Corrosion Of Materials Research Articles

Critical analysis of enhanced photovoltaic thermal systems: a comparative experimental study of PCM, TEG, and nanofluid applications

Phase change materials (PCM), thermoelectric generators (TEG), and nanofluids are popular methods investigated for improving conventional photovoltaic thermal (PVT) systems. These methods are particularly used in warm climates where high temperatures negatively impact photovoltaic (PV) power output and energy efficiency. This experimental study evaluated the effects of 32 °C melting point PCM and TEG integration on PVT units, as well as 42 °C melting point PCM and nanofluid incorporation on concentrated PVT (CPVT) units. Technical, exergetic, and economic performance were compared using a small-scale PVT module. Low-cost commercially available materials were used to construct all PVT units. Industrial metal waste was introduced to enhance the thermal conductivity of paraffin wax and salt hydrate PCMs. The results indicated that applying PCMs, porous media, and concentrator plates increased energy generation, potentially offsetting their higher initial cost and achieving an energy cost of approximately $0.135/kWh. However, TEG and nanofluid implementation remained uneconomical, leading to a 15–35 % increase in energy cost. The water-based CPVT unit, enhanced with paraffin wax and copper fins, demonstrated the best technical performance. This unit achieved electrical, thermal, and exergy efficiencies of approximately 15.5 %, 37.4 %, and 16.7 %, respectively, with more than a 20 % reduction in cell temperature. The study also revealed that severe structural changes caused by corrosion of metallic materials in hydrated PCMs could alter the melting point by more than 30 %. This change negatively impacts heat storage capacity. Conversely, incorporating metal chips in non-hydrated PCMs improved the time to reach the melting point state by 30–60 minutes.

Chemical states of corrosion products in liquid lead from ab initio molecular dynamics

Liquid lead (Pb) is a promising coolant for lead-cooled fast reactors, and has advantages over lead–bismuth eutectic (LBE) in many aspects. But it can also cause severe corrosion to structural materials at high temperatures. In this study, the chemical states of 10 alloying elements as well as H and O in liquid Pb were investigated via ab initio molecular dynamics, and the local structure, dissolution and charge transfer were analyzed systematically. In liquid Pb, the coordination numbers (CNs) of Fe and Ni are the smallest, with the value of 7.72 and 7.01, respectively, and Al, Mn, Mo, Nb, Ti, and Si have the biggest CNs with about 12. This is correlated with the effective atomic radii in liquid Pb. Judged by the dissolution energy, the tendency of alloying elements to dissolve in liquid Pb is Al > Si > Ni > Ti > Cu > Fe > Mn > Nb > Cr > Mo. The calculated Bader charges show that the alloying atoms undergo minimal electron transfer in liquid Pb except Ti. H2, H2O, and O2 will decompose quickly and cannot exist in liquid Pb. Then, the alloying element will form a strong binding with O atom, especially Al and Si. O atoms can lead to an increase in the coordination of alloying atoms in liquid Pb and obviously reduce their diffusion coefficients in most cases. These findings can provide guidance for predicting material corrosion and designing future high-performance corrosion-resistant materials.

Corrosion, permeation and mass transfer mechanisms of alkali metals in corundum refractories

During the operation of the waste liquid incinerator, the alkali metal slag might adhere to the surface of the refractory material to form an inhomogeneous solid slag layer, causing the furnace lining to be simultaneously corroded by three phases of alkali metals: vapor, molten salt, and slag. This phenomenon intensifies the damage to the refractory material. Therefore, this paper investigates the mass transfer and permeation process, phase change process and corrosion rate of Na2CO3 inside corundum refractory materials in three phases: Na vapor, molten Na2CO3 and Na-slag. The results showed that alkali vapor penetrated the interior through the pores, and the NaAlO2 and β-Al2O3 generated by the reaction led to the volume expansion and microcracks. Na vapor continued to penetrate the interior along the cracks and eroded the sample, and the higher the temperature the greater Na vapor penetration. In vapor phase corrosion, the effect of corrosion time on the erosion resistance of corundum refractories is less than that of temperature, and the increase in corrosion time does not lead to the formation of additional new phases. In the molten salt corrosion experiments, it was found that the molten salt corrosion was accompanied by vapor phase corrosion at 1100 °C, and the amount of Na2CO3 has a greater effect on the corroded mass than the temperature. Comparing the corrosion of refractory materials by the three phases of Na2CO3, the molten salt corrosion rate was the highest, followed by the vapor phase corrosion, and finally the slag corrosion. It is concluded that the slag layer can effectively prevent the corrosion of the refractory material by alkali metal molten salts and vapors, thus prolonging the service life of refractories.

Influence of deep rolling on the [formula omitted]’-martensite formation in the subsurface, geometrically necessary dislocations and corrosion resistance of austenitic stainless steel AISI 304

The influence of deep rolling (DR) parameters (speed, number of passes and pressure) on the equivalent total strain, α’-martensite formation, ultra-microhardness, microstructure, and corrosion resistance of an AISI 304 austenitic stainless steel was investigated. The results showed that increasing DR speed led to less heterogeneous strain distributions and relatively high ultra-microhardness, despite an overall reduction in strain and α’-martensite content. This increase in hardness was related to the rise of geometrically necessary dislocations (GNDs) density, found to be one of the primary microstructural features influencing mechanical behavior under high DR speed. The increase in the number of passes elevated the intensity and depth of strain, leading to a 70% increase in the content of α’-martensite, ultra-microhardness, and producing severe grain refinement. The GNDs density decreased in the refined grain layer and increased sharply below it. Increased pressure induced similar results relative to the number of passes, with less impact. Improvement in the material properties is achieved through the interaction of parameters that result in an increase in the severity of the DR process, i.e, a reduction in speed and an increase in the number of passes and pressure. For severe DR conditions, the materials corrosion resistance in a 3.5% NaCl aqueous solution was significantly improved, with an increase of up to 2488% in the polarization resistance, as assesssed by electrochemical impedance spectroscopy. In potentiodynamic polarization tests, the corrosion potential increased from an average value of −0.274 to −0.14 V, and the corrosion current density decreased by approximately 300%.

Safety Management and Accident-Control Strategy for a Commercial-Scale Plant for Supercritical Water Oxidation of Sludge

Supercritical water oxidation is a promising technology for decomposition of industrial wastewater and sludge. However, the system is operated under high temperature and pressure (usually higher than 500 °C and 25 MPa). Corrosion of component materials and salt deposition may lead to leakage or even the burst of the pressure vessel in the SCWO system, resulting in a high level of worry about the safe operation of the system. In this paper, the safety management and accident- control strategies are introduced according to a commercial-scale SCWO plant in China. The safety management strategy refers to the special design and operation strategies of some facilities. Different types of potential accidents are analyzed and the coping strategies for accidents of different levels of severity are described in detail. The strategies are valuable for the safe operation of commercial SCWO plants and other plants operated in high temperature and high pressure.

Corrosion Inhibitive Effects of Orange Juice for Brass in Acidic Medium 5M H<sub>2</sub>SO<sub>4</sub>

Researchers continue to be concerned about corrosion of materials, which motivates them to start projects to address the harmful impacts of this phenomena that affects the desired function of our materials, especially in industries where acid is used in the process of cleaning machines. The purpose of this study is to reduce the corrosion rate of brass in 5M solution of H2SO4 acid using orange juice as inhibitor. The study was conducted using weight loss method. It was observed that for 24 hours the corrosion rate was higher for acid and decreased as the inhibitor was added. In all samples the corrosion rate decreases as the inhibitor were added, however improves over time. For 24 hours the efficiency was higher for acid + 100mil at 14% and it became constant after 48hrs at 32,7%. However, for 72 – 96 hours acid + inhibitor of 60mil there efficiency reported to be 54.3 and 56.4%. Keywords-orange juice, inhibitor, corrosion, acid, efficiency.

Corrosion of some metallic materials embedded in gypsum

AbstractIn the construction area, as well as in the restoration of old and historical buildings, different metallic materials are frequently in contact with gypsum plaster. Due to the high porosity of gypsum plaster, and particularly in high relative humidity environments, the risk of corrosion exists. In the present work, carbon, galvanized and stainless steel, as well as copper, were embedded in gypsum plaster (with varying water/gypsum ratios) and exposed to different environmental conditions, and the corrosion rate was assessed by electrochemical techniques. Stainless steel showed very low corrosion rates, carbon and galvanized steel showed considerable corrosion rates, and copper showed moderate corrosion rates. The higher the humidity, the higher the corrosion rate, independently of the water/gypsum ratio. A comparison with results obtained for the same materials embedded in mortar was performed. Except for stainless steel, the corrosion rates obtained in gypsum are higher than those obtained in mortar, being this difference up to two orders of magnitude. The differences in the pH of both matrices explained the lower corrosion rates measured in mortar.

Data-driven atmospheric corrosion prediction model for alloys based on a two-stage machine learning approach

Alloy material corrosion is a comprehensive problem affected by multi-dimensional factors, including the time, environment, and material element. Its corrosion prediction has been facing the challenges of complex mechanism and small sample size. However, parametric methods are limited in terms of modeling accuracy and generalization performance for high-dimensional feature problems. Non-parametric machine learning algorithms, while having excellent modeling capabilities, need to be optimized in conjunction with the structure of the corrosion problem. Therefore, we develop a two-stage hybrid intelligent machine learning model for improving alloy corrosion prediction accuracy. The model takes the time, environment, and material information of the alloy corrosion process as inputs and the corrosion rate as output. The first stage of the model utilizes tree ensemble learning (TEL) models for initial prediction modeling and feature importance knowledge mining. In the second stage, the neural network (NN) is used to enhance the fusion of the multi-model prediction outputs, and it is optimized using feature importance modification (FIM). The proposed TEL-FIMNN model shows considerable performance improvement over the TEL and ANN models on real low-alloy steel corrosion dataset. Compared to other advanced multi-model fusion methods such as linear regression (LR), support vector regression (SVR), random forest (RF), and Bayesian model averaging (BMA), the proposed model also shows superior results. The TEL-FIMNN model provide a new structure from the perspectives of knowledge mining and fusion enhancement, which has good potential for multi-dimensional corrosion prediction.

Post-Processing Effect on the Corrosion Resistance of Super Duplex Stainless Steel Produced by Laser Powder Bed Fusion.

This study examines the microstructural characteristics and corrosion resistance of super duplex stainless steel (SDSS) produced through laser powder bed fusion (LPBF). The analysis shows that the as-printed samples mainly exhibit a ferritic microstructure, which is due to the fast-cooling rates of the LPBF technique. X-ray and microstructure analyses reveal the presence of minor austenite phases in the ferritic matrix. The process of solution annealing led to a more balanced microstructure. Analyses of corrosion resistance, such as potentiodynamic polarization tests and EIS, indicate that heat treatment has a significant impact on the corrosion behavior of SDSS. Solution annealing and stress relieving at 400 °C for 1 h can improve corrosion resistance by increasing polarization resistance and favorable EIS parameters. However, stress relieving at 550 °C for 5 h may reduce the material's corrosion resistance due to the formation of chromium nitride. Therefore, stress relieving at 400 °C for 1 h is a practical method to significantly enhance the corrosion resistance of LPBF-printed SDSS. This method offers a balance between microstructural integrity and material performance.

Evaluation of influence of dissolved oxygen on corrosion behaviors of FeCrW model alloys in 360 °C water

The dissolved oxygen in a coolant can affect the oxidation properties of structural materials. A desirable oxide phase formation is achieved by manipulating the oxygen level in the coolant, which can mitigate structural material degradation in nuclear power plants. Therefore, the role of dissolved oxygen in the corrosion of structural materials in aqueous environments needs to be understood. In this study, a short-term corrosion test (up to 300 h) of Ferritic/Martensitic steels (F/M steels; FeCrW model alloys), namely, Fe12Cr1W, Fe9Cr1W, and Fe9Cr, in stagnant water at 360 °C was performed in a pressurized autoclave with the dissolved oxygen concentration controlled to 1 ppm or a very low level (<1 ppm). The results of the corrosion tests showed that an increase in the oxygen level in the water elevated the corrosion potential, allowing the phase transition of iron oxide from magnetite (Fe3O4) to hematite (Fe2O3), whereas there was no significant correlation between the concentrations of the alloying elements Cr and W and the oxide growth rate. In addition, hematite was found to mitigate further oxide growth. Finally, a mechanism for the growth of the initial oxide layer was proposed based on the experimental results.

A novel epoxy resin composite coating containing polyaniline modified GO with triple anti-corrosion effects of barrier, passivation and corrosion inhibition

Corrosion of metallic materials can have a detrimental impact on their performance, leading to a shortened service life of engineering equipment and posing risks to both people and the environment. This paper presents a novel epoxy resin (EP)-based composite coating (PFANI-GO/EP) that offers triple corrosion protection functions: barrier, passivation, and corrosion inhibition. Perfluorooctanoic acid-doped polyaniline modified graphene oxide (PFANI-GO) demonstrates superhydrophobicity, effectively enhancing the coating's barrier ability against corrosive substances. The combination of PANI and perfluorooctanoic acid (PFOA) in composite materials aids in the formation of a passivation film and hydrophobic layer, which prevent metal corrosion. After a 15-day immersion in brine, the PFANI-GO/EP coating demonstrates the highest impedance modulus of 1 × 109 Ω·cm2 at 0.01 Hz, compared to pure EP coating, GO/EP coating, and PFANI/EP coating. Therefore, due to its corrosion resistance and prolonged corrosion aging time, PFANI-GO/EP coating shows promising potential for mitigating metal corrosion.

Investigation on corrosion resistance of electroless Ni-W-P coatings co-deposited with SiO2 nanoparticles

The corrosion of materials in sea environment are generally caused by salt spray, tidal action and adhesion of marine organisms. It is necessary to ensure the materials possess the required strength and good corrosion resistance during operation. Although the existing Ni-W-P electroless plating can provide a certain degree of corrosion protection, its corrosion resistance is still limited under harsh marine condition. SiO2 nanoparticles have received extensive concern due to their excellent corrosion resistance, which has been considered as potential candidates for enhancing corrosion resistance in multicomponent electroless coatings. In this study, the electroless Ni-W-P coatings with SiO2 nanoparticles co-deposition on the Q235 substrate was prepared. The coating was characterized through scanning electron microscopy (SEM), x-ray diffraction (XRD), polarization techniques, and electrochemical impedance spectroscopy (EIS). As a result, the Ni-W-P coating co-deposited with SiO2 nanoparticles demonstrates superior corrosion resistance compared to the pure Ni-W-P coating. The surface of SiO2 nanoparticles contain three distinct bonded hydroxyl functional groups, which can influence the ionic reaction in the plating solution and the deposition of elements in the coating. After modified by PVA, it can be uniformly dispersed in the coating, and the composite coating with SiO2 nanoparticles co-deposited is transformed into a nanocrystalline structure. The even distribution of SiO2 nanoparticles fill the defects within the coating, leading to a reduction in porosity, permeability, and susceptibility to penetration of corrosive media. Concurrently, the nanoparticles facilitate surface passivation, forming a stable interface with substrate and coating that inhibits electrochemical reactions and diminishes the rate of self-corrosion reactions. The good and stable corrosion resistance is achieved at the SiO2 concentration of 9 g l−1 and PVA concentration of 1.08 g l−1. These findings offer valuable insights for addressing corrosion challenges in the field of marine engineering.

Safety evaluation of offshore oil and gas well string based on corrosion rate prediction

The combined effects of corrosion, temperature, and pressure can cause safety issues such as shortened lifespan and failure of offshore high temperature and high pressure oil and gas well strings. This paper focuses on a certain sea area and conducts experiments on CO2 corrosion of different string materials under different temperature and partial pressure conditions. Combined with the two-phase flow wellbore temperature and pressure-coupling model, a corrosion rate prediction model based on Back Propagation Neural Network optimized by Genetic Algorithm (GA-BPNN) is established for predicting corrosion rate along the wellbore depth. At the same time, based on the API 5C3 standard, considering the degradation effect of thermally induced metal string strength and the influence of environmental pressure, a safety evaluation model of offshore oil and gas well string based on corrosion rate prediction was established, and analysis of the change law of residual strength of the string and prediction of remaining life under the influence of different factors were carried out.

Mechanistic study of moisture corrosion of FeCr alloys in molten salts by ab-initio molecular dynamics simulations

Molten salts are promising for various energy applications including fuel and solar cells and nuclear energy. These applications face a common challenge: corrosion of structural materials by impurities such as H2O. This work employs ab-initio molecular dynamics simulations to study H2O induced corrosion of FeCr alloys in molten NaF and NaCl salts. H2O is found highly stable in both salts, with infrequent, reversible dissociation into OH− and H+ along with HF or HCl formation. The dissociation tendency correlates positively with the electronegativity and negatively with the size of halogen atoms. Accordingly, H2O reaches the salt/metal interface as a molecule before reacting with metal. Reduction of H+ is found to occur without simultaneous oxidation of specific metal atoms such as Cr, suggesting sequential instead of the commonly proposed concurrent reduction and oxidation. The reduced H atoms prefer to stay at the interface and may re-enter NaF but not NaCl, highlighting the influence of salt chemistry.

Evaluation of soil accelerated corrosion of typical grounding materials used for electrical equipment

Abstract At present, research methods for soil corrosion include sample weight loss methods, physical and chemical properties research, electrochemical research, indoor accelerated corrosion tests, etc. However, most existing soil corrosion evaluation methods have many drawbacks, such as high research costs, long experimental cycles, long results transformation cycles, and significant environmental limitations. In this paper, based on the electrochemical test results of environmental corrosion factors using typical grounding materials, a corrosion simulation solution load spectrum and an accelerated corrosion experimental system corresponding to the soil corrosion environment level were established. The accelerated corrosion samples were thoroughly studied and analyzed using macroscopic morphology observation, microscopic morphology analysis, and energy spectrum analysis. The results show that the soil accelerated corrosion method has strong stability and small deviation, which applies to the study of accelerated corrosion in the soil environment of grounding materials.

Research on Metal Corrosion Behaviour of Indirect Air-cooled Circulating Water System

Abstract The indirect air cooling system of an air-cooled power plant consists of a surface condenser and an aluminum radiator. The radiator is usually made of 1050A pure aluminum, and the circulating water pipe connecting the radiator is made of Q235B carbon steel. This article simulates and controls typical water quality parameters such as dissolved oxygen and pH value in indirect air cooling systems using a self-designed simulation device, and studies the influence of various water quality parameters on material corrosion behavior in intercooled circulating water systems when aluminum and carbon steel coexist. The results indicate that factors such as dissolved oxygen, conductivity, pH value, temperature, and redox potential can all affect the corrosion rate of carbon steel and aluminum materials; The increase in temperature and dissolved oxygen leads to an increase in corrosion rate; The main way carbon steel corrodes the system is by consuming dissolved oxygen; The corrosion behaviour in the water circuit will lead to an overall decrease in pH value. In the presence of multiple metals, the influence of iron ions in the solution significantly increases the corrosion rate of aluminum.

Corrosion of Heat-Transfer Materials Induced by KCl, HCl, and O2 Under Chemical-Looping Conditions

Corrosion of Heat-Transfer Materials Induced by KCl, HCl, and O2 Under Chemical-Looping Conditions

Static corrosion of stainless steel 316H in chemically purified molten NaF-KF-UF4 salt

The purification of salt is indispensable for mitigating the corrosion of structural materials for molten salt reactors or other molten salt applications. This study develops a salt-purification system to synthesize and purify NaF-KF-UF4 salt (FUNaK) using Ar purging and hydrofluorination of impurities. Chronoamperometry is also used to remove metallic impurities in the hydrofluorinated FUNaK. This purified FUNaK is then used for a static corrosion test of stainless steel 316H (SS316H) to study the effectiveness of salt purification in mitigating its corrosion. For comparison, results from a previous study about the corrosion of SS316H by thermally purified FUNaK are used. FUNaK with UF3 is also synthesized for a static corrosion test with the same condition to investigate the impact of UF3 on corrosion. The results show that the corrosion of SS316H is significantly reduced by using the chemically purified FUNaK compared to thermally purified FUNaK.

Utilizing Waste Materials to Enhance Crop Production: A Review

Waste management is a crucial aspect of modern societies, encompassing various activities to ensure the safe and effective disposal of waste materials. It can be classified as hazardous waste, electronic trash (e-waste), industrial waste, and municipal solid waste (MSW). Sustainable waste management practices aim to reduce environmental impact while protecting public health. Urbanization leads to increased residential water consumption, however reusing wastewater for non-potable applications like agriculture can be cost-effective. The overall costs of delivering wastewater for agricultural reuse, including treatment, storage, and transportation, are less the total costs of safe environmental disposal alternatives. Drainage may also be a source of macronutrients (nitrogen, phosphorus, and potassium), which reduces the cost of wastewater for agricultural reuse. The adoption of these principles could lead to a 48% reduction in global greenhouse gas emissions by 2030. The management of hazardous waste, including toxic, flammable, corrosive, or reactive materials, is also a significant concern. In order to safeguard public health and stop the spread of infectious illnesses, animal manure management is crucial. The global generation of construction and demolition waste is expected to double by 2025, with the majority generated in Asia. Sustainable waste management practices are necessary to ensure public health and the environment.

Effects of Selective Laser Melting Process Parameters on Structural, Mechanical, Tribological and Corrosion Properties of CoCrFeMnNi High Entropy Alloy

The structural, tribological, mechanical, corrosion, and other properties of materials produced by laser-based powder bed fusion additive manufacturing methods are significantly affected by production parameters and strategies. Therefore, understanding and controlling the effects of the parameters used in the manufacturing process on the material properties is extremely important for determining optimum production conditions and for saving time and materials. This study aimed to determine the optimal laser parameter values for CoCrFeMnNi high-entropy alloy powders using the selective laser melting (SLM) method. The layer thickness was kept constant during experimentation. 5 different laser powers and 10 varying laser scanning speeds were tested, with hatch spacing from 30 to 90%. After determining the optimal laser parameters for SLM, prismatic samples were fabricated in different build orientations (0°, 45°, and 90°), and subsequently, their structural, mechanical, tribological, and corrosion properties were compared. Melt pool morphology could not be obtained at 20—40 and 60W laser powers and at all laser scanning speeds used at these laser powers. At 100 W laser power, 600 mm/s laser scanning speed, and 70% hatch spacing parameters, an ultimate tensile stress of 550 MPa and elongation of 48% were obtained. Among the samples produced in different build orientations, the sample produced with a 0° build orientation exhibited the highest relative density (99.94%), the highest microhardness (201.2 HV0.1), the lowest friction coefficient (0.7025), and the lowest wear and corrosion rates (0.7875 mpy). Additionally, SLM parameters were evaluated to have a significant impact on the performance of all properties of the samples.Graphical