Search Results (13)

Industrial heat exchangers are widely used in industries such as petrochemicals, energy and power, and food processing, making them one of the most important pieces of heat and mass transfer equipment in industry. During operation, a layer of fouling often adheres to the heat transfer surfaces, which reduces the heat transfer coefficient of the equipment and increases the thermal resistance of the surfaces. Additionally, fouling can corrode the material of the heat transfer surfaces, compromise their integrity, and even lead to perforations and leaks, severely impacting equipment operation and safety while increasing energy consumption and costs for enterprises. The application of anti-fouling coatings on surfaces is a key technology to address fouling on heat transfer surfaces. This paper focuses on introducing major types of anti-fouling coatings, including polymer-based coatings, “metal material + X”-type coatings, “inorganic material + X”-type coatings, carbon-based material coatings, and other varieties. It analyzes and discusses the current research status and hotspots for these coatings, elaborates on their future development directions, and proposes ideas for developing new coating systems. On the other hand, this paper summarizes the current research on the main factors—surface roughness, surface free energy, surface wettability, and coating corrosion resistance—that affect the anti-fouling performance of coatings. It outlines the research hotspots and challenges in understanding the influence of these three factors and suggests that future research should consider the synergistic effects of multiple factors, providing valuable insights for further studies in the field of anti-fouling coatings. Full article

This review article focuses on providing an accumulated knowledge on state-of-the-art composite polymer coating technologies that are studied for corrosion protection. A specific focus has been given to epoxy resin-based composite systems, considering their wide use due to remarkable chemical resistance, excellent adhesion to substrate, thermal stability, and mechanical strength. The addition of various functional polymers to the epoxy matrix has spurred significant advancements in the prevention of corrosion. Light has been shed on the epoxy resin composite systems that are produced by blending with functional polymers like conductive polymers, hydrophobic polymers, etc., and nanofillers. In many cases, the formation of a passive layer at the metal/polymer interface was aided by the addition of such a functional polymer and nanofiller to the epoxy matrix. As a result, corrosive ions are prevented from penetrating by the physical barrier that composite coatings provide. Comparable blends of epoxy and polyamide, epoxy and polyester, and epoxy/poly(vinyl alcohol) and epoxy/polyurethane have superior adhesion, wear, barrier, and anticorrosion properties due to the fine dispersion of nanocarbon and inorganic nanoparticles. The several strategies used to prevent metals from corroding are covered in this review article. Full article

Conventional hole transport layer (HTL) Spiro-OMeTAD requires the addition of hygroscopic dopants due to its low conductivity and hole mobility, resulting in a high preparation cost and poor device stability. Cuprous thiocyanate (CuSCN) is a cost-effective alternative with a suitable energy structure and high hole mobility. However, CuSCN-based perovskite solar cells (PSCs) are affected by environmental factors, and the solvents of an HTL can potentially corrode the perovskite layer. In this study, a Co₃O₄/CuSCN/Co₃O₄ sandwich structure was proposed as an HTL for inorganic Cs₂PbI₂Cl₂/CsPbI_2.5Br_0.5 PSCs to address these issues. The Co₃O₄ layers can serve as buffer and encapsulation layers, protecting the perovskite layer from solvent-induced corrosion and enhancing hole mobility at the interface. Based on this sandwich structure, the photovoltaic performances of the Cs₂PbI₂Cl₂/CsPbI_2.5Br_0.5 PSCs are significantly improved, with the power conversion efficiency (PCE) increasing from 9.87% (without Co₃O₄) to 11.06%. Furthermore, the thermal stability of the devices is also significantly enhanced, retaining 80% of its initial PCE after 40 h of continuous aging at 60 °C. These results indicate that the Co₃O₄/CuSCN/Co₃O₄ sandwich structure can effectively mitigate the corrosion of the perovskite layer by solvents of an HTL and significantly improves the photovoltaic performance and thermal stability of devices. Full article

Engine oil oxidation is one of the major reasons for oil aging which can result in variations in the physical and chemical properties of oil. Organic acids generated by oil oxidation can react with water to form inorganic acids and acidic substances (including organic and inorganic acids) that corrode engine parts, resulting in the generation of rust or damage to engine parts. This is one of the important reasons why oil should be regularly changed. One of the most commonly applied methods for judging the aging degree of engine oil is monitoring its acid number (AN). However, generally, the effect of oil water content on acid value measurement is not considered. When oils are used in engines, they are often contaminated by water due to condensation, which accelerates engine oil aging. Therefore, it is crucial to explore the water content effect on AN in the process of engine oil aging. In this research, a water content sensor was applied to characterize moisture content in oxidized oil samples. The sensor could also obtain oil sample electrical conductivity which corresponded to its dielectric constant. Using a mid-infrared spectrometer to measure oil sample AN at this point to obtain the variation in AN with oxidation time, oil sample AN was connected in series with the water content, dielectric constant and electrical conductivity. These parameters were monitored through sensors, and the effect of water content on AN was studied. Experimental results revealed that with the increase in oxidation time, the water content, electrical conductivity, dielectric constant increase and AN of oil were increased. At the same time, since the temperature had a greater effect on electrical conductivity, the application of an air-conditioned constant-temperature environment removed the effect of temperature change on electrical conductivity. Full article

The interaction between CO₂, formation water, and rock surfaces after CO₂ flooding and the mechanism by which it affects CO₂ storage were studied in this paper. The results show that variations in the solubility of CO₂ in crude oil under pressure are similar to those observed in formation water. The solubility of CO₂ increases as pressure increases under a low-pressure conditions. The solubility of CO₂ in crude oil increases significantly when crude oil is in a low-viscosity state, and this makes it easier to diffuse CO₂ into the oil phase at high temperatures. More resistance is encountered when CO₂ diffuses into the liquid-containing space of an irregular core, making the coefficient of diffusion into the oil–water two-phase flow in the porous medium smaller. After the core is corroded by a CO₂-saturated aqueous solution, the quartz content in the mineral component increases and the plagioclase and potassium feldspar content significantly decrease. The dissolution of the feldspar leads to the formation of a large amount of secondary kaolinite, thus increasing the kaolinite content. In the early stage of CO₂ erosion during dynamic displacement, the combined effect of particle migration and inorganic precipitation leads to a slow growth in core permeability and porosity. As the erosion progresses, the influence of particle migration and inorganic precipitation on permeability gradually decreases, while the porosity of the core gradually increases. The secondary pores play a role, and the erosion of the CO₂–water system makes the permeability and porosity of the core gradually increase. During dynamic displacement, CO₂ is mainly stored in the reservoir in free and irreducible states. Under the pressure of the reservoir, some of the CO₂ participates in erosion reactions and is stored in the rock or the solution in the form of minerals or ions. In addition, a small portion of the CO₂ is dissolved in the residual water and residual oil that remain after the dynamic displacement. The results of this paper can provide some theoretical support for the design of a CO₂ storage site. Full article

Researchers have just discovered an alternative to synthetic corrosion inhibitors, which are hazardous and terrible for the ecosystem, to prevent rusting in the environment. A metal corrodes when it is subjected to corrosive media (acid, base, or saline) and they deteriorate, leading to failure. The most straightforward and affordable corrosion protection and prevention technique in acidic environments has been proven to be corrosion inhibitors. On industrial surfaces, pieces of machinery, or vessels, these inhibitors slow the rate of corrosion, preventing the monetary losses brought on by metallic corrosion. Recently, attention has been directed to developing ecologically appropriate corrosion retardation methods because inorganic and organic inhibitors are harmful and expensive. Recent studies have focused on green mild steel (MS) corrosion inhibitors that mimic industrial processes in acidic conditions. This presentation briefly covers the many types of corrosion, the corrosion process and the most recent studies on using natural plant extracts as corrosion inhibitors. Since they are safe and cost-effective, green corrosion inhibitors are a new trend in preventing corrosion. These inhibitors are produced from various plant parts, and inhibition efficiency (IE) also depends on them. To ascertain the IE of the corrosion inhibitor, some experiments, including computational studies (quantum calculations and MD simulations), electrochemical measurements (electrochemical impedance (EIS) and potentio-dynamic polarization), surface morphology atomic force microscopy (AFM), scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDX) and UV–visible spectroscopy are carried out. It has been demonstrated that the IE is maximum for green corrosion inhibitors compared to synthetic inhibitors. This paper provides an overview of the properties, mechanism of corrosion inhibitors, nature of green corrosion inhibitors and their IE obtained by performing tests. This review article discussion shows that reinforcement with plant extract performs well in aggressive environments, which is evident from electrochemical studies and surface analysis when compared to reinforcement with inhibitors. Full article

Despite intensive efforts to develop hydrothermal liquefaction for the conversion of wet biomass and biowaste feedstocks into valuable bio-oils, severe corrosion of conversion reactor alloys and other core components, induced by the pressurized hot water medium, catalysts, and inorganic and organic corrodants generated during the conversion process, has significantly hindered the industrial deployment of this attractive technology. In this paper, a general review of major operating parameters, including biomass feedstock types, temperature, pressure, and catalysts, was conducted to advance the understanding of their roles in conversion efficiency and the yield and properties of produced oils. Additionally, the corrosion performance of a representative constructional alloy (Alloy 33) was investigated in both non-catalytic and catalytic HTL environments at temperatures of 310 °C and 365 °C, respectively. The alloy experienced general oxidation in the non-catalytic HTL environment but suffered accelerated corrosion (up to 4.2 µm/year) with the addition of 0.5 M K₂CO₃ catalyst. The corrosion rate of the alloy noticeably increased with temperature and the presence of inorganic corrodants (S²⁻ and Cl⁻) released from biowastes. SEM/XRD characterization showed that a thin and compact Cr-rich oxide layer grew on the alloy in the non-catalytic HTL environment, while the surface scale became a double-layer structure, composed of outer porous Fe/Cr/Ni oxides and inner Cr-rich oxide, with the introduction of the K₂CO₃ catalyst. From the corrosion perspective, the alloy is a suitable candidate for construction in the next phase of pilot-scale validation assessment. Full article

The contact surface corrosion of friction high-strength bolt (FHSB) joints was analyzed to examine the characteristics of corrosion products and influence factors in steel bridges. Samples were selected from the Dongying Shengli Yellow River Bridge, which has been in service for 33 years. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were utilized to analyze the microscopic morphology and chemical composition of the corroded surface of the samples. The study identifies that construction quality issues accelerate corrosion of the contact surface and that the contact surface of the aluminum spraying layer transforms from rugged and dense to smooth and porous as corrosion increases. The findings also suggest that the friction coefficient of the FHSB connection node initially decreases and then increases as the corroded surface changes. Corrosion products contained S, Cl, Mn, Si, FeS, and their oxides, indicating that atmospheric, industrial, and Yellow River soil environments contribute to joint corrosion. The study proposes sandblasting and coating the corroded contact surface and deck steel plate with inorganic zinc-rich paint to prevent media penetration and delay substrate corrosion. Adopting ultra-high-performance concrete (UHPC) as the deck structure is also recommended to reduce top plate tensile stress, deck cracking, and media invasion. This study provides insights into the characteristics and mechanisms of FHSB joint corrosion to aid the maintenance, repair, and protection of steel bridges. Full article

Liquid CO₂ is a non-polar fluid, and the injection of CO₂ fluid into a coal seam causes a strong water–rock interaction between the inorganic minerals and organic matter in the coal and acidic fluid. The minerals in the coal are thereby corroded and precipitated to different degrees, and the organic matter is dissolved and extracted, which further changes the physical and chemical properties of the coal and rock. Three kinds of coal samples with different metamorphic degrees were selected as the research objects, and the research methods of theoretical analysis and experimental testing were used to carry out the related research on the modification of coal by liquid CO₂ extraction and dissolution. After the three kinds of coal samples were extracted by liquid CO₂, the pore specific surface area decreased and the CO₂ adsorption decreased with the increase in extraction pressure. The reduction in anthracite adsorption was greater than that of bituminous coal and lignite; after being corroded by different CO₂ pressures, the adsorption capacity of bituminous coal gradually increased with the increase in corrosion pressure, and the increase in adsorption capacity of bituminous coal was larger than that of anthracite and lignite. After corrosion, bituminous coal was suitable for CO₂ geological storage. Full article

Complex wells with high temperature and the presence of carbon dioxide and hydrogen sulfide acid gas require the use of high-temperature and high-density anti-corrosion cement slurry for cementing operations, and conventional cement slurry does not have the advantages of high density, high-temperature resistance, or corrosion resistance. In order to avoid the severe corrosion of cement slurry by carbon dioxide and hydrogen sulfide at high temperatures, solid phase particles with different particle sizes are combined with polymer materials to form a dense, high-density, high-temperature- and corrosion-resistant cement slurry. In this paper, we consider the use of manganese ore powder weighting agent, composite high-temperature stabilizer, inorganic preservative slag and organic preservative resin to improve the corrosion resistance of cement slurry, design a high-density cement slurry that is resistant to high temperature and carbon dioxide and hydrogen sulfide corrosion, and evaluate the performances of the cement slurry at 180 °C. The results show that the manganese ore powder weighting agent effectively improves the density of the cement slurry. Using composite silica fume with different particle sizes as a high-temperature stabilizer can ensure the rheology of the cement slurry and improve the ability of the cement sample to resist high-temperature damage. The use of slag and resin as preservatives can effectively reduce the corrosion degree in cement slurry. The high-temperature corrosion-resistant cement slurry systems with different densities designed using these materials exhibit good rheological properties, with water loss of less than 50 mL and a thickening time of more than four hours. The compressive strength decreased by less than 5.8% after 28 days at high temperatures. After being corroded by hydrogen sulfide and carbon dioxide (total pressure 30 MPa, 16.7% hydrogen sulfide and 6.7% carbon dioxide) under high temperature (180 °C) for 30 days, the corrosion depth of the cement sample was less than 2 mm, the reduction of compressive strength was low, and the corrosion resistance was strong. These research results can be used for cementing operations of high-temperature oil and gas wells containing hydrogen sulfide and dioxide. Full article

Uraniferous bitumens found in black shales from the Permian rocks at Vrchlabí in the Krkonoše Piedmont Basin (Czech Republic) were described and characterized petrologically and mineralogically. The Permian sediments originated from weathering products in metasediments and granitoids of the Krkonoše–Jizera and Orlice–Sněžník crystalline complexes. The organic matter contained up to 4.8 wt.% uranium, as uraninite grains. Elements associated with uraninite, such as Pb, Zr, Cu, and As, may have accumulated from epigenetic fluids in layers rich in organic matter during their late diagenesis. The bitumen structures were extremely heterogeneous, a feature attributed to the radiolytic effects of uranium. Amorphous bitumens, alternating with various forms of nodular and corroded bitumen types from multiple generations, were present. Low and highly altered bitumens with weak anisotropy were recognized, together with halo zones, with reflectance up to 4.37%. The halo zones differed in size, brightness, and reflectance, increasing from the edge to the center. Halos often revealed dark rims between uraninite inclusions and clear zones, originating probably as a result of weaker alterations in organic matter due to the presence of other inorganic components. Uranium concentration was the main factor controlling the degree of radiolytic alteration. The studied uraniferous bitumens are an excellent example of multistage formation and diverse evolution during burial and diagenesis. Full article

Lithium-ion batteries are today among the most efficient devices for electrochemical energy storage. However, an improvement of their performance is required to address the challenges of modern grid management, portable technology, and electric mobility. One of the most important limitations to solve is the slow kinetics of redox reactions associated to inorganic cathodic materials, directly impacting on the charging time and the power characteristics of the cells. In sharp contrast, redox polymers such as poly(2,2,6,6-tetramethyl-1-piperidinyloxy methacrylate) (PTMA) exhibit fast redox reaction kinetics and pseudocapacitors characteristics. In this contribution, we have hybridized high energy Li(Ni_xMn_yCo_z)O₂ mixed oxides (NMC) with PTMA. In this hybrid cathode configuration, the higher voltage NMC (ca. 3.7 V vs. Li/Li⁺) is able to transfer its energy to the lower voltage PTMA (3.6 V vs. Li/Li⁺) improving the discharge power performances and allowing high power cathodes to be obtained. However, the NMC-PTMA hybrid cathodes show an important capacity fading. Our investigations indicate the presence of an interface degradation reaction between NMC and PTMA transforming NMC into an electrochemically dead material. Moreover, the aqueous process used here to prepare the cathode is also shown to enable the degradation of NMC. Indeed, once NMC is immersed in water, alkaline surface species dissolve, increasing the pH of the slurry, and corroding the aluminum current collector. Additionally, the NMC surface is altered due to delithiation which enables the interface degradation reaction to take place. This reaction by surface passivation of NMC particles did not succeed in preventing the interfacial degradation. Degradation was, however, notably decreased when Li(Ni_0.8Mn_0.1Co_0.1)O₂ NMC was used and even further when alumina-coated Li(Ni_0.8Mn_0.1Co_0.1)O₂ NMC was considered. For the latter at a 20C discharge rate, the hybrids presented higher power performances compared to the single constituents, clearly emphasizing the benefits of the hybrid cathode concept. Full article

Concrete is prone to crack formation in the tensile zone, which is why steel reinforcement is introduced in these zones. However, small cracks could still arise, which give liquids and gasses access to the reinforcement causing it to corrode. Self-healing concrete repairs and seals these small (300 µm) cracks, preventing the development of corrosion. In this study, a vascular system, carrying the healing agent, is developed. It consists of tubes connected to a 3D printed distribution piece. This distribution piece has four outlets that are connected to the tubes and has one inlet, which is accessible from outside. Several materials were considered for the tubes, i.e., polymethylmethacrylate, starch, inorganic phosphate cement and alumina. Three-point-bending and four-point-bending tests proved that self-healing and multiple self-healing is possible with this developed vascular system. Full article