Corrosion Rate Of Steel Research Articles

Neural network analysis of safe life of the oil and gas industrial structures

Purpose is to study safe life of industrial (metal) structures under long-time operation in the corrosive-active media of oil and gas wells with the help of neural network analysis. Methods. The MATLAB system (MATrix LABoratory) was selected as the tool environment for interface modelling; the system is developed by Math Works Inc. and is a high-level programming language for technical computations. Of the three existing learning paradigms, we used the “with teacher” learning process, as we believed that a neural network had correct answers (network outputs) for each input example. The coefficients were adjusted so that the network gave answers being as close as possible to the known correct answers. Findings. An artificial neural network has helped obtain a generalized diagram of the expected areas of high viscoplastic characteristics of carbon steels used to manufacture metal structures in the oil and gas industry. While applying the trained neural networks, generalized dependences of the corrosion rates of structural steels on the parameters of media with different concentrations of chlorine ions, sulphate ions, hydrogen sulphide, carbon dioxide, carbon dioxide, and oxygen ions were obtained; they were the basis to predict corrosion behaviour of steels. Originality. For the first time, the possibility of applying neural network modelling to predict local corrosion damage of structural pipe steels has been shown in terms of the “steel 20 – oxygen and chloride-containing medium” system. For the first time, the technological possibility has been demonstrated to use neural network analysis for engineering predictive assessment of corrosion activity of binary systems of simulated solutions, which are most often found under industrial conditions of the oil and gas sector of the economy. Practical implications. The proposed technology of using the neural network analysis will make it possible to expand a range of predicted values beyond experimental data, i.e. to predict the value of Vcor in very dilute or concentrated salt solutions within the acidified and neutral pH ranges. It should be noted that the error of the prediction results shown by the neural network will increase along with distancing from the scope of experimental data.

Roles of Al and Mg on the Microstructure and Corrosion Resistance of Zn-Al-Mg Hot-Dipped Coated Steel.

In this work, a novel zinc-aluminum-magnesium (Zn-Al-Mg, ZM) coated steel was prepared using the hot-dip method. The microstructure and corrosion resistance of the ZM-coated steel were investigated. Compared to the conventional galvanized steel (GI), the ZM coating demonstrated a distinctive phase structure, consisting of Zn phase, binary eutectic (Zn/MgZn2), and ternary eutectic (Zn/Al/MgZn2). The corrosion resistance of the ZM-coated and GI-coated steels was evaluated by neutral salt spray test (NSST), polarization and electrochemical impedance spectroscopy (EIS). The results indicated that ZM-coated steel provided superior long-term corrosion protection in a NaCl environment compared to GI-coated steel. The scanning vibrating electrode technique (SVET) proved to be an effective method for investigating the evolution of the anodic and cathodic on the local coating surface. GI-coated steel exhibited a potential and current density distribution between the cathodic and anodic sites nearly three orders of magnitude higher than that of ZM-coated steel, suggesting a higher corrosion rate for GI-coated steel.

Unraveling the influence of Mo on the corrosion mechanism of Ni-advanced weathering steel in harsh marine atmospheric environments

Ni-advanced weathering steel holds paramount importance in marine atmospheric environments, especially those with heightened Cl− concentrations. The meticulous compositional design plays a crucial role in establishing a rust layer capable of withstanding intrusion by Cl−, making it imperative for the viability of coating-free weathering steel in marine atmospheric environments. This study explores the corrosion evolution and corrosion-resistant mechanisms within a steady-state rust layer in 3Ni weathering steel, with a particular focus on the role of Mo in challenging marine atmospheric conditions. The findings unequivocally demonstrate that the augmentation of the protective properties of the rust layer is directly correlated with an increase in Mo content, transitioning from 0.5 to 1.5 wt.%. This transition is most evident in the reduction of the corrosion rate for the 3Ni-Mo steel, dropping from an initial 1.74 mm a−1 to a robust 1.31 mm a−1 after 768 h of corrosion exposure. The heightened Mo content expedites the formation of a stable and durable rust layer, significantly enriching the proportion of α-FeOOH within this protective layer. The stabilized rust layer of 3Ni-Mo weathering steel exhibits a distinct three-layer structure, comprising an outer layer primarily of γ-FeOOH, an intermediate layer mainly composed of Fe2O3/Fe3O4, and an inner layer predominantly composed of α-FeOOH and β-FeOOH. Additionally, an alkaline interface enriched with NiFe2O4 and CuFe2O4 develops between the inner layer and the substrate. Firstly, Mo promotes the deposition of MoO2, MoO3, and molybdate on both the inner layer and alkaline steel-rust interface to repair corrosion pits and fill cracks. Secondly, Mo facilitates the generation of compounds such as NiFe2O4 and CuFe2O4, which heightens the electronegativity of the intermediate rust layer and the steel-rust interface, preventing Cl−-induced interface acidification and pitting corrosion. The higher Mo content expedites the formation of this alkaline interface and promotes inner layer densification. Most significantly, Mo creates additional nucleation sites for hydroxide oxides through oxide formation, leading to the formation of nano-sized α-FeOOH and β-FeOOH within the inner layer thereby enhancing the stability and compactness of the inner layer. These synergistic effects fortify the resilience of 3Ni-Mo advanced weathering steel in corrosive environments, ultimately strengthening its capacity to withstand environmental challenges.

Effect of tetrakis(hydroxymethyl)phosphonium sulfate (THPS) on the microbial community and corrosion of carbon steel in a simulated crude-oil storage tank environment

The biocorrosion process has been a problem for the oil and gas industry, involving deterioration of facilities, loss of oil quality, metal loss, and oil leaks. In oil storage tanks, the presence of a metallic surface along with crude oil and water poses a biocorrosion risk. Biocides are used to control the biocorrosion of different metallic infrastructures, tetrakis(hydroxymethyl)phosphonium sulfate (THPS) is commonly used due to its low environmental impact and its effectiveness in preventing sulfate-reducing bacteria (SRB) growth. The treatment effect with one THPS application on microbial community and corrosion rates was evaluated in a batch fractionated assay containing water from a crude oil storage tank, carbon steel coupons and crude oil. The effects of the treatment were monitored for 60 days. The number of planktonic bacteria and archaea estimated by qPCR decreased at the beginning of the treatment with THPS, however, 60 days after the application their number was higher, as were the sulfate-reducing microorganisms (SRM) and methanogens (MA). The diversity analysis of the 16S rRNA gene showed that the relative abundance of the genus Desulfovibrio and Methanocalculus was higher on day 8 in the presence of THPS, but by day 60 there were no differences. The biocide did not inhibit bacterial and archaeal biofilm attached to the SAE 1010 carbon steel coupons and produced a decrease in corrosion rates by blocking the surface. The proximity of the corrosion potential to the pitting potential indicated a high susceptibility to localized corrosion. The results suggested that the changes in the microbial community by THPS treatment were related to the corrosion rates of carbon steel, rather than the number of microorganisms attached to the coupon.

Experimental Study on Adsorption and Corrosion Inhibition Properties of <i>Urena lobata</i> Leaves Extract on Mild Steel in Acidic Medium

The corrosion inhibitive effect of <i>Urena lobata</i> leaves extract on mild steel in 1M HCl solution was investigated via gravimetric, Electrochemical and Surface analyses. Adsorption isotherms were investigated using the Langmuir and Freundlich plots. Phytochemicals of the extract were investigated using Gas Chromatography-Mass Spectrometric (GC-MS) technique. The effect of the leaves extract through immersion time, temperature and concentration on the corrosion inhibition were obtained. The results obtained showed that the increase in extract’s concentration increased the inhibition efficiency and the protection was more on the surface of the metal at lower temperature. Maximum inhibition efficiency of 95.8% was obtained at 2.5g/L extract concentration. Corrosion rate of mild steel increased with temperature increase in the acidic solution. The adsorption process reduced as temperature increased thereby indicating physisorption. The Langmuir isotherms gave the best fit indicating chemisorption. Physical adsorption was confirmed for the leaves extract from observations of inhibition efficiency with temperature, activation energy and enthalpy of adsorption values. Hence indicating that the plant extract has mixed properties. The electrochemical results confirmed the inhibitory ability of the plant extract. The inhibition efficiencies (% IE) were attributed to the phytochemical components (alkaloids, saponins, flavonoids, tannins, cynagenic glycosides) present in the extract. The extracts of <i>Urena lobata</i> are effective corrosion inhibitors of mild steel.

Unveiling the potent corrosion-inhibiting power of Ammophila arenaria aqueous extract for mild steel in acidic environments: An integrated experimental and computational study

Plant extracts have emerged as potent inhibiting compounds for metallic corrosion, offering numerous advantages including simple accessibility, low toxicity, eco-friendliness, biocompatibility, effectiveness, and renewability. In this study, the potential of Ammophila arenaria extract as a green corrosion inhibitor for mild steel in 1.0 M HCl over the concentration range of 25–700 ppm was evaluated, using various electrochemical analyses such as Open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results revealed a notable reduction in the corrosion rate of steel, particularly at 700 ppm, where Ammophila arenaria extract demonstrated its highest inhibition efficiency, reaching 83.67% for polarization and 84.32% for EIS. The cathodic and anodic polarization curves indicated that the aqueous extract of Ammophila arenaria functions as a mixed-type inhibitor. The thermodynamic analysis revealed a negative Gibbs free energy value (∆Gads°), suggesting spontaneous physisorption as the predominant adsorption mechanism. To delve into the inhibition mechanism at the molecular level, the surface morphology of mild steel exposed to 1.0 M HCl solutions, both in the absence and presence of Ammophila arenaria aqueous extract, was scrutinized through Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Theoretical techniques, including Quantum Calculation Theory, Non-Covalent Interaction (NCI), and Atom In Molecule (QTAIM), were concurrently employed, providing valuable insights into molecular-level interactions. Remarkably, the computational studies complemented and corroborated the experimental data. These comprehensive results significantly contribute to the understanding of Ammophila arenaria extract's corrosion inhibiting properties, endorsing its potential as a sustainable and environmentally friendly corrosion inhibitor suitable for diverse industrial applications. The synergistic integration of experimental and computational approaches establishes a robust foundation for future endeavors in the field of green corrosion inhibitors.

Optimization on Microbial Anti-Scaling and Corrosion Inhibition Technology for Low Alkalinity and Low Hardness Circulating Cooling Water in Thermal Power Plants

This paper analyzed the potential effectiveness of microbial anti-scaling and corrosion inhibition technology for low alkalinity and low hardness circulating cooling water in thermal power plants and used response surface models to study the effects and optimal conditions of key technical parameters. The results showed that when the nutrient solution dosage, bacterial agent dosage and aeration rate were set at 0.1-0.3 ‰, 0.1-0.5 ‰, and 1-3 L/min, respectively, the calcium hardness, corrosion rate of brass and stainless steel 304 in the water could be controlled within 9.77-15.30 mmol/L, 0.77-6.58 μm/a, and 1.20-4.50 μm/a, respectively. The variance analysis results indicated that the response surface linear model was the most suitable for evaluating the effects of key operation parameters on the application efficiency of the technology. The obtained model furtherly revealed that the nutrient solution dosage and bacterial agent dosage were extremely significant explanatory variable factors affecting the application of microbial technology in inhibition and corrosion control (P < 0.01). Still, the aeration rate did not reach a significant effect (P > 0.05). Based on the regression equation of actual factors, the study further revealed through the hill climbing algorithm that the optimal comprehensive effect of microbial technology in inhibition and corrosion control was achieved when the nutrient solution dosage, bacterial agent dosage, and aeration rate were set at 0.3‰, 0.5‰, and 1 L/min, respectively.

Time-dependent high-pressure CO2-induced corrosion and mechanical degradation in lightweight fly-ash cement/P110 steel system

This study innovatively investigated CO2-induced corrosion and mechanical degradation in lightweight fly-ash cement/P110 casing steel system under normal and high pressures. Key findings revealed time-dependent corrosion and mechanical evolution. Under normal pressure, cement properties peaked at 28 days, contrasting with 21 days under high pressure. Simultaneously, the corrosion rate of steel steadily increased, particularly under high pressure. A two-stage degradation process was proposed based on cement hydration and corrosion competition. Higher pressure accelerated degradation through intensified cement carbonation and cement/casing interfacial cracking. The predicted 30-year carbonation depth under high pressure was 51 mm based on the established fitting equation (H=3.7026t0.2919−4.8205).

Inhibition of Acid Descaling and Pickling Effects on API 5CT Carbon Steel Using Schiff Base Ligand (C24H21N5O2) in 1 M H2SO4 Solution

The objective of this paper was to investigate the inhibition of acid descaling and pickling effects on API 5CT carbon steel using Schiff base ligand (C24H21N5O2) in 1 M H2SO4 solution using Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS) and Weight Loss (WL) techniques. FTIR spectroscopy shows that there was a strong adsorption of SFBL on the carbon steel surface due to formation of a complex surface film. Corrosion rate of carbon steel decreased exceedingly from 0.0155 to 0.0002 while inhibition efficiency of SFBL rose from 78.8 % to 98.9 % between 20 ppm and 100 ppm respectively. PDP measurements revealed a mixed type inhibitor. EIS measurement reveals that the increasing charge transfer resistance was directly proportional to the increase inhibitor concentration and the double layer capacitance dropped from 1.98 to 0.61 indicating a stronger inhibition.

Performance of two high-strength steels under electrochemical corrosive and stressed conditions

The corrosion behaviors of stressed API X-80 and API X-120 pipeline steels were investigated using electrochemical and slow strain rate tensile tests after being immersed in a saline solution containing 3.5% NaCl. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive x-ray spectroscopy (EDX) were used to create images of the flawed steel samples. Corrosion rates for API X-120 pipeline steel were found to be much lower than those of API X-80 pipeline steel in both stressed and saline environments. While different oxide layers were observed on the two steels, the result showed the oxide film was of iron carbonate. It was observed that the API X-120 steel surface was latently smooth in a saline solution environment which reduced the corrosion rate. As a result, the API X-120 pipeline steel was protected and had a delayed time-to-failure in comparison to the API X-80 pipeline steel when it was tested in steel under stress and in solution medium. This failure mechanism will not only be significant to the petroleum sector, but also to the industry that produces pipelines in terms of the choice of fitting material for pipe design. Specifically, this mechanism will have an impact on the design of fittings for pipes.

Transfer learning enables prediction of steel corrosion in concrete under natural environments

Existing machine learning (ML) models for corrosion rate prediction of steel in cementitious materials are typically established based on laboratory datasets obtained under controlled material and environmental conditions, which questions their applicability to more realistic and complex scenarios. Transfer learning (TL), as a branch of ML, can extract knowledge from a source domain, which can be utilized to improve prediction accuracy on a target domain. In this work, a TL paradigm, grounded on an advanced ML model built for steel corrosion in mortars, is proposed to elevate the efficacy of existing ML models in forecasting corrosion rate of steel in concrete under natural environments. The results underscore the prominence of certain features, specifically electrical resistivity, chloride-to-hydroxide concentration ratio ([Cl−]/[OH−]), cement proportion, corrosion potential, porosity, and water content. In addition, the interplay of diverse quantities of features and feature amalgamations exercises a substantial influence on the performance of ML models. It is found that TL strategy enhances the ML model's predictability for corrosion rate in concrete under natural environments. The knowledge pertaining to steel corrosion under controlled laboratory conditions can be transferred to enhance the model's ability to predict steel corrosion in concrete under natural conditions. These results underscore TL's potential in enabling reliable corrosion rate predictions in existing in-service concrete structures, especially with limited data and deficient information for steel corrosion in concrete structures.

Гуанідінійвмісний олігомер як інгібітор мікробної корозії металу

Guanidinium-containing oligomers, a poorly studied class of organic compounds, have attracted attention due to their bactericidal properties. A guanidinium-containing oligomer based on an aliphatic oligoepoxide is a newly synthesized substance with bactericidal activity, which gives it the prospects for use as a microbial corrosion inhibitor. Aim. The goal of the study was to synthesize oligomeric alkyl substituted guanidinium bromide and study of its anticorrosive properties in the presence of steel under the influence of corrosive active sulfate-reducing bacteria. Methods. The guanidine-containing alkyl substituted oligomer was obtained by the reaction of the aliphatic oligoepoxide DEG-1 with guanidine, followed by interaction with alkyl bromide. The anticorrosive properties of the guanidine-containing oligomer were studied using collection strains of sulfate-reducing bacteria: UCM B-11503 Desulfovibrio sp.10, UCM B-11501 Desulfovibrio desulfuricans DSM642, and UCM B-11502 Desulfovibrio vulgaris DSM644. The sulfate-reducing bacteria were grown on Postgate В medium for 14 days at a temperature of 28 ± 2 °C. The number of bacteria was determined by the method of tenfold dilution. The corrosion rate was determined by the gravimetric method. The physicochemical parameters of pH and redox potential of the bacterial culture liquid were studied by the potentiometric method. The accumulation of hydrogen sulfide in the culture liquid was determined by the iodometric method. Lipolytic activity was studied spectrophotometrically using a KFK-3 device by reaction with p-nitrophenyl palmitate, catalase activity — using 0.03% hydrogen peroxide, which formed a stable colored complex with a 4% molybdenum diphosphate solution. The specific activity of the studied enzymes was expressed as unit ∙ mg-1 protein. Protein was determined in the supernatant by the conventional Lowry method. Results. It was shown that the oligomer based on aliphatic oligoepoxide has biocidal properties. A significant inhibition of the development of sulfate-reducing bacteria (SRB) was observed after the oligomer was added; only dozens of bacterial cells were detected in the medium after the exposure period. The corrosion rate of steel in the presence of SBR without addition of inhibitors was 0.15 — 0.35 mg/cm2∙h. The addition of DPC (a quaternary ammonium compound based on N-decylpyridinium chloride) (Kyiv Polytechnic Institute (KPI), Ukraine) to the culture medium led to a decrease in the steel corrosion rate to 0.032 — 0.047 mg ∙ cm-2 h-1 (by 6.5—10.6 times). In the presence of Armohib CI-28 inhibitor (based on Diamine Ethoxylate) (Akzonobel, Holland), the corrosion rate was reduced to 0.02—0.039 mg ∙ cm-2 h-1 (by 4.2 — 12.7 times). The addition of guanidinium-containing oligomer to the medium with bacteria reduced the corrosion rate to 0.075—0.079 mg/cm2 ∙ h (by 2.5—2.7 times). According to the mass loss of steel samples, the degree of metal protection against microbial corrosion in the presence of guanidinium-containing oligomer was 60.15—63.17%. Conclusions. The obtained data indicate that the guanidinium-containing oligomer based on aliphatic oligoepoxy has biocidal and anticorrosive properties and is promising for use as a means of combating microbially induced corrosion.

Study of Anti-Corrosion Properties of Sodium Dodecyl Sulphate and Cetyl Pyridinium Chloride

Surfactant is a surface-active agent. Surfactants have both hydrophilic (water-attracting) and hydrophobic (water-repelling) portions in their molecular structure, effective inhibitors for the protection of mild steel in an acidic medium, the weight loss methods were used at lab temperature to evaluate the effect of surfactant cetyl pyridinium chloride (CPC) and sodium dodecyl sulfate (SDS) on the corrosion protection behavior of Mild steel in 0.5 M H2SO4 solution. Inhibition efficiency, weight loss, corrosion rate, and surface coverage area of Mild steel in different concentrations of surfactant were studied. The results showed that the Inhibition efficiency of cetyl pyridinium chloride is 99.86%, which is greater than that of sodium dodecyl sulfate (99.85%) in the presence of 0.5 M H2SO4.

Study on scale formation and corrosion behavior of heat exchanger steel 20 at different temperatures

This study investigates the scaling and corrosion behavior of steel 20 of cooling water in two locations: oil depot working area and living quarters. Furthermore, it explores the effect of temperature on scaling rate and corrosion rate. Through static scaling test and dynamic scaling prediction, the scaling effect of water quality is analyzed. The results show that the scaling degree of two water quality conditions is different with the change of temperature. The water scaling initiates at 60 °C in the living quarters, while a slight amount of scaling occurs when the temperature reaches 75 °C at working area. Through the utilization of open circuit potential, polarization curve analysis, scanning electron microscope (SEM) imaging and X-ray diffraction, the corrosion potential, corrosion rate, macroscopic and microscopic corrosion samples, as well as corrosion products of steel 20 were comprehensively examined. It was found that, in the temperature range of 30 −50 °C, the corrosion rate of steel 20 in the working area showed a linear trend with water temperature, while the corrosion rate in the living quarters exhibited an exponential function trend with temperature. Considering the combined impact of scaling and corrosion on heat exchanger performance, if the operating conditions can exceed 40 °C, the water quality within the working area poses minimal risks and operational pressure to the heat exchanger. Therefore, it is more suitable as a cooling water source compared to that in living quarters.

The effect of porosity on the corrosion rate of aluminum foam as a sacrificial anode

The objective of this paper is to investigate the effect of porosity on the corrosion rate of aluminum foams as sacrificial anodes. An aluminum bar (6061 series) was cut to 19x19x13 mm. Then the aluminum was drilled to become an aluminum foam. A Carbon steel plate was cut to 40x 40x1 mm. The aluminum foam and the steel were connected by a bolt to become a galvanic couple. The galvanic couples were immersed in fresh water for variation times (32 hours, 168 hours, 335 hours, 504 hours and 672 hours). The temperature was 27 oC. The corrosion test was the weight loss method. The results. The corrosion rate of initial steel is 0.15 millimeter per year (mmy). The corrosion rate of steel decrease from 0.15 mmy to 0.015 + 0.02 mmy when using the aluminum foam as sacrificial anode. The corrosion rate of initial aluminum foam is 0.01 mmy. The corrosion rate of aluminum foam increases from 0.01 to 0.015 – 0.02 mm when used as sacrificial anode. Increasing the porosity of the anode will reduce the corrosion rate of the anode itself.

Identification of carbonation‐induced corrosion of steel in concrete by electrochemical testing

AbstractCarbonation‐induced corrosion of steel in concrete can allow for premature degradation of structures. Corrosion probes in health monitoring systems can assess concrete carbonation and steel corrosion rates. The electrochemical noise (EN) technique has advantages for corrosion sensing. Instrumented concrete columns were fitted with a carbonation chamber for accelerated testing. EN was assessed through statistical evaluation of noise time signatures, noise resistance, and spectral analysis. The mean noise potential for the electrodes showed electronegative potential and correspondingly high rms noise current, indicative of corrosion activation in carbonated concrete. The estimated corrosion rates obtained from the noise impedance were comparable to those resolved from the polarization resistance and noise resistance. The shot noise analysis indicated isolated spontaneous noise events associated with the activation of local steel anodes. The outcomes of the testing indicate that the placement of low‐cost sensors and passive EN measurements can be used to monitor the onset of carbonation‐induced corrosion of steel in concrete and provide estimates on corrosion rates.

Effect of various compositions on corrosion rate of steel in formation water and freezing temperature of high-paraffin model oil

The effects of Gossypol resin and NDP-6 reagents and Z-1 composition (the mixture of NDP-6+Gossypol resin at the ratio of 9:1) on the corrosion rate of steel in the formation water and the freezing temperature of high-paraffin model oil were investigated for the first time under laboratory conditions. In the experiments, a model oil sample prepared in a ratio of 2:1 of commercial oils from Narimanov and Absheron fields of SOCAR was used as a research object, and a formation water sample taken from well No. 1082 of “Bibiheybatneft” OGPI, SOCAR was used as an electrochemical corrosion medium. It was determined that the new composition had a more effective impact on the corrosion rate in H2S-containing formation water and the freezing temperature of high-paraffin oil sample than individual reagents. Thus, the highest efficiency for gossypol resin was observed at a concentration of 110 mg/l, when the corrosion rate was 0.09 g/m2h (corrosion protection efficiency of 98%). The most effective indicator for NDP-6 depressant additive was 1000 g/t, and the freezing temperature of high-paraffin model oil was stated to decrease from +160С to –20С. However, the strongest effect has been observed for the Z-1 composition. Thus, the composition with a concentration of 700 g/t reduces the corrosion rate in the formation water from 4.30 g/m2h to 0.04 g/m2h (corrosion protection efficiency of 99%) and the freezing temperature of model oil from +160С to –90C.

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

Characteristics of Bio-ceramic Coating on Corrosion Rate of Stainless Steel 316L and Titanium (Ti-6Al-4V)

Thermal spray coating improves SS 316L corrosion resistance using biomaterials like hydroxyapatite (HA), zirconium dioxide (ZrO2), and titanium dioxide (TiO2), promoting bone binding and biological fixation. The study examined the impact of bio-ceramic coatings like HA, HA+TiO2, and HA+ZrO2 on the corrosion rate of stainless steel and titanium in Hank's Balance Salt Solution and artificial saliva media. Electrochemical testing with polarization was carried out to determine the performance of biomaterials against corrosion rates. The addition of TiO2 and ZrO2 to HA in both SS316L and Ti6Al4V materials reduced the corrosion rate more than HA. This study revealed that coating with HA, HA + ZrO2, and HA + TiO2 biomaterials results in varying thicknesses and roughness under the same spraying parameters. Bioceramic coatings on implants offer an alternative coating to improve the performance of biomaterials.

Inhibitory effect of marine Bacillus sp. and its biomineralization on the corrosion of X65 steel in offshore oilfield produced water

The issue of material failure attributed to microbiologically influenced corrosion (MIC) is escalating in seriousness. Microorganisms not only facilitate corrosion but certain beneficial microorganisms also impede its occurrence. This study explored the impact of marine B. velezensis on the corrosion behavior of X65 steel in simulated offshore oilfield produced water. B. velezensis exhibited rapid growth in the initial stages, and the organic acid metabolites were found to promote corrosion. Subsequently, there was an increase in cross-linked “networked” biofilms products, a significant rise in the prismatic shape of corrosion products, and a tendency for continuous development in the middle and late stages. The organic/inorganic mineralized film layer formed on the surface remained consistently complete. Metabolic products of amino acid corrosion inhibitors were also observed to be adsorbed into the film. B. velezensis altered the kinetics of the X65 steel cathodic reaction, resulting in a deceleration of the electrochemical reaction rate. The mineralization induced by B. velezensis effectively slowed down the corrosion rate of X65 steel.