Electrochemical Corrosion Studies Research Articles

Step-by-Step Tuning of Tribological and Anticorrosion Performance of Zinc Phosphate Conversion Coatings through Effective Integration of Spherical P-Doped MoS2 Nanoparticles.

Surface coatings with enhanced mechanical stability, improved tribological performance, and superior anticorrosion performance find immense application in various industrial sectors. Herein, we report the development of multifunctional composite zinc phosphate coatings by the effective integration of a structurally and morphologically tuned P-doped MoS2 nanoparticle additive (3P-MoS2) into the zinc phosphate matrix to offer attractive characteristics suitable for industrial applications. The integration of spherical nanoparticles as additive leads to the formation of homogeneous and compact coatings with a densely packed crystalline microstructure having enhanced microhardness, distinctive leaf-like morphology, and comparatively smooth topographical features. The attractive lubricity of the additive (3P-MoS2), coupled with its spherical morphology, facilitates a transition from sliding to rolling friction and contributes significantly toward the performance enhancement of the tuned composition of the composite zinc phosphate coating (0.3-PMS). Thus, the tuned 0.3-PMS coating delivers the lowest specific wear rate (1.334 × 10-5 mm3/Nm) and coefficient of friction (0.114) that significantly outperform bare-zinc phosphate coating. Further, the electrochemical corrosion study results indicate the improvement in corrosion resistance behavior of the composite zinc phosphate coatings with reduced corrosion current density (icorr) and charge transfer resistance (Rct) values, as compared to the bare-zinc phosphate coating. The effect of passivation in conjunction with the barrier protection characteristics of the composite coatings induced by the optimal composition of the integrated additive nanoparticles (3P-MoS2) can efficiently prevent the infiltration of corrosive ions and thereby significantly reduce the rate of corrosion.

Ta–W metal alloy membrane reactor for HI decomposition in I–S thermochemical cycle for hydrogen production

HIx processing section of Iodine-Sulfur (IS) thermochemical cycle suffers from the drawbacks of highly corrosive environment and a low thermodynamic conversion of HI decomposition (∼22% at 450 °C). This study investigates, for the first time, the potential of tantalum-tungsten (Ta–W) metal alloy membrane reactor for the decomposition of HI. A thin film of Ta–W alloy was deposited on clay-alumina support by DC magnetron sputtering under optimized set of parameters. The corrosion resistance of the Ta–W membrane was evaluated through electrochemical corrosion studies and immersion coupon tests in azeotropic HI (57 wt % in water) environment. The results confirmed that Ta–W had a higher corrosion resistance than Ta. HI decomposition was carried out in Ta–W membrane reactor and suitable operating parameters were finalized. An enhanced conversion of ∼98% was obtained at 450 °C and 105 Pa, while no permeation of HI, water and iodine was observed across the membrane.

Investigation on electrochemical corrosion behavior and mechanical properties of Fe-nano particles produced by high-energy ball milling technique

Abstract This study focuses on converting iron particles from grinding sludge, after removing impurities, into Fe-nanoparticles using high-energy ball billing. The goal is to examine the corrosion behaviors and mechanical properties of these Fe-nanoparticles. Nanostructured Fe-powder was synthesized through a process involving 10 h of high-energy ball milling, followed by conventional hot pressing and sintering. Structural and microstructural properties were thoroughly examined using techniques such as X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental diffraction spectroscopy. Upon sintering, SEM and TEM analyses unveiled the formation of a nanostructured alloy within the samples. Notably, the milled sample exhibited high hardness value, measuring at 155 HV. However, it is noteworthy that the un-milled sample demonstrated superior compression strength compared to its milled counterpart. Furthermore, the corrosion behavior of the samples was evaluated through electrochemical corrosion studies. Interestingly, the sample subjected to 10 h of milling (coin number 5) displayed a significantly lower corrosion rate, measuring at 1.3921 mm/year, suggesting enhanced corrosion resistance attributed to the nano structuring process.

Effect of process parameters involved in SWJP on surface integrity and biocompatibility characteristics of AZ31B Mg alloy

This study mainly investigates the influence of combined parametric conditions employed in submerged waterjet peening for biomedical applications. On measuring the microhardness and roughness on the peened surface, the finding corresponded directly with the strengthening of subsurface layers and different parametric combinations. The optimum parametric combination was determined by TOPSIS, considering microhardness and surface roughness as input. Under optimal parametric combinations, surface morphology and topography analysis, XRD analysis, corrosion behaviour examination, and cell morphology and viability analysis were studied and compared to unpeened surface. From the experimental results, the water bubbles create impulsive pressure that impacts the AZ31B Mg alloy's surface, promoting plastic deformation in the subsurface, enhancing the surface morphological and topographical characteristics, and making the alloy more suitable for bioimplant manufacture. Following that, these samples underwent an electrochemical corrosion study, which indicates the peened region's corrosion rate was reduced considerably compared to the unpeened region. In the course of biocompatibility analysis, the non-toxic nature of the peened region in the MG63 cell line was observed after 24 and 72 h.

Electrochemical impedance study of corrosion of pure Ni, Fe, Cr, and Fe‐5Cr alloy in molten nitrides

AbstractMolten nitrates or nitrate–nitrite mixtures have been used as heat transfer fluid as well as thermal energy storage medium in concentrated solar power plants and other industrial applications. However, containment materials in contact with these molten salts are subjected to molten salt corrosion, which has been a concern over the years. In this investigation, the corrosion behavior of pure Ni, Fe, Cr, and Fe‐5Cr alloy (in weight percent) has been examined at 400°C in molten nitrates using electrochemical impedance spectroscopy and gravimetric tests. It is shown that Ni, Fe, and Fe‐5Cr exhibit mass gain, with the best corrosion resistance for Ni followed by Fe‐5Cr and Fe, while pure Cr goes through fast dissolution, forming hexavalent chromium product K3Na(CrO4)2. The increase of salt basicity from Solar Salt to Hitec could accelerate the dissolution of Cr. Nevertheless, the formation of an inner Cr‐containing scale could still offer the alloy good protection because the external insoluble Ni or Fe oxides can protect it from dissolution.

Effect of SrTiO3 incorporation in Mg matrix: Microstructure, mechanical, corrosion and in vitro bioactivity study

In the present study, magnesium-strontium titanate (Mg-SrTiO3) composites were prepared using powder metallurgy route. The physical, mechanical, and electrochemical properties of pure Mg were compared with those of Mg-SrTiO3 composites with varying SrTiO3 concentrations (0, 1 and 5 wt%). X-ray diffraction (XRD) results showed the SrTiO3 and Mg peaks in the composites. Scanning electron microscopy (SEM) of the composite revealed the uniform distribution of reinforcement in the Mg matrix. An electrochemical corrosion study showed that the Mg-SrTiO3 composite has more positive ECORR than pure Mg. The lowest corrosion rate was observed in the Mg-1 %SrTiO3 composite. An in vitro biocompatibility and antimicrobial study revealed that Mg-SrTiO3 composites are non-toxic and have mild antibacterial property.

Electrochemical corrosion study of carbon steel in bio-oil environments

Comprehensive corrosion risk assessments are essential for ensuring the safe and efficient utilization of bio-oil (BO) in industrial applications. In this study, electrochemical measurements (EMs) such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were conducted for carbon steel (CS) at BO storage temperatures of 20 and 50 °C. Different electrolytes were used, including BO, BO+10 wt% methanol (10 ME), BO+20 wt% methanol (20 ME), and 0.1 M acetic acid (0.1AC). To improve data quality in low-conductive environments, various techniques were employed for EMs. Concurrent immersion experiments (IEs) were performed to validate corrosion rate (CR) calculations obtained from EMs. The PDP results revealed uniform corrosion as the prevalent form of CS corrosion in BO environments, while EIS measurements indicated the involvement of adsorption/chelation processes. A well-fit equivalent circuit model was proposed for EIS data. The ratios between CRs obtained from EMs and IEs were around 4.3 and 0.9 at 20 and 50 °C, respectively, for all electrolytes, confirming the reliability of EMs for evaluating CS corrosion in BO environments. This study provides valuable insights into corrosion assessments of structural alloys in BO environments using reliable yet inexpensive EM techniques.

Evaluation of structural and corrosion behavior of chitosan/silver coating on Ti6Al4V/TiO2 nanotubular surface

Materials used in biomedical applications must have good bulk and surface properties. The main goal of this work is to create a multifunctional surface based on chitosan-coated Ag-loaded TiO2 nanotubes to assess their capacity in the corrosion resistance property. In the first phase, Ag-loaded TiO2 nanotubular surfaces with different weight percentages of silver were fabricated at a constant voltage of 2 V under varied time durations of 1 min, 2 min, and 3 min. In the second phase, cathodic electrophoretic deposition (EPD) was used to coat the samples with chitosan by applying 10 V for 5 min as a constant process parameter for coating all the samples. The composition and morphology features of in-house fabricated Ag-loaded TiO2 nanotubular surface with chitosan were studied by different techniques such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), and Contact angle measurement. The corrosion resistance of the coated samples was assessed by using OCP, PDP, and EIS techniques. The results evidenced that chitosan-coated Ag-loaded (2 V 2 min) TiO2 nanotubular surface (TNT-Ag2.2/Ch) showed the best performance as a coating system when compared to an uncoated surface. Also, electrochemical corrosion studies showed better corrosion resistance for this coated sample. In this context, the chitosan that has been deposited serves as a protective barrier, facilitating the penetration of the physiological solution into the underlying metal surface. Overall, the TNT-Ag2.2/Ch coated sample showed 5 times better results when compared with icorr values. Finally, the newly developed chitosan-coated Ag-loaded TiO2 nanotubular surface improve the corrosion resistance of the polished Ti6Al4V alloy.

Electrochemical corrosion study of chitosan-hydroxyapatite coated dental implant

Chitosan (Ch) is a naturally occurring biocompatible and bio-degradable material with high corrosion protective capacities for metals in various corrosive media. Hydroxyapatite (HA) is a significant biodegradable and bioactive material. In the present work, chitosan-hydroxyapatite (Ch-HA) composite coatings with various concentrations of chitosan were made on 316L stainless steel (316L SS) using sol–gel dip coating technique. The coatings were characterized by X-ray diffraction (XRD), FTIR, SEM, and electrochemical measurements. The surface morphology results (SEM) of coated implants exposed the fairly dense microstructures having uniformity without cracks and pores indicating that coating was successfully deposited. From electrochemical analyses, it was observed that the value of corrosion current density and the corrosion rate decreased from 6.03 to 0.15 and 5.56-0.13 respectively indicating that 1.5gCh-HA is the best coating concentration. The electrochemical results demonstrated an improvement in the corrosion resistance of 316L SS than the bare one. The decrease in slope and loop area of cyclic voltammograms reveals about improvement in corrosion resistance. This increment in corrosion resistance of the Ch-HA coated SS implant in the artificial saliva is as 1.5gCh-HA > 2gCh-HA >1gCh-HA >0.5gCh-HA. Furthermore, Ch-HA coatings revealed appropriate adhesion with 316L SS substrate for its use in dental implants.

Advanced Anticorrosive Graphene Oxide-Doped Organic-Inorganic Hybrid Nanocomposite Coating Derived from Leucaena leucocephala Oil.

Metal corrosion poses a substantial economic challenge in a technologically advanced world. In this study, novel environmentally friendly anticorrosive graphene oxide (GO)-doped organic-inorganic hybrid polyurethane (LFAOIH@GO-PU) nanocomposite coatings were developed from Leucaena leucocephala oil (LLO). The formulation was produced by the amidation reaction of LLO to form diol fatty amide followed by the reaction of tetraethoxysilane (TEOS) and a dispersion of GOx (X = 0.25, 0.50, and 0.75 wt%) along with the reaction of isophorane diisocyanate (IPDI) (25-40 wt%) to form LFAOIH@GOx-PU35 nanocomposites. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR); 1H, 13C, and 29Si nuclear magnetic resonance; and X-ray photoelectron spectroscopy. A detailed examination of LFAOIH@GO0.5-PU35 morphology was conducted using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. These studies revealed distinctive surface roughness features along with a contact angle of around 88 G.U preserving their structural integrity at temperatures of up to 235 °C with minimal loading of GO. Additionally, improved mechanical properties, including scratch hardness (3 kg), pencil hardness (5H), impact resistance, bending, gloss value (79), crosshatch adhesion, and thickness were evaluated with the dispersion of GO. Electrochemical corrosion studies, involving Nyquist, Bode, and Tafel plots, provided clear evidence of the outstanding anticorrosion performance of the coatings.

Biocompatibility screening of Mo–Si–Ta glassy alloy films sputtered on additive manufactured Ti–6Al–4V implant prototypes and PCL scaffolds

A ternary system of amorphous alloy with the components Mo, Ti, and Si with the composition Mo54Si33Ta13 has been chosen as the surface coating for the implantable materials to improve Ti6Al4V bioactivity. Ti6Al4V alloy metal powders were used to create the implant prototypes with the 3D metal printer. With the aid of a DC magnetron, the films are sputtered onto the implant prototypes. Elemental composition, amorphous nature, surface chemistry and topography of the as-fabricated microstructure films were comprehensively analysed using X-ray diffraction analysis, X-ray photoelectron spectroscopy and electron/atomic force microscopic techniques. The mechanical properties were studied from Nano indentation method. The coatings were confirmed to be cytocompatible determined from the in-vitro biocompatibility investigations using human osteosarcoma cells. The electrochemical corrosion studies carried out in SBF showed the higher corrosion resistance for the thin film metallic glass (TFMG)-coated customized 3D printed Ti-alloy implants than the pristine specimen.

Electrochemical corrosion study of biomaterials: A bibliometric study based on co-word analysis

Demand for better biomaterials has been increasing. To meet this demand, testing is necessary to screen potential options. Corrosion testing is essential as it relates to durability and biocompatibility. Usually, electrochemical tests are employed in screening candidates for in vivo testing. Researching in the biomaterials field, or any field for that matter, requires continuous consultation of the literature. When conducting a literature search, the amount of information available is often overwhelming. Identifying relevant research trends that can guide decisions about future projects becomes challenging. This study employs bibliometric analysis to identify research trends in electrochemical corrosion studies of biomaterials. By doing this, researchers interested in the subject are provided with relevant information on which to base decisions about future research projects. The method used is called co-word analysis. Keywords have been downloaded from Web of Science using an appropriate search query. The analysis period includes the months from January 2013 to December 2021. This period is divided into three subperiods of three years each: 2013–15, 2016–18, and 2019–21. Evolution analysis identified 5 areas of interest that remained active throughout the entire period: biodegradable magnesium alloys, titanium and its alloys, hydroxyapatite coatings, general biomaterial characterization, and the use of electrochemical impedance spectroscopy. All of them are likely to remain of interest in the following years. One area related to titanium anodization appears to be an active research area with few publications, leaving room for new research. Methodological limitations are properly addressed.

Hydroxyapatite coating for control degradation and parametric optimization of pure magnesium: an electrophoretic deposition technique for biodegradable implants

Design of orthopedic implants is a challenging task to cope with desired properties, therefore, numerous metal-alloy and coating were utilized in the fabrication of implants as alternative options. Magnesium (Mg)-based alloys are among the unique materials owing to their promising properties to avoid cytotoxicity, genotoxicity, and carcinogenicity; however, the fast degradation of Mg limits its clinical applications. In this study, hydroxyapatite (HA) nano-powder was coated on pure Mg as the compositions of both materials are promising biodegradable bone-compatible materials. The electrophoretic deposition (EPD) technique was used to produce a bioactive coating on pure Mg. The research novelty highlighted for the first time, the EPD parameters were optimized via the full Design of Experiment (DoF) approach during HA coating of Mg, while the weight loss of pure Mg and HA coated Mg were investigated in SBF for 7, 14, 21, and 28 days. The surface morphologies of both materials were investigated before and after coating. The bioactivity of the coated samples was examined in Simulated Body Fluid (SBF) and investigated using SEM. Surface roughness, contact angle measurement, scratch test, wear test, an in-vitro study in SBF, electrochemical corrosion, and cellular studies were conducted according to the standard approaches. The results show that HA coated Mg samples are compatible for orthopedic implants in terms of surface roughness, wettability, adhesion, wear sustainability, HA growth, corrosion rate, and cell viability. Thus, the biological, mechanical, and cellular properties of HA-coated implants are suitable and recommended as alternatives to biodegradable implants.

Surface morphology studies and corrosion behaviour of plasma sprayed Cr3C2/8YSZ composite coating on SS316

Austenitic Stainless Steel (SS316) is a commonly used material in marine and offshore locations. The components’ surface in such environments degrades due to chloride and moisture exposure. Hence, adding a ceramic coating to the surface enhances its functionality. In the present work, Cr3C2 and 8YSZ powders are mixed in an equal ratio to deposit unique composite coated layers on the SS316 substrate by plasma spray coating method. The performance of the composite coating is also compared to that of uncoated, Cr3C2-coated, and 8YSZ-coated substrates. The surface morphology and cross-sectional microstructures of the coated SS316 substrate are examined using scanning electron microscope (SEM) images, and The presence of chemical elements in the coatings is determined using Energy Dispersive x-ray Analysis (EDAX) with elemental mapping. Further, the corrosion resistance of the substrate is evaluated using potentiodynamic polarisation and Electrochemical Impedance Spectroscopy (EIS) methods. The results show that the composite coating has a decreased porosity of 1.33% area and a higher microhardness of 880.02HV compared to bare and other coated surfaces. The corrosion analysis reveals that the composite coating has a decreased corrosion current density (Icorr) of 3.233 × 10–6 mA cm−2 and an enhanced charge transfer resistance of 2396.23 ohms.cm2 due to strong passivation and restricted electrolyte penetration into the coating. Further, the electrochemical corrosion study reveals that the composite coating exhibits the lowest corrosion rate of 0.00004306 mm / year.

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

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

Deposition and study of plasma sprayed Al2O3-TiO2 coatings on AZ31 magnesium alloy

In this study, Al2O3, TiO2 and Al2O3+ 3wt%TiO2 coatings were deposited on AZ31 Mg alloy substrate by plasma spraying. The coatings were structurally characterized by scanning electron microscopy and X-ray diffraction. Corrosion experiments were carried out in 3.5% NaCl solution. Adhesion tests were performed according to daimler benz VDI-3198 standard. A coating layer of approximately 70 microns in thickness was deposited. High plasma enthalpy caused phase transformations in alumina-based ceramics. As a result of electrochemical corrosion study, it was determined that the coatings increased the corrosion resistance of AZ31 Mg alloy. While the most corrosion resistant coating is Al2O3+ 3wt%TiO2, the weakest coating against corrosion is TiO2. The adhesion behavior of all coatings to the substrate was at an acceptable quality levels.

Meniscus-confined electrochemical additive manufacturing of copper microstructures: Design, fabrication, characterization, and decorative art technology

For the first time, a room-temperature meniscus-confined electrochemical additive manufacturing (MC-ECAM) process is evaluated as a potential decorative art technology for fabricating copper metal. The MC-ECAM has proven to be an excellent method for large-scale printing of decorative copper artworks such as warli art, plant leaves, and paintings. The inherent nature of the MC-ECAM process has the potential to eliminate the traditional time-consuming route to producing such copper microstructures and provide a one-step and efficient solution. The TEM and FE-SEM results revealed that well-oriented microstructures are prepared without surfactant, indicating the ECAM self-assembly mechanism. A small amount of zinc is added to the copper system to prevent corrosion. The XRD analysis also revealed the formation of copper metal, which barely changed even after 10 months of atmospheric ageing with the addition of 2% zinc. The XPS results show that zinc provides excellent stability for the ECAM-printed copper microstructure, further examined by an electrochemical corrosion study. Zinc act as a barrier to corrosion, and the results show that the Cu-Zn 2% exhibits excellent corrosion resistance than the pure copper microstructures.

Electrochemical corrosion and impedance studies of Ti-30Zr-xNb (x = 7, 10, 13 at.%) alloy in simulated downhole environment

Electrochemical corrosion and impedance studies of Ti-30Zr-xNb (x = 7, 10, 13 at.%) alloy in simulated downhole environment

Unveiling the corrosion perspective of Al-Si alloy/SiC foam interpenetrating phase composite

The corrosion response of the Al-Si alloy/SiC foam interpenetrating phase composite (IPC) has been investigated for the first time in this study. Towards this, SiC foams with varying pores per inch (PPI) index (10, 20, and 30) were employed to fabricate IPCs, designated as, 10PPIC, 20PPIC, and 30PPIC, respectively. The pore size decreased and connectivity of the reinforcement increased with the increase in the PPI index. The electrochemical corrosion studies have revealed that the incorporation of the reinforcing phase in a continuous manner deteriorates the corrosion resistance in all the IPCs except in 20PPIC, where the corrosion resistance is comparable to that of the unreinforced alloy. This is ascribed to the optimum pore size and reinforcement interlinking in this specimen which results in the formation of a less disrupted passive film as well as substantially restricts the pit growth.

Experimental investigations on corrosion performance of heat-treated AZ91 Mg alloy

Current examination stands rooted in corrosion rate estimation for AZ91 magnesium alloy. To evaluate corrosion rate, two different methods like weight loss analysis and electrochemical test were employed. It is important to acquire detail understanding of corrosion performance of magnesium alloy in aggressive biological environments. The bio-corrosion rates of AZ91 samples are estimated at different intervals (3, 15, 32, 48, 72, 86 hr) of exposure to the solution. From the experimental investigation on corrosion behaviour of AZ91 it is evident that the major issue associated with magnesium alloy is faster corrosion rate during initial phase of exposure. However, in the later phase of exposure corrosion rate remains relatively stable. The electrochemical corrosion analysis results showed further negative OCP develops for AZ91 alloy. It shows their lively performance perhaps oxidation of Mg2+ ion by varying stability potential further negative. Microstructure evaluation of the corrode surfaces is done through scanning electron microscope. SEM micrograph of corroded surface conform presence of oxides as a result of corrosion reaction in the solution. Immersion test and electrochemical corrosion study of the alloy was carried out at atmospheric conditions. EDS analysis of alloy sample depicts that throughout processing something like 79.87 % (wt.) of Mg is present in heat-treated AZ91 alloy. Additionally, throughout processing the average grain size of heat-treated AZ91 Mg alloy is mostly 90 µm as against 60 µm for as-cast AZ91 alloy.