Higher Corrosion Rate Research Articles

Hydrostatic test of storage tanks using seawater and corrosion considerations

Hydrostatic testing is an important method for the quality control of storage tanks in industry. After the tanks have been manufactured or repaired, a hydrostatic test is generally carried out with freshwater. Due to lackof freshwater, seawater may be used as an alternative. However, seawater can cause damage to storage tanks. In view of this, the corrosion behavior of welded carbon steel in seawater was investigated in this study. The results showed that the weld metal (WM) is more active and susceptible to corrosion than the base metal (BM). The Linear Polarization Resistance (LPR) and immersion test results showed that the WM has a higher corrosion rate than the BM. In the immersion test, all corrosion rates were less than 3 mpy. Based on the results of the corrosion tests, the hydrostatic test of a storage tank was conducted in a real plant with seawater, and the result was acceptable.

H ALIDE ION AND METHANOLIC EXTRACT OF IRVINGIA GABONESIS AS AN E NHANCED CORROSION INHIBITORY AGENT ON ALUMINIUM IN HCl

The in hibitory efficiencies of methanolic leaf extract of Irvingia gabonensis and the role of a halide ion as an enhancement on the inhibition of aluminium corrosion in HCl medium were studied at varying acid concentrations of 0.01M , 0.05M, 0.1M und er the influence of 3% NaCl. Result of the studies carried out by weight loss techni que showed that I. gabonensis is highly an efficient inhibitor for the corrosion of al umimium in HCl acid environment and its inhibitory efficiencies increases with respect to the time of exposure.. It was observed from the study that in the absence o f the plant extracts, the weight loss increases rapidly indicating an increase in corrosi on rate from 0.003g to 0.026g as acid concentration was increased from 0.01M to 0.1M . Conversely, when the plant extract was introduced, there were remarkable decrease in weight loss from 0.001g at 0.01M of HCl to 0.021g at 0.1M , showing a decrea se in corrosion of the metal. Experimental data proved that the highest corrosion rates w ere observed at the highest acid strength pointing that at a concentration of 0.1M H Cl, 19% efficiency was attained and a maximum efficiency of 67% was obtained at 0.01MHCl showing a correlation between concentration and inhibition of metal. It was also revealed that the inhibitory efficiency of I. gabonensis in HCl medium was magnif icently increased when a salt of halide ion was introduced showing a weight loss of 0.01g through 0.003g as acid strength increased from 0.01M to 0.1M. This could be attributed to that the fact that halide ion facilitates the adsorption of organic cat ions during metal corrosion by forming intermediate bridges between the metal surface and the positive end of the organic inhibitor and this forms a protective hydrophi lic film on the metal surface which provided a barrier to the dissolution of the metal into the acid medium.

In situ mathematically simulation for CO2 internal corrosion in wet natural gas gathering pipelines system by HYSYS

The rate of corrosion due to the presence of carbon dioxide in a carbon steel pipe is an important design consideration for gathering pipelines, particularly in the transport of wet natural gas. To evaluate the corrosion rate in a gathering pipeline, in situ simulation study using HYSYS program employed to predict CO2 corrosion in natural gas gathering pipelines system. The effects of operational conditions, inhibitors, pipe parameters and flow regime on the CO2 corrosion are studied in this paper. Increasing operating pressure leads to increase the pH and decrease the CO2 corrosion rate when the operating pressure over 10 MPa and the solution contents 0.85kmol/m3 iron carbonate. The CO2 corrosion rate does not always increase with temperature, and which will reach a maximum value at 45 °C. A high gas velocity will lead to a high corrosion rate. Less free water present in pipeline may lead to more serious corrosion than that of a large amount of free water. The corrosion rate may be inhibited by liquid hydrocarbon and glycol, and the glycol is not an economic inhibitor, especially when there is a large amount of free water in pipeline. The large diameter and flat pipe are useful for decreasing CO2 corrosion rate. The shear stress and corrosion rate will increase sharply when the slug flow forms in pipeline. Through comparing the data of simulation with field corrosion rate data, feasibility of this numerical simulation method is proved.

Experimental Evaluation of a New Nonaromatic Nonionic Surfactant for Deep Carbonate Stimulation

SummaryMatrix acidizing improves productivity in oil and gas wells. Hydrochloric acid (HCl), because of its many advantages such as its effectiveness, availability, and low cost, has been a typical first-choice fluid for acidizing operations. However, HCl in high-pressure/high-temperature (HP/HT) wells can be problematic because of its high reactivity, resulting in face dissolution, high corrosion rates, and high corrosion inhibition costs. Several alternatives to HCl have been tested; among them, emulsified acid is a favorable choice because of its inherent low corrosion rate, deeper penetration into the reservoir, fewer asphaltene/sludge problems, and better acid distribution due to its higher viscosity. The success of the new system is dependent upon the stability of the emulsion, especially at high temperatures. The emulsified acid must be stable until it is properly placed, and it must also be compatible with other additives in an acidizing package. This study develops a stable, emulsified acid system at 300°F using aliphatic nonionic surfactants.This paper introduces a new nonaromatic, nonionic surfactant to form an emulsified acid for HP/HT wells. The type and quality of the emulsified acid were assessed through conductivity measurements and drop tests. The thermal stability of the system was monitored as a function of time through the use of pressure tubes and a preheated oil bath at 300°F. A LUMisizer® (LUM GmbH, Berlin, Germany) and Turbiscan® (Formulaction, S. A., L’Union, France) were used to determine the stability and the average droplet size of the emulsion, respectively. The viscosity of the emulsified acid was measured at different temperatures up to 300°F as a function of shear rate (1 to 1,000 s−1). The microscopy study was used to examine the shape and the distribution of acid droplets in diesel. Coreflood studies at low and high flow rates were conducted to determine the performance of the newly developed stable emulsified acid in creating wormholes in carbonate rocks. Inductively coupled plasma and computed tomography (CT) scans were used to determine the dissolved cations and wormhole propagation, respectively.Superior stimulation results with a low pore volume of acid to breakthrough (PVBT) were achieved at 300°F with the newly developed emulsified acid system. The wormhole propagation was narrow and dominant compared to branched wormholes resulting from conventional emulsified acid systems. Results indicate that a nonionic surfactant with optimal chemistry, such as a suitable hydrophobe chain length and structure, can form a stable emulsified acid.In this study we introduce a new and effective aliphatic nonionic surfactant to create a stable emulsified acid system for matrix acidizing at HP/HT conditions, leading to a deeper penetration of acid with low pore volume to breakthrough. The successful core flood studies in the laboratory using carbonate cores suggest that the new emulsified acid system may efficiently stimulate HP/HT carbonate reservoirs.

Hydroxyapatite Coating on Stainless Steel 316L using Flame Spray Technique

This study was a preliminary study on flame spray coating with hydroxyapatite (HAp). Coating is one of the technique to improve metal resistance to corrosion. In this study, flame spray coating using HAp was performed on stainless steel 316 L as a material for medical devices. This synthetic compound contains elements which are biocompatible and bioactive in human body where they can stick to body tissues or muscles.HAp has been extensively used as a bone substitute because of its crystal structure, biocompatibility and osteoconductive nature. In this study, 316L SS was coated by HAp using flame spray method with varied oxygen flowrate and air pressure. The result of this study showed that the air pressure of 1 bar and oxygen flowrate of 25 l/min had the thickest coating which was 123.5μm and the lowest corrosion rate which was 0.0261 mm/year. The air pressureof 3 bar and oxygen flowrate of 35 l/min produced the lowest thickness which was 32.5μm and the highest corrosion rate which was 0.0761 mm/year. The use of high air pressure and oxygen flowrate decreased the coating thickness and the corrosion rate. The result revealed that flame spray method was effective to be used to coat HAp on 316L SS.

Effect of Forging Temperature on Biodegradable Mg-0.7%Ca Alloy Properties for Implant Application

The potential of binary Mg-Ca alloy as biodegradable material is considerable interest in implant application among researchers. This research was conducted to investigate the effect of different forging temperature and forging speed on the hardness, microstructure and corrosion rate of Mg-0.7%Ca. The experiment was established by preparing the alloy sample with 0.7%wt calcium content. The forging process was carried out under four different temperature variations of 140°C, 180°C, 220°C, and 260°C (±10°C) with two different speed;25 and 45 strokes per minute (spm). The samples microstructure was examined by optical microscope and scanning electron microscope (SEM) equipped with energy dispersive X-ray (EDX). The mechanical properties of the forged samples were measured in its hardness and plastic deformation ability along with samples cold-working percentage. The corrosion rate was determined by performing the electrochemical test in simulated body fluid. This research found that increases of forging temperature and forging speed provide a higher rate of recrystallization and Mg2Ca compound precipitation results in greater hardness, increase deformation and reduce the cold-working percentage. However, the investigated factors still led to a high corrosion rate compared to a previous study and consequently, reduce the feasibility of the alloy in implant application for biodegradable material.

Effects of substituting Nb with V on thermal analysis and biocompatibility assessment of quaternary NiTiNbV SMA

The developed NiTi-based shape memory alloys are the most widely used materials in commercial applications due to shape memory effect and superelasticity. In this study, it is aimed to investigate the thermal, microstructural, and corrosion behavior of NiTiNb SMA by alloying with different composition of vanadium. The alloys with nominal composition Ni27 Ti50 Nb23-x Vx (x = 1, 2, 5) were manufactured by the arc-melting device under an argon gas atmosphere. The DSC measurements showed that the alloys are low-temperature shape memory alloys and the changes in the composition have not made a significant effect on the phase transformation temperatures. According to thermodynamics parameters, such as enthalpy and entropy changes, it is found that the alloy with 2 (at.%) of vanadium has more stability compared with the other SMAs. The microstructural analysis reveals that the Ni27 Ti50 Nb21 V2 (at.%) alloy has a different dendritic microstructure, whereby, the mapping shows that the dendritic of the alloy almost consists of Nb, while the other alloys Ti are the host element in the dendritic microstructure. It is realized that the manufactured alloys have less biocompatibility since they have shown a high corrosion rate compared to equiatomic NiTi SMAs.

Severe Corrosion of Carbon Steel in Oil Field Produced Water Can Be Linked to Methanogenic Archaea Containing a Special Type of [NiFe] Hydrogenase.

Methanogenic archaea have long been implicated in microbially influenced corrosion (MIC) of oil and gas infrastructure, yet a first understanding of the underlying molecular mechanisms has only recently emerged. We surveyed pipeline-associated microbiomes from geographically distinct oil field facilities and found methanogens to account for 0.2 to 9.3% of the 16S rRNA gene sequencing reads. Neither the type nor the abundance of the detected methanogens was correlated with the perceived severity of MIC in these pipelines. Using fluids from one pipeline, MIC was reproduced in the laboratory, both under stagnant conditions and in customized corrosion reactors simulating pipeline flow. High corrosion rates (up to 2.43 mm Fe0 · yr-1) with macroscopic, localized corrosion features were attributed to lithotrophic, mesophilic microbial activity. Other laboratory tests with the same waters yielded negligible corrosion rates (<0.08 mm Fe0 · yr-1). Recently, a novel [NiFe] hydrogenase from Methanococcus maripaludis strain OS7 was demonstrated to accelerate corrosion. We developed a specific quantitative PCR (qPCR) assay and detected the gene encoding the large subunit of this hydrogenase (labeled micH) in corrosive (>0.15 mm Fe0 · yr-1) biofilms. The micH gene, on the other hand, was absent in noncorrosive biofilms, despite an abundance of methanogens. Reconstruction of a nearly complete Methanococcus maripaludis genome from a highly corrosive mixed biofilm revealed micH and associated genes in nearly identical genetic configuration to that in strain OS7, thereby supporting our hypothesis that the encoded molecular mechanism contributed to corrosion. Lastly, the proposed MIC biomarker was detected in multiple oil fields, indicating a geographically widespread involvement of this [NiFe] hydrogenase in MIC.IMPORTANCE Microorganisms can deteriorate built environments, which is particularly problematic in the case of pipelines transporting hydrocarbons to industrial end users. MIC is notoriously difficult to detect and monitor and, as a consequence, is a particularly difficult corrosion mechanism to manage. Despite the advent of molecular tools and improved microbial monitoring strategies for oil and gas operations, specific underlying MIC mechanisms in pipelines remain largely enigmatic. Emerging mechanistic understanding of methanogenic MIC derived from pure culture work allowed us to develop a qPCR assay that distinguishes technically problematic from benign methanogens in a West African oil field. Detection of the same gene in geographically diverse samples from North America hints at the widespread applicability of this assay. The research presented here offers a step toward a mechanistic understanding of biocorrosion in oil fields and introduces a binary marker for (methanogenic) MIC that can find application in corrosion management programs in industrial settings.

A Comparative Experimental Study of Alternative Iron Sulfide Scale Dissolvers in the Presence of Oilfield Conditions and Evaluation of New Synergists to Aminopolycarboxylic Acids

SummaryIssues such as high corrosion rate, hydrogen sulfide (or H2S) generation, and scale reprecipitation have required the use of alternative dissolvers such as tetrakis(hydroxymethyl)phosphonium sulfate (THPS)–ammonium chloride (or NH4Cl) blend and chelating agents to dissolve iron sulfide (or FeS) scales. However, there are many aspects of these dissolvers that need investigation. This paper provides a guideline to select the best dissolver under various oilfield conditions by an extensive laboratory study. Furthermore, the iron sulfide scale removal is enhanced by the use of new synergists to the chelating agents.The application of THPS and diethylenetriaminepentaacetic acid (DTPA) in well tubulars or pipelines requires laboratory testing to determine the optimal conditions such as dissolver concentration, treatment time, and dissolver/scale (D/S) ratio (cm3/g) at 150°F. This evaluation considers oil-wet scales, mixed scales, presence of additives, and presence of salts during the treatment. Synergists such as potassium chloride (or KCl), potassium iodide (or KI), potassium formate (or HCOOK), sodium fluoride (or NaF), and potassium citrate (or K-Citrate) were added to ethylenediaminetetraacetic acid (EDTA), DTPA, and hydroxyethylethylenediaminetriacetic acid (HEDTA), and the scale solubility was evaluated at 150 and 300°F. Inductively coupled plasma–optical emission spectrometer analysis of the supernatant solution at various intervals of time up to 48 hours revealed the kinetics of the dissolution process. H2S generated from the scale dissolution process was measured using Draeger tubes. Corrosion tests helped in measuring the damage to the tubulars as a result of the dissolver’s contact with N-80 coupons.Solubility tests indicated the dissolver’s scale removal capacity at different concentrations. The work also accounted for the consumption of the dissolver for the scale removal. The optimal blend was chosen considering both the dissolution capacity and the dissolver consumption. For THPS–ammonium chloride blend, 0.75 mol/L THPS (30 wt%) and 2 mol/L NH4Cl (10 wt%) proved to be the optimum dissolver concentration at 150°F. Similarly, for DTPA, 0.4 mol/L K2-DTPA was evaluated to be the most effective dissolver concentration. The THPS–ammonium chloride blend was found to dissolve the iron sulfide slowly compared with K2-DTPA and 15% hydrochloric acid (HCl). The presence of crude oil on the scale hindered its solubility with K2-DTPA by 8%. The presence of calcium carbonate influenced higher selectivity of chelating the calcium ions by K2-DTPA. However, the overall fraction of scale removal was not affected. Adding corrosion inhibitors (CIs) did not affect the scale solubility significantly and also helped in maintaining an acceptable corrosion rate of N-80 coupons below 0.05 lb/ft2 at 150°F. The reaction of HCl and the iron sulfide scale generated 1,800 ppm of H2S in comparison with 0- and 10-ppm by THPS–ammonium chloride blend and K2-DTPA, respectively. Adding potassium iodide and potassium citrate to EDTA helped in improving the scale solubility at 150°F. Sodium fluoride improved the scale dissolution by EDTA and DTPA at 300°F.This paper addresses oilfield-like conditions on scale solubility by evaluating the role of mixed scale, scale mass, presence of hydrocarbons on the scale, and presence of monovalent/divalent ions in dissolver solution. A detailed and direct comparison of HCl, THPS–ammonium chloride blend, and DTPA in dissolving iron sulfide at various conditions enables easier selection of the dissolver for a field treatment. New synergists for iron sulfide scale dissolution are introduced in this paper. This work can help oilfield companies understand the nuances of applying different alternative iron sulfide dissolvers.

Simulation study of wormhole formation and propagation during matrix acidizing of carbonate reservoirs using a novel in-situ generated hydrochloric acid

Optimum acid selection based on reservoir condition is one of the key elements in achieving a successful treatment in carbonate matrix acidizing. High reaction and corrosion rate of regular hydrochloric acid especially in tight reservoirs with high temperatures is considered as a limitation of this acid. One alternative in a high-temperature reservoir is to use in-situ generated hydrochloric. The objective of this study is to simulate acidizing treatment using both regular hydrochloric and in-situ generated hydrochloric acid. A continuum two-scale model for linear and radial flow geometry was used to simulate dissolution pattern. A finite-volume method with an implicit backward Euler scheme was used to solve the governing equations. The results of the simulation in a linear system showed that, due to low face dissolution, the in-situ generated hydrochloric at low injection rates could create longer wormholes with less pore volume to breakthrough. The results also proved that using the in-situ generated hydrochloric acid could lead to less face dissolution and deeper penetration of acid into the reservoir. This acidizing system is very suitable in situations where a low injection rate is needed and regular hydrochloric cannot be used due to higher pore volume to breakthrough and high corrosion rate. Cited as : Kiani, S., Jafari, S., Apourvari, S. N., Mehrjoo, H. Simulation study of wormhole formation and propagation during matrix acidizing of carbonate reservoirs using a novel in-situ generated hydrochloric acid. Advances in Geo-Energy Research, 2021, 5(1): 64-74, doi: 10.46690/ager.2021.01.07

Characterization and Corrosion Behavior Evaluation of Nanostructured TiO2 and Al2O3-13 wt.%TiO2 Coatings on Aluminum Alloy Prepared via High-Velocity Oxy-Fuel Spray

In this study, nanostructured titania (TiO2; n-TO) and nanostructured alumina-titania (Al2O3-13 wt.%TiO2; n-ATO) coatings were successfully deposited on the 6061 aluminum alloy by applying the high-velocity oxy-fuel process. The n-TO coating showed limited pores or microcracks accompanied by both partially and fully melted areas within splats. The n-TO coating exhibited about 25% higher microhardness compared with the n-ATO coating. The agglomerated non-molten nanostructured TiO2 particles that are randomly dispersed and embedded within the n-TO coating microstructure act as arresters of cracks through either branching or blunting crack tips, resulting in about 17% higher bonding strength, as compared to the n-ATO coating with a looser microstructure. The n-TO coating demonstrated superior hardness, higher wear resistance, and smoother wear scar than the n-ATO and uncoated Al substrate. The electrochemical test indicated that the n-ATO coating had about a 50% higher corrosion rate than the n-TO coating because of its looser structure. The immersion test revealed that the n-ATO coating had been severely attacked by blistering and deep cracks corrosions, whereas limited attacks could be distinguished using the n-TO coating in the substrate interface. Based on the results, the n-TO coating can effectively protect the Al alloy substrate against 3.5 wt.% NaCl solution.

Corrosion Evaluation of Geopolymer Concrete Made with Fly Ash and Bottom Ash

Environmental pollution caused by CO2 releasing from the production of cement is a great challenge for the construction industry and has triggered exploration into more sustainable alternatives. Geopolymer Concrete (GPC) is a potential sustainable solution that does not involve the use of cement as a binder. GPC is produced by mixing the alumino-silicate source materials such as fly-ash with alkali activators such as potassium hydroxide (KOH) and potassium silicate (K2SiO3). Unlike Ordinary Portland Concrete (OPC), the characteristics of GPC depend on the precursor materials and therefore vary for different mixes. Consequently, corrosion behavior needs to be evaluated separately for individual mixes. This has narrowed the scope of existing published work on corrosion behavior of GPC. In this study, GPC and OPC specimens were prepared and exposed to accelerated corrosion exposure. Half-cell potential and linear polarization resistance were used to evaluate the corrosion rate in GPC and OPC. Under accelerated conditions, the corrosion rate of the GPC specimens was between 10 µm/year and 20 µm/year exhibiting a moderate to high rate of corrosion. Meanwhile, the corrosion rate of the OPC specimens was between 40 µm/year and 60 µm/year indicating a very high corrosion activity. It can be concluded that GPC has a higher resistance to chloride-induced corrosion; with a low corrosion rate and lower mass loss percentage, compared to OPC.

Electrochemical corrosion behavior of copper in graphene-based thermal fluid with different surfactants

This study investigates the effect of different surfactant-dispersed graphene nanofluid on the electrochemical behavior of copper. This study was achieved by measuring the open circuit potential and potentiodynamic polarization of copper in the nanofluids at room temperature. The test media includes surfactant-free graphene nanofluid and graphene nanofluid dispersed using four different surfactants, which are sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Gum Arabic, and Tween 80. The surface characterization and elemental composition of the copper sample before and after the corrosion tests were determined using a scanning electron microscope coupled with energy-dispersive X-ray spectroscopy. The phase formation after corrosion was also evaluated by measuring X-ray diffraction. The quantity of copper dissolved in the test media was evaluated using an inductively coupled plasma mass spectrometry (ICP-MS). The open-circuit potential measurements revealed that the current free corrosion potential of copper in the different surfactant-aided graphene nanofluids are different. The electrochemical corrosion potential, Tafel slopes, and corrosion rates revealed the better corrosion performance of copper in the nanofluid of different surfactants in the increasing order GA, SDS, Tween 80, and SDBS. Copper in GA-based graphene nanofluid was found to have the lowest corrosion rate while that of SDBS has the highest corrosion rate. However, the ICP-MS result revealed a discrepancy in the corrosion behavior and quantity of copper dissolved in the different test media. This could be attributed to the dissimilar dissolution-redeposition rate of copper in different media.

Microstructure and Discharge Performance of Aluminum Al 6061 Alloy as Anode for Electrolyte Activated Battery

Electrolyte activated battery finds its important use during natural disaster emergencies, such as floods and typhoons. Nevertheless, high corrosion rate will deteriorate the discharge performance of the battery and it is influenced by the type of electrolyte and discharge current. In this study, the corrosion and discharge performance of a commercial Al 6061 aluminum alloy as an anode are investigated at different discharge currents (0.001, 0.01, and 1 mA) and in different electrolytes, namely salt water, urea, and distilled water. Scanning electron microscopy results show that electrode in salt water has the most serious corrosion, followed by that of in urea and in distilled water. These electrode-electrolyte combinations are further investigated with potentiodynamic polarization, galvanostatic discharge, and electrochemical impedance spectroscopy (EIS) to understand their discharge potential, discharge behavior, and corrosion mechanism. Among all combinations, aluminum in water is found to have the highest discharge performance with discharge potentials ranging from 716 to 744 mV, regardless of discharge current.

Examination of Reinforcement Steel Bars Exposed to the Atmosphere

Reinforcement steel bars are often exposed to the atmosphere before use in concrete structures. This exposure results in corrosion of these reinforcement bars. Corrosion of reinforcement bars is a common form of degradation of reinforced concrete structures. The electrochemical attack affects the mechanical properties of steel rebars. This study analysed the effect of exposing reinforcing steel bars to the atmosphere. The bars were divided into two; one part was exposed to the atmosphere for a period of four months during the rainy season while the other was unexposed. Afterwards; some mechanical, corrosion and metallographic tests were carried out on the steel samples. The results obtained showed that the hardness, impact strength and ductility increased with exposure while the yield and tensile strengths decreased with exposure. The exposed bar had high corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not follow a particular trend

Examination of Reinforcement Steel Bars Exposed to the Atmosphere

Reinforcement steel bars are often exposed to the atmosphere before use in concrete structures. This exposure results in corrosion of these reinforcement bars. Corrosion of reinforcement bars is a common form of degradation of reinforced concrete structures. The electrochemical attack affects the mechanical properties of steel rebars. This study analysed the effect of exposing reinforcing steel bars to the atmosphere. The bars were divided into two; one part was exposed to the atmosphere for a period of four months during the rainy season while the other was unexposed. Afterwards; some mechanical, corrosion and metallographic tests were carried out on the steel samples. The results obtained showed that the hardness, impact strength and ductility increased with exposure while the yield and tensile strengths decreased with exposure. The exposed bar had high corrosion rates than the unexposed bar in 1M hydrochloric acid (HCl) while in 1M sodium chloride (NaCl), the corrosion rates for both the exposed and unexposed bars did not follow a particular trend.

Assessment of Groundwater Quality for Industrial Purposes Using Geographical Information System (GIS) in Zahedan, Sistan and Baluchestan Province, Iran

Introduction: Water quality is essential for industries because they play an important role in countries’ economic development. Groundwater is one of the most widely used resources, and when the ionic constituents were increasing higher than the allowable limit, it increases the cost of maintenance and production in the industries. Materials and Methods: In order to evaluate groundwater corrosiveness and scaling potential in Zahedan City, 29 groundwater wells and GIS-based geostatistical mapping techniques were analyzed clemically. The physicochemical parameters were invetsiagted and the most popular corrosion and scaling indices were determined as Langelier Index (LI), Aggressive Index (AI), Ryznar Index (RI), Puckorius Index (PI), and Larson–Skold Index (LS). Using ArcGIS 10.6.1 software, the zoning maps were plotted for LI, AI, RI, PI, and LS indices. Results: The results showed that total dissolved solids (TDS) and electrical conductivity (EC) values in all of the samples exceeded the World Health Organization (WHO) drinking water standard. AI values of 58.62% samples showing moderate corrosiveness, and the remaining 17 samples have a scaling nature with very less corrosivity. Based on the LI values, 55.2% of samples have a corrosive nature. Concerning RI values, 59% of the samples have a corrosive tendency. According to the PI values, the entire groundwater of this region has a significant corrosive tendency, and 96% of samples exceeded the LS &gt; 1.2, showing a high rate of localized corrosion. Conclusion: The zoning and spatial analysis of water quality showed that water quality was treated for industrial purposes in the entire studied region.

Micro and nano-enabled approaches to improve the performance of plasma electrolytic oxidation coated magnesium alloys

Magnesium (Mg) and its alloys have become a hot research topic in various industries owing to the specific physical and chemical properties. However, high corrosion rate is considered the key lifetime - limiting. Plasma electrolytic oxidation (PEO) method is a simple strategy to deposit an oxide layer on the surface of light metals such as magnesium alloys, to control corrosion rate and promote some other properties, depending on their performances. Nevertheless, their features including their micropore size, distribution, and interconnectivity, and microcracks have not been improved to an acceptable level to support long-term performances of the magnesium-based substrates. Studies have introduced micro/nano-enabled approaches to enhance various properties of PEO coatings such as corrosion resistance, tribological properties, self-healing ability, bioactivity, biocompatibility, antibacterial properties, or catalytic performances. These strategies consist of incorporating of micro and nanoparticles into the PEO layers to produce multi-functional surfaces or the formation of multi-layered coatings to cover the defects of PEO coatings. In this perspective, the present paper aims to overview various nano/micro-enabled strategies to promote the properties of PEO coatings on magnesium alloys. The main focus is given to the functional changes that occurred in response to the incorporation of various types of nano/micro-structures into the PEO coatings on magnesium alloys.

Functionally gradient magnesium-based composite for temporary orthopaedic implant with improved corrosion resistance and osteogenic properties

Magnesium (Mg) is a potential alternative for conventional orthopaedic implant materials owing to its biodegradation behavior and physical characteristics similar to natural human bone. Due to its biomimetic mechanical attributes, Mg in orthopaedic applications could reduce the risk of the ‘stress shielding effect’. However, the major limitation of Mg is its high in-vivo corrosion rate. Thermal sprayed coatings of osteoconductive ceramics like hydroxyapatite (HA) have been explored as a potential solution, albeit with limited success due to the low melting point of Mg, which restricts the ease of fabricating surface-adherent ceramic coating. The present study focuses on overcoming this limitation through a Mg-HA functionally gradient material (FGM) system, which is expected to provide a highly corrosion-resistant surface and uniform mechanical integrity throughout the structure. In addition to corrosion resistance, the FGM system has improved biocompatibility and osteoconductivity without compromising its mechanical stability. The FGM, with a compositional gradient of Mg-HA composite, consisting of Mg at the core and increasing HA towards the outer layer, has been fabricated through spark plasma sintering. Mechanical properties of the overall structure were better than those of the best individual composite. More importantly, corrosion resistance of the FGM structure was significantly improved (~154%) as compared to individual composites. In addition, alkaline phosphatase activity, osteogenic gene expression and cell viability, all pertaining to efficient osteogenic differentiation, were enhanced for FGM and 15 wt% HA reinforced composites. These observations suggest that the FGM structure is promising for temporary biodegradable orthopaedic implants.

Corrosion Behavior of Ferritic-Martensitic Steel in H2O Containing CO2 and O2 at 50°C to 245°C and 8 MPa

To understand the corrosion mechanisms of structural materials in low-temperature components of direct supercritical CO2 power cycles, immersion experiments were performed in aqueous environments expected at these conditions. A ferritic-martensitic steel (UNS K91560) was selected as the candidate material. Steel specimens were fully submerged in H2O pressurized with 99% CO2 and 1% O2 to 8 MPa, and heated up to temperature (50°C, 100°C, 150°C, or 245°C), with a test duration of 500 h. Corrosion rates were calculated based on mass loss. Scanning electron microscope, x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy were used to characterize microstructure, phases, crystallinity, and composition of the corrosion product layer. Experimental results show that specimens exposed at 100°C had the highest corrosion rate, followed by the specimens exposed at 50°C. The specimens exposed at the highest temperature exhibited the lowest corrosion rate. An outer noncontinuous, nonprotective Fe-rich oxide layer and a well-adhered inner oxide layer containing both Fe and Cr formed on the specimen surfaces. The inner oxide layer changed from amorphous to crystalline as the temperature increased.