Corrosion Resistance Research Articles

Effects of ultrasonic impact treatment on the corrosion resistance of laser-cladded CrMnFeCoNi high-entropy alloy coatings

Ultrasonic impact treatment (UIT) was performed on the surface of the laser-clad CrMnFeCoNi high-entropy alloy coatings. The fluences of the UIT on the microstructure, microhardness, nanoindentation metrics and corrosion resistance of the coatings were explored. Furthermore, the enhancing mechanisms of the corrosion resistance of these coatings by the UIT were clarified. The results showed that the UIT markedly enhanced the corrosion resistance of the laser-clad CrMnFeCoNi high-entropy alloy coatings, and the enhancing effect continuously improved with the increasing of the UIT time. The most significant enhancement of corrosion resistance occurred under the action of UIT with a current of 1.6 A for 20 min. Compared to the untreated group, corrosion potential rose by 65.68 %, corrosion current density fell by 74.95 %, and equivalent resistance increased by 340.37 %. Corrosion morphology analysis showed that the primary forms of corrosion before the UIT were stress corrosion and pitting, which vanished after the UIT with a significant improvement in pitting. Analysis of corrosion products revealed an increased Cr content and a decreased FeOOH and O content on the coating surface after the UIT, leading to enhanced corrosion resistance. Additionally, microstructural analysis showed that large columnar crystals in the laser-clad CrMnFeCoNi high-entropy alloy coatings transformed into finer columns, drastically reducing the grain size of the surface. Concurrently, surface microhardness and nanoindentation mechanical properties markedly improved after the UIT, with the effects growing stronger over time. After the UIT with the current of 1.6 A for 20 min, the increasement of surface microhardness reached 109.01 %. A comprehensive analysis of the fluences on the corrosion resistance of laser-clad CrMnFeCoNi high-entropy alloy coatings by the UIT indicated that the refinement of grain size, improvement of the stress state of the coating, increasement of Cr element and its compounds, and decreasement of FeOOH content are the main reasons of enhanced corrosion resistance.

Exploring heat treatment on the corrosion resistance of SA106B tubes in high temperature pressurized water with different flow velocities

The SA106B carbon steel was widely used for the pipeline in pressurized water reactor and suffered from severe high temperature corrosion. In this work, we expected to improve its corrosion resistance through simple heat treatment. The results showed that the tubes after the treatment normalized at 920 ℃ for 20 min and subsequently cooled in air displayed the best corrosion resistance due to the elimination of banded ferrite/pearlite structure, the reduction in the area ratio of anode/cathode and the decrease in grain size. In addition, the oxidation process and the effect of flow velocity were also discussed in detail.

TRC truss – Proof of concept by experimental investigation

The study develops textile-reinforced concrete (TRC) trusses, reinforced with 3D textiles. It is argued that, by taking advantage of textiles’ ability to conform to complex shapes and their corrosion resistance, TRC truss structures enable a substantial reduction in material and weight through efficient load transfer mechanisms. An experimental investigation explores the design methodology and manufacturing possibilities, as well as the macro-structural response and the cracking and failure mechanisms under flexural loading. Additionally, the study investigates the effects of various reinforcement layouts associated with different anchoring feasibilities and reinforcement ratios on the structural performance.It was found that TRC trusses maintain their structural performance compared to full cross-sectional rectangular TRC beams while achieving significant material savings and weight reduction (about 50 %). It was also found that effective anchoring is a dominant parameter governing structural response. Results from this study highlight the high potential of TRC trusses as a sustainable alternative for structural components.

Structure and Selected Properties of SnO2 Thin Films.

Magnesium and its alloys are attractive temporary implants due to their biocompatibility and biodegradability. Moreover, Mg has good mechanical and osteoinductive properties. But magnesium and Mg alloys have one significant disadvantage: poor corrosion resistance in a physiological environment. Hence, a deposition of various layers on the surface of Mg alloys seems to be a good idea. The purpose of the article is to analyze the structure and morphology of two MgCa2Zn1 and MgCa2Zn1Gd3 alloys coated by SnO2 ALD (atomic layer deposition) films of various thickness. The studies were performed using scanning electron microscopy (SEM), X-ray fluorescence (XRF), and an X-ray diffractometer. The corrosion activity of the thin films and substrate alloys in a chloride-rich Ringer's solution at 37 °C was also observed. The corrosion tests that include electrochemical, immersion measurements, and electrochemical impedance spectroscopy (EIS) were evaluated. The results indicated that SnO2 had a heterogeneous crystal structure. The surfaces of the thin films were rough with visible pores. The corrosion resistance of SnO2 measured in all corrosion tests was higher for the thicker films. The observations of corrosion products after immersion tests indicated that they were lamellar-shaped and mainly contained Mg, O, Ca, and Cl in a lower concentration.

Integrated design of multifunctional lightweight magnetic cellulose-based aerogel with 1D/2D/3D hierarchical network for efficient microwave absorption

Developing electromagnetic wave absorption materials that are both multifunctional and high-performance, while using rational dimensional design and component strategies, remains extremely challenging. Herein, multidimensional, gradient porous, electrically, and magnetically conductive carbon nanocellulose aerogels composed of nanocellulose and highly oriented Ni chains are prepared through freeze-drying and subsequent low-temperature annealing. Interestingly, the Ni/CNCA composite achieves exceptional microwave absorption with a minimum reflection loss (RLmin) value of −62.0 dB and a maximum effective absorption bandwidth (EAB) of 6 GHz, covering the entire Ku-band. The superior electromagnetic wave absorption stems from 1D/2D/3D double-supported interpenetrating network with satisfactory impedance matching, dielectric/magnetic losses, interface/dipole polarization, and multiple/reflection scattering. Furthermore, the Ni/CNCA exhibits a low density, excellent mechanical adaptability, hydrophobicity, and corrosion resistance. This work introduces innovative approaches for developing lightweight, multifunctional microwave absorbers for practical applications.

Structure and Selected Properties of SnO2 Thin Films

Magnesium and its alloys are attractive temporary implants due to their biocompatibility and biodegradability. Moreover, Mg has good mechanical and osteoinductive properties. But magnesium and Mg alloys have one significant disadvantage: poor corrosion resistance in a physiological environment. Hence, a deposition of various layers on the surface of Mg alloys seems to be a good idea. The purpose of the article is to analyze the structure and morphology of two MgCa2Zn1 and MgCa2Zn1Gd3 alloys coated by SnO2 ALD (atomic layer deposition) films of various thickness. The studies were performed using scanning electron microscopy (SEM), X-ray fluorescence (XRF), and an X-ray diffractometer. The corrosion activity of the thin films and substrate alloys in a chloride-rich Ringer’s solution at 37 °C was also observed. The corrosion tests that include electrochemical, immersion measurements, and electrochemical impedance spectroscopy (EIS) were evaluated. The results indicated that SnO2 had a heterogeneous crystal structure. The surfaces of the thin films were rough with visible pores. The corrosion resistance of SnO2 measured in all corrosion tests was higher for the thicker films. The observations of corrosion products after immersion tests indicated that they were lamellar-shaped and mainly contained Mg, O, Ca, and Cl in a lower concentration.

Corrosion study of CA-PVD coated perforation cutter blades of different metallurgies used for liquid shampoo packaging

Perforation cutters must tackle aggressive corrosion and wear while filling sachets/pouches containing shampoo liquids and conditioners. The present work aims to enhance the durability of the perforation cutters through the application of PVD coatings. Further, this study investigates the role of surface energy and wettability to understand the corrosion behavior of different cutter metallurgies (SS420, D2, and HSS M2) and different coatings in shampoo liquids and conditioners. Two PVD coatings, namely Titanium Nitride (TiN) and Chromium Nitride (CrN), were chosen for this work. The most popular FMCG hair shampoo and conditioner combination in South Asia was selected for the study. The coated cutters were exposed to 20% concentration by volume of different shampoo solutions and their corrosion rates were compared with uncoated cutters. The CrN-coated SS420 specimen exhibited the most significant improvement in corrosion resistance with low wettability compared to all other specimens tested in various solutions. In contrast, the uncoated M2 specimen suffered the most severe corrosion with high wettability in various solutions. An inverse correlation was observed between wettability and corrosion resistance for the various specimens. The findings of this study give a better understanding of the corrosion of perforation cutters by shampoo liquids, elucidating the impact on their longevity and providing insights into the potential benefits of PVD coatings for enhancing their durability.

Spatial degradation characteristics and numerical prediction for life of MWCNTs-reinforced concrete by salt freezing

Nanotechnology is of great importance towards the multiscale enhancement of mechanical strength, anti-cracking, corrosion and/or abrasion resistance of concrete. To optimize the durability of concrete structure in a frigid and saline environment, the multi-walled carbon nanotubes (MWCNTs) were introduced along with the evaluation of spatial deterioration characteristics and numerical prediction for its service life in this work. The degree and mechanism of salt freeze-thaw damage relief of MWCNTs-reinforced concrete (CNTC) were investigated by establishing relief rate (Rf, RE and Rp) and damage parameters (Df, DE and Dp) in terms of compressive strength, relative dynamic elastic modulus and porosity. Macroscopic results showed that the presence of MWCNTs substantially delayed the evolution of spatial damage of concrete. The optimum dosage of MWCNTs for the degradation mitigation was also determined to be 0.05 wt% from the microscale scanning electron microscopy, mercury intrusion and mesoscale X-CT scanning techniques, which was responsible to the well-dispersed MWCNTs without entanglement. The synergic effects of filling, nucleation and bridging of MWCNTs in hydrating concrete decreased the porosity and effectively inhibited micro-crack propagation of concrete under the salt freezing effects. Besides, the evolutionary relationships between Df, DE and Dp were established, and a three parameters-dependent prediction index D had been established on the basis of the entropy method and grey system theory GM(1,1) model. The experimental results were in good agreement with the prediction model, and further showed that the salt- freeze-thaw damage of CNTC was significantly reduced.

Self-assembled Ti3C2Tx membrane driven by Marangoni effect for anti-corrosive and anti-wear applications

The recent rise of Ti3C2Tx has extended the applications in epoxy resin due to its large specific surface area and excellent mechanical properties. Whereas, the synergy between epoxy and Ti3C2Tx restricts properties enhancements when Ti3C2Tx is subjected to random orientation and discontinuous distribution. To optimize the barrier and lubrication characteristics of Ti3C2Tx, we have successfully prepared Ti3C2Tx membrane by using the Marangoni effect self-assembled method to move Ti3C2Tx nanosheets to the same latitude and deposit them on epoxy resin for the first time. Meanwhile, micro-arc oxidation technology was adopted to enhance the bonding strength of the substrate with epoxy. Due to the effective corrosion resistance offered by the Ti3C2Tx membrane, even after 28days of immersion, the pure epoxy coating had completely failed, while the |Z|0.01Hz value of the multilayer coating still increased by 36.5 % compared to MAO/EP/EP. Furthermore, the wear rate and the friction coefficient reduced by 58.2 % and 21.4 % in comparison to the pure epoxy coating. This exceptional lubrication property stems from the interlayer shear sliding of the expansive Ti3C2Tx nanosheets, effectively preventing direct contact between the friction ball and the epoxy.

Local valence analysis of 316L austenitic stainless steel produced by laser powder bed fusion

Ultra-rapid cooling of laser powder bed fusion (LPBF) generates a cellular solidification microstructure with submicron-sized periodicity accompanied by non-negligible segregation. In 316L austenitic stainless steel, an important corrosion-resistant alloy, the effect of segregation, particularly variations in Cr concentration, on the corrosion resistance of the LPBF product is unknown. Local valence analysis of the LPBF-produced 316L by electron energy-loss spectroscopy revealed no obvious changes in the energy-loss near-edge structures of Cr and Fe measured within the solidification cellular microstructure, at the cell boundary, or at the melt-pool boundary. This result indicates that solidification segregation in the LPBF-produced 316L is unlikely to affect the corrosion resistance of the material.

Effect of Ti on the corrosion resistance of Al-Cr-Fe-Mn-Mo-Ni single and multi-phase CCAs

Five Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Tix compositionally concentrated alloys were synthesized, forming alloys with an FCC matrix. At Ti concentrations of 5 at% and above, an L21 phase enriched in Al, Ti and Ni was present within the FCC matrix. At Ti concentrations of 9.6 at% Ti and above, a three-phase microstructure containing FCC+L21+Laves phases was formed, with the Laves third phases enriched in Cr and Mo. Ti(IV) was a prominent constituent in the passive film. Resistance to localized corrosion improved with Ti concentration before reaching an optimal concentration and beginning to decrease, likely due to the formation of new phases.

Microstructure, mechanical and electrochemical behavior of magnetron-sputtered carbothermic reduced iron-boride ceramic coatings

In this study, magnetron sputtered carbothermic reduced iron boride (FeB) coatings were developed on grey cast iron (GCI) substrates at different substrate temperatures. The impact of substrate temperature on structural, mechanical, and corrosion behavior was examined for two FeB deposition scenarios: FeB coatings deposited at room temperature (RT) and at 500 °C substrate temperature. The evolution of phases and microstructure was studied using XRD and FESEM, respectively. The mechanical properties, creep, deformation behavior, and adhesion strength (scratch test) of the deposited coatings were investigated using nanoindentation at ambient temperature. The highest hardness and Young’s modulus of 16 GPa and 231 GPa respectively, were achieved at 500 °C due to microstructural enhancement. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to evaluate the corrosion behavior of the coatings. The results show that substrate temperature strongly influences the surface morphology of the coatings, which in turn governs the mechanical and corrosion behavior of the FeB coating. The FeB-coated GCI at 500 °C substrate temperature showed higher resistance to scratching, better mechanical properties, and improved corrosion resistance which is attributed to the enhanced adhesive strength, refined microstructure, and formation of protective oxide layers of FeB on the surface of the coatings.

Adhesion promotion and corrosion resistance of mixed phosphonic acid monolayers on AA 2024

Mixed monolayers were used to prepare surfaces of AA 2024 with precisely controlled corrosion protective and adhesive properties. In this study, the corrosion inhibition and adhesion promotion as a function of the composition of mixed phosphonic acid monolayers on AA 2024 was investigated. Mixed monolayers were formed by competitive adsorption of n-dodecylphosphonic acid (DPA) and 12-aminododecylphosphonic acid (ADPA) from ethanolic solution. Their compositions were determined by X-ray photoelectron spectroscopy. Atomic force microscopy studies and polarization modulation infrared reflection–absorption spectroscopy as well as contact angle studies proved the formation of monolayers with varying surface chemistry. The wet-adhesion strength was tested by 90° peel tests after application of an epoxy-amine adhesive. Linear sweep voltammetry was performed to evaluate the corrosion inhibition of the monolayers, and the corrosion resistance of the metal/adhesive composite was investigated by means of its corrosive delamination behavior. The electrochemical measurements demonstrated that reducing the surface concentration of ADPA improved the corrosion inhibition of the monolayer. However, the corrosive delamination experiments revealed that the improved corrosion inhibition by the self-organized DPA is of minor importance for the corrosion behavior of the metal/adhesive composite, as the adhesive properties dominate.

Ultrafast pressureless sintering of high conductivity Ni-based cermets inert anode for Carbon‐free electrolytic aluminum

Cermet is a promising inert anode material to solve the problem of high carbon emission and bearing C-F harmful gas generation of primary aluminum produced from bauxite using molten electrolysis with carbon anode. However, a major challenge for traditional methods is to ensure that the cermet inert anode simultaneously has good conductivity, corrosion resistance, and strength. Herein, a new ultrafast pressureless sintering (UPS) method is developed to greatly improve the conductivity of metal ceramic inert anode materials while ensuring good corrosion resistance and strength. In a departure from conventional practice that metal phase undergoes local enrichment accompanied by irregular formation of ceramic particles at low heating rates, here UPS achieves rapid diffusion and uniform distribution of metal phase at regular ceramic particle interfaces during liquid phase sintering. The new method is applicable to Ni-based cermet and the production of Ni-based cermet inert anode with excellent conductivity in a few tens of seconds has been demonstrated, which is able to improve the quality of cermet inert anode requiring a low energy input. The conductivity of cermet produced by the applied UPS process is 15-fold higher than that of other pressureless sintering processes with low heating rates. These Ni-cermet inert anodes exhibit high corrosion resistance and density with excellent mechanical properties. This rapid sintering technique facilitates the structural design of inert anodes and develops a pathway of new systems with scalable, efficient, and high-quality sintering of composite materials.

Ultrafast pressureless sintering of high conductivity Ni-based cermets inert anode for Carbon‐free electrolytic aluminum

Cermet is a promising inert anode material to solve the problem of high carbon emission and bearing C-F harmful gas generation of primary aluminum produced from bauxite using molten electrolysis with carbon anode. However, a major challenge for traditional methods is to ensure that the cermet inert anode simultaneously has good conductivity, corrosion resistance, and strength. Herein, a new ultrafast pressureless sintering (UPS) method is developed to greatly improve the conductivity of metal ceramic inert anode materials while ensuring good corrosion resistance and strength. In a departure from conventional practice that metal phase undergoes local enrichment accompanied by irregular formation of ceramic particles at low heating rates, here UPS achieves rapid diffusion and uniform distribution of metal phase at regular ceramic particle interfaces during liquid phase sintering. The new method is applicable to Ni-based cermet and the production of Ni-based cermet inert anode with excellent conductivity in a few tens of seconds has been demonstrated, which is able to improve the quality of cermet inert anode requiring a low energy input. The conductivity of cermet produced by the applied UPS process is 15-fold higher than that of other pressureless sintering processes with low heating rates. These Ni-cermet inert anodes exhibit high corrosion resistance and density with excellent mechanical properties. This rapid sintering technique facilitates the structural design of inert anodes and develops a pathway of new systems with scalable, efficient, and high-quality sintering of composite materials.

Mo2Ti2C3 and PTFE synergistically functionalized corrosion-resistant, thermally conductive, super abrasion-resistant epoxy resin composite coating

Epoxy resin (EP) matrix composites are a widely used polymer-based protective coating material. However, the low lubricity leads to frictional wear problems that make their large-scale development and application a serious challenge. Based on this, a multifunctional composite coating (MPT-EP) with low wear, high lubricity, high thermal conductivity, and corrosion resistance was prepared by introducing polytetrafluoroethylene (PTFE) and lamellar Mo2Ti2C3 as a composite lubricant into epoxy resin matrix using a simple solvent dispersion method. The results showed that the introduction of the composite lubricant resulted in enhanced hardness and mechanical properties of the composite coating. Compared with the single epoxy resin coating (0.31), the friction coefficient (COF) of the composite coating was only 0.22, and the friction surface did not show obvious abrasion marks. The surface temperature of the composite coating was up to 51.4 °C when it was placed on a hot bench at 60 °C for 60 s. In addition, the COF of the composite coating did not change significantly after being immersed in acid, alkali and salt solutions. Therefore, the Mo2Ti2C3-induced multifunctional epoxy resin matrix composites have important application potential and research value in the field of ultra-wear-resistant and high lubrication protective coatings.

Research on improving the efficiency of electricity transmission

A study of ways to modernize the current-carrying part of overhead lines to improve the efficiency of electricity transmission through the use of innovative types of wires was conducted. The technical and economic characteristics of AC, ACCR, and AERO-Z wires were analyzed. The results of the analysis revealed that further improvement of the design of AC wires should be based on new progressive developments that would meet such technical requirements as reliability, survivability and durability; corrosion resistance; high adhesion ability; resistance to vibration during operation under the influence of adverse climatic factors; resistance to environmental temperature effects. As an innovative solution to this issue, high-temperature (ACCR) and specially designed (AERO-Z) wires have been developed in foreign countries. A comparative analysis of the types of wires used in Ukrainian power grids with innovative types of wires used in power grids of foreign countries was performed. The results of the comparison of AC, ACCR, and AERO-Z wires show that the factor that limits the scope of application of ACCR wire, even for spans with extremely high requirements for power transmission characteristics, is its extremely high cost. This is because the technical characteristics of this wire are better than those of AC wire and it has a relatively low cost compared to ACCR wire, and its special design is adapted to adverse climatic conditions that affect the characteristics of electricity transmission.

Effects of TiC and Ni reinforcements on the microstructure, corrosion resistance and wear behaviour of AA6061 matrix composite

Effects of TiC and Ni reinforcements on the microstructure, corrosion resistance and wear behaviour of AA6061 matrix composite

Effect of NOX and SOX Contaminants on Corrosion Behaviors of 304L and 316L Stainless Steels in Monoethanolamine Aqueous Amine Solutions

This work is devoted to evaluating the corrosion behaviors of SS 304L and SS 316L in monoethanolamine solutions (MEA) containing SOX and NOX pollutants, examining both lean and CO2-loaded conditions at 25 °C and 40 °C. Electrochemical techniques (potentiodynamic and cyclic polarization) were used along with Scanning Electron Microscopy, Confocal Microscopy and weight loss measurements. The results reveal that the introduction of SOX and NOX pollutants increased the corrosion rate, whereas CO2 loading primarily reduced the corrosion resistance in the lean MEA solution, while its impact on solutions with SOX and NOX was less pronounced. This suggests that SOX and NOX play primary roles in the metal’s dissolution. Also, SS 316L demonstrated superior corrosion resistance compared to 304L in nearly all of the cases examined. Elevated temperatures were also found to intensify the corrosion rate, indicating a correlation between the corrosion rate and temperature. A microscopic observation and EDX analysis revealed that corrosion products are characterized by high concentrations of iron (Fe) and oxygen (O) as well as carbon (C). There is also an indication of the possible formation of amine complexes, suggesting a potential for amine degradation. No pitting corrosion was observed in SS 304L and SS 316L across any tested solution. Finally, the immersion results expose a tendency for passivity in all amine solutions and at both temperatures after several days of exposure. Moreover, they confirm the very low corrosion rate calculated from potentiodynamic curves due to minimal weight loss after 24 days of immersion.

Carbon dot enhanced electrodeposited coatings for advanced early-stage corrosion sensing

This work explores a novel approach for metal corrosion by integrating carbon dots (CDs) into electrodeposited (ED) coatings. We detail the synthesis and properties of CDs, making them suitable for corrosion detection. Characterization techniques like Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscope (SEM), Energy Dispersive X-ray Analysis (EDX), Fluorescent Microscopy and Photoluminescence Spectroscopy (PL).A Design of Experiment (DOE) optimized parameters like CD concentration, curing temperature, and voltage for improved coating performance. The optimized conditions (0.4 wt% M-CDots, 165 °C curing, and 36.2 V) resulted in enhanced adhesion and corrosion resistance.CD-infused coatings demonstrated superior adhesion and mechanical stability compared to controls. Electrochemical tests confirmed a 10 % improvement in corrosion resistance and PL study demonstrated an approximately 60 % enhancement in emission intensity. The adhesion was not affected by introducing carbon dots to the coating. Monitoring the onset of metal corrosion on samples in salt spray cabinets was achieved through the use of a UV source. The photoluminescence of M-CDs offered real-time, non-destructive monitoring of early-stage corrosion through quenching in the presence of exposed metal surfaces.This research presents a significant advancement by integrating CD-based sensing into corrosion-resistant coatings, holding promise for various industries and leading to improved safety, reduced maintenance costs, and extended equipment lifespans. Notably, the biocompatible and disposable nature of CD-based sensors further enhances their practical application.