In order to improve the wettability of polymer surfaces, oxygen plasma modification technology was used to treat the surface of polyethylene terephthalate (PET) under the condition of 200 W for 90 min using sample holders with inclination angles of 30°, 45° and 60°.The nanostructures with tilt angles and lengths of 32.5° and 2.36 μm,45.2° and 2.15 μm,59.5° and 2.00 μm were prepared, respectively.Anisotropic wetting of liquid droplets and directional flow behavior of liquid were studied on the PET surfaces after modified by plasma.Additionally,the direction opposite to the tilted nanostructure was referred to as the Y+direction, the direction along the tilted nanostructure was referred to as the Y- direction, and the direction perpendicular to Y± was referred to as the X± direction.Results showed that the contact angle of the droplet on the PET surfaces modified by plasma decreased, and the wetting length increased with the increase of inclination angle of the sample holders.Meanwhile, the static contact angle of the droplet in the X± direction was greater than that in the Y± direction,and the wetting length in the X± direction was smaller than that in the Y± direction.Continuous water injection was carried out on the PET surfaces modified by plasma.The droplets were pinned in the Y- direction and flowed in the Y+direction.Furthermore, the average flow velocities of droplets on the plasmamodified surface at 30°,45° and 60° inclination angles were 0.017 0,0.021 0 and 0.022 7 mm/s,respectively.Among them,the droplets on the PET surfaces after modified by plasma at 60° inclination angle had a flow velocity of 2.39 times that of the original surfaces in the Y+direction.
The use of additives facilitates the deposition of copper on metal substrates.In this work,using choline chloride glacial acetic acid(Ch Cl-Gl A) as a low eutectic solvent and copper acetate as the main salt, the effects of ascorbic acid(C6H8O6), disodium ethylenediamine tetraacetic acid(EDTA-2Na) and diethylenetriaminepentaacetic acid(DTPA) as additives on electrodeposition of copper on iron substrate were investigated.Electrochemical behavior was studied by cyclic voltammetry (CV) and chronoamperometry (CA); scanning electron microscopy(SEM) and X-ray diffraction(XRD) were used to observe and analyze the morphology and composition of the coating.The UV-visible absorption spectrum of the complex formed in the electrodeposited solution with different additives was analyzed by a UV-Vis-NIR spectrophotometer.Results indicated that in Ch Cl-Gl A, the electrodeposition of copper involved two steps of oxidation-reduction with the first step of Cu2+→Cu+and the second step of Cu+→Cu.All three additives promoted the deposition of copper in Ch Cl-Gl A,and ascorbic acid had the best effect,which could obtain a copper coating with good performance at room temperature.The electrodeposition of copper in Ch Cl-Gl A followed a three-dimensional instantaneous nucleation process and was an irreversible reaction controlled by diffusion.Moreover,the diffusion coefficients of Cu2+and Cu+could reach 4.003 9×10-7cm2/s,4.762 7×10-7cm2/s,respectively.The copper crystal prepared with ascorbic acid as additive was a polygonal sheet-like structure with distinct grains,and the optimal crystal plane was the (111) crystal plane.Besides,the average grain sizes of the copper layer with additives DTPA,EDTA-2Na and C6H8O6were 50.71,55.12 and 52.73 nm.The average grain size of the copper layer without additive was 44.73 nm.
The active properties,easy oxidation and poor corrosion resistance of AZ31 magnesium alloy have always been the biggest challenges in its practical application.In order to improve its corrosion resistance, reduce the corrosion rate and prolong its service life, a stable and corrosion-resistant aluminum phosphate-polymethyl methacrylate (AP/PMMA) superhydrophobic coating was prepared on the surface by impregnation method.The microstructure, chemical composition, phase composition and molecular structure of the coating were analyzed by scanning electron microscope (SEM),X-ray energy dispersive spectrometer (EDS),X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FTIR).Moreover, the hydrophobicity and corrosion resistance were tested by contact angle meter (CA), Tafel curve and EIS.Results showed that with the increase of immersion time, the contact angle (WCA) of the coating increased first and then decreased.The surface contact angle of the coating prepared by the 60 s immersion sample could reach 154.7 °, showing superhydrophobicity.The surface corrosion current density was 2.289 × 10-9A/cm2, which was 4 orders of magnitude lower than that of the magnesium substrate.The corrosion potential was increased from-0.941 V to-0.735 V after polishing, indicating that the AP/PMMA superhydrophobic coating could effectively improve the corrosion resistance of AZ31 magnesium alloy.
Wind turbine blades of coal-fired thermal power plants are not only subject to erosion from SOxand NOxdue to incomplete desulfurization and denitrification during service, but also face corrosion from coastal salt spray.In addition, in the high-temperature flue gas atmosphere, the abrasion of wind turbine blades will be accelerated after collision with high ash corrosive particles in the combustion environment.In order to improve the corrosion resistance and wear resistance of wind turbine blades,the “two-step” oxygen -acetylene flame welding technology was used to prepared Ni60A +WC spray welded layers on the surface of Q355D low alloy steel substrate, and the wear resistance and corrosion resistance of spray welded layers with different mass fraction of WC hard phase in three corrosion solutions were evaluated by means of wear test and electrochemical test.Results showed that Ni60A+WC spray welded layer could significantly improve the wear resistance and corrosion resistance of the wind turbine blades, and played a good protective role.When the mass fraction of WC hard phase was 65%Ni60A+35%WC,the spray welded layer had the best wear resistance and corrosion resistance;Moreover,the spray welded layer had the best corrosion resistance to Cl-, but poor corrosion resistance to sulfides and nitrides.The initiation and propagation of cracks caused by high-speed particles and the formation of fatigue sources were the main mechanisms of wear failure in spray welded layers.In particular, the galvanic corrosion between hard phases and carbides and the substrate was the main corrosion mechanism of the spray welded layer, and the corrosion failure mode of the spray welded layer was selective corrosion.This work has certain reference significance for further extending the service life and cost saving of fan blades in thermal power plants.
For improving the corrosion resistance of carbon steel surfaces, a phosphorus free and chromium free fluorozirconic acid composite oligomeric silsesquioxane conversion film was prepared using fluorozirconic acid composite amino/hydroxyl polyhedral oligomeric silsesquioxane(NH2/OH-POSS).The corrosion resistance, surface morphology and composition of the composite film were characterized by saltwater immersion, electrochemical testing, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).Results showed that the optimal process for the fluoro-zirconate solution combined with the NH2/OH-POSS aqueous solution was 1.2 g/L fluorozirconic acid, 4.5 g/L oligomeric silsesquioxane, pH of 4, the temperature of 30 ℃, the passivation time of 2 min.The saltwater immersion test and electrochemical test indicated that the corrosion resistance of the composite conversion film was significantly improved compared to the pure fluorozirconic acid conversion film.SEM results revealed that the addition of oligomeric silsesquioxane filled the cracks and pores in the fluoro-zirconate film,making the film denser.XPS results confirmed that both oligomeric silsesquioxane and fluoro-zirconate participated in the formation of the conversion film.
In order to investigate the aging behavior of acrylic polyurethane coatings in environments with high ultraviolet radiation intensity and large temperature differences, the aging processes of water-based and solvent-based acrylic polyurethane coatings were studied using UV-high and low-temperature artificial accelerated aging methods.Techniques such as super depth-of-field imaging, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and energy-dispersive spectroscopy (EDS) were employed to analyze the changes in microscopic morphology, molecular structure and elemental atomic fraction on the surfaces of the coatings.The performance changes and aging patterns of solvent-based and water-based coatings during the aging process were examined through electrochemical impedance spectroscopy (EIS), water contact angle measurements, adhesion strength tests and glossiness assessments.Results showed that the water-based acrylic polyurethane coating system exhibited cracking, whereas the solvent-based coating system exhibited layering.Both coatings experienced significant reductions in glossiness, water contact angle and adhesion strength.The aging rate of the two coating systems initially increased rapidly and then slowed down, with an early appearance of the rate transition inflection point.Infrared spectroscopy analysis indicated that both coatings shared similar aging mechanisms, while EDS analysis demonstrated a faster aging rate for the water-based coating.Additionally, the weight of each performance index was calculated by entropy method, and the comprehensive aging grade under the test was obtained, which verified that the solventbased acrylic polyurethane coating system had relatively good weather resistance.
High Entropy Alloys (HEA) are a new type of metal material with broad application prospects in the high-end equipment manufacturing industry.Due to the unique phase structure and “four major effects” of high entropy alloys, which endow them with excellent mechanical properties such as strength,hardness,toughness and wear resistance,high entropy alloys have become a research hotspot in the field of materials.Corrosion is a common and unavoidable form of failure in metallic materials,and high entropy alloys are widely used in industrial fields due to their excellent corrosion resistance.Thus, it is necessary to focus on studying the corrosion resistance performance, corrosion resistance mechanism and laws of high entropy alloys for better developing high-performance high entropy alloys.This article firstly briefly described the definition and classification of high entropy alloys, then summarized the preparation methods of high entropy alloys, and provided a detailed overview of the research status of high entropy alloy corrosion resistance.Different preparation processes and process parameters had a direct impact on the microstructure of high entropy alloys, and high entropy alloy components had broad design space.Therefore, by adjusting the preparation process parameters and component composition, the corrosion resistance of high entropy alloys could be further optimized.At last,the research topics and ideas for future high entropy alloys were discussed.
In recent years, achieving “near zero emissions” of high salt drilling and production wastewater in oil and gas fields has become the primary approach for its treatment, aiming to protect the environment while enabling resource recovery and reuse.Evaporation and concentration, as a common method for brine separation, may cause scaling on heat transfer surfaces during the evaporation process, due to the presence of various impurity salts in the wastewater.Hence, how to effectively prevent scaling and improve evaporation efficiency has become a research focus in the industry.Herein, this paper reviewed the technological advancements in calcium and magnesium scaling prevention at home and abroad from three perspectives: physical processes, coating materials and chemical antiscaling methods.The underlying mechanisms and current challenges were summarized and analyzed.Furthermore, the development direction of scale inhibition technology was prospected, and research ideas for efficient scale inhibition in the future were provided.
Organic high molecular polymer superhydrophobic coatings have a wide range of material choices, high comprehensive performance,simple preparation methods, and are easy to realize large-scale industrial applications,making them the most likely superhydrophobic materials to be widely promoted.Herein, this paper briefly summarized the design principles of superhydrophobic coatings, reviewed the research progress on several major types of high molecular polymer-based superhydrophobic coatings and their properties both domestically and internationally,and identified the factors limiting their application along with potential solutions.The key to achieving practical applications of organic polymer superhydrophobic coatings lied in ensuring their stability, resistance to environmental damage and excellent comprehensive performance.Thus, gradient design of coatings, high-polymer structure design and optimization of coating application and curing conditions were important pathways to achieve high-performance superhydrophobic coatings.
Laser weapons have entered the actual combat application stage, and the research on anti-laser protection for air and space weapons is becoming increasingly urgent.Prolonged high-energy laser irradiation leads to problems such as reduced metal reflectance,mass loss of ablated layer of the ablative layer and insufficient heat insulation toughness.Based on this,a composite laser protection strategy based on the principles of reflection and heat insulation was proposed.In this study, by adjusting spraying power, spraying distance and other parameters, supersonic flame spraying technology and plasma spraying technology were used to prepare NiCoCrAlTaY bond coating and yttria-stabilized zirconia(YSZ) top coating double-layer coatings, to explore the influence of surface roughness and porosity on reflectivity, and to investigate the laser protection performance of the coatings.Results showed that the larger the spraying power or spraying distance, the more obvious the layer effect, and the more cross-sectional pores were observed in the coating.The surface roughness of the coating decreased first and then increased with the increase in spraying distance.When the secondary reflection structure was removed, the coating surface hadRa=1.8 μm.WhenRa=0.5 μm, the wedge-shaped structure of the coating increased the reflectivity by about 2.4%compared to that of the coating whenRa=1.8 μm.It was pointed out that the layered pores were key to the high-reflection wedge structure, the spherical voids were the laser absorption points,and the process parameter of 14.7%porosity (39 kW,100 mm) was the best.In the laser ablation experiment,with the increase in laser power density, the cracks in the coating gradually increased until holes were ablated.The line ablation rate increased approximately in a parabolic manner.With low laser power density (<3 800 W/cm2), the surface structure changed slightly; as the power increased, the surface cracks increased and deepened, and the petal-like structure in the recondensing zone increased.With high laser power density (>8 050 W/cm2), partial peeling and ablation of the coating surface caused the coating to fail.
Metal alloys are subjected to molten salt corrosion in concentrating solar thermal power systems, leading to a reduction in their lifetime.In order to extend the service life of Incoloy 800H alloy in molten carbonate salt corrosion, Incoloy 800H alloys with varying aluminum(Al) and chromium (Cr) contents were prepared by vacuum induction melting.The corrosion mechanisms of Al and Cr elements on the resistance of 800H alloy to molten carbonate salt corrosion were investigated through analysis and testing methods such as X-ray diffraction (XRD),scanning electron microscopy (SEM) and transmission electron microscopy (TEM).Results showed that the corrosion rate of Incoloy 800H alloy with 3%(mass fraction, the same below) Al content was 1 071.00 μm/a, while that with 2.75%Cr content was 359.56 μm/a after immersion in carbonate molten salt (32.1%Li2CO3+33.4%Na2CO3+34.5%K2CO3) at 650 ℃for 240 h.The corrosion products were mainly LiFeO2and NiO.This was attributed to the fact that as the Al content increased, the oxide passivation film formed on the surface of the alloy became thicker and denser, providing better protection.The reduction of Cr content led to a decrease in the generation of soluble Cr oxides, an increase in the formation of other protective oxides, and a reduction in the precipitation of Fe elements in the substrate, thus improving the alloy’s corrosion resistance.
In order to investigate the effect of ion magnetron sputtering parameters on the scanning electron microscopy (SEM) images of nonconductive materials with different surface properties, the advantages and limitations of various ion magnetron sputtering conditions, including target material, sputtering time and sputtering cycles were studied, along with their applicable ranges.Results showed that the gold target exhibited good continuity with large grain nucleation of gold.Due to its high sputtering energy, it easily caused thermal loss on the sample surface, and the gold grains adhered to the surface.Therefore, gold targets were found to be suitable for low -magnification SEM imaging(<10 000) and materials with a certain surface hardness.In contrast, the platinum target showed poor continuity with small platinum grain nucleation and lower sputtering energy.It was more likely to embed into the sample surface, forming a morphological framework, making it suitable for high-magnification SEM imaging (>30 000) and most non-conductive materials.Using a method of fewer, multiple ion magnetron sputtering cycles, reducing the sputtering cycles appropriately not only weakened the effect of the gold film on the material’s morphology and structure but also helped conserve resources and protect the environment.This result provides experimental guidance for researchers to scientifically and accurately analyze SEM images of samples.
In order to effectively reduce the occurrence of pollution flashover accidents caused by surface contamination of transmission line insulators, a new fluorocarbon coating material was prepared by combining modified nano-TiO2, PTFE and fluorocarbon resin FEVE using compressed air spraying technology.The optimum addition amount of modified TiO2particles was discussed.The microstructure was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM).The hydrophobicity, self-cleaning properties and anti-ultraviolet aging resistance were analyzed using a contact angle measurement instrument.The results showed that the optimum addition amount of modified nano-TiO2was 4%,the adhesion of the coating reached grade 0,and the maximum static contact angle was 121°.The surface of the anti-pollution flashover composite coating prepared with modified TiO2exhibited numerous micro-nano scale columnar cone tip structures, resulting in higher roughness.Its hydrophobicity, self-cleaning ability, and anti-ultraviolet aging resistance were improved, demonstrating excellent antipollution flashover performance.
To further improve the service life of the films in the marine environment,NiCrN films with different substrate bias voltages were deposited on a 304 stainless steel substrate by arc ion plating technology.The effects of the substrate bias voltage on the composition, microstructure, mechanical properties and corrosion resistance of the films were systematically investigated using scanning electron microscopy (SEM),X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation, multifunctional surface properties tester and electrochemical workstation methods.Results showed that the films were primarily composed of metallic Cr, metallic Ni and CrN ceramic phases.As the bias voltage amplitude increased, the thickness and hardness of the films increased, then decreased.When the bias voltage amplitude was-150 V, the hardness reached the maximum value of 2 030 HV.When the substrate bias amplitude was-50 V, the film had the best wear resistance,and the wear rate was the lowest.The corrosion potential of the film shifted positively with the increase of substrate bias amplitude,and the corrosion current density was gradually reduced.When the bias amplitude was-150 V, the corrosion resistance of the film was the best.
Since the western part of the Sulige Gas Field is a water-bearing gas reservoir, the pipelines are prone to corrosion, which severely affects the normal production operations of the gas field and results in significant economic losses and safety risks.In this study, the corrosion of gathering and transportation pipelines in the target gas field was analyzed.Based on this analysis, corrosion coupon experiments, scanning electron microscopy (SEM), confocal Raman microscopy and X-ray diffraction (XRD) techniques were employed, combined with water and gas quality analyses, to investigate the corrosion patterns of the pipelines.The primary controlling factors of corrosion, including chloride ions,microorganisms, CO2partial pressure, total pressure and flow rate, were identified.Furthermore, the weight of each controlling factor was determined according to different corrosion characteristics.Results showed that when uniform corrosion of the samples was used as the evaluation criterion, the CO2partial pressure had the greatest influence on the corrosion rate, accounting for 58.00%of the weight.When pitting corrosion of the samples was used as the evaluation criterion, microorganisms had the greatest influence on the corrosion rate, accounting for 34.00%of the weight.
The B10 copper-nickel alloy pipeline used for seawater transportation on a certain platform was found to have corrosion perforation at the weld joint between the elbow and the flange during a shutdown inspection.In this study, the failure mechanism of corrosion perforation was analyzed using macroscopic morphology observation,scanning electron microscopy (SEM),energy-dispersive spectroscopy (EDS),X-ray diffraction (XRD) and metallographic examination.Results showed that “sugar cube”-like intergranular corrosion morphologies were commonly observed at the bottom of corrosion pits on the flange, in erosion-wear areas, corrosion grooves, perforated regions and at the bottom of corrosion pits on the elbow.Locally, a “stepped” exfoliation morphology was observed, where grains were progressively stripped layer by layer.The preferentially corroded grain boundaries formed a circuit, and the surrounded grains were selectively denickelized and dissolved, resulting in grain spalling.The reduced hardness and coarse columnar grain structure of the flange further decreased the material’s corrosion resistance.The corrosion perforation of the copper-nickel alloy pipeline occurred in the erosion-sensitive zones and the weld heat-affected zones with the poorest corrosion resistance.This failure was the result of the synergistic effects of erosion wear, intergranular corrosion and selective dealloying.Enhanced corrosion monitoring is recommended for similar locations in service pipelines.
Through long-term corrosion monitoring of the air-foam flooding injection well string on site, the corrosion characteristics of the inner and outer walls of J55 tubing at the upper and lower well sections in the air-foam flooding test area injection well environment were studied.The morphologies of the corrosion products were characterized by SEM and 3D confocal microscopy, and the compositions of the corrosion products were analyzed by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis.Furthermore, the corrosion mechanism was explored and discussed.The results showed that J55 oil pipe had severe overall corrosion and varying degrees of localized corrosion, with more severe corrosion in the downhole section.The corrosion products on the inner and outer surfaces of different sections of the tubing were different, mainly including Fe0.925O,FeSx,Fe3O4and FeO(OH).The structure of carbon steel tubing might form cracks and be transgranular micro-cracking during the service of air-foam flooding.
In the deep repair process of aircraft wing endplates, spoiler and other parts, the efficient removal of foam adhesive without damaging the aluminum alloy has been paid much attention in the field of aviation repair.In this study,the cured products of foam adhesive were analyzed using infrared spectroscopy and thermogravimetric analysis.Based on the swelling theory, dichloromethane was identified as the primary solvent for the adhesive remover.TiO2-modified SiO2nanocapsules were introduced into dichloromethane as adsorbents and slow-release agents to reduce VOC emissions, extend the operating time of the adhesive remover, and improve its performance through mechanisms such as physical adsorption, physical isolation and slow release.Meanwhile, paraffin and polyethylene sheets were used as surface barriers, and Halox630 corrosion inhibitor was added to the formulation of the adhesive remover to effectively reduce the volatilization of the remover and the corrosion of the substrate.Results showed that the developed foam adhesive remover exhibited excellent degumming performance on residual foam adhesive on the surface of aluminum alloy, as well as outstanding softening and swelling effects on thermosetting adhesives.
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