Corrosive Solution Research Articles

Elastic wave properties in ultra-high strength steel (HV670) exposed to various corrosive solutions

Elastic wave properties in ultra-high strength steel (HV670) exposed to various corrosive solutions

A novel dual-functional layer exhibiting exceptional protection and photocatalytic activity by organic functionalization of plasma electrolyzed layer

The formation of inorganic-organic hybrids (IOH) on the metallic substrates would play a decisive role in improving their structural and functional features. In this work, the growth of organic coating (OC) consisting of coumarin-3-carboxylic acid (3-CCA) and albumin (ALB) on the inorganic layer (IC), produced by plasma electrolysis of AZ31 Mg alloy, led to enabling organically synergistic reactions on the porous inorganic surface, forming a flake-like structure sealing the structural defects of IC. Synergistic actions between OC and IC endow the flake-like structures with chemical protection and photocatalytic performance. Upon contact with a corrosive solution, the IOH layer possesses stable morphologies that delay the corrosive degradation of the whole structure. The electrochemical stability of the sample produced by immersion IC in the organic solution for 10 h (IOH2 sample) was superior to the other samples as it had the lowest corrosion current density (1.69×10−10 A.cm−2) and the highest top layer resistance (1.2 × 107 Ω.cm2). Moreover, the IOH layer can photodegrade the organic pollutants in model wastewater, where the highest photocatalytic efficiency of 99.47% was found in the IOH2 sample. Furthermore, computational calculations were performed to assess the relative activity of different parts of the ALB and 3-CCA structures, which provide helpful information into the formation mechanism of the IOH materials.

Corrosion Inhibition of Mild Steel In (1 M Hcl) Solution Using Plant Extract and The Synergistic Effect of Iodide Ions

The corrosion inhibitive impacts of a mixture (4:1) of Citrus Limon leaf (CLL) extract and potassium iodide additives when the mild steel was exposed to the corrosive solution (1M HCl) were evaluated using the weight-loss method at temperatures of )303, 313, 323, and 333( K. It was noted that the mixture acts as an inhibitor of mild steel corrosion at concentrations of )1.25, 2.5, 3.75, 5, and 6.25( ml/L. It was observed also that the inhibition efficiency (%I) of the mixture increased with an increase in temperature in the presence of the synergistic effect of the iodide ion. It was found that at the highest mixture concentrations and temperatures, the inhibition competence increased to 95.20%. Inhibitor adsorption characteristics were reached by the Langmuir isotherm and were compatible. The adsorption thermodynamic parameters that were calculated supported the mixed-adsorption of the mixture on a mild steel surface. A surface analysis technique (SEM) used to confirm the occurrence of an adsorption process on the surface.

Deterioration of alkali-activated and Portland cement-based mortars under sulfur oxidizing bacteria corrosion

This study investigated the deterioration behavior of the metakaolin based alkali-activated mortar (MK-M), flay-ash-based alkali-activated mortar (FA-M) and granulated blast furnace slag powder-based alkali-activated mortar (SG-M) under simulated microbial induced acid corrosion (MIAC). For comparison, the MIAC induced corrosion of the Ordinary Portland cement-based mortar (OPC) was also studied. The pH variation of the corrosive solution (sulfur oxidizing bacteria liquid medium), visually observation, and mass loss were monitored to estimate the deterioration. X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA) were used to analyze the composition and morphology of different samples. The results revealed that the three alkali-activated cement-based mortars displayed a higher alkalinity compared to the Portland cement-based mortar. MK-M and SG-M exhibited better resistance to MIAC with a smooth surface and without the formation of typical corrosives owing to the stable structure of N-A-(S)–H and the lower content of calcium ion. However, SG-M suffered severe corrosion, which was similar to OPC-M, with the formation of abundant gypsum and ettringite and visually changed morphology for its high content of calcium ion and degenerated structure.

Anion Exchange Membrane Water Electrolysis: The Future of Green Hydrogen

Hydrogen-derived power is one of the most promising components of a fossil fuel-independent future when deployed with green and renewable primary energy sources. Energy from the sun, wind, waves/tidal, and other emissions-free sources can power water electrolyzers (WEs), devices that can produce green hydrogen without carbon emissions. According to recent International Renewable Energy Agency reports, most WEs employed in the industry are currently alkaline water electrolyzers and proton-exchange membrane water electrolyzers (PEMWEs), with ∼200 and ∼70 years of commercialization history, respectively. The former suffers from inherently limited current densities due to inevitable gas crossover, operates using corrosive (7 M) alkaline solutions, and requires large installation footprints, while the latter requires expensive and scarce precious metal-based electrocatalysts. An emerging technology, the anion-exchange membrane water electrolyzer (AEMWE), seeks to combine the benefits of both into one device while overcoming the limitations of each. AEMWEs afford higher operating current densities and pressures, similar Faradaic efficiencies when compared to PEMWEs (>90%), rapid ramping/load-following responsiveness, and the use of non-noble metal catalysts and pure water feed. While recent reports show promising device performance, close to 3 A/cm2 for AEMWEs with 1 M KOH or pure water feed, a deeper understanding of the mechanisms that govern device performance and stability is required for the technology to compete and flourish. Herein, we briefly discuss the fundamentals of AEMWEs in terms of device components, catalysts, membranes, and long-term stability/durability. We provide our perspective on where the field is going and offer our opinion on how specific performance and stability tests should be performed to facilitate the development of the field.

Facile fabrication of Mxene coated metal mesh-based material for oil /water emulsion separation

The present study was set out to synthesize Mxene (Ti3C2Tx) and functionalized Mxene nanoparticles and fabricating Mxene coated stainless steel meshes using the dip-coating methodology to investigate the capability of Mxene nanoparticles in oil-water emulsion separation. O/W mixtures separation with extraordinary 100% of effectiveness and purity using designed grid was observed. Most specifically, Mxene fabricated mesh showed good resistance to corrosive solutions of HCl and NaOH and was used to separate O/W at harsh medium condition with a separation efficiency of more than after 96.0% replicated experiment, and its super-hydrophilicity persisted in spite of the air exposure condition, extreme fluids immersion, or abrasion. The XRD, FTIR, SEM, FESEM, AFM and DLS tests have been performed to characterize the Mxene coating and its effectiveness on the O/W separation. These analyzes confirm the fabricated tough super-hydrophilic stainless-steel mesh explored in this research can basically be utilized as a highly effective useful mesh for O/W fluid separation under different sever circumstances. The XRD pattern of the resulting powder shows a single phase formation of Mxene, the SEM and FESEM images confirms creation of coated mesh with approximately 30 µ pore size, AFM tests verify that structures (both in nm and µm sizes) formation with high RMS (Root Mean Square) roughness values of 0.18 µm and 0.22 µm for Mxene and carboxylic-Mxene coated mesh. The DLS tests prove the droplets size distribution of emulsion has been augmented after several O/W separation, which confirmed the coagulating mechanism of oil droplets once contacting with the Mxene and carboxylic Mxene coatings of the mesh.

Microstructure of cementitious materials under the coupling effects of Cl− and Mg2+ in a marine tidal environment

To reveal the deterioration mechanism of cementitious materials serving in the marine tidal environment, this study investigates the microstructures of cementitious materials under the coupling effects of Cl− and Mg2+. This study mainly analyzes the phase composition, pore structure distribution, and micromorphology of the hardened cementitious materials with 30 % fly ash (FA), 30 % ground granulated blast furnace slag (GGBS), or a combination of 15 % FA and 15 % GGBS under different Mg2+ concentrations. The effects of Mg2+ concentration and mineral admixture type on chemically bound chloride ions and their microstructures are investigated. The results show that a large amount of Friedel’s salt is formed under the coupling effects of 0.6 mol/l Cl− and 0.1 mol/l Mg2+. A corrosive solution with a high concentration of Mg2+ is not conducive to the forming of Friedel’s salt. In a Cl− or Cl−-Mg2+ environment, GGBS can chemically bind more chloride ions than FA. With the increase of Mg2+ concentration, more pores and cracks appear on the sample surface. In a Cl−-Mg2+ corrosive solution, cementitious materials with mineral admixtures are more porous than pure cementitious materials. Cementitious materials hardened with GGBS are more porous than those materials hardened with FA. Thus, GGBS is more conducive to improving the materials’ resistance to chloride ions than FA.

Fabrication of superhydrophilic mask non-woven fabric with cellulose/GO composite coating for oil/water separation

Superwettable coatings have aroused considerable attention in oil/water separation materials research benefit from their many advantages, such as various preparation methods, high separation efficiency, and low cost. However, many of these coatings are not suitable for practical separation due to the complex composite methods and poor biodegradability. The development of novel superwettable oil/water separation materials with simple fabrication and eco-friendly coating has become a noteworthy target in oil/water separation fields. Since the outbreak of COVID-19, a large number of waste masks abandoned in the natural environments have caused serious environmental hazards. The mask non-woven fabric (MNF) from waste disposable medical masks is a good separation material for its rich microporous. Herein, regenerated degreasing cotton cellulose and graphene oxide (GO) were used to successfully construct an environmentally friendly composite coating on the MNF through a simple dip coating method, and the obtained Cellulose/GO@MNF has excellent superhydrophilicity and underwater superoleophobicity. The fabricated coating possesses favorable chemical stability and nice mechanical strength after being destroyed by corrosive solutions (acid, alkali, salt solution) and physical processing (scratches). Various oil/water mixtures can be separated with high separation efficiency (>98%), and the separation efficiency is absent a substantive drop even after 10 separate cycles. Water can be removed quickly and continuously from the oil/water mixture by the as-fabricated MNF linking with a peristaltic pump. Besides, toluene oil-in-water emulsion can also be separated effectively. What is more significant is that, the Cellulose/GO@MNF fabric fabricated via a simple method and using biodegradable coating materials has potential application prospects in solving both recycling problems of waste masks and oil/water pollution.

Effect of grain structures and precipitation characteristics on the corrosion behaviour of Sc-containing Al-Cu-Li alloy

ABSTRACT The intergranular corrosion behaviour of Al-Cu-Li-Sc alloy with different microstructures was systematically investigated in this work. The SKPFM characterisation revealed that the AlCuSc (W) phase has more negative potential compared to the Al matrix and undergoes dealloying in the intergranular corrosion solution. The dealloying rate of the W phase in the corrosive solution is relatively slow, which does not lead to serious pitting characteristics. As denser anodic T1 precipitates formed on low-angle grain boundaries of the partially recrystallised sample will reduce the precipitates on the sub-grain interior, resulting in the low-angle boundary being prone to preferential corrosion and reduced intergranular corrosion resistance. The complete recrystallised sample exhibits corrosion of grain interior and propagates along corroded bands parallel to {111}Al habit planes of T1 precipitates, reducing the expansion rate of corrosion along the grain boundaries. Restraining the IGC along the low-angle grain boundary and inducing crystallographic corrosion to improve the intergranular corrosion resistance.

Corrosion Behavior of Petroleum Pipeline Steel in the Sulfur Ion Enriched Solution with Quinoline

Localized corrosion is a serious, hazardous destroyer of steel petroleum pipelines meant for long-time use. However, previous studies on localized corrosion primarily focused on local corrosion morphology and corrosion rate of bulk metals because detecting the corrosion state of occlusive metals is difficult. Herein, we employ a simulating occluded battery unit to disclose the local corrosion behavior of the steel petroleum pipeline (N80 steel) in an occlusive S2–-enriched solution. After simulating localized corrosion in the S2–- containing corrosion solution using the occluded battery unit, the occlusive solution was acidified and the migration amount of S2– to the occluded area increased. Despite the increase of S2– concentration, the addition of quinoline corrosion inhibitor (0.8 wt%) still effectively impedes the corrosion of the occluded metal. Moderately raising the environmental temperature can stimulate the activity of the inhibitor and promote the inhibition effect. The quinoline corrosion inhibitor displays the maximum inhibition rate at an elevated temperature of 50°C. Meanwhile, a maximum over the temperature of 60°C-70°C will likely accelerate the failure of the inhibitor.

Synthesis and characterisation of sulfated-nanocrystalline cellulose in epoxy coatings for corrosion protection of mild steel from sodium chloride solution

Biomaterials such as nanocrystalline cellulose (NCC) have attracted considerable attention in coating production industries due to their sustainable and renewable attributes. This work presents NCC obtained from the hydrolysis of microcrystalline cellulose and sulfation treatment of NCC to obtain sulfated-NCC (S-NCC) using a chemical agent for corrosion protection of mild steel in 3.5 wt.% NaCl solution. Two types of anticorrosion coatings were formulated by incorporating either NCC or S-NCC of different loading ratios (10 wt.% to 50 wt.%) to epoxy-matrix to form composite coatings. The structural characterisations of NCC and S-NCC showed that the sulfation introduced sulfate ester groups on NCC. The morphological characterisations displayed that the average particle sizes obtained for both ranged between 40 nm and 50 nm. Electrochemical measurements were conducted to obtain the anticorrosion behaviour of the composite coatings in the corrosive solution. The results indicated that the sulfation of NCC improved the anticorrosion performance to 99.7%, and the best performance was obtained from a coating containing 20 wt.% S-NCC. Finally, a mechanism for corrosion protection of S-NCC coating was proposed where electrostatic repulsion of chloride species from the coated mild steel occurred. This study, therefore, demonstrates the applicability and importance of S-NCC in improving the anticorrosion performance of epoxy coatings for maritime applications.

Assessing residual stresses in the surface layer of the ZK60 alloy after an exposure to corrosion solution

Magnesium alloys preliminary immersed in a corrosion solution suffer from embrittlement, referred to as pre-exposure stress corrosion cracking (PESCC). It was suggested that PESCC can be attributed to the corrosion product film-induced stress (CPFIS), which is known to be responsible for SCC in many alloys. However, the internal stress associated with the formation of the corrosion products (CP) layer on Mg alloys have not been investigated as yet. Thus, in the present study, the internal residual stresses of the first and second kinds were assessed in the alloy ZK60 exposed to the corrosion solution, using the deflection of the thin plate and by the X-ray diffraction technique, respectively. It is found that the deposition of CP on the surface of the alloy ZK60 creates the compressive internal stresses of both kinds — I and II. The macro residual stress of the kind I in the thin plate is found to be not exceeding 3 MPa, while the micro residual stress of the second type in the surface layer of 20 – 30 µm can be as high as 290 MPa and cause plastic deformation of the bare metal with the internal stress which cannot be relieved by the removal of CP.

Investigation of corrosion inhibitor used in cement

Steel bar corrosion inhibitor can be incorporated into concrete (or mortar) with a small amount, or coated on the cement surface to protect the steel materials. It can prevent or delay the corrosion of metal bars by directly acting on the steel bars in concrete (or mortar), but it does not affect the structure and properties of concrete. In this paper, the single component corrosion inhibitor was screened and evaluated at room temperature by salt water immersion test and static coupon weight loss method. The results show that hydrazine hydrate and KNO3 can effectively prevent the corrosion of reinforcement after being placed in simulated corrosion solution for 7 days. When the concentration of hydrazine hydrate and KNO3 is greater than 0.5%, the corrosion inhibition rate of KNO3 is 95.44% (100mg·L−1).

Corrosion-induced deceleration-to-acceleration of fatigue crack growth for deep-sea Ti6Al4V ELI titanium alloy

The Ti6Al4V ELI titanium alloy is a promising structural material for deep-sea equipment due to the advanced mechanical properties. The damage evolution of the Ti6Al4V ELI induced by cyclic loading accompanying with marine corrosion should be quantified to achieve structural integrity design for deep-sea equipment. However, synchronous acceleration testing for fatigue and corrosion is still challenging, due to the lack of equivalent acceleration ratio between fatigue and corrosion. Here we propose a calculation algorithm to determine the corrosion acceleration ratio based on the electric charge transmission during the corrosion process. Accordingly, we design a testing equipment with controllable current through corrosive solution. The corrosive acceleration ratio is modified by controlling current intensity. Then we observe for the first time that a deceleration-to-acceleration tendency for corrosion-fatigue testing for the Ti6Al4V ELI specimens. In addition, we reveal that this inconspicuous phenomenon is attributed to the competition between the corrosion-induced crack tip blunting and the material volume degradation. These findings provide insights for assessing the Ti6Al4V ELI, thereby designing for the deep-sea equipment.

Fabrication of metal-based superhydrophilic and underwater superoleophobic surfaces by laser ablation and magnetron sputtering

Fabricating underwater superoleophobic surfaces is an advanced technique for controlling undesirable oil and wax adhesion on engineering structures and household appliances. This article presented a facile method based on the combination of laser ablation of stainless steel substrates followed by magnetron sputtering of a metallic tungsten target to fabricate superhydrophilic and underwater superoleophobic surfaces. The results showed that the laser-ablated stainless steel substrate without coatings exhibited hydrophilicity and underwater oleophobicity. However, its transition to superhydrophilicity and underwater superoleophobicity with a 0° water contact angle and higher than 156° underwater oil contact angles occurred after the deposition of a thin tungsten film followed by annealing at 300 °C. The prepared surface maintained its wetting behavior for more than 4 weeks, even in corrosive aqueous HCl and NaOH solutions. According to the data from SEM and XPS, this distinguished wetting behavior resulted from the presence of the regular microscale texture patterns, abundant hydroxyl content, and low carbon content on the tungsten layer after annealing at 300 °C. Thus, laser ablation combined with magnetron sputtering of tungsten demonstrated effective results in fabricating superhydrophilic and underwater superoleophobic surfaces that are independent of the initial wetting of the substrates.

A durable and environmental friendly superhydrophobic coatings with self‐cleaning, anti‐fouling performance for liquid‐food residue reduction

AbstractA durable and environmentally‐friendly superhydrophobic coatings for liquid‐food residue reduction were prepared by using stearic acid (SA) modified organic montmorillonite (SA@OMMT) and poly(dimethylsiloxane) (PDMS). Due to the natural hydrophobicity of SAs, SA@OMMT provides low surface energy as well as roughness for the coating. PDMS not only provided low surface energy in the coating but also contributed to the bonding of SA@OMMT as a result of its high adhesive properties. In addition, PDMS has good physical properties after curing, which can effectively improve the physical properties and durability of a superhydrophobic coating by the self‐assembly method using a PDMS/n‐hexane solution. For 1 wt.% SA@OMMT and 5 wt.% PDMS, the resulting SA@OMMT/PDMS (SOP) coating showed the water contact angle (WCA) and water sliding angle (WSA) of 156.3°and 2°, respectively. The prepared coatings have good physical and chemical stability, and they still have superhydrophobicity after physical abrasion tests and exposure to the corrosion solutions. In the meanwhile, the prepared coating also has flexibility and superhydrophobicity after bending and folding. Finally, the coating surface shows highly effective antifouling ability to liquid and solid pollutants. The coating can be applied against different substrates and has potential application in the field of liquid‐food residue reduction.

Optimization of the Composition of Cement Pastes Using Combined Additives of Alumoferrites and Gypsum in Order to Increase the Durability of Concrete

The reliability of concrete structures is closely related to the durability of the concrete materials stable under external environmental conditions. The present study is aimed at analysing the effect of a prospective hardening additive containing calcium alumoferrites and calcium sulfate (AFCS) as a substitute (5–15%) for Portland cement. The hardened cement pastes were characterized by water absorption, shrinkage, strength and corrosion resistance. It was shown that replacing a part of Portland cement with the AFCS additive results in an increase in the strength of fine-grained concrete and in the water resistance grade of concrete. The use of the AFCS additive in the mixed cements reduces the shrinkage of cement stone, resulting in shrinkage-free fine-grained concretes. The increased corrosion resistance of the hardened cement paste is caused by a chemical (saturation) equilibrium between corrosive medium and a cement stone. Penetration of sulphate ions from corrosive solution into the hardened cement paste is much lower, unlike Portland cement. Following saturation of the hardened cement paste with sulphate ions, their further penetration into the cement stone does not occur. Based on the results of the study, recommendations were developed for the use of the hardening alumoferrite-gypsum additive to Portland cement, which allows to improve the mechanical and corrosion characteristics of concrete.

Effect of solution annealing temperature on the localised corrosion behaviour of a modified super austenitic steel produced in an open-air atmosphere

Two annealing heat treatments were investigated regarding localised corrosion behaviour on Nb and Mn-bearing super austenitic stainless steel. The material was designed based on physical metallurgical principles supported by Thermo-Calc modelling and was produced in an open-air atmosphere based on pre-sorted SS scrap plus ferroalloys elements. The production method aims for metal waste valorisation considering small foundries without an atmosphere-controlled process. Secondary phases at annealing temperatures were experimentally analysed by different microstructural characterisation methods and correlated by the Thermo-Calc modelling. In addition, electrochemical techniques and SKPFM were used to study the relationship between observed phases and localised corrosion performance. As the main results, a good correlation was observed between Thermo-Calc calculations and the microstructural characterisation. In particular, M23C6 carbides, σ phase, and Nb-MX were identified for the sample treated at 1120 °C, while for the sample treated at 1180 °C, σ phase and Nb-MX were identified, no M23C6 were detected. As regards localised corrosion behaviour, the M23C6 carbides and σ phase for sample 1120 °C generated Cr and Mo depletion zones and diminished the corrosion resistance in corrosive aqueous solutions. In the case of sample 1180 °C, the σ-phase with a smaller size and volume fraction than sample 1120 °C was observed, leading to a more uniform Cr and Mo distribution through the microstructure, obtaining high corrosion resistance and showing promising corrosion behaviour, similar to commercial SS 254smo considering its production in open-air.

Deterioration of mechanical properties at the anchor-mortar interface considering the effect of two-phase corrosion

Factors in the environment may cause corrosion of the anchor rod and mortar, thus degrading the mechanical properties of the anchor rod-mortar interface and eventually leading to failure of the anchor structure. In this paper, a method is designed to accelerate the migration of corrosive ions (Cl-，SO42-) from solution to penetrate the mortar, resulting in the corrosion of both the mortar and the bolt. Taking corrosion of the steel bar as the control, the deterioration law for the interfacial anchor-mortar bond during two-phase corrosion was studied. The mechanical properties deteriorating mechanism of the anchor-mortar interface was revealed based on changes in the composition and amount of corrosion products and the damage extent of anchor rods and mortars. The test results showed that, in acidic environments, the rib height of the bolt decreased due to corrosion, which led to a decrease in the mechanical bite force of the interface. The needle and rod-shaped ettringite generated by the mortar during corrosion can destroy the internal structure of mortar, promote more corrosive solution to participate in the chemical reaction, and reduce the radial binding force on the steel bar. In an alkaline environment, corrosion of the rebar is slow. The plate ettringite formed by the mortar during corrosion provides a filling effect and delays the corrosion reaction of the rebar. Corrosion of the reinforcement and mortar results in deterioration of the interface bond strength between the bolt and mortar. Based on the test results, the current model of bond slip was modified to include deterioration of the anchor and mortar material properties and weakening of the restraining effect of the mortar. A model for the anchor-mortar bond-slip relationship was proposed and included corrosion of both materials. The results of this research will provide guidance for future studies of the failure mechanisms of anchorage structures and evaluations of the durability of anchored slopes.

Self-healing fluorinated poly(urethane urea) for mechanically and environmentally stable, high performance, and versatile fully self-healing triboelectric nanogenerators

Fully self-healing triboelectric nanogenerators (TENGs) capable of recovering damaged triboelectric layers and electrodes are highly desirable as power supplies or self-powered sensors for next-generation electronics. However, the viable application of fully self-healing TENGs is limited due to their poor mechanical and environmental stabilities and output performances. These arise due to the poor mechanical strength, chemical stability, and triboelectric properties exhibited by the triboelectric layers. Herein, a self-healing fluorinated poly(urethane urea) with high mechanical strength, chemical stability, excellent healing efficiency, and outstanding triboelectric performance is synthesized. By sandwiching the self-healing fluorinated poly(urethane urea) with a self-healing ionogel, a fully self-healing TENG named FSI-TENG is obtained with an output power density of 2.75 W m−2, which is the highest compared with other reported fully self-healing TENG. Due to the mechanical strength and chemical stability of the self-healing fluorinated poly(urethane urea), the FSI-TENG exhibits a reliable electrical output performance after being stored at − 30 °C and 90 °C, immersed in corrosive solutions, bent, trampled, and even ran over by a car. Thus, the FSI-TENG can be used for high-output energy generation and as a self-powered sensor to detect water leaks, body movements, and the speed of a car. After damage, the FSI-TENG can be healed to completely restore its electrical output performance, mechanical properties, and environmental stability, ensuring its reliability and service life.