Metal Corrosion Research Articles

Small Organic Molecules with Anchoring Adsorption Enhance Corrosion Inhibition of Zinc Electrodes in ZnSO4 Medium

AbstractIn this study, trimercapto‐S‐triazine trisodium salt (TMT) with threefold rotational symmetry as a corrosion inhibitor was introduced into 2 mol ⋅ L−1 ZnSO4 medium. By electrochemical measurements, the corrosion inhibition efficiency of the zinc electrodes was 92.52 % when the concentration of TMT corrosion inhibitor was 2 mmol ⋅ L−1. Based on the microstructural characterization and theoretical analysis of Zn electrodes, it was confirmed that S and N atoms of TMT corrosion inhibitor serve as alternately zinc‐philic adsorption sites with sixfold rotational symmetry for the formation of intermolecular complexes. Adsorption energies of TMT on Zn surfaces were calculated and indicated that the bonds of Zn−N and Zn−S promoted anchoring adsorption on sixfold symmetric (002) plane of zinc. Meanwhile, TMT corrosion inhibitor can adsorb Zn2+ from the electrolyte and directionally deposit them on the surface of Zn (002), effectively avoiding the occurrence of dendrites. This study changes the common knowledge that organic corrosion inhibitors must form hydrophobic films to have corrosion inhibition performance, and provides a new approach for using small organic molecules with anchoring adsorption as metal corrosion inhibitors.

Spinodal Zr–Nb alloys with ultrahigh elastic admissible strain and low magnetic susceptibility for orthopedic applications

Metallic biomaterials, such as stainless steels, cobalt–chromium–molybdenum (Co–Cr–Mo) alloys, and titanium (Ti) alloys, have long been used as load-bearing implant materials due to their metallic mechanical strength, corrosion resistance, and biocompatibility. However, their magnetic susceptibility and elastic modulus of more than 100 GPa significantly restrict their therapeutic applicability. In this study, spinodal Zr60Nb40, Zr50Nb50, and Zr40Nb60 (at.%) alloys were selected from the miscibility gap based on the Zr–Nb binary phase diagram and prepared by casting, cold rolling, and aging. Their microstructure, mechanical properties, corrosion resistance, magnetic susceptibility, and biocompatibility were systematically evaluated. Spinodal decomposition to alternating nanoscale Zr-rich β1 and Nb-rich β2 phases occurred in the cold-rolled Zr–Nb alloys during aging treatment at 650 °C. In addition, a minor amount of α phase was precipitated in Zr60Nb40 due to the thermodynamic instability of the Zr-rich β1 phase. Spinodal decomposition significantly improved the mechanical strength of the alloys due to nanosized dual-cubic reinforcement. The Zr–Nb alloys showed an electrochemical corrosion rate of 94–262 nm per year in Hanks’ solution because of formation of dense passive films composed of ZrO2 and Nb2O5 during the polarization process. The magnetic susceptibilities of the Zr–Nb alloys were significantly lower than those of commercial Co–Cr–Mo and Ti alloys. The cell viability of the Zr–Nb alloys was more than 98 % toward MC3T3-E1 cells. Overall, the spinodal Zr–Nb alloys have enormous potential as bone-implant materials due to their outstanding overall mechanical properties, extraordinary corrosion resistance, low magnetic susceptibility, and sufficient bicompatibility. Statement of significanceThis work reports on spinodal Zr–Nb alloys with heterostructure. Spinodal decomposition significantly improved their mechanical strength due to the nanosized dual-cubic reinforcement. The Zr–Nb alloys showed large corrosion resistance in Hanks’ solution because of formation of dense passivation films composed of ZrO2 and Nb2O5 during the polarization process. The magnetic susceptibilities of the Zr–Nb alloys were significantly lower than those of commercial Co–Cr–Mo and Ti alloys. The cell viability of the Zr–Nb alloys was more than 98 % toward MC3T3-E1 cells. The results demonstrate that spinodal Zr–Nb alloys have enormous potential as bone-implant materials due to their outstanding overall mechanical properties, high corrosion resistance, low magnetic susceptibility, and sufficient biocompatibility.

In-situ modification of nickel electrode by coupling the microbial corrosion and microbial reduction using Shewanella oneidensis for enhanced electrocatalysis

Shewanella oneidensis is a facultative anaerobe with the ability to use different terminal electron donors and acceptors. Therefore, S. oneidensis can be used either as an oxidizing agent for microbial corrosion of metals or as a reducing agent for microbial synthesis of metal nanoparticles depending on the metal type. Herein, we have shown that S. oneidensis MR-1 can be used for both microbial corrosion of nickel foam (NF) and microbial synthesis of Ni nanoparticles under environmentally benign conditions. It is found that S. oneidensis MR-1 can accelerate the corrosion process to form metal hydroxides on the surface of NF in the presence of Fe3+, and the obtained electrode shows improved electrocatalytic activity toward oxygen evolution reaction with an overpotential of 0.265 V to achieve a current density of 10 mA cm−2. However, the corrosion process of NF by S. oneidensis MR-1 is severely inhibited in the presence of Fe2+. In addition, aside from the corrosion process of NF, we have for the first time shown that Ni nanoparticles can be synthesized by the reduction of Ni2+ ions using S. oneidensis MR-1. The results show that the microbial energy metabolism of S. oneidensis MR-1 facilitates the electron transfer from electron-donating NF to the electron-accepting metal ions (Fe3+, Ni2+) across the microbes, coupling the corrosion process (Ni → Ni2+) and metal ions reductions (Fe3+ → Fe2+, Ni2+ → Ni), which demonstrates great potential for in-situ modification of electrode with microorganism and provides new avenue for electrode fabrication.

Generation of a lignin-polyester coating for the corrosion protection of steel surfaces applied by atmospheric plasma spraying

The natural process of metal corrosion causes significant losses in a wide range of industries, requiring substantial efforts to contain its effects. An alternative approach to corrosion protection is the use of renewable organic coating materials. This research proposes the use of lignin-polyester blends as coating materials. Due to the abundance of functional groups in the lignin structure, it can act as corrosion inhibition centers in the coating. The coatings are deposited on stainless steel surfaces by a novel process route via atmospheric plasma powder spraying (APPS). To determine the effect of the lignin content on the corrosion performance, the specific amounts of lignin and polyester have been varied in 10 % increments from 0 % to 100 % with constant coating parameters. The as-produced coatings exhibited thicknesses that ranged from 11 μm to 30 μm, respectively for the pure lignin and polyester coatings. Additionally, scanning electron microscopy (SEM) analysis demonstrated the meltability of the lignin and polyester powder through the plasma process. Coatings containing a greater proportion of polyester exhibited superior meltability and better coverage. Furthermore, it was observed that the APPS promoted cross-linking of the lignin particles, as determined by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). This, in conjunction with well-balanced lignin-polyester ratios, was instrumental in achieving advanced corrosion resistance as evidenced by Potentiodynamic polarization measurement (PDP). The lignin proportion between 40 % and 60 % produced the highest corrosion inhibition efficiency, with a maximum inhibition of 96 %. Furthermore, pull-off adhesion tests suggest that lignin contributes to the overall cohesive strength of the blend.

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.

A highly stable zinc anode protected by a corrosion inhibitor for seawater-based zinc-ion batteries

The island-based energy storage is of urgent need for the grid construction combined with renewable energy for offshore operation. The direct use of seawater as a substitute of deionized water shows its great promise for aqueous zinc-ion batteries in such a specific situation. However, the metal corrosion, dendrite growth, and hydrogen evolution stand out in the harsh seawater environment. To address these challenges, we proposed a corrosion inhibitor that was effective in the field of metal anti-corrosion, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), to inhibit anode corrosion caused by Cl– and active H2O molecules by forming a stable solid electrolyte interphase (SEI) film in the seawater-based electrolyte. Besides, PBTCA can chelate with other cations present in seawater, such as Ca2+ and Mg2+, thereby preventing the aggregation and precipitation of sparingly soluble species. Under a current density of 5 mA cm−2, the seawater-based zinc-ion battery exhibited an exceptional cycle life exceeding 2000 h and maintained a Coulombic efficiency of over 99.6% after 2000 cycles. Additionally, the performance of the Zn||ZVO full battery was significantly enhanced with the addition of PBTCA. This study provides a simple, low-cost, and efficient approach for making the seawater-based zinc-ion batteries useable.

High-performance liquid metal-based SiC/Graphene-Mo hybrid nanofluid for hydraulic transmission

A novel liquid metal-based SiC/Graphene-Mo hybrid nanofluid (LMNF) has been fabricated. The nanoparticles are uniformly dispersed, and LMNF temperature-viscosity characteristics is stabler in a wider temperature range than traditional hydraulic media. With this, the LMNF tribological performance on Al2O3 and SS316L friction pairs is studied: The LMNF has superior severe-pressure and high-temperature lubrication with the nanoparticle-enabled wear resistance. The SS316L surface forms composite nanofilm with the LMNF, which prevents adhesive wear and mitigates liquid metal corrosion. Comparatively, the nanoparticles function as "micro-bearings" on the Al2O3 surfaces to assist lubrication. These benefits are reflected in the gear pump volumetric efficiency and wear rate of our industry-level hydraulic system, approving LMNF as a potential hydraulic transmission medium in harsh conditions.

Study on the Application of Fluorinated Polyimide in the Acidic Corrosion Protection of 3-nitro-1,2,4-trizole-5-one (NTO)-Based Explosive Formulations.

3-nitro-1,2,4-triazol-5-one (NTO) has been widely used as a kind of insensitive single-compound explosive owing to its excellent balance between safety and explosive energy. To reduce its possible acid corrosion and extend its application to insensitive ammunition, acid protection research on NTO-based explosives is significant. Traditionally, the acid protection effect was evaluated by metal corrosion, which is time-consuming and qualitative. An efficient and quantitative method is desirable for evaluating the acid protection effect and exploring novel protection materials. Herein, a polyimide of 4,4'-(hexafluoroisopropene)diphthalic anhydride (6FDA)/2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl (TFMB) was synthesized by replacing the 4,4'-diaminodiphenyl ether (ODA) monomer with a TFMB monomer to act as an acid-protective coating material for NTO-based explosives. Compared with three other coating materials, polyvinylidene fluoride (PVDF), polyetherimide (PEI), and copolyimide (P84), the fluorinated polyimide exhibits the best acid protection effect. Moreover, a new method was constructed to obtain the pH time-dependent curve in order to evaluate efficiently the acid protection effect of the polymer materials. By the virtue of molecular dynamic simulation (Materials Studio 2023), the interfacial effects of the coating materials with NTO-based explosives were obtained. The study provides an interpretation of the acid protection effect on the molecular level, suggesting that the higher content of fluorine atoms is beneficial for stabilizing the active hydrogen atom of the NTO by forming intermolecular hydrogen bonds.

In Situ Thermal Interactions of Cu-Based Anti-Corrosion Coatings on Steel Implemented by Surface Alloying

Incorporating expensive alloying elements into bulk steel for corrosion protection is undesirable, considering that only the surfaces are exposed to aggressive environments. Therefore, this work focused on developing and optimizing a new surface functioning technology through in situ observation of thermal interactions between the metallic powders at elevated temperatures. The study revealed that the Cu-Ni powder mixture, with 12.5 wt% Ni, began to melt at 1099.5 °C and was fully melted at 1175 °C, significantly different from the Cu-Ni solid solution and bulk Cu or Ni. As a result of high-temperature reactions, copper penetration of up to 35 µm for pure copper and 55 µm for copper-chromium composite coatings occurred due to liquid metal corrosion. In contrast, the copper-nickel composite coating exhibited a cupronickel solution microstructure with FeNi dendrites and a nickel-rich transition layer. This cupronickel coating, with a chemical composition of 89.3 wt% Cu, 6.2 wt% Ni, and 4.5 wt% Fe, demonstrated uniform thickness, superior surface morphology, and continuous coverage on the steel substrate. Furthermore, the Ni-rich transition layer played a vital role in preventing copper penetration along the grain boundary of the steel matrix while forming a chemical binding between the coating and the substrate. The practicality of the coating was further confirmed through the hot-rolling procedure and subsequent electrochemical corrosion tests, which resulted in a 44% improvement in corrosion resistance.

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.

Upgrading/Deacidification of Bio-Oils by Liquid–Liquid Extraction Using Aqueous Methanol as a Solvent

Oxygenated compounds such as acids in bio-oils (BO) have been related to the corrosion of metals and their storage instability when applied as fuels. Therefore, upgrading BO by removing acids (deacidification) can be a valuable technique to reduce corrosivity using specific separation processes. Therefore, the objective of this paper was to evaluate the effect of the water content in the solvent (aqueous methanol), the carboxylic acid content in the BO and extraction temperature on the deacidification process by liquid–liquid extraction (LLE), as well as the effect of the same parameters on the quality of the deacidified BO through physical–chemical and GC-MS analyses. The results show that an increase in the water content (5 to 25%) in the solvent and an increase in the carboxylic acids content (24.38 to 51.56 mg KOH/g) in the BO reduce the solvent’s capacity to extract carboxylic acids while increasing the temperature (25 to 35 °C) of the deacidification process promoted an increase in its capacity to remove them. Consequently, the highest deacidification efficiency (72.65%) is achieved with 5% water in methanol at 25 °C for BO1 (TAN = 24.38 mg KOH/g). Therefore, the deacidification process through LLE using aqueous methanol contributed significantly to BO upgrading.

Performance study of novel metal corrosion probes based on the adjust method of series and parallel connections

Rod-type metal corrosion probes based on electromechanical impedance (EMI) technique can quantitatively assess the amount of corrosion, which have a promising application in pipeline corrosion monitoring and have received much more attention. In the field of structural health monitoring, the EMI technique based on series and parallel connections has been widely studied and is very promising, but it is yet to be used in the probe design. In this work, a kind of novel metal corrosion probe with two piezoelectric elements in series and parallel connections was proposed, and its performance was investigated comprehensively by combining theoretical analysis with experiment research. Theoretical models of the proposed probe in the longitudinal vibration mode for both series and parallel connections were established, and verified by the experimental results. Influences of the thicknesses of piezoelectric layer and ceramic layer on the probe performance were analyzed. Artificial quantitative corrosion tests and accelerated corrosion tests were designed to evaluate the quantitative corrosion monitoring capacity. Temperature sensitivity tests were conducted to study the temperature dependence. The wireless impedance measurement was performed to confirm the online monitoring ability. Comparisons for the probe performance between the series and parallel connections were also presented. This work provided a comprehensive understanding for this kind of novel probe, which is beneficial to develop low-cost, high-precision, high-stability pipeline corrosion real-time monitoring technology.

Hexakis[p-(hydroxymethyl)phenoxy]cyclotriphosphazene as an Environmentally Friendly Modifier for Polyurethane Powder Coatings with Increased Thermal Stability and Corrosion Resistance.

Protection against fire and the corrosion of metals is necessary to ensure human safety. Most of the fire and corrosion inhibitors do not meet the ecological requirements. Therefore, effective and ecological methods of protecting metals are currently a challenge for researchers. In this work, the influence of hexakis(4-(hydroxymethyl)phenoxy)cyclotriphosphazene (HHPCP) on the characteristics of powder coatings was examined. The coatings' properties were investigated by measuring the roughness, hardness, adhesion to the steel surface, cupping, gloss, scratch resistance, and water contact angle. The thermal stability was studied by furnace test and TGA analysis. The corrosion resistance test was carried out in a 3.5% NaCl solution. The distribution of phosphazene-derived segments in the coating was examined by GD-EOS analysis. Modified coatings show better corrosion and thermal resistance and can be used for the protection of the steel surface. Their better corrosion resistance is due to the electroactive properties of the phosphazene ring and its higher concentration at the coating surface, confirmed by GD-EOS analysis. The increase in thermal resistance is due to the effect of the formation of phosphoric metaphosphoric and polyphosphoric acids during the decomposition of HHCPC, which remain in the condensed char phase and play a crucial role in surface protection.

The Use of Plant Extracts as Green Corrosion Inhibitors: A Review

The corrosion of metals is very important, both economically and environmentally, and is a serious concern. Since the past decades, traditional (chemical) corrosion inhibitors to prevent corrosion have been and are still being used. Although these inhibitors can be said to be a good choice among other protection techniques because of their good efficiency, the toxicity of many of them causes environmental problems, and, due to the change in the laws on the use of chemicals, many of them are no longer allowed. Hence, during the past years, research on green corrosion inhibitors (GCIs) increased and very favorable results were obtained, and now they are very popular. It can be said that biodegradability and easy preparation are their most important factors. Meanwhile, the use of plants, especially their extracts, has been studied a lot. Plant extracts contain compounds that have anti-corrosion properties. In this review, the use of plants as GCIs is investigated, focusing on recent advances in their use. Also, the phenomenon of corrosion, corrosion protection (including coatings, nanoparticles, and chemical inhibitors), and other GCIs are briefly reviewed.

STUDYING THE PHYSICAL AND CHEMICAL PROPERTIES OF AMINE AND AMIDE CONTAINING ORGANIC INHIBITORS

In this work, new inhibitors of metal corrosion in sulfuric acid environments are studied depending on the duration of the process, inhibitor concentration and temperature. The main parameters for the synthesis of new metal corrosion inhibitors St.3 and St.12 grades using amine and amide containing organic substances are determined and methods for obtaining these inhibitors are described. The physicochemical properties of amine and amide containing organic inhibitors of corrosion and scaling in acidic process environments have been studied.

Quantitative study on the metal dissolution reaction with multivalent cations by a modified SECM mode: Pure Ti as a case

Metal corrosion exhibits coupled multi-reaction features, making it challenging to quantitatively study the dissolution reaction with variable-valent cations, particularly in valence quantification. This work develops a novel scanning electrochemical microscopy mode and applies it to Ti dissolution study in acidic fluorides. This mode identifies the potential-dependent corrosion reactions and quantifies the valence evolution of Ti from HER to transpassive regions. Results provide direct electrochemical evidence for soluble Ti(z≤3), for the first time, and revise the reported dissolution equation. The proposed mode overcomes the drawbacks of macro-electrochemical analysis based on coupling information and provides an effective quantitation method for anodic reactions.

Preparation of efficient hydrochloric acid corrosion inhibitor from natural grease

Abstract To alleviate the metal corrosion problem caused by incomplete acid discharge during pickling or acidification, a corrosion inhibitor, long chain fatty hydrazides (LCFH), with a significant corrosion inhibition effect was synthesized from natural grease. The corrosion inhibition and adsorption properties of LCFH on carbon steel in 1 M HCl solution were studied by static sample weight loss test, electrochemical impedance spectroscopy, and potentiodynamic polarization curve. The results showed that LCFH exhibits excellent corrosion inhibition performance in HCl solution. The inhibition efficiency increases with the increase of inhibitor concentration. When the concentration of LCFH is 40 mg/L, the inhibition efficiency can reach 97.9%. The potentiodynamic polarization curve shows that LCFH is a corrosion inhibitor that mainly inhibits the cathodic reaction. The corrosion inhibitor is spontaneously adsorbed on the surface of low-carbon steel in physical form, which conforms to the Langmuir isothermal adsorption model.

Study on the disinfection effect of chlorine dioxide disinfectant (ClO2) on dental unit waterlines and its in vitro safety evaluation

BackgroundEnsuring the safety of dental unit waterlines (DUWLs) has become a pivotal issue in dental care practices, focusing on the health implications for both patients and healthcare providers. The inherent structure and usage conditions of DUWLs contribute to the risk of biofilm formation and bacterial growth, highlighting the need for effective disinfection solutions.The quest for a disinfection method that is both safe for clinical use and effective against pathogens such as Staphylococcus aureus and Escherichia coli in DUWLs underscores the urgency of this research.MaterialsChlorine dioxide disinfectants at concentrations of 5, 20, and 80 mg/L were used to treat biofilms of S. aureus and E. coli cultured in DUWLs. The disinfection effectiveness was assessed through bacterial counts and culturing. Simultaneously, human skin fibroblast cells were treated with the disinfectant to observe changes in cell morphology and cytotoxicity. Additionally, the study included corrosion tests on various metals (carbon steel, brass, stainless steel, aluminum, etc.).ResultsExperimental results showed that chlorine dioxide disinfectants at concentrations of 20 mg/L and 80 mg/L significantly reduced the bacterial count of S. aureus and E. coli, indicating effective disinfection. In terms of cytotoxicity, higher concentrations were more harmful to cellular safety, but even at 80 mg/L, the cytotoxicity of chlorine dioxide remained within controllable limits. Corrosion tests revealed that chlorine dioxide disinfectants had a certain corrosive effect on carbon steel and brass, and the degree of corrosion increased with the concentration of the disinfectant.ConclusionAfter thorough research, we recommend using chlorine dioxide disinfectant at a concentration of 20 mg/L for significantly reducing bacterial biofilms in dental unit waterlines (DUWLs). This concentration also ensures satisfactory cell safety and metal corrosion resistance.

Corrosion of copper exposed to water-in biodiesel-diesel emulsion fuel stabilized with polyglycerol polyricinoleate emulsifier

Despite emulsification of water in-diesel can decrease harmful exhaust emissions, unstable emulsion can result in formation of free water which can accelerate metal corrosion in the fuel delivery system of a diesel engine. This study aimed to formulate and assess stability of 5 vol% water in 5 vol% biodiesel in diesel emulsion fuel (W5B5) and investigate its effects towards copper corrosion. Stable W5B5 was successfully prepared with 3 vol% polyglycerol polyricinoleate (PGPR). After 1200 h of storage, W5B5 remained stable, indicated by mean droplet diameter of 627.6 ± 7.5 nm, sedimentation index of ∼3 %, and absence of free water formation. Upon exposure to copper, mean droplet diameter of W5B5 increased by 2.7 times compared to prepared W5B5. Viscosity and total acid number (TAN) values of copper exposed W5B5 increased by 26 % and 270 %, respectively, indicating enlargement of water droplets and degradation of fuel during immersion. Corrosion rate of copper exposed to W5B5 decreased by 92 % between 240 and 1200 h of immersion. Corrosion rate of copper in W5B5 was 5.5 times and 3.0 times higher diesel and biodiesel, respectively. Higher initial TAN of W5B5 than other fuels, attributed to addition of PGPR to form stable water-fuel emulsion, influenced the higher corrosion rate observed in W5B5 compared to other fuels. To minimize corrosive nature of W5B5, future research should focus on developing stable formulation with low initial acidity value comparable to or even lower than biodiesel. The contribution to knowledge from the study yielded valuable insights into the stability of emulsion fuel, corrosion behaviour, and impact of emulsifier acidity on corrosion rates.

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.