Decrease In Corrosion Rate Research Articles

Improving high temperature corrosion resistance of Cr3C2–25NiCr coating by incorporating nano yttria-stablized zirconia

The hot corrosion behavior of Cr3C2–25NiCr composite coatings reinforced with nano yttria stabilized zirconia (YSZ) was evaluated under actual boiler conditions in a thermal power plant at 850 °C with cyclic thermal loading. The nano YSZ content was varied between 5 and 10 wt%, and the coatings were applied using the high-velocity oxy-fuel (HVOF) method. A comparative analysis of the impact of varying nano YSZ content on hot corrosion performance was conducted through weight change measurements, while corrosion products were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and cross-sectional analysis. Results indicated that increasing nano YSZ content improved the corrosion resistance of the coatings at high temperatures in the boiler environment, with lower weight gain and the formation of protective oxide scales. Higher nano YSZ content in the coating matrix led to a decrease in corrosion rates during the hot corrosion tests. The corrosion rates for the 5 wt% and 10 wt% YSZ–Cr3C2–25NiCr coated specimens were 4.82 mpy and 3.45 mpy, respectively, reflecting reductions in corrosion rates of 80.79% and 89.26%. The addition of YSZ significantly decreased the corrosion rate, with further reductions observed as the YSZ content in the Cr3C2–25NiCr coating increased. XRD analysis confirmed the presence of Ni, Cr2O3, Cr3C2 and ZrO2–Y2O3 phases, indicating that YSZ particles remained in the coating matrix after exposure.

Electrodeposition of Sacrificial Layer, Al2O3/ZnTPP film, onto NiTi Orthodontic Wire: Surface Characterizations and Electrochemical Investigations

Background: NiTi (nickel-titanium) alloy wires are widely used in orthodontics due to their unique properties, such as shape memory and superelasticity. However, these wires can be susceptible to corrosion in the oral environment, which can compromise their mechanical performance and longevity. Zinc tetraphenyl porphyrin (ZnTPP) is a corrosion inhibitor that forms a protective layer on the aluminum oxide (Al2O3) surface, acting as a barrier against corrosive agents. Objective: The electrodeposition of a sacrificial layer of Al2O3 with ZnTPP was carried out onto Ni- Ti orthodontic wire to enhance the corrosion resistance. Methods: 10 mM aluminum nitrate was dissolved in 10 mL of 0.1 M phosphate buffer solution (PBS), which was used as an electrolyte. Firstly, electrodeposition of Al2O3 on NiTi wire was carried out by using cyclic voltammetry by potential scanning between 0 and -2.0 V at a scan rate of 50 mV/s for 50 cycles. Secondly, 10 mL of 1 mM ZnTPP in 0.1 M PBS and ethanol (1:1) was prepared and used as an electrolyte. Electrodeposition of ZnTPP onto Al2O3/NiTi wire was achieved by cyclic voltammetry through the potential window of 0 to -2.0 V at a scan rate of 50 mV/s for 50 cycles. Results: The ZnTPP/Al2O3/NiTi wire displayed a potentiodynamic polarization resistance of 412931 Ω, with high stability compared to the bare NiTi wire (396421 Ω). Additionally, the corrosion rate for the ZnTPP/Al2O3/NiTi wire was measured as 0.254 mm/year, which was notably lower than that of the bare NiTi wire (0.540 mm/year). This decrease in corrosion rate can be attributed to the presence of the ZnTPP/Al2O3 film, which renders the NiTi wire electrically insulative and significantly increases its impedance compared to the bare NiTi wire. Conclusion: The bilayer coating of Al2O3 and ZnTPP has proven to significantly improve the corrosion resistance and stability of the wires. Thus, these materials can be considered for coating orthodontic archwires with improved corrosion stability.

Insights into heat treatments of biodegradable Mg-Y-Nd-Zr alloys in clinical settings: Unveiling roles of β' and β1 nanophases and latent in vivo hydrogen evolution

Heat treatment serves as a viable strategy to effectively mitigate the intense corrosion of biodegradable WE43 alloys. However, limited comprehension of the passivation mechanisms underlying heat treatment and the dilemma to quantitatively examine the evolution of hydrogen gas in vivo introduce uncertainties in designing heat treatments for developing clinically applicable WE43. This work aims to advance this knowledge by applying cutting-edge atom probe tomography to provide atomic-scale insights into the passivation roles of rare earth (RE)-rich β1 (Mg3(Y, Nd)) and β' (Mg12NdY) nanophases induced by T6 heat treatment at 250 °C, and employing machine learning-based image analysis techniques to quantitatively unveil WE43’s in vivo gas evolution during a 12-week implantation. It was found that nanosized β1 and β' phases can effectively improve WE43′s corrosion resistance by inducing an accelerated passivation effect on the surface and confining the distribution of hydrogen ions in the matrix. Female rats presented slightly higher corrosion rates than male rats in weeks 1 and 4 but lower hydrogen gas volumes in vivo, while male rats possessed a superior ability to metabolise hydrogen gas in vivo. Notably, latent gas evolution against the corrosion rates was found which peaked at week 4 and subsided at week 12 despite the gradually decreased corrosion rates from week 1 to 12. This study offers insights for engineering heat treatments to develop clinically applicable WE43 with acceptable corrosion rates and in vivo gas generation at various implantation stages. Statement of SignificanceThe study aimed to reveal the role of β1 and β' nanophases on the good corrosion resistance of WE43. The influence of these nanophases on WE43′s corrosion performance has not been totally understood. Similarly, the understanding of hydrogen gas evolution as it relates to the magnesium implant's corrosion rate lacks clarity. Atom probe tomography (APT) indicates β1 and β' nanophases trap hydrogen, removing H2 from the lattice and disabling its catalytic role in Mg oxidation. Machine learning-aided analyses of computed tomography (CT) scan images indicate latent gas evolution, contradicting the monotonic in vivo H2 evolution that is widely accepted.

Diffusion mechanisms and corrosion resistance of nanostructured ZrN-Cu coating obtained by hybrid HiPIMS-DCMS

Globalisation has brought numerous benefits regarding the cost-effective transportation of goods. Still, the shipping industry faces challenges such as corrosion, biofouling, and restrictions on heavy pollutant products used in paintings. This study proposes a solution using a multifunctional coating based on zirconium nitride and copper nano-structured coating, applying high-power impulse and direct current magnetron sputtering processes (i.e., HiPIMS and DCMS, respectively). The coating’s morphological, structural, and chemical features were analysed using advanced characterisation techniques (SEM, EDX, STEM, SAED and EELS). Potentiodynamic polarisation (PP) and Electrochemical Impedance Spectroscopy (EIS − up to 30 days) were employed to study the corrosion resistance in saline solution (3.5 wt. % NaCl). Besides, activated ZrN-Cu exhibited a corrosion rate decrease from ∼ 354 x 10−4 to 52 x 10−4 mm/yr when compared to its inactivated counterpart. Besides, a ∼3.5-fold impedance increasing was exhibited by activated ZrN-Cu after 30 days of exposure to saline solution, meaning an increase in corrosion resistance compared to the non-activated ZrN-Cu. SEM micrographs revealed that the copper diffusion in ZrN-Cu can be provoked by a strong oxidising agent (NaOCl) or by an electrical potential. Based on the chartered evidence, a diffusion mechanism is proposed for the biocidal release (Cu) in the obtained ZrN-Cu films. The present study depicts a solution that offers a controlled biocide release and corrosion resistance, opening the possibility of its application in the maritime industry.

Hydrate formation and its influence on natural gas pipeline: Simulation study

Natural gas transportation is plagued with the twin problem of hydrate and corrosion that occurs when a hydrate prone gas is conveyed in such a manner that the pipeline operating conditions fall within hydrate formation region of the hydrate phase envelop. This study simultaneously studied this twin problem, establishing their interdependent using gas sample from Niger Delta that was meticulously simulated and analysed for hydrate formation possibilities with the aid of Unism software. CO2 corrosion was simulated using NORSOK M-506 standard model in matlab. Major factors considered are the relationship between corrosion rate and temperature, corrosion rate and PH, corrosion-temperature relationship for varying CO2 mole percent, and PH values. The result from this study established that both type I and type II hydrates could form at the operating conditions of 5OC and 60 bar. Rate of corrosion decreases and increases with increase in PH and temperature respectively to a certain temperature of approximately 78 OC, then a dip in rate of corrosion. Corrosion-temperature relationship for varying PH and CO2 mole percent shows a decrease in corrosion rate with an in increase in PH, and an increase with increase in CO2 mole percent, with a rise as high as 5,7 mm/year at a 3 mole percent. This value and trend portray a bad omen for the affected pipeline. This study recommends that natural gas to be transported by pipeline should be sweetened and processed to remove H2S, CO2 and mercaptans if present and also to satisfy maximum dew point specification.

Study on corrosion behavior and first-principle analysis of M50 steel in lubricating oil contaminated by salt water

The corrosive wear of M50 steel in lubricating oil contaminated with saline is a form of wear that often occurs within the main shaft bearings of aviation engines carried by aircraft working at sea. In the present paper, the corrosion behavior of M50 steel in lubricating oil contaminated with saline was studied. The open-circuit potential, polarization curve and impedance spectrum were analyzed by rotating electrochemical corrosion wear test. A three-layer interface microscopic molecular model was established with Materials Studio to simulate the dynamic corrosion evolution process of M50 steel self-matching pairs and the adsorption energy was calculated. The results show that the corrosion type is pitting corrosion. With the increase of saline concentration, the corrosion area becomes wider and shallower, and the size of the pitting core gradually decreases. The weight loss of M50 steel increases over time, but the trend slows down, which is also shown in the MS simulation results. Electrochemical tests show that the tribocorrosion of M50 steel is related to load, speed. As the load increases, the corrosion rate decreases. And, as the speed increases, the corrosion rate increases. This has practical significance for extending the understanding of tribocorrosion of M50 steel in marine atmospheric environments.

Enhanced hydrophobicity of polyurethane coating for steel protection through replication and nanomaterial integration

Polyurethanes (PU) are widely used in corrosion protection, anti-biofouling coatings, and self-cleaning glass, yet their low hydrophobicity poses durability challenges. This study addresses this by enhancing PU coatings’ hydrophobicity by refining surface roughness and forming tailored porous structures. Using drop, spin, dip, and spray coating techniques, hydrophobic PU coatings were fabricated on 304 steel plates. To further enhance hydrophobicity, 0.5 w/v% graphene nanoplatelets (GNP) were introduced into the coatings. Additionally, stainless-steel 500 mesh was incorporated to create patterned surfaces, increasing surface roughness and tailoring the porous structure. The analysis included optical and scanning electron microscopy, water contact angle (WCA) measurements, Fourier transform infrared spectroscopy, electrochemical corrosion tests, and atomic force microscopy. Incorporating GNP notably increased WCA by 20–23° and reduced corrosion rates in a 3.5% NaCl solution. Likewise, applying stainless-steel mesh improved surface roughness, raising WCA by 3-8° and decreasing corrosion rates. The study observed changes in porous structure, with pore size reduction correlating with increased roughness and decreased corrosion rates upon mesh application and GNP addition. This comprehensive examination highlights the potential of PU coatings for various applications and underlines the importance of tailored porous structures in enhancing their performance and versatility. Spin coating emerged as the optimal technique, yielding uniform, defect-free coatings with the highest WCA.

Unveiling the Effect of Grain Size on Biodegradation of Magnesium

It is known that the grain size plays a major role in the mechanical properties of magnesium. The aim of the present study is to evaluate its role in long‐term corrosion rate. Samples of pure magnesium with grain sizes in the range of 0.9–82 μm are produced through severe plastic deformation and annealing treatments. The mechanical properties are evaluated using tensile tests and the corrosion behavior is evaluated using immersion tests in Hank's solution. A maximum yield stress of ≈150 MPa is observed in the sample with 1.8 μm of grain size and an elongation larger than 25% is observed in the ultrafine‐grained sample. Ultrafine‐ and fine‐grained magnesium display uniform corrosion with a decreasing corrosion rate while coarse‐grained magnesium displays localized corrosion with an accelerated corrosion rate. A corrosion rate of ≈0.2 mm year−1 is observed in the ultrafine‐ and fine‐grained magnesium. The corrosion product layer of the fine‐grained magnesium contains elements absorbed from the media. An analysis of the data in the literature suggests that grain refinement changes the corrosion type from localized to uniform corrosion. The exact relationship between grain size and the corrosion rate remains elusive.

Effect of graphene on microstructure, strain hardening and corrosion behaviour of dual phase Mg-Li matrix processed through liquid metallurgy route

The significance of this study lies in the potential enhancement of magnesium (Mg)-based materials through the addition of graphene, aiming to improve their mechanical properties and corrosion resistance. This research investigates the development of graphene-Mg composites, employing a liquid metallurgy route to fabricate a dual-phase structured Mg-8Li composite. Mg-Li dual-phase composites are of interest due to their lightweight nature and promising mechanical properties, making them suitable for applications in aerospace, automotive, and structural engineering. Graphene was incorporated into the Mg matrix at varying percentages (0.2, 0.4 and 0.6 wt.%), and the resulting materials were subjected to microstructural, mechanical, and corrosion analyses. Microstructural characterization results reveals that the increase in graphene content results in decrement in grain size of α-Mg and β-Li up to ∼33 and ∼11.5% respectively. Likewise, additions of graphene improvise tensile and yield strength of base matrix up to ∼47 and ∼44% respectively. Strain hardening exponent (n) values of base material decrease from 0.21 to 0.17 with respect to graphene addition which confirms the effect of graphene that acts as effective barrier to slip that decreases the deformation. Corrosion analysis revealed a decrease in corrosion rate and increased pitting resistance with the addition of graphene, indicating improved corrosion resistance. Electrochemical impedance spectroscopy results depict that the composite with 0.4 wt.% graphene exhibits larger semi conducting loop with higher charge transfer resistance ( Rct) value of 128 Ω cm2.

Corrosion behaviour of superaustenitic stainless steel N08029 in harsh acidizing environment

It is vital to examine the resistance to corrosion of corrosion resistant alloys (CRAs) in severe oilfield corrosive environments such as acidizing to validate their performance. Super austenitic stainless steel (SASS) UNS N08029 was recently developed to offer competitive and improved corrosion resistance in extreme and aggressive environments. However, no systematic studies have evaluated the N08029 performance in acidizing conditions. In this study, N08029 was investigated in harsh acidizing conditions of different HCl concentrations (up to 25 % HCl), long immersion duration (up to 48 h), and at elevated temperatures (up to 80 °C) using both weight loss and electrochemical measurement techniques. Interestingly, all the test methods show that the corrosion resistance of the SASS increases with increasing the concentration of HCl acid. This may be due to the formation of ferric chloride protective layer on the steel surface after the dissolution of the formed chromium oxide layer by the increasing acid concentration. The decrease in the corrosion rate observed at higher HCl concentrations is because the higher concentration of HCl causes the more ferric chloride layer to form on the metal's surface. This layer protects the metal from further acid attack. Also, after 24 h immersion duration, a decrease in corrosion rate with further increase immersion duration was observed which may is also due to the formation of more ferric chloride protective layer. However, the corrosion resistant of the SASS was observed to decrease with increase in temperature of the test solution. The decreased resistance of the SASS to corrosion with increase in temperature is associated with the instability or damage of the passive/protective film on the surface of the SASS at elevated temperatures.

Assessing the effect of different biodiesels on corrosion of nickel alloy

This investigation explores the corrosion behaviour of Ni alloy (UNS718), which is a potential material for storing biodiesel and making engine components. The study also examines the connection between Ni alloy corrosion and biodiesel degradation. Immersion tests were conducted using in-house biodiesels to evaluate the corrosion rates of Used Cooking Oil (UCOB), Karanja oil (KOB), and Jatropha oil (JOB) biodiesels on Ni alloy (UNS718). The results highlighted the role of corrosion product morphology and the formation of corrosion-driven pitting, cracks, etc., on Ni alloy when exposed to different biodiesels such as KOB, JOB, and UCOB. The study utilized gravimetric techniques to measure the corrosion rate and advanced analytical tools such as FESEM, EDS, XPS, NMR and XRF. It revealed decreased corrosion rates of Ni alloys with prolonged biodiesel immersion. For example, after 2160 h, Jatropha biodiesel exhibited a corrosion rate of 0.000699 mm/year, while the corrosion rates of Ni alloy exposed to UCOB and KOB were 0.001398 mm/year and 0.001048 mm/year, respectively. The study also suggests a detailed mechanism of Ni alloy corrosion when exposed to different biodiesels such as Karanja, Jatropha, and Used Cooking Oil.

Cellulose nanofibers of oil palm fronds as a filler in nanocomposite coating for corrosion protection of copper

Cellulose nanofibers (CNF) create a physical barrier preventing contact with corrosive substances and improving corrosion prevention. Oil palm fronds (OPF), the primary source of underused biomass waste from plantations, were processed into CNF. The OPF-CNF, mixed with hydroxyethyl cellulose as the matrix, forms a nanocomposite. Corrosion analysis using electrochemical methods demonstrated that copper coated with cellulose-rich nanocomposite containing 5 % CNF had a significantly decreased corrosion rate with an efficiency of 97.92 %. This CNF-based coating, combining barrier and passivation mechanisms, enhances performance, providing a competitive, eco-friendly alternative to conventional coatings.

Effect of spinach (Spinacia oleracea) leaf extract on the aluminum (Al) as a green corrosion inhibitor in HCl medium

Green corrosion inhibitors have recently attracted much attention due to their non-toxic properties, especially plant extracts. This study used spinach leaf extract (Spinacia oleracea) as a corrosion inhibitor on aluminum in an HCl medium. Spinach leaf extract (Spinacia oleracea) was obtained by maceration method, using ethanol as the solvent, which was then distilled to purify the extract. The corrosion inhibition properties were studied by the gravimetric method. The results showed that spinach leaf extract (Spinacia oleracea) can efficiently decrease the corrosion rate of aluminum in an HCl medium, achieving a maximum efficiency of 96.7742 %. Spinach leaf extract (Spinacia oleracea) formed a protective layer on the aluminum surface via adsorption and chemisorption, thus increasing surface coverage and blocking mass transfers. As the inhibitor concentration increases, the corrosion rate decreases, and the corrosion inhibition efficiency increases. This study shows that spinach leaf extract (Spinacia oleracea) is a viable organic corrosion inhibitor option with high efficiency.

Corrosion of Copper-Nickel Alloys in Seawater-Based Electrolytes

Copper nickel materials are used for their corrosion resistance due to the protective film that forms in seawater. The development of this film over time depends on the exposure condition, and it is critically important to understand the aging process for CuNi components used in marine systems to ensure passivity under sulfide contaminated conditions. Here we study the formation of the protective film over time and its effect on corrosion performance. Electrochemical impedance spectroscopy (EIS) measurements during exposure are used to develop a model of film growth on CuNi 70/30 alloys. These electrochemical measurements are coupled with surface analytical techniques such as glow discharge-optical emission spectroscopy (GD-OES) and X-ray photoelectron spectroscopy (XPS) to characterize the composition of the surface oxide. GD-OES results show that as the protective layer forms, nickel mainly remains at the metal surface and the outer layers are copper enriched oxides and chlorides. There is also incorporation of various elements from the seawater within the film. The rate of this film growth is correlated to the resulting decrease in corrosion rate. Different exposure conditions, such as under flow, are investigated.The translation of these protective film mechanisms to additively manufactured CuNi materials is also of interest, to ensure similar performance with these materials. Evaluating corrosion performance of these newly developed materials involves careful comparison to existing knowledge of film growth and potential for breakdown.

Combined bulk nanostructuring and surface modifications of titanium substrate for improved corrosion behavior

Titanium has proven to be a game-changing biomaterial in biomedical engineering. Titanium and its alloys offer superior properties such as machinability, mechanical strength, biocompatibility, and corrosion resistance, making them indispensable for safer and more efficient biomedical treatments. While commercially pure titanium (Cp-Ti) is an exceptional material for medical applications, it has some limitations. Allergic reactions can manifest as localized inflammation around the implant, and corrosion compromises implant stability. Corrosion starts with cracking from the surface and disrupts the protective passive oxide layer when touching body fluids, and failure occurs. This study utilized a combination of techniques including grain refinement of Cp-Ti via equal channel angular pressing (ECAP), two-step anodization (for creating titanium oxide nanotubes coatings), annealing at 450°C and 570°C, and immersion in simulated body fluid (SBF) to create a Hydroxyapatite (HA) film coating. These methods addressed various challenges and provided a positive approach to improving corrosion behavior. The microstructure of Nano-Ti was evaluated by Transmission Electron Microscopy (TEM). The morphology of the as-anodized samples and corroded areas were investigated using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The crystalline phases of titanium nanotubes (TNTs) were evaluated through X-ray diffraction (XRD). The presence of hydroxyapatite particles was analyzed and characterized by FESEM coupled with Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR). The corrosion behavior was evaluated using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Results indicated that grain refinement and successive surface modifications significantly impact corrosion performance. The nanostructured (Nano-Ti) sample, after the final modification stage, exhibited an approximately 11-fold decrease in corrosion rate and over a 450-fold rise in polarization resistance (7.4 MΩ) compared to as-anodized Cp-Ti sample and a 7-fold increase in its Cp-Ti counterpart, and showed excellent adhesion strength compared to other samples.

Research on anti-corrosion behavior of modified waterborne Acrylic-based coating containing CuO/Polyaniline nanocomposite on mild steel in 3.5 wt% NaCl solution

This research examines the anti-corrosion properties of an acrylic coating containing CuO/Polyaniline nanocomposite (CuO/PANI n-composite) and the effect of different composition percentages of the n-composite. Electrochemical tests were carried out on mild steel alloy in 3.5 % NaCl solution for 60 days in a saline environment. The electrochemical current noise (ECN) results of prepared coatings were interpreted using the wavelet method. The standard deviation of partial signal (SDPS) plots derived from wavelet, as well as the electrochemical impedance spectroscopy (EIS) technique demonstrated that the quantity of electric charge (Q) decreased with the addition of the n-composite, due to the decreased corrosion rate. Moreover, the modified coating with 20 % composition of the n-composite demonstrated more inhibiting effects in a short and long time compared to other compositions. The EIS measurements showed that the value of coating resistance for 20 % CuO/Polyaniline nanocomposite after 1 day immersion is 1510 kΩ cm2. The results indicated that the 20 % composition of the n-composite exhibited excellent inhibiting properties with an efficiency of 97.57 % and 97.62 % after 1 and 60 Immerging time/day, respectively. The prepared n-composite has been characterized using X-ray diffraction (XRD) analysis, Field-Emission Scanning Electron Microscopy (FE-SEM), and Transmission Electron Microscopy (TEM), which revealed suitable synthesis of the CuO/PANI n-composite. Therefore, this research demonstrates a successful approach to developing the anti-corrosion effect of acrylic coating by the incorporation of CuO/PANI n-composite.

Performance Evaluation of Tetraethylammonium Iodide as Corrosion Inhibitor for Pipeline Protection

To maintain the integrity and safety of the pipeline, different chemicals are used as corrosion inhibitors in the flow-assurance industry. Ionic liquids (ILs) are a promising new class of corrosion inhibitors for pipelines in the oil and gas industry due to their negligible vapour pressure, high thermal stability, and ability to be tailored for specific applications. This research investigated the effectiveness of tetraethylammonium iodide (TEAI) as a corrosion inhibitor at 0.01, 1 and 5 wt% concentrations. TEAI showed a decrease in corrosion rate with increasing concentration, with the lowest rate of 0.59 mm/year at 5 wt% concentration. TEAI+MEG mixtures also showed the lowest corrosion rate of 0.6 mm/year at 5 wt% concentration. The work is new, and these results suggest that ILs have the potential to be used as effective corrosion inhibitors in flow assurance applications. It provides an avenue for further exploration of ionic liquids as corrosion inhibitors.Keywords: Corrosion inhibition, flow assurance, ionic liquids, mild steel, surface coverage, TEAI

Application of Celtis Zenkeri Exudates as Corrosion Inhibition for Galvanised Steel Exposed to Acidic Media

This study investigated the performance of Celtis zenkeri exudates in preventing galvanised steel exposed to acid concentrated water and soil. The study was performed in order to find an alternative coating substance that can reduce the corrosion of galvanised steel pipes exposed to corrosive water and soil media. Various steel specimens were cut into portions and coated with the exudates at 25 - 50µm thickness. To accelerate the rate of corrosion, 0.5M hydrochloric acid (HCl) was added to tap water in a container. Also, the same concentration of HCl was equally added to soil samples. Uncoated steel specimens were immersed in the acid concentrated water and soil, servicing as control sample. The rate of corrosion was monitored for 30 days (720 hours). The inhibition efficiency of the exudates for both corrosive media was compared. Results showed that the weight loss and corrosion rate of galvanised steel decreased with increase in coating thickness. Comparatively, the weight loss and corrosion rate in the uncoated specimens were higher than the coated specimens. With 25 - 50µm coating thickness, the decrease in corrosion rate ranged from 0.01272 to 0.0027mm/yr for specimens immersed in water and from 0.2226 to 0.0185mm/yr for specimens buried in soil, while for uncoated specimens, the corrosion rate was 0.2793mm/yr and 0.4150mm/yr for specimen immersed in water and soil respectively. The inhibition efficiency of Celtis zenkeri exudates increased with coating thickness, which ranged from 54.46 – 99.03% for specimens immersed in water and 46.36 – 95.54% for specimens buried in soil at 25µm – 50µm coating thickness. The results demonstrated that Celtis zenkeri exudates can be used as corrosion inhibitor for steel exposed to corrosive media.

Understanding the adsorption of imidazole corrosion inhibitor at the copper/water interface by ab initio molecular dynamics

Understanding the adsorption mechanisms of organic corrosion inhibitors at metal/water interfaces is crucial for designing corrosion inhibitors. Imidazole adsorption at copper/water surfaces was investigated via ab initio molecular dynamics simulations. The adsorption energy of imidazole on copper in water is slightly more positive than that in vacuum, which is attributed to the hydrogen bond interaction between imidazole and water molecules. Imidazole adsorption changes interfacial water density and dipole distribution, disrupts hydrogen bond networks, and decreases water residence time at the interface. These characteristics are considered to be correlated to the decreased corrosion rate induced by imidazole adsorption.

Electrodeposition of Zn/TiO2 coatings on Ti6Al4V produced by selective laser melting, the characterization and corrosion resistance

Recently, additive manufacturing techniques have begun to be implemented extensively in the production of implants. Ti6Al4V alloy is a material of choice for implants due to its low density and high biocompatibility. Recent research, however, has demonstrated that Ti6Al4V alloy emits long-term ions (such as Al and V) that are hazardous to health. Surface modifications, including coating, are therefore required for implants. The electrodeposition method was utilized to deposit Zn-doped TiO2 onto the surfaces of Ti6Al4V samples, which were manufactured via the selective laser melting method. The effects of processing time, amount of TiO2 addition, microstructure of anode materials, and resistance to wear and corrosion were investigated. The coating hardness and thickness increased with increasing processing time and TiO2 concentration. It has been observed that the addition of TiO2 to zinc anode coatings results in an increase in wear and a decrease in corrosion rate. It was noted that the specimens exhibiting the most significant wear also possessed the highest hardness value. The specimens were generated utilizing a graphite anode, underwent a 30-min processing time, and comprised 10 g l−1 of TiO2.