Search Results (636)

The development of hybrid organic coatings for corrosion protection remains a key research priority. This study focuses on synthesising Layered Double Hydroxide (ZnGa-LDHs) intercalated with environmentally friendly disodium sebacate (SB) corrosion inhibitor, forming ZnGa-SB. To overcome the challenge of limited dispersibility in organic coatings, ZnGa-SB was combined with Graphene Nanoribbons (GNR), produced through the oxidative unzipping of multi-walled carbon nanotubes (MWCNT). The resulting composite, ZnGa-SB/GNR, was synthesised using an in situ hydrothermal method and incorporated into polyurethane (PU) enamel. The synergy between high-barrier GNRs and active ZnGa-SB creates a “labyrinth effect” that effectively inhibits the diffusion of corrosive species. Microstructural analysis, including XRD, FT-IR, Raman, TGA, FE-SEM, and EDS, confirmed the nanofiller structure. The nanofillers were embedded into acrylic resin (AC) for short-term anticorrosive testing in a 0.1 M NaCl solution and then into PU for long-term evaluation in a 3.5 wt% NaCl solution, using electrochemical impedance spectroscopy (EIS). The PU/ZnGa-SB/GNR coating exhibited a high impedance modulus of 5.90 × 10⁷ Ω cm² at |Z|_0.01 Hz, even after 2688 hours of immersion, indicating enhanced corrosion resistance. This coating demonstrated superior performance in cross-cut and pencil hardness tests and sustained less damage in salt spray analysis compared to other coatings. The synergistic effect offers a promising approach for developing next-generation hybrid anti-corrosive coatings. Full article

To address the corrosion and degradation of metallic materials in seawater, tidal, and similar environments, this study employs lysine (C₆H₁₄N₂O₂) to modify graphene oxide (GO) via a hydrothermal process. The modified graphene oxide (f-GO) and poly(l-lysine) (PL) composite was characterized structurally and functionally using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) to characterize its structure and properties. A composite coating was prepared using modified graphene oxide (f-GO) and polyurethane (PU), which underwent electrochemical testing, hardness testing, corrosion rate testing, adhesion testing, impact resistance testing, and salt spray corrosion resistance testing. Experimental results indicate that C-N stretching vibration peaks appeared at all reaction temperatures. At 85 °C, f-GO85 exhibited optimal modification with a layer spacing of 1.471 nm, 72% transmittance, and superior thermal stability, confirming successful lysine grafting onto the GO surface. Corrosion resistance testing of the composite coating revealed enhanced adhesion and impact resistance, reduced corrosion rate, decreased corrosion current density in polarization curves, positive shift in corrosion potential, and higher impedance values in impedance curves, indicating improved coating density and corrosion resistance. Salt spray tests demonstrated that incorporating lysine-modified graphene oxide significantly improved the anti-corrosion performance of polyurethane coatings. Optimal corrosion resistance was achieved when the modified graphene oxide content was 0.2 wt%. Full article

In this study, the service behavior of an X65 oil and gas pipeline in seawater and production water environments was simulated by a corrosion experiment, and the influence of surface treatment (polishing and scratching) on its corrosion behavior was systematically analyzed. The corrosion resistance of the material was evaluated by means of scanning electron microscopy (SEM), an electrochemical test, and uniform corrosion rate calculations. The results show that the corrosion degree of X65 steel in an oilfield production water environment is significantly higher than that in a seawater environment. The uniform corrosion rate of the welding area is as high as 1.05 mm/y, which is more sensitive than that of the matrix material. The surface treatment has a significant effect on the corrosion behavior. The polishing treatment reduces the corrosion current density of the matrix material from 472.44 μA/cm² to 313.10 μA/cm², and the polarization resistance increases to 14.07 kΩ·cm², which effectively improves its corrosion resistance. The scratch treatment significantly reduces the corrosion resistance of the material, and the corrosion current density of the welding area at the scratch site is as high as 313.00 μA/cm², even more than that of the untreated matrix material. The study further points out that the scratches and welding areas generated during the pipeline cleaning process will significantly aggravate the tendency of local corrosion and pitting corrosion due to their microstructure heterogeneity. This study provides a clear theoretical basis and engineering guidance for the anti-corrosion design and maintenance of offshore oil and gas pipelines in complex water quality environments. Full article

In order to explore the influence of different current forms on the protection effect of cathodic protection systems for intelligent test piles of oil and gas gathering and transportation pipelines, X80 steel was taken as the research object to simulate the soil corrosion environment, and cathodic protection performance test experiments were carried out under three current forms: direct current (DC), conventional pulse (P) and high-frequency pulse (HP). Through a polarization curve test, electrochemical impedance spectroscopy (EIS) analysis, surface morphology observation and corrosion rate test, the effects of three current forms on cathodic polarization effect, polarization resistance, corrosion product composition and protection efficiency were compared. The results show that high-frequency pulse current can make the pipeline steel reach the protection potential in a shorter time, and under the same average current density, its polarization resistance is 23.6% and 15.8% higher than that of DC and conventional pulse, respectively. The anti-interference ability of conventional pulse current is better than that of DC. In the presence of stray current, the fluctuation amplitude of protection potential is only 21.1% of DC. The protection stability of DC is good, but the polarization speed is slow, and the phenomenon of “over protection” easily occurs in the process of long-term protection. Combined with economic analysis, high-frequency pulse current has significant advantages in high-corrosion-risk environments. Conventional pulse is suitable for stray current interference areas, while DC is more suitable for long-distance pipeline protection with low corrosion risk. The research results can provide a theoretical basis and technical support for the selection of the current form of pipeline cathodic protection systems. Full article

Metal materials are widely used in power grid infrastructure, but they are prone to metal corrosion due to long-term exposure to various environmental conditions, resulting in significant losses. The existing superhydrophobic coatings have good anti-corrosion performance, but poor wear resistance. Therefore, it is extremely important to improve the wear resistance of superhydrophobic coatings. In this study, a kind of fluorine-modified SiO₂ particle was prepared with pentafluorooctyltrimethoxysilane (FAS-13) as the low surface energy modifier, following the fabrication of a superhydrophobic coating on metal substrate via a PDMS-doped spray deposition method to reinforcement wear resistance property. XPS, FT-IR and Raman spectra confirmed the successful introduction of FAS-13 on SiO₂ particles, as evidenced by the characteristic fluorine-related peaks. TGA revealed that the fluorine modified SiO₂ (F-SiO₂) particles exhibited excellent thermal stability, with an initial decomposition temperature of 354 °C. From the perspective of surface morphology, the relevant data indicated a peak-to-valley height difference of only 88.7 nm, with Rq of 11.9 nm and Ra of 8.86 nm. And it also exhibited outstanding superhydrophobic property with contact angle (CA) of 164.44°/159.48°, demonstrating remarkable self-cleaning performance. And it still maintained CA of over 150° even after cyclic abrasion of 3000 cm with 800 grit sandpaper under a 100 g load, showing exceptional wear resistance. In addition, it was revealed that the coated electrode retained a high impedance value of 8.53 × 10⁸ Ω·cm² at 0.1 Hz after 480 h of immersion in 5 wt% NaCl solution, with the CPE exponent remaining close to unity (from 1.00 to 0.97), highlighting its superior anti-corrosion performance and broad application prospects for metal corrosion prevention. Full article

Salt permeation erosion is a key factor leading to the deterioration of service performance and shortening the lifespan of asphalt pavement in salt-rich areas. In this environment, the combined action of water and salt accelerates the decline in the asphalt–aggregate interface, leading to distress, such as raveling and loosening, which severely limit pavement durability. The authors systematically reviewed the research progress on asphalt–aggregate adhesion in a saline corrosion environment and discussed the complex mechanisms of adhesion degradation driven by intrinsic factors, including aggregate chemical properties, surface morphology, asphalt components, and polarity, as well as environmental factors, such as moisture, salt, and temperature. We also summarized multi-scale evaluation methods, including conventional macroscopic tests and molecular dynamics simulations, and revealed the damage evolution patterns caused by the coupled effects of water, salt, heat, and mechanical forces. Based on this, the effectiveness of technical approaches, such as asphalt modification and aggregate modification, is explored. Addressing the current insufficiency in research on asphalt adhesion under complex conditions in salt-rich areas, this study highlights the necessity for further research on mechanisms of multi-environment interactions, composite salt erosion simulation, development of novel anti-salt erosion materials, and intelligent monitoring and early warning, aiming to provide a theoretical basis and technical support for the weather-resistant design and long-term service of asphalt pavement in salt-rich regions. Full article

To evaluate the slip resistance of high-strength bolted friction-type connections subjected to different corrosion-protection treatments, calibration tests were performed on six representative faying-surface conditions: sand-blasted (uncoated), epoxy zinc-rich primer, waterborne inorganic zinc-rich coating, alcohol-soluble inorganic anti-corrosion anti-slip primer, a complete multi-layer protective coating system, and cold galvanizing. Fifteen test groups comprising 45 tensile specimens were examined to determine slip factors, which were then compared with values recommended in domestic and international design standards. The results show that sand-blasted surfaces (W type) exhibit stable slip factors of μ = 0.43–0.45; alcohol-soluble inorganic primer surfaces (S type) provide the highest slip resistance with μ = 0.49–0.51, representing an increase of approximately 13%–18% compared with sand-blasted surfaces; and cold-galvanized surfaces (D type) achieve favourable performance with μ ≈ 0.44. Waterborne inorganic zinc-rich surfaces (A type) yield μ ≈ 0.33, corresponding to a reduction of about 25%, and are suitable for non-slip-critical connections. In contrast, epoxy zinc-rich primers (C type) and complete multi-layer coating systems (X type) present lower slip factors of μ = 0.26–0.28 and μ ≈ 0.23, corresponding to reductions of approximately 35%–45% and about 50%, respectively, indicating that the X-type treatment is unsuitable for slip-critical applications. The influence of bolt diameter is limited, with slip-factor variations within 5%–8% under the same surface condition, and no statistically significant effect confirmed by two-way ANOVA. These findings provide a quantitative experimental basis for the design, classification, and future standardization of friction-type bolted connections with coated faying surfaces. Full article

Superhydrophobic surfaces have gained considerable attention due to their ability to repel water and reduce surface adhesion, and they are now widely applied for self-cleaning, anti-fouling, anti-icing, and corrosion resistance purposes. In this study, either a computer numerical control (CNC) machine or photolithographic techniques were employed to fabricate molds with microwells, followed by soft lithography to obtain a polydimethylsiloxane (PDMS) micropillar array. An etching process was then carried out. It was found that, as etching time increased, the diameters of micropillars decreased, leading to a decrease in the solid fraction of the composite surface and increases in contact angles. When the ratios of spacing to diameter (W/D) and of height to diameter (H/D) both exceeded 1.5, the contact angle was found to exceed 150° and the original PDMS micropillar surface with a contact angle of around 135° became superhydrophobic. A drastic decrease in sliding angle was also observed at this threshold. Changes in contact angles with different W/D values were in good agreement with values calculated using the Cassie–Baxter equation, and the droplet state was verified by a pressure balance model. Meanwhile, the PDMS etching rate when using acetone as the solvent was approximately 6–8 times faster than that when using 1-Methyl-2-pyrrolidone (NMP), a result which is comparable to data in the literature. Full article

Antifouling coatings have to provide antibacterial performance combined with good mechanical and chemical properties. The good anticorrosive performance of tannins on steel surfaces and antibacterial activity of phytochemicals from conifers could provide a solution in the form of Scots pine bark extract. In this study, epoxy compositions with different ratios of the characterised extract (TPC, HPLC analysis of phytochemicals) were tested physically (density), mechanically (Shore D hardness, three-point bending test, Charpy impact test), chemically (DSC curing analysis, FTIR spectroscopy, chemical resistance), and microbiologically (antibacterial activity). The results were analysed and the performance of the composites was evaluated. Full article

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

The research and development of new accident-tolerant fuel cladding materials has emerged as a critical focus in international academic and engineering fields following the Fukushima nuclear accident. Due to the outstanding resistances in corrosion and radiation as well as high-temperature creep properties, oxide dispersion-strengthened (ODS) FeCrAl alloys have been studied extensively during the past decade. Current review articles in this field have primarily focused on the effects of chemical composition on the anti-corrosion performance and species of nano-oxide. However, several key issues have not been given adequate attention, including processing methods and parameters, high-temperature stability mechanisms, post-deformation microstructural evolution and high-temperature mechanical properties. This paper reviews the progress of basic research on ODS FeCrAl alloys, including preparation methods, the effects of preparation parameters, the thermal stability and irradiation stability of oxides, the microstructural deformation, and the mechanical properties at elevated temperatures. The aspects mentioned above not only provide valuable references for understanding the effects of preparation parameters on the microstructure and properties of ODS FeCrAl alloys but also offer a comprehensive framework for the subsequent optimization of ODS FeCrAl alloys for nuclear reactor applications. Full article

Hexavalent chromium [Cr(VI)] is the toxic form of chromium often used in industry for its hardness, bright colors, and anticorrosive properties. Cr(VI) is a known human lung carcinogen, making its inhalation an occupational hazard. Growing evidence emphasizes the neurotoxic potential of Cr(VI), though it is not linked to brain cancers. Few studies consider neurotoxicity in chromate workers, reporting impaired olfactory discrimination and an increased risk of death from mental health disorders. A major factor limiting translation of most rodent Cr(VI) studies to human populations has to do with vitamin C, which can reduce the toxic Cr(VI) to non-toxic Cr(III). Rats and mice synthesize vitamin C and are likely more resistant to Cr(VI) than humans. Here, we considered Cr(VI) neurotoxicity in guinea pigs (Cavia porcellus), which do not endogenously synthesize vitamin C. We exposed Hartley guinea pigs (both sexes) to occupationally relevant concentrations of Cr(VI) via oropharyngeal aspiration weekly for 90 days. We observed behavioral effects in the open field assay, elevated plus maze, Y-maze, and novel object recognition test during weeks 9–12 of exposure. After euthanasia, we assessed Cr accumulation and essential metal dyshomeostasis in the hippocampus. We observed significantly increased hippocampal Cr accumulation in females, while males exhibited essential metal dyshomeostasis. Full article

Sulfonate greases, which have excellent performance characteristics—high dropping point, good mechanical and structural stability, water resistance, high thermal oxidation stability, and good anticorrosive properties—are widely used in various industries. The greases are exposed to water during operation: moisture in the environment, water-based coolants, operation in the presence of water vapor, etc. Water can affect the properties of the greases during operation. The subject of the study was a commercial complex grease thickened with overbased calcium sulfonate, with a water additive in amounts ranging from 1% to 50% by weight. This paper presents two standardized methods for testing the thermal oxidation stability of lubricants—according to ASTM D942 and ASTM D8206, in standard programs, and with an extension of oxidation duration to 100 h and a temperature increase to 100 °C. The aim of the study was to investigate how the addition of water affected the thermal oxidation stability of this grease. The presentation concludes with an analysis of FTIR differential spectra. The tests showed that as the water content in the grease samples increased, its resistance to oxidation decreased. Water also caused a change in the consistency of the grease at a concentration of just 1% by weight. Mechanical stress affected the thermal oxidation stability of the grease tested. Each method presented separate mechanisms of oxidation initiation, including different sample quantities during the test, the presence of water in the classic method, and different contact with oxygen as a catalyst for this reaction. The work provided a comprehensive presentation of the possibilities for testing the thermal oxidation resistance of greases and a detailed comparison of the two methods. Full article

To address the issues of insufficient protection and poor durability in concrete during service, this study developed a novel polymer–silicate composite gel system by combining silane with fluorocarbon resin emulsion and applied it to mortar specimens. The chloride ion resistance enhancement of mortar provided by the novel gel system was evaluated using the RCM method and natural chloride ion penetration tests, with SEM images employed to analyze its anti-permeation mechanism. Results indicate that the chloride ion migration coefficient of the novel composite gel system is 4.91 × 10⁻¹² m²/s, representing a 63.97% reduction compared to the single fluorocarbon gel system. Within the 0–5 mm depth range, free chloride ion contents at 14, 28, and 56 days decreased by 55.35%, 50.10%, and 43.64%, respectively, demonstrating excellent resistance to chloride penetration. Acid and alkali resistance tests demonstrated that the system retained the inherent corrosion resistance of the fluorocarbon component. Carbonation tests demonstrated that the system exhibited a slight decrease in carbonation resistance compared with the pure fluorocarbon gel system, while still maintaining a satisfactory performance level. Overall, the polymer-silicate composite gel system significantly enhanced the mortar’s resistance to chloride ion penetration. Full article

Pre-coated metal sheets (PCM), as a popular product in modern coating industries, offer significant advantages such as simple processing, lightweight properties, and excellent manufacturability. The pretreatment layer within its coating system has a significant impact on overall corrosion resistance. In this study, through a comparative analysis of two chromate-free pretreatment systems, we conducted a thorough investigation into the combination of the pretreatment layer and examined the impact on the corrosion performance of pre-coated metal sheets. It was found that the phytic acid-based pretreatment layer enhances the adhesion between the primer and the substrate by forming strong chemical bonds with the primer layer, which effectively inhibits the lateral diffusion of corrosive media to the metal surface. Consequently, pre-coated metal sheets with the phytic acid-based pretreatment exhibit superior anti-foaming performance compared to the system using the silane-based pretreatment layer. This provides a new insight into the design and development of Cr-free pretreatment systems with better corrosion resistance performance. Full article