in 0.1M HCl medium using the electrochemical method by Potentiostst at four temperatures (293, 303, 313, and 323 K) and 200 ppm as constant concentration for each drug. The results showed that these drugs gave good efficiencies equal to 98.836% and 94.285 % for Spiramycin and Isosorbide dinitrate at 293 K, respectively, by adsorption process on the metallic surface. They act as mixed-type inhibitors due to shifting corrosion potential either to active or noble direction. The corrosion data were measured and debated, where the corrosion current density was decreased after adding expired drugs to the corrosive medium due to inhibiting the cathodic and anodic reactions (i.e., the dissolution and reduction reactions). Using SEM exam, the inhibited surface of specimens was characterized to confirm the coverage of the surface by drug molecules. The adsorbed layer by Spiramycin was better than that by Isosorbide dinitrate. Also, the Fourier transform infrared spectra were used to limit the active site attracted to the surface by adsorption that confirmed the attraction by hydroxyl and nitro groups, as illustrated by the mechanism of inhibition. In addition, the antibacterial activity of the inhibitors against some types of bacteria was tested to confirm the formation of an inhibition zone against bacteria. The quantum chemical parameters exhibited a good correlation with the inhibition efficiency.

Mitigation effect of natural lettuce oil on the corrosion of mild steel in sulfuric acid solution: chemical, electrochemical, computational aspects

ABSTRACT The inhibition vigor of natural lettuce oil against corrosion of mild steel (MSt) 1.0 M H2SO4 solutions was investigated using chemical, electrochemical, and computational studies. The anti-corrosion efficacy (%AE) increases with the increase in the amount of doses of lettuce oil and reaches 95.83% from the galvanostatic polarization. The anti-corrosion process was demonstrated by the adsorption of lettuce oil onto the surface of MSt. The adsorption is spontaneous due to the negative signs of free energy of adsorption. The adsorption is subjected to Langmuir isotherm. Lettuce oil inhibits the pitting corrosion of MSt in chloride -containing solutions by transferring the pitting potential to the noble directions. Density functional theory (DFT) and Monte Carlo (MC) simulations were performed on the four components of natural lettuce oil. The adsorption of the inhibitors on the Fe(110) in the solutions is in parallel form. The results obtained from DFT and MC simulations predicted that α-Lactucerol and Lactupicrin give the MC simulations were performed on the four components of natural lettuce oil. The adsorption of the inhibitors on the Fe(110) in the solutions is in parallel form. The results obtained from DFT and MC simulations predicted that α-Lactucerol and Lactupicrin give the highest %AE.

光沢剤を含むアルカリジンケート浴から電析したZn-Ni合金皮膜の耐食性

Zn–Ni alloys were electroplated on an Fe plate with thicknesses of 40 μm at 500 A·m−2 and 293 K in unagitated zincate solutions. The reaction product of epichlorohydrin and imidazole (IME) was added in the solution as a brightener at the concentration of 0-5 ml/dm−3. The corrosion resistance of the obtained Zn–Ni alloys films was investigated from the polarization curve in 3 mass% NaCl solution before and after the corrosion treatment (formation of corrosion products) in NaCl solution for 48 h. Before the corrosion treatment, the corrosion current density of plated films rarely changed regardless of addition of IME into the zincate solution because the reduction reaction of dissolved oxygen rarely changed. However, in films plated from the solution containing IME, the anode reaction was suppressed and the corrosion potential shifted to noble direction. The suppression of anode reaction with an addition of IME in plating solution is attributed to the increase in γ-phase in plated films. On the other hand, after the corrosion treatment, the morphology of Zn chloride hydroxide of corrosion product was uniformly formed on the surface with increasing the concentration of IME. The reduction reaction of dissolved oxygen was suppressed with increasing the concentration of IME, resulting in decrease in corrosion current density.

Electrochemical investigation of freshwater biofilm on FTO surface: Oxide film perspective

AbstractThe contemporary field of bacterial biofilm electrophysiology is a greater importance to understanding the interfaces of active biofilm/material. The electrophysiology of freshwater active biofilm was studied using Fluorine‐doped tin oxide (FTO) electrodes. The open circuit potential and microscopic studies were revealed the attachment of biofilm on the FTO surface. The shift of potential to noble direction up to +402 mV vs SCE was observed on the FTO after 240 h exposure of freshwater. The open‐circuit potential (OCP) was revealed the attachment of biofilm on the FTO surface. Cyclic Voltammetry studies were employed to analyze the redox behavior of biofilm on FTO with different time intervals. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were also used to analyze the electrochemical communications between FTO and biofilm interfaces. The present work was investigated to explain electrochemical interfaces between n‐type oxide film and electro active bacterial biofilm.

Development of Hydroxyapatite Coating on Titanium Alloy for Orthopedic Applications

Titanium and its alloys have long been employed in biomedical applications due to its remarkable features, such as good bio-compatibility, resistance to bodily fluid effects, tremendous tensile strength, flexibility, and high corrosion resistance. If these materials are used as bio-implant, it releases toxic ions like aluminium and vanadium in the body fluid environment after implantation to overcome the problem Ti-6Al-4V alloy was coated with hydroxyapatite (HAp) which provides better bioactivity, osteocompatibility, and antibacterial activity. The present work is to synthesize HAp from snail shells using a simple wet precipitation method. The prepared SHAp was coated on the Ti-6Al-4V alloy using electro-deposition method. The coated alloy was characterized by various techniques such as FTIR, XRD, FESEM, EDAX, AFM and antibacterial activity. The spherical like structures was observed on the coated metal surface using FESEM. The potentiodynamic polarization study indicate that the breakdown potential (Eb) and repassivation potential (Ep) of uncoated sample was found to be 175.5 mV and −105.1 mV and for the coated sample was noticed at 357.2 mV and −50.2 mV respectively. The potential shift was moving towards the noble direction and it controls the rate of corrosion on coated Ti-6Al-4V. The zone of inhibition values were found to be 11.0 ± 0.45 mm for gram negative bacteria and 8.2 ± 0.28 mm for gram positive bacteria which was confirmed by the antibacterial activity study. The anti-bacterial activity of SHAp coated Ti-6Al-4V was superior to E. coli than Staphylococcus aureus. It is concluded that SHAp coated Ti-6Al-4V alloy may be considered a better material for orthopedic applications.