Increase In Corrosion Rate Research Articles

Pengaruh ketahanan korosi logam alumunium terhadap variasi pada larutan asam klorida 0,1 M dan 0,5 M

Background: Corrosion is a decrease in the quality of a material or metal to electrolyte reactions in the environment that affect the life of the material. Corrosion processes occur in acidic environments, sea water, rainwater, and soil are the result of chemical reactions that are also caused by electrochemical processes. The purpose of this study was to determine the corrosion resistance of aluminum metal to variations in 0.1 M and 0.5 M Hydrochloric Acid solution. This research uses an aluminum plate that will be immersed for 5 days with 0.1 M HCl and 0.5 M HCl solution. Methods: The method of data collection is by scanning Scanning Electron Microscopy (SEM) on each aluminum plate specimen that has been given corrosion treatment by heating at a temperature of 60 C HCl solution is one of the factors causing corrosion of metals. Finding: If in the free environment, air, temperature, and acidic substances are most commonly found as a factor causing corrosion. The increased corrosion rate is due to the higher concentration of the cause of corrosion. Conclusion: In this discussion, HCl as a concentration is used, and aluminum as a metal is tested.

More than the barrier effect: Biodegradable Mg-Ag alloy membranes for guided bone/tissue regeneration

Magnesium (Mg) and its alloys have emerged as promising candidates for guided bone/tissue regeneration (GBR/GTR) due to their good mechanical properties, biosafety, and biodegradability. In this study, we present a pioneering application of Mg-Ag alloys featuring tunable corrosion behaviors for GBR/GTR membranes, showcasing their in vitro antibacterial effects, cell migration, and osteogenic differentiation abilities. Mg-Ag alloys with different Ag contents were engineered to facilitate the cell migration of murine fibroblasts (L929) and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The Mg-Ag alloy consisted of recrystallized α-Mg grains and fine Mg4Ag second phases, with an observable refinement in the average grain size to 5.6 µm with increasing Ag content. Among the alloys, Mg-9Ag exhibited optimal mechanical strength and moderate plasticity (tensile yield strength of 205.7 MPa, elongation of 20.3%, and a maximum bending load of 437.2 N). Furthermore, the alloying of Ag accelerated the cathodic reaction of pure Mg, leading to a slightly increased corrosion rate of the Mg-Ag alloys while maintaining acceptable general corrosion. Notably, compared with pure Mg, Mg-Ag alloys had superior antibacterial effects against Porphyromonas gingivalis (P. gingivalis) and Staphylococcus aureus (S. aureus). Taken together, these results provide evidence for the significant clinical potential of Mg-Ag alloys as GBR/GTR membranes.

Experimental and numerical investigation on the buckling behavior of corroded CST under axial compression

To examine the local buckling performance of Q345B circular steel tubes (CST) after corrosion, 20 specimens with varying degrees of corrosion are obtained through accelerated corrosion testing. Subsequently, axial compression experiments are conducted to observe the impact of corrosion on the buckling behavior. Several parameters, including the diameter-to-thickness ratio, thickness, and corrosion rate, are considered. As the corrosion rate increases, the modulus of elasticity, yield strength, ultimate strength, and elongation at failure of Q345B steel decrease. The maximum geometric imperfection of corroded circular steel tubes (CST) shows a linear relationship with the corrosion rate, with all specimens of corroded CST buckling at the section with the maximum geometric imperfection. The thickness of uniform corrosion has a power relation with the corrosion rate of CST. The local buckling load and ultimate load of CST decrease by 28.6% and 26.4%, respectively, when the corrosion rate reaches 15.5%. Finite element analysis, validated by experimental results, is performed to analyze the buckling performance of corroded CST using the ABAQUS software. Current specifications slightly overestimate the local buckling load and ultimate load, as the effect of corrosion is not included. New modified models for predicting the local buckling load and ultimate load of corroded CST are developed based on current specifications, providing accurate predictions of the buckling behavior of corroded CST.

Effect of Al content on in-situ formation of Al2O3 protective layer on Ni-Al coatings in high-temperature chloride molten salt

The microstructure, strength, toughness, and resistance to chloride molten salt corrosion of Ni-Al coatings with varying Al content were investigated. Increasing the Al content from 9.9 to 61.1 at.% resulted in a decrease in adhesion strength and toughness, while an increase in corrosion rate. Contrary to previous reports, it is noteworthy that Ni-Al coatings with the lowest Al content exhibited superior resistance corrosion due to the formation of an oxidation layer which effectively blocked corrosion. This protective layer was primarily in-situ formed through the reaction between crystalline water present in the molten salt and an appropriate amount of Al. The balance between Al and O content is precisely regulated, resulting in the in-situ formation of Al2O3 protective.

Degradation of RC Columns under Combined Exposure to Axial Loading, Stray Currents, and Chloride Ingress.

Coastal regions, home to a significant portion of the world's population, confront a formidable challenge: the corrosive impact of chloride-rich environments on vital infrastructure. These areas often host essential transportation systems, such as trains and metros, reliant on pre-existing electrical infrastructure. Unfortunately, complete isolation of this infrastructure is rarely feasible, resulting in the emergence of stray currents and electrical potentials that expedite corrosion processes. When coupled with conducive mediums facilitating chemical electrocell formation, the corrosion of reinforced concrete elements accelerates significantly. To combat this issue, international standards have been established, primarily focusing on augmenting the thickness of reinforcement bar covers and restricting stray voltage between rails and the ground. Nevertheless, these measures only provide partial solutions. When subjected to service loads, these elements develop cracks, especially when exposed to stray currents and chlorides, dramatically increasing corrosion rates. Corrosion products, which expand in volume compared to steel, exert internal forces that widen cracks, hastening the deterioration of structural elements. The study deals with the degradation of reinforced concrete columns under the combined action of loads, chloride-rich environments, and electrical voltage-simulating stray currents. In these conditions, degradation and reduction of load-bearing capacity accelerate compared to unloaded conditions, significantly amplifying the corrosion rate. Astonishingly, even in the absence of mechanical loads, stray currents alone induce tensile stresses in elements due to corrosion product formation, leading to longitudinal cracks parallel to the reinforcement bars.

Electrochemical behaviour of Ti6Al4V porous structures fabricated by powder metallurgy route

In this investigation, the powder metallurgy process was used to fabricate porous structures of Ti6Al4V alloy by adding space holder powder particles. The samples were fabricated with varying levels of compaction pressure and other process parameters were kept unchanged in order to investigate the variation in electrochemical behaviour. It was observed that a lower level of compaction pressure resulted in an increase in corrosion current density and rate and a decrease in polarisation resistance. The sample's inability to achieve passivity against electrochemical corrosion, when fabricated using a lower level of compaction pressure, was linked to a higher number of interconnecting micropores. The results of the microstructure analysis confirmed the significant densification of the powder particles when higher compaction pressure was used. The study recommends that a compaction pressure of 300 MPa or higher may be used for fabricating porous structures for biomedical applications.

Preparation of nanocomposites for corrosion treatment

Nano-copper oxide was prepared by utilizing photolysis method and characteristic by using FT-IR, XRD and SEM; the nano size was about 51 nm, environmental impact (pollution reduction) can be improved by using nanostructure particles in preventing corrosion, and nanocomposites have also proven to be an effective alternative to other hazardous and toxic compounds. The results of the current article indicated that the inhibition efficiency increases with increasing concentration of nano-oxide which is added to methyl orange, curcumin, the corrosion rate (CR), inhibition effectiveness were studied at different temperatures. The results showed an increase corrosion rate and a decrease in inhibition efficiency with increase temperature.
 KEY WORDS: Corrosion, Inhibitors, Copper oxide, Nanocomposites
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 501-509. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.17

Biocorrosion of 5083 aluminium alloy by Citrobacter freundii SKC-4 in seawater

The 5083-aluminium alloy, a widely utilized aluminium-magnesium alloy known for its high strength and excellent corrosion resistance, is commonly employed in various applications, including shipbuilding. Despite its inherent resistance to seawater, the presence of microorganisms such as sulphate reducing bacteria (SRB) significantly exacerbates its corrosion. In this study, immersion and electrochemical tests were performed on 5083 aluminium alloy in both sterilized seawater and seawater enriched with SRB Citrobacter freundii SKC-4. Prior to the corrosion tests, Citrobacter freundii SKC-4 was cultivated in modified Luria-Bertani medium under specific conditions. The results demonstrated increased corrosion rates in the presence of the bacteria, with extended immersion leading to greater weight loss of the alloy. Analyses using Scanning Electron Microscope-Energy Dispersive Spectroscopy Mapping and Fourier Transform Infrared confirmed the formation of biofilms by Citrobacter freundii SKC-4 on the alloy's surface, clearly indicating the occurrence of biocorrosion.

Decision Analysis to Avoid Unplanned Shutdown and Catastrophic Failure Due to Sour Crude Oil Processing in Crude Distillation Unit (CDU)

The Crude Distillation Unit (CDU) plays a pivotal role as the primary production unit in crude oil processing. Changes in the operational patterns of crude oil processing have unveiled potential issues that demand the refinery's capability to process Sour Crude. This type of crude oil contains relatively high impurity levels, with a Total Acid Number (TAN) of 0.3 Mg KOH/g and a sulfur content of 1.5 wt%. This has the potential to impact the remaining life and damage modes of equipment and pipes in the Preheater System due to an increase in corrosion rates. This study aims to identify the root causes and propose alternative solutions to address the possibility of damage, particularly leaks, in the Preheater system of the CDU. The focus is on preventing unplanned shutdowns and reducing the risk of catastrophic issues that may arise from the damage to the CDU's preheater system. These steps are crucial to ensuring the continuity of feed supply for secondary processes and valuable product stocks, essential for the operations of Refinery unit. The research employs Fault Tree Analysis (FTA) and Analytic Hierarchy Process (AHP) methods to evaluate several alternative solutions. The analysis results are expected to provide guidance in selecting the most effective and efficient solution, minimizing the risk of preheater system damage, and maintaining the optimal performance of the CDU.

Corrosion Behaviour of Aluminium Matrix Composite Reinforced with Boron Carbide in 3.5% NaCl

The corrosion behavior of Aluminium matrix composite reinforced with micro-size boron carbide was investigated in a 3.5% NaCl solution. The sample was prepared using the stir casting technique with compositions of 2, 4, 6, 8 and 10 wt% of B4C particles. Potentiodynamic polarisation methods were used to derive the electrochemical parameters while hardness analysis methods were used to derive the mechanical properties. A field emission scanning electron microscope (SEM) was employed to investigate the particle boron carbide distribution on the matrix and surface morphology of the metal surface before and after the corrosion test. The X-ray diffraction (XRD) analysis was used to investigate the received powders and matrix samples for phase recognition and the presence of reinforcement particles (B4C) in the composite samples. The findings demonstrated that in a 3.5% NaCl solution, the aluminium matrix composite corrosion rate was inferior to that of the base alloy. At the same time, the corrosion rates of the composite increased with the increase in the composition of B4C in matrix aluminium. Passive layer breakdown due to agglomeration of boron carbide particles caused the increased corrosion rate. Hardness analysis has shown that the value of hardness was improved with the increase in the composition of B4C in the aluminium matrix.

Experimental study on the bond-slip behaviour between corroded bars and concrete

Pull-out tests were conducted to investigate the effects of corrosion of the both longitudinal bar on the bond-slip behaviour of reinforced concrete specimens. The main experimental variables include concrete strength (26.7 MPa, 37.7 MPa, 45.2 MPa) and expected corrosion rate (0%, 4%, 8%, 12%), with a total of 36 specimens fabricated. The results show that the relative bonding strength of specimens under different concrete strengths gradually decreases with increasing corrosion rate, but the higher the concrete strength is, the faster its degradation rate. Based on the experimental results of this work and the achievements of other scholars, a modified relative bonding strength degradation model is presented by accounting for the influence coefficient of concrete strength.

Peculiarities of interaction between oxygen and solute/vacancy in commercial-type zirconium-based alloys: A first-principles study

Unveiling the interaction between dissolved oxygen and solutes/vacancies during the initial stages of oxide layer formation at microscale is significant for the peculiarities of Zr-based alloys oxidation exposed in PWRs or LWRs. We perform ab-initio calculations of the diluted zirconium-based alloys with dissolved Nb and Sn solutes, vacancy and oxygen atom and discuss the solute-oxygen and vacancy-oxygen binding. Our analysis shows that with increasing content of Nb solutes the attractive interaction between niobium and oxygen becomes much stronger, which results in a decrease in corrosion rate of these alloys at the bre-breakaway regime caused by diffusion of oxygen. An increase in content of Sn in an alloy results in enforce of the repulsive interaction between Sn atom and oxygen, which causing tin-enriched alloys are characterized by an increased corrosion rate. We conclude that the dissolved oxygen can be localized near Nb atom rather than near Sn atom if both impurities are second-nearest neighbors, the dissolved oxygen can capture single vacancy and small vacancy clusters in zirconium matrix. This study provides a deep insight into the details of oxygen segregation in zirconium-based alloys exploited in nuclear-power plants.

ANALISIS PENGARUH VARIASI HOLDING TIME ANNEALING TERHADAP LAJU KOROSI TITANIUM PADA LARUTAN CAIRAN TUBUH SINTETIS

Biomaterials are crucial for bone implants due to their biocompatible and inert nature, ensuring no adverse effects within the human body. Titanium is renowned for its exceptional corrosion resistance. This research aims to analyze the impact of annealing holding time and pH of synthetic body fluid on the hardness and corrosion rate of titanium. The annealing process was performed at 700°C, with holding times of 30, 60, and 90 minutes. As an electrolyte medium, a Hanks' solution with pH variations of 4, 6, and 8 was used and maintained at 37°C. Potentiodynamic corrosion testing demonstrated the lowest corrosion rate in specimens treated with 30 minutes of annealing at pH 8, measuring 0.32 x 10-2 mmpy. The 30-minute annealing exhibited the lowest corrosion rate, which was confirmed by Electrochemical Impedance Spectroscopy (EIS) results showing a higher Rp value, indicating a lower corrosion rate. This is attributed to the presence of a passive Rutile TiO2 layer formed during the annealing process, as confirmed by X-ray Diffraction (XRD) analysis. Metallography observations indicated that the microstructure of untreated specimens consisted of α and β phases. Scanning Electron Microscopy (SEM) analysis of specimens annealed for 30 minutes revealed an oxide layer on the surface without any visible pores. However, an increase in annealing holding time led to the formation of pores, particularly noticeable after 90 minutes of annealing. The presence of pores in the oxide layer resulted in an increased corrosion rate with longer annealing holding times. Conversely, hardness testing demonstrated that longer annealing holding times resulted in higher hardness values.

A novel application of CO2 corrosion inhibitory potentials of banana peel extract on mild steel: Experimental studies

The corrosion inhibitory effect of banana peel extract on mild steel in a CO2 corrosion environment is studied using weight loss method. The corrosion mechanism is studied with respect to process parameters such as the concentration of the extract, pH, temperature, and immersion time. The extract production is done using maceration method, while FTIR analysis is used to confirm the constituents of the chemical functional groups. The morphology of the corroded coupons’ surface examines SEM microscopy. The results show that the respective corrosion rate increase of 0.184–0.347 mgcm−2h−1 and 0.128–0.354 mgcm−2h−1 are obtained when temperature and immersion time increased from 35 to 75 °C and 48 to 240 h, respectively. Also, a decrease in corrosion rate of 1.01–0.128 mgcm−2h−1 and 0.035–0.0 is noted when the concentration and pH increased from 0.0001 to 1.0 g/l and 3–12, respectively. Changes in these respective experimental parameters yielding corrosion inhibitory efficiencies of (98.0–95.1), (99.1–96.0), (96.1–98.0) and (99.1–100) %. FTIR analysis confirmed the presence of electron copious functional groups such as alkane, amine, alcohol, carboxylic acid, ester and nitro compound that contain O2 and N2 atoms that can donate lone pair electrons and bind metal ions. The SEM micrographs indicated that more severity of the corrosion effects is associated with low pH and high temperature conditions. That is in good agreement with corrosion test results. Hence, a strong correlation is established between the process conditions and the corrosion mechanism. It therefore concludes that banana peel has potential for CO2 corrosion mitigation.

Friction stir processing of AZ91 hybrid composites with exfoliated multi-layered graphene: A Taguchi-Grey relational analysis

Friction Stir Processing (FSP) involves the use of Silicon Carbide (SiC) and Graphite (Gr) nanoparticles as reinforcements to enhance the properties of AZ91 Mg alloy composites. The relationship between FSP processing parameters and surface properties of Mg alloy composites with SiC and Gr nanoparticles is poorly understood. The present study addresses this and investigates the impact of SiC and Gr volume percentages (%vol), tool traverse speed (TTS), and tool rotational speed (TRS) on the corrosion behavior and microhardness of AZ91 alloy composites. FSP turns graphite into layered graphene, making it more corrosion-resistant and stronger through various strengthening mechanisms. Taguchi optimization yielded optimal settings in runs H7 (1500 rpm-20 mm/min-13 %vol) and H8 (1500 rpm-40 mm/min-7 %vol) for high microhardness and low corrosion rate. Conversely, runs H1 (500 rpm-20 mm/min-7 %vol) and H3 (500 rpm-60 mm/min-13 %vol) resulted in reduced microhardness and increased corrosion rate. Integrating Taguchi and Grey Relational Analysis (GRA) optimized the multi-objective enhancement of microhardness and corrosion resistance, achieving 3rd-level values for TRS, TTS, and %vol. Notably, the reinforcement percentage, followed by TRS and TTS, simultaneously improved these responses.

CHARACTERIZATION OF CORROSION BEHAVIOR OF INCONEL 617 WELDED JOINTS USING CMT-GMAW MULTI-CONTROL WELDING

This work addressed the effect of CMT-GMAW multi-control welding of Inconel 617 alloy with different wire feed rates (8.9, 9.4, and 9.9 m/min) on the microstructure, hardness, and electrochemical properties. The weld joints are composed of columnar dendritic structure with cellular crystals. Electron backscattered diffraction (EBSD) study showed equiaxed dendrite at the center of weld metal with growth direction perpendicular to the fusion boundary. The weldments showed diffraction peaks at 43.53[Formula: see text], 50.12[Formula: see text], and 74.82[Formula: see text], and these peaks mainly represent gamma ([Formula: see text]) and gamma prime ([Formula: see text]) phases along with the carbide peaks of Ti (C, N), M[Formula: see text]C6 and M6C. The Base metal (BM) had a lower hardness (232 ± 10 HV[Formula: see text]) and lower corrosion rate (0.212 mpy) than the weld joints. The increase in wire feed rate (WFR) results in the decrease of microhardness (267 ± 5 − 251 ± 6 HV[Formula: see text]) and increase in corrosion rate (1.833-28.140 mpy). The base metal exhibited higher potential ([Formula: see text]) and lower current density ([Formula: see text]) than the weld joints. As wire feed rate (WFR) increases, heat input increases; solidification time increases, grain boundaries coarsen, resulting in a lower grain boundary (GB) density, and hence increased carbide precipitation and segregation in weld zone leading to higher stable anodic current density, which caused corrosion resistance to deteriorating. The BM was more corrosion resistant than the weld joints. The metallurgical and physical changes caused by the welding process affect the corrosion resistance of the weld joints. This leads to the weld metal corroding faster than the base metal.

Experimental study on impact toughness of structural steel and its butt-welded joint at low temperature and corrosion

The safe and life extension utilization of steel structures in cold offshore regions demand studies on the toughness of structural steel at low temperature and corrosion. In present work, the effects of low temperature and corrosion on impact toughness of the typical structural steel of Q235 and its butt-welded joint are studied. Constant current acceleration associated with salt spray acceleration corrosion experiment are performed to corrode specimens. The Charpy impact tests for Q235 steel and its butt-welded joint at different temperatures and corrosion times are carried out. The micro-morphologies of impact fracture surface are also studied by scanning electron microscopy (SEM). It can be found that the impact energies of Q235 steel and its butt-welded joint are degraded as temperature decreases and corrosion rate increases. The effect of corrosion on impact energy is aggravated by low temperature. The impact toughness of Q235 steel and its butt-welded joint are influenced by the coupling effect of low temperature and corrosion. This study can provide information for the fracture resistant design of steel structures in low temperature and corrosion environment.

Mechanical Properties Evaluation of Magnesium-Based Alloy Used for Dental Implant Synthesis

Background: Mg as well as its alloys are differing from other biomaterials through providing compatible physical and mechanical characteristics to the human bones. Also, their elastic modulus and densities were somewhat close to one another and thus removing elastic mismatches between the bone and implants. Furthermore, the Mg present naturally in bone structure, and it is essential metal for metabolism. Some mechanical properties (Hardness, diametral tensile) and corrosion resistance of enforced Mg by Strontium and alloyed with another biocompatible elements (Zn, Mn) were examined. Materials and methods: 135 samples were prepared for microhardness, diametral tensile, and corrosion test, divided to two groups 1st one pure Mg as a control group, 2nd group Mg alloy with different concentration of alloying elements to select the optimum ratio for alloying elements which consist of Zinc, Manganese, and Strontium). Result: Alloying of Mg with Zn, Mn and Sr, shows improvement in mechanical properties but dropping in corrosion resistance when compared with pure Mg. Conclusions: Alloying of pure Mg by ternary Zn, Mn and Sr have a valuable improvement in mechanical micro hardness and diametral tensile properties, but increases corrosion rate in comparison with pure Mg due to the effect of galvanic corrosion

Laser re-melting of modified multimodal Cr3C2–NiCr coatings by HVOF: Effect on the microstructure and anticorrosion properties

Abstract Modified multimodal (MMP) Cr3C2–NiCr coatings were fabricated by high-velocity oxy-fuel (HVOF) spraying deposited on a CuCrZr alloy substrate. However, due to the lack of its inevitable porosity, an additional laser re-melting (LRM) approach is highly required to improve the coating performance. Therefore, the LRM technique is employed in this study to improve the microstructure properties of an MMP Cr3C2–NiCr coating by HVOF. Solid-state phase transformation from Cr3C2 to Cr7C3 occurred during the LRM process. After the LRM process, the coating exhibits the presence of Cr3C2 nanoparticles that serve as reinforcement. These nanoparticles demonstrate minimal lattice misfit and exhibit high stability throughout the LRM process. The surface of the coating undergoes modification, resulting in the formation of homogeneous nano (20–130 nm), micron (150 nm to 0.3 μm), and submicron (2–3 μm) Cr3C2 structures, along with high-density microstructures, after the LRM process. Nano-Cr3C2 particle reinforced with high total work function and incredibly increased corrosion rate significantly improves coating corrosion resistance. Overall, porosity decreased from 3.9% of the HVOF coating to 0.3% of the LRM. As a result, the current density of anticorrosion decreased from 33.7 to 4.35 µA·cm−2, and the Vickers microhardness average values ranged from 1,050 to 1,300 HV0.3, indicating improved microstructure development and related properties.

Development of Al-Mg Alloy for the Protection of Steel Structure in 3.5% Nacl

Aluminium (Al) is thoroughly used as a sacrificial metal for the protection of steel in seawater. Aluminium is rarely used as a sacrificial anode without being alloyed due to its built-in properties to get passivates and form a passive layer and the continuity of its layer depends on the chemical composition and microstructure. In this paper, Aluminium-Magnesium(5xxx) system is considered because magnesium remarkably affects the chemical properties by changing the microstructure of Aluminium from a homogeneous solid solution to a complex structure with multiple intermetallic phases. In this research work developing Aluminium-Magnesium alloys containing 2.5 and 4.5 weight percent magnesium. The microstructures of pure aluminium and developed alloys were studied and the effect of the distribution of magnesium whether as a second phase particle, intermetallic compound or precipitates on the performance of aluminium sacrificial anode was discussed. Standard weight loss method and potentiodynamic tests are used to evaluate the performance of alloy sacrificial anode. The result shows that as the magnesium content increases corrosion rate of developed alloy increases and corrosion potential shifts in more negative directions. Corrosion potential is increased by 250 mV at 4.5% magnesium because of the formation of an intermetallic compound of aluminium& Magnesium (β phase - Al3Mg2) at the grain boundary. Magnesium improves the corrosion rate of developed alloy,it acts as a depassivators for the passive film of Aluminium by forming intermetallic compound and this compound has different electrochemical properties that leads to corrosion of aluminium and improves the performance of aluminium sacrificial anode.