Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon ...Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.展开更多
To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstru...The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.展开更多
Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and neg...Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and negative charges renders the zwitterion-based materials with electrostatically induced hydration properties, which enables a high resistance towards oily pollutants, nonspecific protein adsorption, bacterial adhesion and biofilm formation. This review starts from the working mechanism of zwitterions and covers the fabrication strategies of zwitterion-based functional coatings, namely the zwitterion-bearing binder route, the zwitterion-bearing additive route and the post-generation of coatings containing zwitterionic precursors. The applications of zwitterion-based functional coatings are discussed, including medical implants, marine antifouling and oil-resistant coatings, with focus on the relevant mechanisms of the zwitterion-containing coatings for a specific performance. Finally, some comments and perspectives on the current situation and future development of zwitterion-based functional coatings are given.展开更多
Low alloy steels are widely used in bridges,construction,chemical and various equipment and metal components due to their low cost and excellent mechanical strength.Information in the literature related to the prepara...Low alloy steels are widely used in bridges,construction,chemical and various equipment and metal components due to their low cost and excellent mechanical strength.Information in the literature related to the preparation,advantages and disadvantages,and applications along with research progress of various types of protective coatings suitable for low-alloy steel surfaces is reviewed,while a conclusive and comparative analysis is also afforded to the numerous factors influencing the protective ability of coatings.The characteristics of coatings drawn from the latest published literature are discussed and suggest that the modification of traditional metal coatings and the development of new organic coatings under the consideration of environmental protection,low cost,simplicity and large-scale industrial application are simultaneously proceeding,which holds promise for improving the understanding of corrosion protection in related fields and helps to address some of the limitations identified with more conventional coating techniques.展开更多
The presence of clay coatings on the surfaces of quartz grains can play a pivotal role in determining the porosity and permeability of sandstone reservoirs,thus directly impacting their reservoir quality.This study em...The presence of clay coatings on the surfaces of quartz grains can play a pivotal role in determining the porosity and permeability of sandstone reservoirs,thus directly impacting their reservoir quality.This study employs a multiphase-field model of syntaxial quartz cementation to explore the effects of clay coatings on quartz cement volumes,porosity,permeability,and their interrelations in sandstone formations.To generate various patterns of clay coatings on quartz grains within three-dimensional(3D)digital sandstone grain packs,a pre-processing toolchain is developed.Through numerical simulation experiments involving syntaxial overgrowth cementation on both single crystals and multigrain packs,the main coating parameters controlling quartz cement volume are elucidated.Such parameters include the growth of exposed pyramidal faces,lateral encasement,coating coverage,and coating pattern,etc.The coating pattern has a remarkable impact on cementation,with the layered coatings corresponding to fast cement growth rates.The coating coverage is positively correlated with the porosity and permeability of sandstone.The cement growth rate of quartz crystals is the lowest in the vertical orientation,and in the middle to late stages of evolution,it is faster in the diagonal orientation than in the horizontal orientation.Through comparing the simulated results of dynamic evolution process with the actual features,it is found that the simulated coating patterns after 20 d and 40 d show clear similarities with natural samples,proving the validity of the proposed three-dimensional numerical modeling of coatings.The methodology and findings presented contribute to improved reservoir characterization and predictive modeling of sandstone formations.展开更多
Oxidation behavior of NiCrAlY nanocrystalline coatings with different Cr contents at 1050 and 1150℃is investigated.The results indicate that Al2O3 scales can be formed on NiCrAlY nanocrystalline coatings after oxidat...Oxidation behavior of NiCrAlY nanocrystalline coatings with different Cr contents at 1050 and 1150℃is investigated.The results indicate that Al2O3 scales can be formed on NiCrAlY nanocrystalline coatings after oxidation at high temperature.And their formation and thickening cannot be affected by the change of Cr contents in NiCrAlY coatings.During service,Cr in the coating can affect the microstructure of Ni-based single crystal superalloy.At 1050℃,Cr in the coating can diffuse into the superalloy,destroy its microstructure,and lead to the formation of interdiffusion zone and the precipitation of needle-like topologically closed-packed phase.The higher the Cr content in NiCrAlY the coating is,the more obvious the phenomenon is.However,after oxidation at 1150℃for 100 h,no obvious changes were observed in the microstructure of CMSX-4 single crystal superalloy beneath the three kinds of NiCrAlY nanocrystalline coatings.展开更多
A novel NiAlTa blade tip protective coating is designed and its oxidation,hot corrosion,and interdiffusion with DD5 single-crystal superalloys are investigated.NiAlTa coatings exhibit low oxidation rates.The dragging ...A novel NiAlTa blade tip protective coating is designed and its oxidation,hot corrosion,and interdiffusion with DD5 single-crystal superalloys are investigated.NiAlTa coatings exhibit low oxidation rates.The dragging effect of Ta on Al hinders the external diffusion of Al.Ta that accumulates at the Al_(2)O_(3)grain boundaries reduces the internal diffusion of O by combining or reacting with it.NaCl aggravates the hot corrosion through self ustaining cycles of chlorination/oxidation.β-NiAl phase fails first as a diffusion channel for the corrosive medium.Significant element interdiffusion occurs.An interdiffusion zone and a secondary reaction zone are formed.Interdiffusion changes the percentage of elements,causing a phase transition of the coating.The volume change caused by the phase transition induces bulging and cracking of the oxide film.Furthermore,the oxidation,hot corrosion,and interdiffusion mechanisms are discussed.展开更多
The corrosion degradation of organic coatings in tropical marine atmospheric environments results in substantial economic losses across various industries.The complexity of a dynamic environment,combined with high cos...The corrosion degradation of organic coatings in tropical marine atmospheric environments results in substantial economic losses across various industries.The complexity of a dynamic environment,combined with high costs,extended experimental periods,and limited data,places a limit on the comprehension of this process.This study addresses this challenge by investigating the corrosion de-gradation of damaged organic coatings in a tropical marine environment using an atmospheric corrosion monitoring sensor and a random forest(RF)model.For damage simulation,a polyurethane coating applied to a Fe/graphite corrosion sensor was intentionally scratched and exposed to the marine atmosphere for over one year.Pearson correlation analysis was performed for the collection and filtering of en-vironmental and corrosion current data.According to the RF model,the following specific conditions contributed to accelerated degrada-tion:relative humidity(RH)above 80%and temperatures below 22.5℃,with the risk increasing significantly when RH exceeded 90%.High RH and temperature exhibited a cumulative effect on coating degradation.A high risk of corrosion occurred in the nighttime.The RF model was also used to predict the coating degradation process using environmental data as input parameters,with the accuracy show-ing improvement when the duration of influential environmental ranges was considered.展开更多
Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/met...Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/methodology/approach–In this context,the aim was to determine the optimal adhesion parameters for bonding GFRP samples with natural and primed surfaces to steel samples with cataphoresis coatings.Then,single-lap joint samples with different bond thicknesses of 1 mm,2 mm and 3 mm were prepared.Finally,tensile tests were performed on the samples.Findings–The results showed that GFRP specimens with natural surfaces,characterised by the highest surface roughness,exhibited the lowest bond strength.But,the highest bonding performance was achieved in specimens where primed GFRP was bonded to cataphoresis coated steel,especially with a bond thickness of 1 mm,and achieving a yield strength of 20 MPa.This situation explains the characteristic difference between surface roughness and chemical coating,which are two essential pre-treatments in adhesive bonding.While surface roughness provides mechanical interlocking,excessive roughness can hinder the adhesive’s wetting ability,causing it to remain suspended on the surface as described in the Cassie–Baxter theorem.In contrast,it has been observed that,despite low surface roughness,chemical coatings enhance the bonding between primer paint and adhesive molecules,and–as stated in the Wenzel theorem–improve the surface wettability.Originality/value–As a preliminary preparation in the adhesive method,primer paint is applied to steel surfaces and GFRP material surfaces in classical industrial applications.In this research,the application of the catapheresis process to the steel substrate instead of primer paint and the bonding of primer-painted GFRP materials to this surface make a unique contribution to the research.展开更多
Enhancing the lubricating properties and antibacterial adhesion resistance of implantable medical materials is critical to prevent soft tissue injury during implantation and the formation of bacterial biofilms.Prior s...Enhancing the lubricating properties and antibacterial adhesion resistance of implantable medical materials is critical to prevent soft tissue injury during implantation and the formation of bacterial biofilms.Prior studies may have exhibited limitations in the preparation methodologies and long-term stability of coatings for implantable medical materials.In this study,we developed a multilayered hybrid hydrogel coating method based on the rate difference of polymerization initiation on the material surface.The acquired coating with persistent lubrication capability retained its functionality after 2×10^(4) cycles of friction and 21 days of PBS immersion.A quaternary ammonium salt coating with antibacterial properties was introduced to further functionalize the coating.Animal experiments demonstrated that this coating exhibited remarkable effects on delaying encrustation and bacterial colonization.These studies indicate that this simple method of introducing lubricating and antibacterial coatings on catheters is likely to enhance the biocompatibility of medical devices and has broad application prospects in this field of medical devices.展开更多
This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the...This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the extinction ratio and Q-factor of the setup.The resonator is coated with silver in crescent shapes,ranging from 40 nm to 65 nm in thickness.Coupling is achieved with a silica waveguide,simulating the tapered fiber coupling method.Notably,the resonator exhibits a maximum sensitivity of 220 nm/RIU when coated with 55-nm-thick silver in conjunction with a 4-nm-thick layer of thiol-tethered deoxyribonucleic acid(DNA).This biosensor holds promise for biomolecule detection applications.展开更多
In order to simultaneously improve the oxidation resistance and the electrical conductivity of solid oxide fuel cell(SOFC)interconnectors,a composite coating of Co–W/NiO was fabricated on ferritic stainless steel by ...In order to simultaneously improve the oxidation resistance and the electrical conductivity of solid oxide fuel cell(SOFC)interconnectors,a composite coating of Co–W/NiO was fabricated on ferritic stainless steel by composite deposition and pre-oxidation.Based on phase identification and microstructural analysis,the novel coating was confirmed to effectively suppress Cr diffusion to form a compact Cr-rich layer.Thus,the oxidation rate has been reduced to 9.46×10−15 g^(2)cm^(−4)s^(−1),which showed a imporvement of 56.4%in oxidation resistance.The area specific resistance value of Co–W/NiO coated steel was evaluated as 27.6 mΩcm^(2),much lower than that of Co–W coating as 53.38 mΩcm^(2),which is adequate for SOFC application.Furthermore,the mechanism of the improvement has been investigated that the addition of NiO led to the formation of Ni–Co spinels and Ni–W composites,which affected the surface microstructure of the coating.Thus,the composite Co–W/NiO coated ferritic stainless steel exhibited the optimal combination for oxidation resistance and electrical conductivity.展开更多
A novel type of microcapsule-encapsulated corrosion inhibitor was prepared in a water-based solution with a pH range of 7-8,and it was applied to the composite organic coating of magnesium alloy plasma electrolytic ox...A novel type of microcapsule-encapsulated corrosion inhibitor was prepared in a water-based solution with a pH range of 7-8,and it was applied to the composite organic coating of magnesium alloy plasma electrolytic oxidation to enhance its corrosion resistance and self-healing properties.The morphology,chemical composition,structure,and functional properties of the composite coating were investigated by scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),polarization curve,alternating current impedance,and salt immersion test.The experimental results showed that,after immersion in a 3.5 wt%NaCl solution for 12 h,the coating could effectively protect AZ91D from corrosion.When the coating was damaged,the exposed alloy surface would release metal ions in the corrosive environment and react with the corrosion inhibitor 8-hydroxyquinoline to form a Mg(8-HQ)_(2) chelate,exhibiting significant self-healing behavior.The study results demonstrate the broad application prospects of microcapsule technology in the coating field,providing new ideas for the development of efficient anti-corrosion coatings.展开更多
The as-deposited coating-substrate microstructure has been identified to substantially influence the high-cycle fatigue(HCF)behavior of Ni-based single-crystal(SX)superalloys at 900℃,but the impact of degraded micros...The as-deposited coating-substrate microstructure has been identified to substantially influence the high-cycle fatigue(HCF)behavior of Ni-based single-crystal(SX)superalloys at 900℃,but the impact of degraded microstructure on the HCF behavior remains unclear.In this work,a PtAl-coated third-generation SX superalloy with sheet specimen was thermal-exposed at 1100℃ with different durations and then subjected to HCF tests at 900℃.The influence of microstructural degradation on the HCF life and crack initiation were clarified by analyzing the development of microcracks and coating-substrate microstructure.Notably,the HCF life of the thermal-exposed coated alloy increased abnormally,which was attributed to the transformation of the fatigue crack initiation site from surface mi-crocracks to internal micropores compared to the as-deposited coated alloy.Although the nucleation and growth of surface microcracks occurred along the grain boundaries in the coating and the interdiffusion zone(IDZ)for both the as-deposited and the thermal-exposed coated alloys,remarkable differences of the microcrack growth into the substrate adjacent to the IDZ were observed,changing the crack initiation site.Specifically,the surface microcracks grew into the substrate through the cracking of the non-protective oxide layers in the as-deposited coated alloy.In comparison,the hinderance of the surface microcracks growth was found in the thermal-exposed coated al-loy,due to the formation of a protective Al_(2)O_(3) layer within the microcrack and theγ′rafting in the substrate close to the IDZ.This study will aid in improving the HCF life prediction model for the coated SX superalloys.展开更多
Magnesium(Mg)and its alloys are lightweight as well as biocompatible and possess a high strength-to-weight ratio,making them suitable for many industries,including aerospace,automobile,and medical.The major challenge ...Magnesium(Mg)and its alloys are lightweight as well as biocompatible and possess a high strength-to-weight ratio,making them suitable for many industries,including aerospace,automobile,and medical.The major challenge is their high susceptibility to corrosion,thereby limiting their usability.The considerably lower reduction potential of Mg compared to other metals makes it vulnerable to galvanic coupling.The oxide layer on Mg offers little corrosion resistance because of its high porosity,inhomogeneity,and fragility.Chemical conversion coatings(CCs)belong to a distinct class because of underlying chemical reactions,which are fundamentally different from other types of coating.Typically,a CC acts as an intermediate sandwich layer between the base metal and an aesthetic paint.Although chromate CCs offer superior performance compared to phosphate CCs,yet still they release carcinogenic hexavalent chromium ions(Cr^(6+));therefore,their use is prohibited in most European nations under the Registration,Evaluation,Authorization and Restriction of Chemicals legislation framework.Phosphate-based CCs are a cost-effective and environment-friendly alternative.Accordingly,this review primarily focuses on different types of phosphate-based CCs,such as zinc,calcium,Mg,vanadium,manganese,and permanganate.It discusses their mechanisms,current status,pretreatment practices,and the influence of various parameters-such as pH,temperature,immersion time,and bath composition-on the coating performance.Some challenges associated with phosphate CCs and future research directions are also elaborated.展开更多
The atmospheric corrosion monitoring(ACM)technique has been widely employed to track the real-time corrosion behavior of metal materials.However,limited studies have applied ACM to the corrosion protection properties ...The atmospheric corrosion monitoring(ACM)technique has been widely employed to track the real-time corrosion behavior of metal materials.However,limited studies have applied ACM to the corrosion protection properties of organic coatings.This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors,both applied on ACM sensors,to observe their corrosion protection properties over time.Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments,which allowed for monitoring galvanic corrosion currents in real-time.Throughout the corrosion tests,the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating.The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis.This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings.Compared with the blank epoxy coating,the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
文摘Black nickel coatings have emerged as a research hotspot in materials science due to their excellent performance and broad application prospects.In this study,nickel-based black coatings were fabricated on low-carbon steel substrates via photo-assisted electrodeposition.A systematic investigation was conducted on the effects of cerium ion concentration and nano-ceria(CeO_(2))particle content in the electrolyte on the coating properties,along with an analysis of the temporal evolution of coating’s corrosion resistance.When the cerium ion concentration in the electrolyte was 0.05 mol/L,the coating exhibited a uniform black appearance with a light absorption rate of 95%,an emissivity of 0.87,maximum impedance,and the lowest corrosion tendency,demonstrating optimal comprehensive performance.The coating prepared with a nano-ceria concentration of 6 g/L in the electrolyte exhibited an emissivity of 0.9,achieved a 5B adhesion grade(ASTM D3359-09),and demonstrated a one-order-of-magnitude reduction in corrosion current density compared to coatings fabricated without nano-ceria in the electrolyte.With prolonged storage time,the coating's impedance slightly increased,leading to improved corrosion resistance.
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金supported by the National Natural Science Foundation of China(Nos.52105330,52175307)the Natural Science Foundation of Shandong Province,China(No.ZR2023JQ021)。
文摘The Sn−2Al filler metal was utilized to bond W90 tungsten heavy alloys by the ultrasonic-assisted coating technology in atmospheric environment at 250℃.The effects of ultrasonic power and ultrasonic time on microstructure and interfacial strength of Sn−2Al/W90 interface were investigated.The ultrasound improved the wettability of Sn−2Al filler metal on W90 surface.As the ultrasonic power increased and ultrasonic time increased,the size of Al phase in seam decreased.The maximum value of Sn−2Al/W90 interfacial strength reached 30.1 MPa.Based on the acoustic pressure simulation and bubble dynamics,the intensity of cavitation effect was proportional to ultrasonic power.The generated high temperature and high pressure by cavitation effect reached 83799.6 K and 1.26×10^(14) Pa,respectively.
基金Sponsored by the National Key Research and Development Program of China(Grant No.2020YFE0100300)the National Natural Science Foundation of China(Grant No.51973036)。
文摘Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and negative charges renders the zwitterion-based materials with electrostatically induced hydration properties, which enables a high resistance towards oily pollutants, nonspecific protein adsorption, bacterial adhesion and biofilm formation. This review starts from the working mechanism of zwitterions and covers the fabrication strategies of zwitterion-based functional coatings, namely the zwitterion-bearing binder route, the zwitterion-bearing additive route and the post-generation of coatings containing zwitterionic precursors. The applications of zwitterion-based functional coatings are discussed, including medical implants, marine antifouling and oil-resistant coatings, with focus on the relevant mechanisms of the zwitterion-containing coatings for a specific performance. Finally, some comments and perspectives on the current situation and future development of zwitterion-based functional coatings are given.
基金This paper is supported by Key Scientific Research Project in Shanxi Province(Grant Nos.201903D111008 and 202003D111001)National Natural Science Foundation of China(Grant No.52071227)+4 种基金Fundamental Research Program of Shanxi Province(Grant No.202103021223293)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2021L306)Scientific Research Fund of Taiyuan University of Science and Technology(Grant No.20202044)Award Fund for Outstanding Doctors in Shanxi Province(Grant No.20212041)Postgraduate Education Innovation Project of Shanxi Province(Grant Nos.2022Y686 and 2022Y684).
文摘Low alloy steels are widely used in bridges,construction,chemical and various equipment and metal components due to their low cost and excellent mechanical strength.Information in the literature related to the preparation,advantages and disadvantages,and applications along with research progress of various types of protective coatings suitable for low-alloy steel surfaces is reviewed,while a conclusive and comparative analysis is also afforded to the numerous factors influencing the protective ability of coatings.The characteristics of coatings drawn from the latest published literature are discussed and suggest that the modification of traditional metal coatings and the development of new organic coatings under the consideration of environmental protection,low cost,simplicity and large-scale industrial application are simultaneously proceeding,which holds promise for improving the understanding of corrosion protection in related fields and helps to address some of the limitations identified with more conventional coating techniques.
基金the Helmholtz association for funding the main parts of the modeling and simulation research work under the program“MTET:38.04.04”。
文摘The presence of clay coatings on the surfaces of quartz grains can play a pivotal role in determining the porosity and permeability of sandstone reservoirs,thus directly impacting their reservoir quality.This study employs a multiphase-field model of syntaxial quartz cementation to explore the effects of clay coatings on quartz cement volumes,porosity,permeability,and their interrelations in sandstone formations.To generate various patterns of clay coatings on quartz grains within three-dimensional(3D)digital sandstone grain packs,a pre-processing toolchain is developed.Through numerical simulation experiments involving syntaxial overgrowth cementation on both single crystals and multigrain packs,the main coating parameters controlling quartz cement volume are elucidated.Such parameters include the growth of exposed pyramidal faces,lateral encasement,coating coverage,and coating pattern,etc.The coating pattern has a remarkable impact on cementation,with the layered coatings corresponding to fast cement growth rates.The coating coverage is positively correlated with the porosity and permeability of sandstone.The cement growth rate of quartz crystals is the lowest in the vertical orientation,and in the middle to late stages of evolution,it is faster in the diagonal orientation than in the horizontal orientation.Through comparing the simulated results of dynamic evolution process with the actual features,it is found that the simulated coating patterns after 20 d and 40 d show clear similarities with natural samples,proving the validity of the proposed three-dimensional numerical modeling of coatings.The methodology and findings presented contribute to improved reservoir characterization and predictive modeling of sandstone formations.
基金supported by the National Natural Science Foundation of China(No.52001142)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_3793).
文摘Oxidation behavior of NiCrAlY nanocrystalline coatings with different Cr contents at 1050 and 1150℃is investigated.The results indicate that Al2O3 scales can be formed on NiCrAlY nanocrystalline coatings after oxidation at high temperature.And their formation and thickening cannot be affected by the change of Cr contents in NiCrAlY coatings.During service,Cr in the coating can affect the microstructure of Ni-based single crystal superalloy.At 1050℃,Cr in the coating can diffuse into the superalloy,destroy its microstructure,and lead to the formation of interdiffusion zone and the precipitation of needle-like topologically closed-packed phase.The higher the Cr content in NiCrAlY the coating is,the more obvious the phenomenon is.However,after oxidation at 1150℃for 100 h,no obvious changes were observed in the microstructure of CMSX-4 single crystal superalloy beneath the three kinds of NiCrAlY nanocrystalline coatings.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences,Grant(No.XDB 047010204)Liaoning Key Laboratory of Aero-engine Material Tribology for both financial and facility support
文摘A novel NiAlTa blade tip protective coating is designed and its oxidation,hot corrosion,and interdiffusion with DD5 single-crystal superalloys are investigated.NiAlTa coatings exhibit low oxidation rates.The dragging effect of Ta on Al hinders the external diffusion of Al.Ta that accumulates at the Al_(2)O_(3)grain boundaries reduces the internal diffusion of O by combining or reacting with it.NaCl aggravates the hot corrosion through self ustaining cycles of chlorination/oxidation.β-NiAl phase fails first as a diffusion channel for the corrosive medium.Significant element interdiffusion occurs.An interdiffusion zone and a secondary reaction zone are formed.Interdiffusion changes the percentage of elements,causing a phase transition of the coating.The volume change caused by the phase transition induces bulging and cracking of the oxide film.Furthermore,the oxidation,hot corrosion,and interdiffusion mechanisms are discussed.
基金supported by the National Key R&D Program of China(No.2022YFB3808803)the National Natural Science Foundation of China(No.52371049)the National Science and Technology Resources Investigation Program of China(No.2021FY100603).
文摘The corrosion degradation of organic coatings in tropical marine atmospheric environments results in substantial economic losses across various industries.The complexity of a dynamic environment,combined with high costs,extended experimental periods,and limited data,places a limit on the comprehension of this process.This study addresses this challenge by investigating the corrosion de-gradation of damaged organic coatings in a tropical marine environment using an atmospheric corrosion monitoring sensor and a random forest(RF)model.For damage simulation,a polyurethane coating applied to a Fe/graphite corrosion sensor was intentionally scratched and exposed to the marine atmosphere for over one year.Pearson correlation analysis was performed for the collection and filtering of en-vironmental and corrosion current data.According to the RF model,the following specific conditions contributed to accelerated degrada-tion:relative humidity(RH)above 80%and temperatures below 22.5℃,with the risk increasing significantly when RH exceeded 90%.High RH and temperature exhibited a cumulative effect on coating degradation.A high risk of corrosion occurred in the nighttime.The RF model was also used to predict the coating degradation process using environmental data as input parameters,with the accuracy show-ing improvement when the duration of influential environmental ranges was considered.
文摘Purpose–This research aims to investigate how the adhesion performance of GFRP composite components,commonly used in railway vehicles,is affected when bonded to cataphoresis coated steel substrate surfaces.Design/methodology/approach–In this context,the aim was to determine the optimal adhesion parameters for bonding GFRP samples with natural and primed surfaces to steel samples with cataphoresis coatings.Then,single-lap joint samples with different bond thicknesses of 1 mm,2 mm and 3 mm were prepared.Finally,tensile tests were performed on the samples.Findings–The results showed that GFRP specimens with natural surfaces,characterised by the highest surface roughness,exhibited the lowest bond strength.But,the highest bonding performance was achieved in specimens where primed GFRP was bonded to cataphoresis coated steel,especially with a bond thickness of 1 mm,and achieving a yield strength of 20 MPa.This situation explains the characteristic difference between surface roughness and chemical coating,which are two essential pre-treatments in adhesive bonding.While surface roughness provides mechanical interlocking,excessive roughness can hinder the adhesive’s wetting ability,causing it to remain suspended on the surface as described in the Cassie–Baxter theorem.In contrast,it has been observed that,despite low surface roughness,chemical coatings enhance the bonding between primer paint and adhesive molecules,and–as stated in the Wenzel theorem–improve the surface wettability.Originality/value–As a preliminary preparation in the adhesive method,primer paint is applied to steel surfaces and GFRP material surfaces in classical industrial applications.In this research,the application of the catapheresis process to the steel substrate instead of primer paint and the bonding of primer-painted GFRP materials to this surface make a unique contribution to the research.
基金financially supported by the National Natural Science Foundation of China(Nos.52373296 and 52173287)。
文摘Enhancing the lubricating properties and antibacterial adhesion resistance of implantable medical materials is critical to prevent soft tissue injury during implantation and the formation of bacterial biofilms.Prior studies may have exhibited limitations in the preparation methodologies and long-term stability of coatings for implantable medical materials.In this study,we developed a multilayered hybrid hydrogel coating method based on the rate difference of polymerization initiation on the material surface.The acquired coating with persistent lubrication capability retained its functionality after 2×10^(4) cycles of friction and 21 days of PBS immersion.A quaternary ammonium salt coating with antibacterial properties was introduced to further functionalize the coating.Animal experiments demonstrated that this coating exhibited remarkable effects on delaying encrustation and bacterial colonization.These studies indicate that this simple method of introducing lubricating and antibacterial coatings on catheters is likely to enhance the biocompatibility of medical devices and has broad application prospects in this field of medical devices.
基金supported by the Airlangga University through Mandate Research Grant(Nos.216/UN3.15/PT/2022 and 217/UN3.15/PT/2022)。
文摘This paper presents a biosensor utilizing a whispering gallery mode(WGM)resonator characterized by azimuthal symmetry and crescent-shaped coatings of silver.The study investigates the impact of the coupling gap on the extinction ratio and Q-factor of the setup.The resonator is coated with silver in crescent shapes,ranging from 40 nm to 65 nm in thickness.Coupling is achieved with a silica waveguide,simulating the tapered fiber coupling method.Notably,the resonator exhibits a maximum sensitivity of 220 nm/RIU when coated with 55-nm-thick silver in conjunction with a 4-nm-thick layer of thiol-tethered deoxyribonucleic acid(DNA).This biosensor holds promise for biomolecule detection applications.
基金supported by Hubei Natural Science Foundation of Hubei(2023AFB111).
文摘In order to simultaneously improve the oxidation resistance and the electrical conductivity of solid oxide fuel cell(SOFC)interconnectors,a composite coating of Co–W/NiO was fabricated on ferritic stainless steel by composite deposition and pre-oxidation.Based on phase identification and microstructural analysis,the novel coating was confirmed to effectively suppress Cr diffusion to form a compact Cr-rich layer.Thus,the oxidation rate has been reduced to 9.46×10−15 g^(2)cm^(−4)s^(−1),which showed a imporvement of 56.4%in oxidation resistance.The area specific resistance value of Co–W/NiO coated steel was evaluated as 27.6 mΩcm^(2),much lower than that of Co–W coating as 53.38 mΩcm^(2),which is adequate for SOFC application.Furthermore,the mechanism of the improvement has been investigated that the addition of NiO led to the formation of Ni–Co spinels and Ni–W composites,which affected the surface microstructure of the coating.Thus,the composite Co–W/NiO coated ferritic stainless steel exhibited the optimal combination for oxidation resistance and electrical conductivity.
基金Funded by the National Natural Science Foundation of China(No.52271066)Basic Research and Innovation Project for Vehicle Power+1 种基金Key Project of"Two-Chain Integration"in Shaanxi Province(No.2023-LL-QY-33-3)Xi'an Key Laboratory of Corrosion Protection and Functional Coating Technology for Military and Civil Light Alloy and Key Project of Shaanxi Natural Science Foundation Research Program(No.2021JZ-54)。
文摘A novel type of microcapsule-encapsulated corrosion inhibitor was prepared in a water-based solution with a pH range of 7-8,and it was applied to the composite organic coating of magnesium alloy plasma electrolytic oxidation to enhance its corrosion resistance and self-healing properties.The morphology,chemical composition,structure,and functional properties of the composite coating were investigated by scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),polarization curve,alternating current impedance,and salt immersion test.The experimental results showed that,after immersion in a 3.5 wt%NaCl solution for 12 h,the coating could effectively protect AZ91D from corrosion.When the coating was damaged,the exposed alloy surface would release metal ions in the corrosive environment and react with the corrosion inhibitor 8-hydroxyquinoline to form a Mg(8-HQ)_(2) chelate,exhibiting significant self-healing behavior.The study results demonstrate the broad application prospects of microcapsule technology in the coating field,providing new ideas for the development of efficient anti-corrosion coatings.
基金financially supported by National Key Research and Development Program of China(No.2022YFB 3708100)the Science Center for Gas Turbine Project,China(No.P2021-A-IV-002-001)+1 种基金the National Natural Science Foundation of China(Nos.52331005 and 52201100)the State Key Laboratory for Advanced Metals and Materials,China(No.2024-Z02).
文摘The as-deposited coating-substrate microstructure has been identified to substantially influence the high-cycle fatigue(HCF)behavior of Ni-based single-crystal(SX)superalloys at 900℃,but the impact of degraded microstructure on the HCF behavior remains unclear.In this work,a PtAl-coated third-generation SX superalloy with sheet specimen was thermal-exposed at 1100℃ with different durations and then subjected to HCF tests at 900℃.The influence of microstructural degradation on the HCF life and crack initiation were clarified by analyzing the development of microcracks and coating-substrate microstructure.Notably,the HCF life of the thermal-exposed coated alloy increased abnormally,which was attributed to the transformation of the fatigue crack initiation site from surface mi-crocracks to internal micropores compared to the as-deposited coated alloy.Although the nucleation and growth of surface microcracks occurred along the grain boundaries in the coating and the interdiffusion zone(IDZ)for both the as-deposited and the thermal-exposed coated alloys,remarkable differences of the microcrack growth into the substrate adjacent to the IDZ were observed,changing the crack initiation site.Specifically,the surface microcracks grew into the substrate through the cracking of the non-protective oxide layers in the as-deposited coated alloy.In comparison,the hinderance of the surface microcracks growth was found in the thermal-exposed coated al-loy,due to the formation of a protective Al_(2)O_(3) layer within the microcrack and theγ′rafting in the substrate close to the IDZ.This study will aid in improving the HCF life prediction model for the coated SX superalloys.
基金Uchchatar Avishkar Yojna(UAY)(Phase II)project(codeIITBBS_004)Prime M inister’s Research Fellows(PMRF)。
文摘Magnesium(Mg)and its alloys are lightweight as well as biocompatible and possess a high strength-to-weight ratio,making them suitable for many industries,including aerospace,automobile,and medical.The major challenge is their high susceptibility to corrosion,thereby limiting their usability.The considerably lower reduction potential of Mg compared to other metals makes it vulnerable to galvanic coupling.The oxide layer on Mg offers little corrosion resistance because of its high porosity,inhomogeneity,and fragility.Chemical conversion coatings(CCs)belong to a distinct class because of underlying chemical reactions,which are fundamentally different from other types of coating.Typically,a CC acts as an intermediate sandwich layer between the base metal and an aesthetic paint.Although chromate CCs offer superior performance compared to phosphate CCs,yet still they release carcinogenic hexavalent chromium ions(Cr^(6+));therefore,their use is prohibited in most European nations under the Registration,Evaluation,Authorization and Restriction of Chemicals legislation framework.Phosphate-based CCs are a cost-effective and environment-friendly alternative.Accordingly,this review primarily focuses on different types of phosphate-based CCs,such as zinc,calcium,Mg,vanadium,manganese,and permanganate.It discusses their mechanisms,current status,pretreatment practices,and the influence of various parameters-such as pH,temperature,immersion time,and bath composition-on the coating performance.Some challenges associated with phosphate CCs and future research directions are also elaborated.
基金financially supported by the National Natural Science Foundation of China(No.52371049)the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(YESS,No.2020QNRC001)the National Science and Technology Resources Investigation Program of China(Nos.2021FY100603 and 2019FY101404)。
文摘The atmospheric corrosion monitoring(ACM)technique has been widely employed to track the real-time corrosion behavior of metal materials.However,limited studies have applied ACM to the corrosion protection properties of organic coatings.This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors,both applied on ACM sensors,to observe their corrosion protection properties over time.Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments,which allowed for monitoring galvanic corrosion currents in real-time.Throughout the corrosion tests,the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating.The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis.This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings.Compared with the blank epoxy coating,the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
