Chemical Corrosion Research Articles

Effect of acid mine drainage on the mechanical properties of AISI 1020 carbon steel and AW6060 aluminium

Acid mine drainage severely affects metallic materials due to the high acidity and oxidising capacity of these lixiviates. A study was carried out to evaluate the time evolution of the mechanical properties of AISI 1020 carbon steel and AW6060 aluminium in contact with acid mine drainage. Weight loss, fatigue and tensile strength were evaluated in two different scenarios, one involving erosion corrosion (dynamic scenario) and the other involving chemical corrosion only (static scenario). Over 80 days of exposure in a static scenario, weight loss is almost 2% for aluminium and 0.5% for steel, fatigue strength is reduced by 28% for steel and ultimate tensile strength is reduced by almost 5% for aluminium and by 2.5% for steel. In a dynamic scenario, the weight loss after 4 days of exposure is 30–35% for both materials, the fatigue strength is reduced by almost 50% for steel, the ultimate tensile strength is reduced by 33% for aluminium and by almost 5% for steel. Acid drainage causes an increase in brittleness and a decrease in stiffness of these materials, much more rapidly in a dynamic environment favoured by the effects of erosion corrosion.

Performance assessment of alko-amine corrosion inhibitors for use as an admixture in reinforced concrete structures: Experimental investigation and mechanism of action

Corrosion in reinforced concrete (RC) is a major issue in the construction industry, giving rise to structural failure, huge repair costs, and safety concerns. To mitigate RC corrosion, chemical corrosion inhibitors (CCI) are commonly used. This study aims to investigate the performance of different alko-amine CCIs for corrosion control in reinforced concrete (RC) structures subjected to chloride-rich conditions. The experimental program was divided into two levels: investigations comprised of quick testing on bare rebars, suitable for industries, and analysis which comprised of electrochemical investigation in simulated concrete pore solution and testing on rebar embedded in concrete, suitable for research labs. The interaction between inhibitors and steel was examined through surface analytical techniques such as AFM and XPS. Finally, the inhibition mechanism for the CCI was proposed. The alko-amines were found to show a strong dependence on their molecular structure for the formed film integrity. Monoethanolamine (MEA) and methyl ethanolamine (MeEA) formed a denser and more uniform film compared to dimethyl ethanolamine (DMeEA) and ethyl monoethanolamine (EMEA). MeEA showed the highest inhibition efficiency in both simulated pore solution environments and when used as an admixture in RC.

Phosphorous recovery from sewage effluent by vanadium-substituted composite synthesized via reverse coprecipitation route

MgFe2O4/MgO (S-sample) and a novel V-modified MgFe2O4/MgO (V-sample) nanocomposites were successfully synthesized using the reverse coprecipitation method and were carefully characterized by X-ray diffractometry, Infrared and 57Fe Mössbauer spectroscopies, magnetization, electron microscopy (both transmission and scanning) and surface area analysis to comprehend their structural, morphological, hyperfine and magnetic properties before and after P adsorptions. MgFe2O4 and V-modified MgFe2O4 phases (with 30 nm average in “diameter”) govern the nanocomposite magnetic properties and these phases are chemically stable in phosphate-rich effluents. 50 nm in size MgO phase is responsible for P adsorption, but it showed chemical corrosion, as suggested by surface analysis. Adsorption kinetic revealed that there are two controlling steps: film and intraparticle diffusion. The nanocomposite materials fitted better to the Freundlich isotherm model, indicating that the adsorption site distribution for P is heterogeneous, and a multilayer adsorption mechanism is favored. Multicycle reuse experiments with secondary sewage effluent were performed, and the adsorption capability of the V-sample over 3 consecutive adsorption cycles was 11 mg g−1, a value 30 % higher than that found for the S-sample. The desorption efficiency of the V-sample was about 97 %, while the S-sample reached 76 %. The V-substituted composite is a promising nanoadsorbent for water remediation process in phosphate-rich effluents and should be also tested in remediation of other contaminants.

Advances and Significances of Nanoparticles as Concrete Additives: A Comprehensive Review

Nanotechnology, a significant technological advancement in the current century, has brought about revolutionary changes in numerous fields by manipulating matter at the nanoscale. This review paper examines the various applications of nanoparticles in the concrete industry, emphasizing their potential to improve mechanical qualities, thermal performance and sustainability. This study investigates multiple synthesis strategies, such as grafting, sol–gel, chemical and biological procedures, which offer concrete engineers a diverse range of options to tailor the properties of nanoparticles. The utilization of this particular material results in notable enhancements in many mechanical properties of concrete, including its compressive and flexural strength, toughness, thermal conductivity and self-sensing capabilities. These improvements ultimately contribute to the overall enhancement of the concrete’s structural integrity and energy efficiency. Adding nanoparticles to concrete has also been shown to help it develop self-healing properties. This means that structures last longer and require less maintenance. Making building materials more resistant to chemical corrosion, wear and environmental forces is also a big step in making them last longer. The growing emphasis on sustainability within the building industry has generated heightened attention toward utilizing self-healing concrete, which frequently incorporates nanoparticles. To make the building industry more environmentally friendly, using less traditional cement and recycling personal safety equipment (PPE) like vinyl and latex gloves can help protect the environment. This review also highlights the significant problems in employing nanoparticles in concrete: obtaining equal dispersion, handling-costs and addressing environmental and health concerns. However, nanotechnology is advancing construction concrete research to improve mechanical properties and durability.

Development of a shear creep damage model of jointed rock masses considering the influence of freeze-thaw and chemical corrosion

Development of a shear creep damage model of jointed rock masses considering the influence of freeze-thaw and chemical corrosion

Construction of Ferric-Oxide-Doped Nickel-Iron Hydroxide Electrocatalysts by Magnetic-Field-Assisted Chemical Corrosion toward Boosted Oxygen Evolution Reaction.

Transition-metal-based oxygen evolution reaction (OER) catalysts have attracted widespread attention due to their inexpensive prices, unique layered structures, and rich active sites. Currently, designing low-cost, sustainable, and simple synthesis methods is essential for the application of transition-metal-based catalysts. Here, magnetic field (MF)-assisted chemical corrosion, as a novel technology, is adopted to construct superior OER electrocatalysts. The produced Ni(Fe)(OH)2-Fe2O3 electrode exhibits an overpotential of 272 mV at a current density of 100 mA cm-2, presenting a 64 mV reduction compared to the electrode without an MF. The experimental results indicate that an MF can induce the directional growth of Fe2O3 rods and reduce their accumulation. In addition, an external MF is beneficial for the lattice dislocation of the obtained catalysts, which can increase the surface free energy, thus reducing the activation energy and accelerating the electrochemical reaction kinetics. This work effectively combines a magnetic field with chemical corrosion and electrochemical energy, which offers a novel strategy for the large-scale development of environmentally friendly and superior electrocatalysts.

A Passive-Active Anti/Deicing Coating Integrating Superhydrophobicity, Thermal Insulation, and Photo/Electrothermal Conversion Effects.

Anti/deicing coatings that combine active and passive methods can utilize various energy sources to achieve anti/deicing effects. However, poor photothermal or electrothermal performance and inevitable heat loss often reduce their anti/deicing efficiency. Herein, copper sulfide loaded activated biochar (AC@CuS) as photo/electric material, polydimethylsiloxane as hydrophobic component, thermally expandable microspheres as foaming agent, and an anti/deicing coating integrating thermal insulation, superhydrophobicity, photo/electrothermal effects was successfully constructed. Benefiting from the synergistic effect of superhydrophobicity and thermal insulation, the freezing time of water droplets on the coating surface is extended from 150 to 2140 s, showing excellent passive anti-icing performance. AC@CuS exhibits photo/electrothermal effects, and porous expanded microspheres reduce heat loss, which endows the coating with desirable photo/electrothermal conversion performance. Under the conditions of 0.2 W/cm2 electric power density (EPD) and 0.1 W/cm2 optical power density (OPD), the temperature of the coating increases from 24 to 96.4 and 113 °C, respectively. Interestingly, with a coheating of 0.05 W/cm2 weaker OPD and 0.05 W/cm2 lower EPD, the ice on the coating surface can be quickly melted in 2.5 min, showing synergistic deicing performance. In addition, the WCA of the prepared coating remains above 150° after mechanical damage, rain impact, UV irradiation, chemical corrosion, and high-temperature treatment, and good superhydrophobic durability ensures the anti/deicing durability of the coating.

Oxhide gelatin-regulated aramid nanofiber/liquid metal films with sandwiched structure for electromagnetic interference shielding

Liquid metal (LM) based electromagnetic interference (EMI) shielding materials with high conductivity and continuous deformation capacity are important needs for meeting modern advanced electronic equipment. However, an independent free-standing film with LM is difficult to achieve due to its unique fluidity properties. Here, a simple alternating filtration film-forming method was utilized to orderly construct a sandwiched EMI shielding film with LM stabilized by bio-based oxhide gelatin (gel) as the intermediate conductive layer, and two films of aramid nanofibers/oxhide gel (ANF/gel) as the external insulating protective layers. This design not only prevents LM from being exposed to environmental conditions, but also reduces the risk of chemical corrosion in practical applications. Under optimal LM addition conditions, the sandwiched film (0.3-3 L) exhibited better EMI shielding performance of 50.4 dB in the X-band than the blended film (0.7 dB), as well as excellent mechanical properties (tensile strength of 65.8 MPa, strain 8.6 %). More importantly, the sandwiched film still maintained reliable EMI shielding performance after being experienced largely physical deformation. This study provides a new solution for preparing LM-based EMI shielding composites, and is expected to arouse pursuit of high EMI shielding effects of bio-based gel while also paying attention to their safety.

Mechanical responses of chemically corroded sandstone under cyclic disturbance: Insights from fatigue properties and macro-micro fracturing mechanism

Engineering rock masses are likely to be subjected to coupled chemical corrosion and cyclic load disturbance, deteriorating the internal structure of rocks and further threatening the long-term stability of engineering structures. In this study, to investigate the combined effect of cyclic loading and chemical corrosion, the cyclic uniaxial compression tests are conducted on sandstone specimens chemically corroded by different corrosion times (0, 20, 40, 60 days) and pH values (1, 3, 7, 11, 13). Our results indicate that chemically corroded sandstone specimens featured by an increase in irreversible strain and hysteresis energy density compared with natural rocks. A coupling damage variable is proposed to reflect the initial damage induced by chemical corrosion and the mechanical damage induced by cyclic disturbance, and the accumulation rate of coupled chemical-fatigue damage variables significantly increases with increasing corrosion time or enhancing acidity and alkalinity. Fatigue failure modes of tested specimens transform from splitting failure to unidirectional shear failure as corrosion time increases, and chemically corroded specimens are featured by ductile failure characteristics compared to natural state. Moreover, X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) are employed to analyze the micro-fracturing mechanism of sandstone. Cement minerals dominate the reactions in acidic solutions, whereas quartz takes the lead in alkaline conditions. Due to pronounced influence of cement minerals on the macroscopic mechanical properties of sandstone, acid corrosion specimens tend to experience more severe damage. Micro-cracks inside rocks under cyclic loading have sufficient time to pass through weakly bonded particles, and chemical reactions markedly weaken inter-particle bonding degree, and thus the fatigue fracture of chemically corroded specimens predominantly exhibits intergranular (IG) fracture.

Numerical simulation study of cavitation characteristics of jet hydrofoil surface

To mitigate the adverse effects of cavitation on the performance degradation and chemical corrosion of hydraulic machines, a jet hydrofoil physical model based on the structure of a guide vane model of a high-pressure mixed-flow hydraulic turbine was established. A density correction turbulence model based on filters was adopted to numerically simulate the cavitation characteristics on the surface of the jet hydrofoil. The results demonstrate that when the jet speed is 12 m/s and the jet angle is −15°, the scheme exhibits the best cavitation suppression effect among all combinations of jet angles and speeds. Cavities near the jet structure are prematurely collapsed after being pressurized, and the cavitation suppression effect in the low-pressure area at the trailing edge is also satisfactory. The time-averaged bubble volume fraction reaches its minimum at 2.17%, with the time-averaged bubble volume fraction being 27.3% of the prototype hydrofoil. At flow speeds of 2.4 m/s and 7.2 m/s, small-angle jet fluid accumulated will stick to the closed cavities on the surface of the hydrofoil and cause them to rupture, while the jet fluid at the jet angle of 60° and speeds of 7.2 m/s and 12 m/s will directly cut off the bubbles.

Research on surface corrosion resistance of sintered NdFeB by rotating transverse magnetic field assisted EDM-milling

Sintered NdFeB, owing to its outstanding magnetic properties, finds widespread applications in diverse fields. However, its susceptibility to corrosion limits its utility. To enhance its corrosion resistance, a rotating transverse magnetic field is incorporated into the electrical discharge machining milling (EDM-M) process. Comparative experiments are conducted on sintered NdFeB by EDM-M, fixed transverse magnetic field assisted EDM-M(FTMEDM-M), and rotating transverse magnetic field assisted EDM-M(RTMEDM-M). Results indicate that the RTMEDM-M process yields the least surface cracks, the least "caves", and the recast layer which is the most uniform and the most continuous. Its impedance value is the highest, self-corrosion potential is the largest, and self-corrosion current density is the lowest according to its electrochemical impedance spectroscopy (EIS). In addition, its mass loss per unit area is the least, with the latest and the weakest reaction of chemical corrosion of the workpiece surface.

In vitro Biomineralization Ability of Magnesium-Doped Coral Hydroxyapatite Coating Prepared by Pulsed Laser Deposition

Coral hydroxyapatite (CHA) is a calcium phosphate that has a similar inorganic composition to human bone and the porous structure of coral stone. Due to its interconnected network like pore structure, it can serve as a framework for bone conduction. In this study, CHA films and Mg-CHA films were deposited on titanium and silicon substrates by Pulsed laser deposition, and then the films were heat treated respectively. Studies on the adhesion of the coating showed that the heat-treated Mg-CHA film adhered better to the titanium substrate. The experimental study on biomineralization in vitro showed that a small amount of porous structure appeared in the heat-treated Mg-CHA after immersion in SBF for three days, and the porous structure was visible after immersion for seven days. After 14 days, a new apatite layer formed on the surface. This suggested that magnesium undergoes chemical corrosion in SBF, leading to rapid ion exchange, which results in the formation of porous structures and promotes the development of an apatite-like layer. In summary, the heat-treated Mg-CHA films had superior biomineralization properties.

Preparation and Properties of Lightweight Geopolymer by Bio-Based Foaming Agent.

Lightweight geopolymers have the advantages of a wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, and are expected to replace traditional building insulation materials. In this paper, a green bio-based foaming agent with a small 1 h settlement distance, high average foaming multiple and low bleeding ratio was obtained by a Cetyltrimethylammonium Bromide/yeast solution. When the amount of Cetyltrimethylammonium Bromide is 0.50 wt%, the foam prepared by the yeast and Cetyltrimethylammonium Bromide solution exhibits the improved 1 h settlement distance, the large average foaming multiple, the small bleeding ratio and uniform foam size. Subsequently, a lightweight geopolymer based on metakaolin and fly ash (or silica fume) was successfully prepared by the bio-based foaming agent, and the effects of different foam content on the properties of the geopolymer, such as dry density, water absorption, thermal conductivity, compressive strength and morphology, were studied. With an increase in foam content, the dry density, thermal conductivity and compressive strength of the geopolymer gradually decrease, the water absorption increases, regardless of whether silica fume or fly ash are added. Herein, it is confirmed that the foaming agent based on yeast can be effectively used to prepare lightweight geopolymers, which can provide vast opportunities to turn into candidates for novel inorganic thermal insulation materials.

Impact of Chemical Corrosion on Mechanical Properties of Boroaluminosilicate Pharmaceutical Glasses.

Boroaluminosilicate (BAS) glasses have excellent chemical durability and mechanical properties and are widely used in the pharmaceutical packaging industry. The corrosion behavior of boroaluminosilicate (BAS) glasses have been investigated for many years; however, the impact of chemical corrosion on mechanical properties of boroaluminosilicate glasses has not been well understood. In this work, the BAS glass samples were corroded in a 20 mM Glycine-NaOH buffer solution (pH = 10) at 80 °C for various durations. Within the corrosion durations, the corrosion of the glass is dominated by congruent dissolution. The results show that the elemental composition and structure of the glass surface are not altered significantly during the congruent dissolution, and the corrosion rate is mainly affected by the Si concentration in the solution. The structural change in the process of micro-crack decay is the main factor affecting the mechanical properties of the glass surface. Corrosion leads to the growth of micro-cracks and tip passivation, which causes the hardness and elastic modulus of the glass to first decrease and then increase. As corrosion proceeds, the microcracks are completely destroyed to form micropores, and the pore size and number increase with the corrosion process, resulting in the decrease in surface mechanical properties again. This work reveals the main influencing factors of congruent dissolution on mechanical properties and provides an important reference for the improvement of pharmaceutical glass strength.

Heat-induced aliquation and phosphating of nickel as efficient catalysts for hydrogen evolution in alkaline seawater

Developing electrolytic seawater catalysts with excellent performance is crucial for efficient hydrogen production. In this study, Ni2P nanoparticles anchored on NiMo oxides, denoted as NiMo-P, are synthesized through heat-induced aliquation and phosphating of Ni in the ammonium nickel molybdate. Physicochemical characterizations reveal that the abundant Ni2P nanoparticles are uniformly distributed on NiMo oxides. Electrochemical data reveal that a mere overpotential of 103 mV is sufficient to achieve −100 mA cm−2 in alkaline simulated seawater, which is significantly lower than that of Pt foil (179 mV) and commercial Pt/C (165 mV). This remarkable activity observed in NiMo-P may be due to the superior water dissociation activity and hydrogen desorption ability of the Ni2P nanoparticles, as calculated by density functional theory, which surpasses that of Pt. Meanwhile, the NiMo-P exhibits outstanding stability, as evidenced by the chronoamperometric curve. The current remains at 98.1% of its initial value after 500 h, which can be attributed to the etching-hydrolysis method that strengthens the catalyst-carrier interaction. Besides, the inherent repulsion toward chlorine ions at the cathode effectively avoids chemical corrosion. Importantly, when coupled with the previously reported anode, NiMo-P also exhibits exceptional performance in alkaline seawater.

Polyaniline/hollow glass beads/carbon fiber powder composite film for multifunctional military tarpaulins

In this paper, a composite film with a thickness of 0.25 mm was prepared, which has the functions of infrared stealth, ultraviolet protection, sound absorption, and thermal insulation. Firstly, polyaniline was synthesized through chemical oxidative polymerization using aniline as a monomer, acetic acid as a dopant, and ammonium persulfate as an oxidant. Then, the synthesized polyaniline (PANI), hollow glass beads (HGB), and carbon fiber powder (CFP) were sequentially added to waterborne polyurethane, and a film coating machine was used to prepare a multifunctional composite film of PANI/HGB/CFP. Finally, the composite film's infrared properties, ultraviolet protection properties, sound absorption properties, thermal constants, resistance to water penetration properties, bending properties, tensile properties, chemical corrosion resistance, and aging resistance were tested. The results show that the prepared PANI/HGB/CFP composite film has an infrared emissivity of 0.668 and an ultraviolet protection factor (UPF) of 1072, indicating that it can block more than 99 % of ultraviolet rays. Additionally, it has an acoustic absorption coefficient of 0.386. At the same time, the thermal conductivity is 0.04629 W/mK, making it a highly efficient material for heat preservation and thermal insulation. The prepared PANI/HGB/CFP composite film is expected to be a new multifunctional military tarpaulin.

Corrosion characteristics of Fe, Ni and Ti based alloys near the critical point of water and during supercritical water gasification and oxidation of municipal sludge

Supercritical water gasification (SCWG) and oxidation (SCWO) were promising technologies for treating municipal sludge; however, corrosion hindered their development. To obtain the candidate material for preheaters, corrosion characteristics of 316, 316 L, Incoloy 800, 825, and TA-10 were investigated at 350 °C and 400 °C. For SCWG and SCWO reactors, corrosion behaviors of 316, Incoloy 800, 825, Inconel 600, 625, and Hastelloy C276 were explored at 450 °C and 520 °C, with and without oxidants. Near the critical point of water, corrosion rates of all materials were below 0.4 mm·a−1, with 316 L being the candidate material. According to the pH variation, materials underwent activation (350 °C) and passivation (400 °C) pathways. During SCWG and SCWO, Incoloy 825 and Inconel 625 were prioritized at 450 ℃ and 520 ℃, exhibiting corrosion rates below 0.40 mm·a−1 and 0.50 mm·a−1, respectively. Chemical corrosion dominated and double-layer oxide films (Fe3O4-FeCr2O4 and NiO-Cr2O3) formed.

Innovative TiO2-doped polyvinyl alcohol sponge for efficient oil–water separation and dye degradation in wastewater treatment

Regular problems faced due to oil spills and soluble contaminants have increasingly caused serious water pollution. Therefore, there is an urgent need to develop efficient strategies to purify wastewater. This study aims to formulate a synergistic treatment technology of sorption and ultraviolet light catalysis for oil–water separation and degradation of dyes in wastewater. In this study, TiO2 doped PVF sponge (DTMS-TiO2@PVF) was prepared with a water contact angle of 151.5° and a removal rate of 98.86 % of MB in 120 min. Meanwhile, DTMS-TiO2@PVF sponge could easily realize the selective separation of oil–water mixtures. Its saturated sorption capacity for oil and organic solvent was 4.13–10.05 g/g. In addition, DTMS-TiO2@PVF sponge had better environmental stability, which could withstand chemical corrosion (acid, alkaline, and salt solutions). Therefore, DTMS-TiO2@PVF sponge showed great potential for application as an efficient oil–water separation and photocatalytic material, especially in the field of treating oil wastewater and water purification.

Oxygen-functionalized Fe3O4@o-polypyrrole acting as high-efficiency oxidase mimics and their application in glutathione colorimetric sensing

The enzyme-like properties of nanozymes may be considerably affected by the structure and surface groups, which thus need to be optimized. Here, through a simple NaOH chemical corrosion method, the chemical structure similar to N-Methylpyrrolidone (NMP), which possessed intrinsic oxidase-like activity, was introduced into polypyrrole (PPy), and then this nanomaterial became oxygen-functionalized PPy (o-PPy) with excellent oxidase-like activity from PPy without this property. Furthermore, after compounding magnetic Fe3O4, the obtained nanocomposites Fe3O4@o-PPy nanoparticles (Fe3O4@o-PPy NPs) showed superiorities in separation during synthesis and real-time control of enzyme catalysis. Studies have found that the enzymatic activity of Fe3O4@o-PPy NPs depended on the amount of functionalized oxygen and the conjugation extent of o-PPy. Fe3O4@o-PPy NPs had efficient oxidase-like activity under a wide range of pH and temperature. Based on the oxidase-like activity of Fe3O4@o-PPy NPs, a colorimetric sensor for glutathione (GSH), which presented rich color changes and satisfactory colorimetric resolution by adding the amaranth, was realized. We believe that the functional modification and structural regulation of PPy can not only realize its wider application but also promote the discovery of novel and efficient nanozymes.

Fabrication of binder-free iron nanosheet arrays by an electrodeposition method for flexible Fe//I2 batteries anodes

Aqueous iron-iodine batteries (Fe//I2) are considered as a promising for portable and wearable electronics by virtue of the high theoretical specific capacity (∼960 mA h g−1) and rich natural abundance of Fe. However, the low actives utilization ratio of Fe foil and poor flexibility limit their practical usage. Here, we fabricate binder-free Fe nanosheet arrays electrode (Fe-CC) as anode by a simple and controllable electrochemical technique for flexible Fe//I2 batteries, which dramatically improve actives utilization ratio, avoid electrode damage/fracture caused by chemical corrosion and enhance the reaction kinetics. As a result, the assembled aqueous Fe-CC//I2@AC/CNT battery exbibits a stable cycling of 400 cycles, superior to that of Fe foil and anode-free Fe//I2 batteries. With the use of polyacrylamide-FeSO4 hydrogel electrolyte, a flexible quasi-solid-state Fe-CC//I2@AC/CNT battery is further designed. It has a high specific capacity of ∼195.4 mAh g−1 at a high rate of 3 A g−1, better than previous zinc ion batteries and Fe//I2 batteries. We also demonstrate the good ambient stability in terms of temperature and pressure and excellent flexibility of the quasi-solid-state Fe-CC//I2@AC/CNT battery. This work promotes the development of low-cost and high safety flexible iron-ion batteries on portable and wearable electronics.