Search

Structural materials used in nuclear reactor environments are subjected to coupled extremes such as high temperature, irradiation, and corrosion which act in concert to degrade their functional performance. Connecting alloy microstructure such as grain boundaries, and accumulating point defects with corrosion attack and pore morphology is critical to understanding underlying mechanisms. We uncover the compositional variations and morphology at multiple length scales in corrosion-damaged Ni-Cr alloy after exposure to oxidants in molten fluoride salts. A complex network of dense corrosion pores is detected by surface-level SEM observations. The corrosion pores take on a 1-dimensional morphology and are enriched with Ni and depleted of Cr 1–5 µm from the pore surface. STEM-EDS and 4D-STEM strain maps acquired simultaneously highlight the local variations in composition and structure of a ≤ 200 nm Cr-rich layer identified from a cross-section taken at the bottom of an isolated corrosion pore between the Ni-Cr alloy matrix and the embedded salt. However, the absence of an observed interface between the Ni-Cr alloy matrix and the FCC-structured Cr-rich layer suggests that Cr plating from the salt did not transpire. These findings support a proposed Cr lattice diffusion mechanism rather than Cr-precipitation from the salt to accommodate temperature transient conditions during sample cooling. Through the development of a 1D phase field model, these results are rationalized by formation energies for the Ni- and Cr-oxidation into the molten salt. This study reveals the locally altered microstructure caused by high temperature corrosion in non-steady-state molten salt nuclear reactor environments.

Diamond-like Carbon (DLC) has been used as a coating material of choice for a variety of technological applications owing to its favorable bio-tribo-thermo-mechanical characteristics. Here, the possibility of bringing DLC into orthopedic joint implants is examined. With ever increasing number of patients suffering from osteoarthritis as well as with the ingress of the osteoarthritic joints malaise into younger and more active demographics, there is a pressing need to augment the performance and integrity of conventional total joint replacements (TJRs). Contemporary joint replacement devices use metal-on-polymer articulations to restore function to worn, damaged or diseased cartilage. The wear of polymeric components has been addressed using crosslinking and antioxidants; however, in the context of the metallic components, complications pertaining to corrosion and metal ion release inside the body still persist. Through this review article, we explore the use of DLC coatings on metallic bearing surfaces and elucidate why this technology might be a viable solution for ongoing electrochemical challenges in orthopedics. The different characteristics of DLC coatings and their feasibility in TJRs are examined through assessment of tribo-material characterization methods. A holistic characterization of the coating-substrate interface and the wear performance of such systems are discussed. As with all biomaterials used in TJRs, we need mindful consideration of potential in-vivo challenges. We present a few caveats for DLC coatings including delamination, hydrophobicity, and other conflicting as well as outdating findings in the literature. We recommend prudently exploring DLC films as potential coatings on metallic TJR components to solve the problems pertaining to wear, metal ion release, and corrosion. Ultimately, we advise bringing DLC into clinical use only after addressing all challenges and concerns outlined in this article.

The dealloying corrosion behavior of the FCC Ni20Cr (wt%) in molten LiF-NaF-KF (FLiNaK) salts at 600 °C under varying applied potentials was investigated. Using in-operando electrochemical techniques and a multi-modal suite of characterization methods, we connect electrochemical potential, thermodynamic stability, and electro-dissolution kinetics to the corrosion morphologies. Notably, under certain potential regimes, a micron-scale bicontinuous structure, characterized by a network of interconnected pores and ligaments riched with the composition of the more noble (MN) element, becomes prominent. At other potentials both MN and less noble (LN) elements dealloy but at different rates. The dealloying process consists of lattice and grain boundary diffusion of Cr to the metal/salt interface, interphase Cr oxidation, accompanied by surface diffusion of Ni to form interconnected ligaments. At higher potentials, the bicontinuous porous structure undergoes further surface coarsening. Concurrently, Cr(II), Cr(III), and Ni(II) begin to dissolve, with the dissolution of Ni occurring at a significantly slower rate. When solid-state transport of Cr is exceeded by the interfacial rates, dealloying depths are limited.

A comprehensive 3D imaging analysis was conducted to investigate the corrosion process in reinforced concrete (RC) samples at various stages of the accelerated galvanostatic corrosion process. A state-of-the-art X-ray computed tomography (CT) scan technology was utilized to collect high-resolution 3D images of the specimen. The CT imaging was complemented and validated using a multi-faceted approach utilizing Scanning electron microscopy (SEM) and Raman spectrometry techniques. The distribution and evolution of voids, corrosion products, and cracks were investigated. A localized corrosion was observed that has some similarity to pitted corrosion but not as wide spread along the bar. The micro-scale imaging investigations revealed a gradual increase in the diameter of voids as the time of corrosion increased, especially after 8 days of accelerated corrosion process at which a significant decrease in small-sized voids (≤0.11 mm) accompanied by an increase in other void sizes was observed. At 10 and 12 days of accelerated corrosion process, the volume of larger-sized voids (≥0.35 mm) continued to increase, indicating a rapid corrosion progress and the formation of corrosion-induced cracks. In addition, a thorough X-ray CT analysis allowed us to differentiate between various categories of corrosion products. Notably, iron oxides and iron hydroxides were found to dominate the corrosion products. Understanding the composition and distribution of these corrosion products is essential as they play a significant role in the degradation and deterioration of the concrete structure. The coexistence of iron oxides and iron hydroxides in the region of corrosion products were confirmed using Raman spectroscopy analysis. The CT scan images captured the evolution of cracks at different time intervals, revealing a strong correlation between the initiation of cracks and the presence of corrosion products. Subsequently, during the cracking in the matrix, while the propagation of corrosion products within the matrix contributed to the expansion of cracks. SEM images and elemental analysis confirmed that these cracks were filled with corrosion products. [ABSTRACT FROM AUTHOR]

Epoxy-nanomaterials offer a promising solution to combat corrosion threatening civil infrastructure. To examine the impact of nano silica on corrosion resistance, varying amounts of nano silica, ranging from 0.0 to 3 wt%, were introduced into the epoxy matrix. Mechanical properties were studied through studying the dog-bone tensile strength and tribological aspects were assessed through mass loss abrasion tests. Corrosion resistance performance was studied using electrochemical impedance spectroscopy (EIS) and salt spray tests. Nano structure of the coated specimens was studied after salt spray tests using SEM-EDX analysis. Micro Chromatography (M-Ct) technique was employed to investigate the pore formation in the epoxy matrix. Besides, atomic force microscopy (AFM) was introduced to study surface roughness. The test results displayed a notable improvement (5–10 %) in tensile strength upon the introduction of nano silica. Taber tester results showed a reduction in mass loss with the addition of nano silica. Electrochemical impedance spectroscopy (EIS) studies further established a significant increase in corrosion resistance, having an impedance of 12 GOhm.cm2 for epoxy matrix samples containing 2.5 % nano silica after a 768-h salt spray test. SEM-EDX analysis revealed the absence of iron content in the epoxy matrix reinforced with uniformly distributed nano silica. Surface roughness assessments illustrated that nanolaminates contributed to an increase in overall roughness, minimizing surface irregularities in the epoxy matrix. Micro-CT scanning results proposed a decrease in epoxy matrix porosity upon the addition of nano silica. AI based prediction model helped to understand the relationship between surface roughness and corrosion. In summary, the experimental findings suggest valuable insights for future advancements in the development of protective coatings for worldwide civil infrastructures. [ABSTRACT FROM AUTHOR]

Copper (Cu)-based hybrid composites were fabricated by powder metallurgy, incorporating Graphite (Gr) and Carbon nanotube (CNT) reinforcements at various fractions. The composites were formed using a cold pressing technique and subsequently sintered at various temperatures. The structural properties of the hybrid composites were evaluated using Scanning Electron Microscopy (SEM), Energy Dispersion Spectrum (EDX) and X-ray diffraction (XRD). Hardness, compression, wear and corrosion tests were performed to show the effect of the reinforcements. It was shown that the hardness of Gr and CNT reinforcements have significantly improved the properties of pure Cu. The Cu-Gr-2CNT hybrid composite, which was subjected to sintering at a temperature of 850°C, exhibited the highest level of hardness, showing a significant increase of 51.4% in comparison to the pure Cu sample. While the compressive stresses increased in the Cu matrix with the addition of Cu-Gr, it increased to 350 MPa with the addition of 2 wt% CNT. The hardness value exhibited a similar increase and was measured to be 122 HV in Cu-Gr-2CNT. During the wear tests, the coefficient of friction values fell by 9.2% for Cu-2CNT, by 3.88% for Cu-CNT, by 3.92% for Cu-Gr-2CNT, and by 5.27% for Cu-Gr-CNT, as compared to pure Cu. The comprehensive findings demonstrated that the tests and analyses yielded consistent results, and the utilization of various combinations of Gr and CNT reinforcements enhanced the mechanical, tribological, and corrosion resistance properties of the fabricated hybrid composites. Nevertheless, the combination of Cu-Gr-2CNT yielded the most advantageous outcomes. [ABSTRACT FROM AUTHOR]

Biomedical coatings were elaborated by pulsed electrodeposition with hydrogen peroxide (H 2 O 2) into electrolytes on Ti 6 Al 4 V substrates, and the effect of H 2 O 2 concentration on the electrolyte and the heat treatment was studied. The experimental procedures employed in this study produce a consistent hydroxyapatite coating. This coating is well-suited for use in bio-implants, as it enhances the integration of the implant with surrounding bone tissue and improves the mechanical performance. The coatings' surface morphology and chemical composition were assessed using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDXS) for x-ray microanalysis. X-ray diffraction (XRD) was also utilized to identify the phases and composition of the coatings. Nanoindentation and scratch tests were conducted to analyze the nanomechanical properties and adhesion behavior. Potentiodynamic polarization was employed in the Ringer solution to evaluate the corrosion resistance and replicate the conditions of the human body environment. The results of our thorough investigation revealed that employing pulsed electrodeposition with 9 % H 2 O 2 in the electrolyte, combined with subsequent heat treatment, facilitated the creation of coatings comprising two distinct phases: stoichiometric hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP). Our meticulous research underscores the significance of this process in achieving these specific coating compositions. Under these tests listed above, this composite demonstrated favorable mechanical properties (E = 30.45 GPa and H = 72.2 MPa). It also exhibited superior scratch adhesion and a critical load of 23 MPa and 12 N, respectively. Additionally, an improvement in tribological comportment was observed, and the wear volume decreased from 4.15 106 μm3 to 2.44 106 μm3. The HAP coating heat treated with 9 % H 2 O 2 exhibited the highest corrosion resistance, with E corr at −0.189 V/SCE and i corr at −1.11 μA cm−2 [ABSTRACT FROM AUTHOR]

Illustration of discharging processes of Si@ZIF-8 anode in KOH electrolyte. [Display omitted] • Si@ZIF-8 anodes universally exhibit longer discharge times than bare Si anodes. • Si NWs@ZIF-8 exhibited the highest average discharge voltage of 1.16 V. • The contact mode of the Si anode with water and OH– can be controlled by adjusting ZIF-8 structure. Si-air batteries have a high energy density, high theoretical voltage, and long lifetime, but they present a low anode utilization rate in a potassium hydroxide electrolyte. In this work, a ZIF-8 protective layer was prepared and modulated by a secondary growth method and then applied to protect the Si flat and Si nanowire (NW) anodes of a Si-air battery. By adjusting the conversion ratio, particle size, and crystallinity of ZIF-8 on the Si surface, the contact mode of the Si anode with water and OH– was controlled, thus achieving long-term corrosion and passivation resistance. Si NWs@ZIF-8 exhibited the highest average discharge voltage of 1.16 V, and the Si flat@ZIF-8 anode achieved the longest discharge time of 420 h. This work confirms that ZIF-8 acts as an anode protective layer to improve the properties of Si-air batteries and also provides valuable insights into the protection of Si anodes by MOFs. [ABSTRACT FROM AUTHOR]

NiFe‐based hydroxides are well‐established as efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline purified water. However, they usually degrade rapidly in seawater electrolysis because of concentrated Cl− anions in seawater. In this work, a facile approach utilizing an ultrafast dipping method is presented to fabricate durable and scalable NiFe hydroxides, enhanced by interfacial akaganéite FeOOH for seawater splitting. This study reveals significantly improved electrocatalytic stability of NiFe hydroxides at an ampere‐level current density of 1000 mA cm−2 for 100 h in alkaline seawater. It is realized by the formed FeOOH in a specific akaganéite phase whose lattice tunnels are well filled by intrinsic Cl− anions, that serve to electrostatically repel corrosive chlorides in electrolyte. This anionic design also provides superior corrosion protection for other active metal‐based OER electrocatalysts when deployed in alkaline purified water and allows for facile scaling up of the anode, facilitating the practical utilization for seawater electrolysis. [ABSTRACT FROM AUTHOR]

ABSTRACT Nickel‐aluminum bronze (NAB) is extensively utilized across various industries, particularly marine applications due to its exceptional corrosion resistance. The mechanical properties of NAB are highly dynamic, and influenced by factors such as manufacturing processes, operating environments, and microstructure. This variability introduces complexities and challenges in addressing fatigue, the most common failure mode in metals. This review offers a thorough examination of the fatigue properties of NAB in both their conventionally fabricated and additively manufactured (AM) forms. This review explains the mechanisms that modulate fatigue in NAB by analyzing the existing literature and identifying critical factors such as microstructure, defects, and processing parameters. The goal is to improve the comprehension and dependability of NAB by contrasting the fatigue resistance of cast and AM NAB. The ultimate objective of this comprehensive examination is to predict and reduce component failures, thereby extending the service life and performance of NAB components in demanding environments. [ABSTRACT FROM AUTHOR]

The corrosion behavior of WC-4.3 wt%MgO-2wt.%ZrO 2 composite in alkaline solution with 5 % oil-based cutting fluid as medium was studied by electrochemical and microstructure analysis methods. The results showed that WM2Z composite has better corrosion resistance than YG3 and YG6 in alkaline environment. A stable passivation film was formed inside the WC phase after dissolution on the surface, which was the key reason for its high corrosion resistance. However, large areas of WC phase fell off in cemented carbide. In the process of corrosion-friction coupling experiment, due to the more excellent corrosion resistance and mechanical properties of WM2Z composites, the corrosion resistance and friction properties of WM2Z composites are better than that of YG3 cemented carbide. The corrosion-friction coupling effect on WM2Z was low, and the degree of damage to the topography after the experiment was relatively light. [ABSTRACT FROM AUTHOR]

Oxygen electrocatalysts play a key role in renewable and fossil‐free energy production. Bifunctional catalysts active for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) allow use of the same material system for both energy production (ORR) and fuel generation (OER). However, optimizing the performance of bifunctional catalysts requires in depth understanding of the catalyst structure, its surface chemistry in terms of active sites and the underlying catalytic mechanism. Here, the catalytic performance of CoCrFeNi thin films is investigated, synthesized using high‐power impulse magnetron sputtering, as bifunctional oxygen electrocatalysts. The film crystal structure and morphology, and thereby the catalytic performance, can be tuned by the ion acceleration (bias) to the substrate. To further enhance the catalytic activity, anodization is used to electrochemically modify the films, forming a thicker oxide layer enriched in Co and Ni cations which significantly improves the ORR performance. Anodization improves the catalyst stability during OER, with an OER potential of 1.45 V versus the reversible hydrogen electrode (RHE) at 10 mA cm−2 for more than 24 h. While the corrosion resistance is high both before and after anodization, in terms of catalytic activity the anodized films outperformed the as‐deposited ones. This makes anodized films excellent electrocatalyst candidates in corrosive alkaline environments such as fuel cells and electrolyzers. [ABSTRACT FROM AUTHOR]

This study aims to examine the variation in corrosion characteristics and tensile properties of WE43 magnesium alloy in an actual marine atmospheric environment by means of outdoor exposure tests. The macroscopic corrosion morphology, microstructure, and tensile properties were analyzed. The results indicated that WE43 alloy will corrode rapidly during exposure under marine atmospheric environmental conditions, resulting in a loose and porous Mg(OH)2 layer on the surface. The Mg matrix was mainly consumed as an anode, leading to the occurrence of corrosion pits. With the increase in exposure time, both the tensile strength and plasticity of WE43 alloy gradually deteriorated. After exposure for six months, the elongation and area reduction were significantly reduced, with a reduction ratio of more than 50%. After 18 months of exposure, the ultimate strength of the alloy decreased from 359 MPa to 300 MPa. According to an analysis of fractures in the alloy, the corrosion pits on the sample surface were the main reason for the decrease in tensile properties. [ABSTRACT FROM AUTHOR]

The corrosion behavior of the TiTaNbZrAg alloys with different amounts of tantalum (0%, 10% and 20%) and with distinct surface topography (smooth and rough) was investigated in phosphate buffer solution (PBS) for long-time immersion (1000 h). By this approach, we expect to bring about new insights into the influence of both the amount of Ta in the alloy composition and the surface topography on the corrosion behavior of the Ti-based alloys. The corrosion resistance was studied by Open Circuit Potential (OCP), Potentiodynamic Polarization (PP), and Electrochemical Impedance Spectroscopy (EIS). From the potentiodynamic investigations, it was observed that all types of samples showed good corrosion resistance (i.e., Rcorr < 10 µm y−1) and may be used successfully for medical applications. However, the samples with smooth surfaces and with a certain amount of Ta (10% and 20%) exhibit the best corrosion performance (Rcorr < 1 µm y−1). As regards the samples with rough surfaces, the results evidenced that they showed lower corrosion resistance (1 < Rcorr < 3 µm y−1), suggesting that the Ta presence does not necessarily hinder the corrosion processes. Actually, the synergetic effect of both the presence of Ta and surface roughness plays an important role in corrosion resistance. [ABSTRACT FROM AUTHOR]

Heavy crude oil processing presents significant challenges owing to its complex composition and requirement for processing conditions, which increase the process safety risk in crude processing units, such as fixed equipment, for instance pressure vessels and pipes. The aim of this work is to evaluate the influence of heavy crude oils named A and B and the effect of sulfur-rich compounds and organic acids on the performance at high temperatures of three metallic alloys (5Cr-1/2Mo/ASTM A335GP5, X6CrNiMoTi17122/AISI-SAE 316Ti and Ni66.5Cu31.5/Monel 400) and propose an alternative to be used in pressure vessels and piping in refineries. This work was based on the need to understand the corrosivity of two heavy crude oils (A and B) from eastern Colombia in three materials, evaluated at three temperatures (200 °C, 250 °C and 300 °C) under the same conditions of pressure (200 psi) and rotation velocity (600 rpm) in a dynamic autoclave to simulate atmospheric conditions and conditions in vacuum refinery towers. An understanding of how these factors interact with the fundamental principles of corrosion kinetics is essential for developing an effective corrosion mitigation strategy. The results were interesting for applications requiring high corrosion resistance. X6CrNiMoTi17122/AISI-SAE 316Ti is a solid candidate for this application, with corrosion rates of 0.2 to 0.87 mpy. Ni66.5Cu31.5/Monel 400 exhibited significant corrosion rates up to 74.89 mpy, especially at higher temperatures (300 °C). 5Cr-1/2Mo/ASTM A335GP5 showed a generally moderate corrosion rate (2.04–5.57 mpy) in the evaluated temperature range. [ABSTRACT FROM AUTHOR]

Legislative framework addresses the issues of alloy corrosion, demanding the restricted use of probable carcinogenic, mutagenic, and toxic-for-human-reproduction (CMG) metals like nickel, cobalt, and chromium and demanding the development of new biomaterials. The aim of this research was to evaluate and compare the ion release of standard dental alloys and their hypoallergenic equivalents. Six types of orthodontic alloy wires (nickel–titanium (NiTi), coated NiTi, stainless steel (SS), Ni-free SS, and cobalt–chromium (CoCr) and titanium–molybdenum (TMA) were immersed into artificial saliva of pH 5.5 and 6.6. Release of metal ions was measured by inductively coupled plasma–mass spectrometry after 3, 7, 14 and 28 days. The data were analyzed using analysis of variance, and results with p < 0.05 were considered significant. NiTi released more Ti and Ni ions compared to the coated NiTi; SS released more iron, chromium, and nickel compared to the nickel-free SS. CoCr released cobalt in a high concentration and low amounts of chromium, nickel, and molybdenum compared to the molybdenum and titanium released by TMA. Release of metals from dental orthodontic alloys in vitro was overall lower at pH 6.6 and for the hypoallergenic equivalents when compared to standard dental alloys. [ABSTRACT FROM AUTHOR]

The microstructure evolution of Al0.3FeCoNiCrx (x = 0, 0.3, 0.5, 1, 1.5) high-entropy alloys (HEAs) were studied using X-Ray diffraction technique and scanning electron microscope equipped with energy dispersive spectrometer. The short-term and long-term corrosion behaviours of these alloys in 3.5 wt.% NaCl solution were studied by electrochemical impedance spectroscopy, potentiodynamic polarisation measurement, immersion test and corrosion morphology analysis. The results show that all the designed HEAs present single-phase FCC structure, and the increase in Cr content changes the microstructural morphology from cellular to a typical dendritic–interdendritic state. Without the influence of phase transformation, the corrosion resistance of Al0.3FeCoNiCrx HEAs gradually increases with the increase in Cr content. Our designed alloys exhibit excellent corrosion resistance compared to the existing HEAs in the AlFeCoNiCr composition system. [ABSTRACT FROM AUTHOR]

This study investigates the effects of natural inhibitors (pomegranate, algae, and tomato extracts) on the corrosion resistance of titanium (grade 2). To deepen understanding the inhibition mechanism, Molecular Dynamic (MD) and Monte Carlo (MC) simulations were employed to analyze adsorption behaviors and identify optimal adsorption sites on titanium oxide (TiO2) surfaces for compounds within the inhibitors. Results indicate non-flat adsorption orientations, with pomegranate peel extract components showing superior inhibition capabilities, attributed to the formation of strong O-H chemical bonds with the TiO2 surface. In the experimental part of the study Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) were conducted. Two electrolytes were tested: a solution 3.5% NaCl and a solution 0.5 M NaOH. All the tests were performed with 5% of inhibitor and with the reference solution. Also, inhibition efficiency was calculated on the base of PDP tests. The study found that pomegranate extract can act as a good corrosion inhibitor for titanium alloy in aqueous solutions 0.5 M NaOH. This was demonstrated by the increase in the corrosion potential and impedance modulus and decrease in the corrosion current density after the addition of pomegranate extract to the solution. However, in a 3.5% NaCl solution, the efficacy of pomegranate extract was less pronounced, probably due to the high aggressivity of the electrolyte. Tomato and algae extract have instead shown very low inhibition effects in all the tested conditions. [ABSTRACT FROM AUTHOR]

With the development of electronic packaging technology toward miniaturization, integration, and high reliability, the diameter and pitch of solder joints continue to shrink. Adjacent solder joints are highly susceptible to electrochemical migration (ECM) due to the synergistic effects of high-density electric fields, water vapor, and contaminants. Dust has become one of the non-negligible causal factors in ECM studies due to air pollution. In this study, 0.2 mM/L NaCl and Na2SO4 solutions were used to simulate soluble salt in dust, and the failure mechanism of an Sn-58Bi solder ECM in the soluble salt in dust was analyzed by a water-droplet experimental method. It was shown that the mean failure time of the ECM of an Sn-58Bi solder in an NaCl solution (53 s) was longer than that in an Na2SO4 solution (32 s) due to the difference in the anodic dissolution characteristics in the two soluble salt solutions. XPS analysis revealed that the dendrites produced by the ECM process were mainly composed of Sn, SnO, and SnO2, and there were precipitation products—Sn(OH)2 and Na2SO4—attached to the dendrites. The corrosion potential in the NaCl solution (−0.351 V) was higher than that in the Na2SO4 solution (−0.360 V), as shown by a polarization test, indicating that the Sn-58Bi solder had better corrosion resistance in the NaCl solution. Therefore, an Sn-58Bi solder has better resistance to electrochemical migration in an NaCl solution compared to an Na2SO4 solution. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) has attracted considerable attention as a biodegradable material for medical implants owing to its excellent biocompatibility, mitigating long-term toxicity and stress shielding. Nevertheless, challenges arise from its rapid degradation and low corrosion resistance under physiological conditions. To overcome these challenges, titanium (biocompatibility and corrosion resistance) has been integrated into Mg. The incorporation of titanium significantly improves mechanical and corrosion resistance properties, thereby enhancing performance in biological settings. Mg–Ti alloys are produced through mechanical alloying and spark plasma sintering (SPS). The SPS technique transforms powder mixtures into bulk materials while preserving structural integrity, resulting in enhanced corrosion resistance, particularly Mg80-Ti20 alloy in simulated body fluids. Moreover, Mg–Ti alloy revealed no more toxicity when assessed on pre-osteoblastic cells. Furthermore, the ability of Mg–Ti-based alloy to create composites with polymers such as PLGA (polylactic-co-glycolic acid) widen their biomedical applications by regulating degradation and ensuring pH stability. These alloys promote temporary orthopaedic implants, offering initial load-bearing capacity during the healing process of fractures without requiring a second surgery for removal. To address scalability constraints, further research is necessary to investigate additional consolidation methods beyond SPS. It is essential to evaluate the relationship between corrosion and mechanical loading to confirm their adequacy in physiological environments. This review article highlights the importance of mechanical characterization and corrosion evaluation of Mg–Ti alloys, reinforcing their applicability in fracture fixation and various biomedical implants. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

The corrosion behavior and electrochemical damage mechanisms induced by sulfate‐reducing bacteria (SRB) on copper (Cu) were investigated in this study. Electrochemical impedance spectroscopy revealed that SRB accelerated the corrosion of Cu, albeit with a mitigating effect observed due to the formation of a protective and dense biofilm. However, upon the rupture of this protective film, the corrosion tendency of Cu significantly increased. Surface analysis corroborated these findings, with the predominant corrosion product identified as Cu2S, a result further supported by thermodynamic calculations. The accelerated corrosion of Cu was primarily attributed to the physiological metabolism of SRB, which generates hydrogen sulfide as the principal agent driving corrosion processes. [ABSTRACT FROM AUTHOR]

The alloying contents with the same Zn/Ca atomic ratio of 0.13 on the corrosion behavior of Mg‐Zn‐Ca (ZX) alloys were investigated. The second phases in ZX10, ZX20, ZX30, and ZX51 alloys were identical with a majority of Mg2Ca and very few Ca2Mg6Zn3 and their distribution changed from isolated to continuous state in ZX30 and ZX51. ZX10 had the lowest corrosion rate of 0.55 mm/year after 168 h immersion in simulated body fluid solution due to the smallest number of sites of galvanic corrosion. The corrosion rate of ZX30 alloy was the highest (0.72 mm/year), while though ZX51 alloy had the most Mg2Ca, its corrosion rate was reduced to 0.69 mm/year, resulting from the small size and thin Mg2Ca. In situ microstructure observation demonstrated the high fraction Mg2Ca phase and continuous Mg2Ca with bulky size were the main reason for the fast corrosion rate. [ABSTRACT FROM AUTHOR]

In view of the simultaneous demand for surfactants and corrosion inhibitors in oilfield production, new surfactants with both low interfacial tension and corrosion inhibition function were successfully prepared in this work by amidation and carboxymethylation using fatty acids and amines as raw materials. The interfacial tension of the surfactant was investigated using a rotational interfacial tensiometer, and the critical micelle concentration was determined. The corrosion inhibition properties of the dual-functional agents were measured by weight loss experiments, electrochemical tests, and scanning electron microscopy (SEM). The results showed that the prepared surfactants exhibited interfacial tension as low as 10−2 mN m−1. The dual-functional surfactants possessed both low interfacial tension and promising corrosion inhibition effects. Electrochemical tests and SEM analysis showed that an adsorption layer preventing corrosion was formed on the surface of A3 steel. The adsorption of the dual-functional surfactants followed the Langmuir isotherm. The experimental data were also supported by quantum calculations. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to explore how graphene can improve the mechanical and anti-corrosion properties of TiO2-SiO2 sol-gel coating. This sol-gel coating has been prepared on aluminum alloy substrate using graphene as both nano-filler and corrosion inhibitor. Design/methodology/approach: To examine the effect of graphene on mechanical properties of sol-gel coating, the abrasion resistance, adhesion strength and scratch resistance of coating have been evaluated. To reveal the effect of graphene on the anti-corrosion property of coating for aluminum alloy, the electrochemical impedance spectroscopy (EIS) has been conducted in 3.5 Wt.% NaCl medium. Findings: Scanning electron microscopy images indicate that graphene nanoplatelets (GNPs) have been homogeneously dispersed into the sol-gel coating matrices (at the contents from 0.1 to 0.5 Wt.%). Mechanical tests of coatings indicate that the graphene content of 0.5 Wt.% provides highest values of adhesion strength (1.48 MPa), scratch resistance (850 N) and abrasion strength (812 L./mil.) for the sol-gel coating. The EIS data show that the higher content of GNPs improve both R1 (coating) and R2 (coating/Al interface) resistances. In addition to enhancing the coating barrier performance (graphene acts as nanofiller/nano-reinforcer for coating matrix), other mechanism can be at work to account for the role of the graphene inhibitor in improving the anticorrosive performance at the coating/Al interface. Originality/value: Application of graphene-based sol-gel coating for protection of aluminum and its alloy is very promising. [ABSTRACT FROM AUTHOR]

Purpose: As a commonly engine coolant, ethylene glycol can produce corrosive acid byproducts at high temperatures when the car is running, specifically oxalic acid (OA), which can shorten the service life of engine. At the same time, chloride ions can also be introduced during coolant preparation processes. Therefore, this paper aims to investigate the synergistic corrosion behavior of Cl− and OA on ADC12 aluminum alloy. Design/methodology/approach: The electrochemical tests, scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction and X-ray photoelectron spectroscopy) were used. Findings: The results showed that the corrosion rate of the aluminum alloy increased with the increase of OA and Cl− concentrations. After adding Cl−, the surface film of the aluminum alloy was further damaged, Cl− has a synergistic effect with OA and their interaction further accelerated the corrosion of the aluminum alloy. Nevertheless, as the immersion time increased, the corrosion rate of the aluminum alloy gradually diminished due to the formation of aluminum oxalate. Originality/value: The corrosion of ADC12 aluminum alloy was studied in OA, Cl− and their mixed solutions; the synergistic effect of OA and Cl− on the corrosion of ADC12 aluminum alloy was discussed, and aluminum oxalate formed inhibited its corrosion. [ABSTRACT FROM AUTHOR]

With the advancement of modern construction technology, reinforced concrete (RC) has become the most widely used composite construction material. Corrosion of embedded reinforcement bars in RC structures, which is essentially the result of carbonation and chloride attack, is regarded as one of the weaknesses. Hence, many research studies have been conducted to evaluate the effect of corrosion on the service life of RC structures. However, so far no proper equation has been derived to predict the extent of carbonation-induced corrosion. Identifying this research gap, the present study intends to derive an equation for the coefficient of carbonation (K), which is the governing measure of the rate of carbonation. This paper identifies concrete grade, exposed CO2 gas concentration, and exposed Relative Humidity (RH) level as the major parameters affecting the carbonation process. The behaviour of each factor along with K was identified by conducting a modified accelerated carbonation test (ACT). These experimentally derived K values were statistically analysed under the principle of multiple linear regression, to derive an equation for predicting K values for RC structures. Based on the results, this paper proposes two user-friendly mathematical models covering the entire environmental RH range to predict the K values of RC structures. [ABSTRACT FROM AUTHOR]

In this study, Bi alloy AA1100/TiO2/AA5083 composites were produced by accumulative press bonding (APB) for the first time. In the first step, two bars of aluminum alloys 1100 and 5083 with 5 wt.% of uniformly scattered TiO2 particles were stacked together and pressed with a 50% reduction ratio. Then, this process was continued up to six steps. Corrosion properties of composites were studied by potential dynamic polarization and electrochemical impedance spectroscopy measurement in 3.5 wt.% NaCl solution. So, in this investigation and as its novelty, a considerable improvement was revealed in the main electrochemical parameters as a result of enhancing the influence of APB steps and the inert character of the particles. Moreover, using the wear test, the wear resistance of these bi alloy composites has been studied vs the APB steps. Also, the wear and electrochemical experiments showed that corrosion and wear resistance of samples were improved by the APB steps by 70% and 34%, respectively. [ABSTRACT FROM AUTHOR]

Passivity breakdown mechanism of high-strength 7068 alloy is studied. Breakdown potential varied linearly with log aCl‒, pH, and square root of scan rate in potentiodynamic polarization tests. Mott-Schottky analysis showed that the dominant defect is cation vacancy. Passive layer characteristics like cation vacancy density and defect annihilation rate are determined. Critical cation vacancy density for pitting obtained from point defect model and the theoretical values are somewhat compatible. Chloride concentration of 0.01 M is too dilute to cause severe localized corrosion, whereas beyond 0.5 M, saturation is achieved in terms of breakdown potential and the cation vacancy density. [ABSTRACT FROM AUTHOR]

The corrosion behavior of the TiN monolayer and CrN/TiN multilayer coatings deposited via cathodic arc evaporation physical vapor deposition (CAE‐PVD) on the Ti–6Al–4V substrates were evaluated in Ringer's and Hank's physiological saline electrolytes. XRD (x‐ray diffractometry) and scanning electron microscopy (SEM) analysis were used to characterize the coatings. The corrosion behavior of coatings was assessed by impedance spectroscopy and potentiodynamic polarization techniques. The results showed that the corrosion resistance of coatings was increased in the order of TiN‐Ringer's < TiN‐Hank's < CrN/TiN‐Ringer's < CrN/TiN‐Hank's. Therefore, it can be concluded that the CrN/TiN coating, due to having a large number of interfaces and a smoother surface with fewer macroparticles and pinholes, is more efficient in raising the corrosion resistance properties of titanium than TiN monolayer coating. Moreover, it was observed that Ringer's solution is a more severe environment than Hank's solution. Both coatings, because of the precipitation of a protective corrosion products layer on their surface, showed an enhancement in corrosion resistance with increasing the immersion time from 1 to 14 days in Hank's. The results suggest TiN monolayer and CrN/TiN multilayer coatings as promising candidates for biomedical applications. [ABSTRACT FROM AUTHOR]

This investigation is dedicated to producing hybrid nanocomposites based on AA2024, achieved through the utilization of powder metallurgy methods encompassing mechanical milling and hot pressing. The research focused on studying how changes in B4C content influence the mechanical, wear, and corrosion behavior of AA2024/h-BN/B4C hybrid nanocomposites. The findings revealed that as the B4C content increased, the relative density values decreased, and higher porosity values were observed in the hybrid nanocomposite samples. Among the tested samples, the hybrid nanocomposite with 4 wt% B4C exhibited the most favorable properties. It demonstrated significantly higher hardness and ultimate tensile strength compared to AA2024 matrix alloy, with values of 161 HB and 372 MPa, respectively. In contrast, the matrix alloy showed hardness and ultimate tensile strength values of 105 HB and 237 MPa, respectively. Furthermore, the wear resistance of hybrid nanocomposite with 4 wt% B4C displayed approximately 14 times greater wear resistance under 40 N load compared to the unreinforced AA2024 matrix alloy. The corrosion test results have revealed that the corrosion resistance of the hybrid nanocomposite reinforced with 4wt% B4C is nearly 47% higher compared to the corrosion resistance of the unreinforced AA2024 alloy. This nanocomposite exhibits the highest polarization resistance of 5.21 Ω.cm2. [ABSTRACT FROM AUTHOR]

The effect of ion irradiation on the microstructure, mechanical, and corrosion properties of Cr/ZrO2 coating was investigated. The monoclinic to tetragonal phase transition is observed under heavy ion irradiation, and the tetragonal phase is stabilized by the irradiation‐induced defect clusters. With increasing irradiation fluence, grain growth, and irradiation‐induced hardening effects are observed. After lead‐bismuth eutectic (LBE) corrosion at 650°C for 1000 h, the irradiated coatings can still maintain structural integrity and protect the substrate from lead/bismuth corrosion. However, in contrast to the unirradiated coating, the irradiation‐induced defects provide a channel for the rapid inward diffusion of oxygen atoms from the LBE, leading to the formation of a thicker Cr‐rich oxide layer beneath the ZrO2 coating. This study also provides insight into how irradiation‐induced microstructural changes affect zirconia's properties as a corrosion protection layer. [ABSTRACT FROM AUTHOR]

An experimental study is conducted on ten pre-tensioned concrete (PC) beams with different local corrosion degrees and positions to investigate the effect of corrosion on the transfer length and retraction slip of prestressing strand. A novel model, incorporating the combined effects of Hoyer effect and strand corrosion, is proposed to predict the corrosion-induced retraction slip of prestressing strand in PC beams. The accuracy of the proposed model is validated by experimental results. Results indicate that the transfer length and retraction slip of prestressing strand increase with the increase of corrosion loss, and this effect weakens when the local corrosion position changes from the end of the beam to the mid-span of the beam. The transfer length and retraction slip of prestressing strand increase by 30.6% and 5.18 times, respectively, once the corrosion loss reaches 33.5%. The retraction slip of corroded prestressing strand is positively correlated with the diameter of strand, but negatively correlated with the compressive strength of concrete. The diameter of strand, compared with the compressive strength of concrete, has a more significant effect on the corrosion-induced retraction slip. [ABSTRACT FROM AUTHOR]

Compatibility tests are carried out on Ni-based Hastelloy alloys and stainless steel under the influence of the molten chloride salt NaCl-CaCl2-CeCl3 to investigate the corrosion behavior of molten salts with structural materials. Weight change measurements before and after the reaction tests show that the Hastelloy alloys have better corrosion resistance than stainless steel. The effects of molten salt purification on the corrosion behavior in the Hastelloy alloys are explored. The composition of the reacting phases is identified from transmission electron microscopy analysis and the corrosion mode is homogeneous corrosion with Cr and Fe diffusion, followed by Mo and Ni elution. [ABSTRACT FROM AUTHOR]

This study investigates a Zn–Mg alloy, enhanced for biodegradability and biocompatibility, by introducing trace amounts of Sr and subjecting it to hot‐rolling. The resulting Zn–Mg–Sr alloy shows a reduced average grain size to 3.35 μm and a transformed Mg2Zn11 phase from lamellar to finely dispersed particles, while maintaining a uniform SrZn13 phase distribution. The as‐rolled alloy exhibits significantly improved mechanical properties, with a tensile strength of 340 MPa and 40% of elongation, attributed to grain‐boundary strengthening, reinforcement by second‐phase particles, and the presence of intragranular dislocations and nanoscale precipitates. This microstructural refinement enhances the elongation by hindering crack propagation. Corrosion resistance tests reveal the superior performance of the as‐rolled alloy, owing to the finely distributed eutectic particles, which mitigated localized corrosion and altered the corrosion morphology from localized to finer corrosion pits. In vitro biocompatibility assessments show over 80% cell viability in C3H10 cultures with 50% Zn–Mg–Sr alloy extract, indicating low cytotoxicity. Furthermore, the alloy exhibits promising bone‐promoting properties, highlighting its potential for biomedical applications. [ABSTRACT FROM AUTHOR]

The study investigates the impact of powder metallurgical factors on the corrosion rate (CR) of biodegradable zinc (Zn)-hydroxyapatite (HAP) materials. Factors such as HAP weight percentage (wt%), compaction pressure (CP), heating rate (HR), sintering temperature (ST), and dwell time (DT) were examined. Static immersion test was performed to determine the CR of the samples. The results showed an increase in CR with increased HAP wt%, while factors like CP, HR, and ST led to lower CR. The CR decreased with an increase in DT upto 18 min and thereafter increased. HAP wt% was found to be the most significant factor, contributing 57.95% on CR. A genetic algorithm-based optimization was conducted to minimize CR of Zn-HAP materials. The experimental CR value obtained at optimized levels, i.e., 3 wt% HAP, 34 MPa CP, 25 °C/min HR, 480 °C ST, and 30 min DT, were found to be 0.121 mm/yr, which was within the range of the predicted value 0.08 ± 0.044 mm/yr. This work presents a statistical modeling approach for predicting the CR of Zn-HAP composite for biomedical applications. [ABSTRACT FROM AUTHOR]

This study focused on the synthesis of Ti36-Al16-V16-Fe16-Cr16 high-entropy alloys (HEAs) through spark plasma sintering to ascertain their corrosion resistance performance. Varied sintering temperatures, ranging from 700 to 1100 °C were employed to discern their impact on the alloy's characteristics. The fabricated HEAs underwent characterization using scanning electron microscopy and X-ray diffraction. A potentiodynamic polarization measurement was employed to compare the electrochemical properties of HEAs sintered at different temperatures in sulfuric and chloride aggressive media. The study outcomes indicate that the HEA sintered at 1000 °C exhibited superior corrosion resistance compared to other HEAs at other temperatures. This study contributes valuable insights into the nuanced relationship between sintering temperature, microstructure, and corrosion resistance of Ti36-Al16-V16-Fe16-Cr16 HEAs. [ABSTRACT FROM AUTHOR]

This research aimed to achieve three main objectives: studying the effect of milling time on graphite exfoliation, reducing fabrication heating time to prevent aluminum carbide formation, and investigating the impact of (alumina/graphene)/silver on aluminum properties. Four aluminum nanocomposites were produced using cold and hot pressing at 560 °C for 50 min under 1000 MPa. Raman analysis confirmed graphite exfoliation with alumina to graphene after 40 h of milling. The hot-pressed aluminum-5(alumina/graphene)/10 silver exhibited the smallest crystallite size at 79.926 nm and the highest hardness at 61 HV. It also demonstrated the lowest wear rate under different applied loads (45 and 90 N). The coefficient of friction was measured under 90 N, revealing the lowest mean coefficient of friction of 0.5 for aluminum-5(alumina/graphene)/10 silver, attributed to the presence of graphene and silver as solid lubricants. Aluminum/(alumina/graphene) showed superior corrosion resistance in the absence of silver, reducing the corrosion rate from 0.01 mm/year for pure aluminum to 0.0073 mm/year with the addition of 5 (alumina/graphene). The aluminum-5(alumina/graphene)/10 silver recorded a corrosion rate of 0.0114 mm/year. [ABSTRACT FROM AUTHOR]