The phosphated and cerium nitrate post-sealed galvanized steel was firstly scratched to expose zinc layer and then placed in neutral salt spray （NSS） chamber for different durations. The microstructure and compositi...The phosphated and cerium nitrate post-sealed galvanized steel was firstly scratched to expose zinc layer and then placed in neutral salt spray （NSS） chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and finally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are fine needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3＋, Ce4＋, PO43-, Zn2＋ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.展开更多
The phosphated zinc layer was post-sealed with molybdate to obtain the composite coating without pores.The composition of the formed coating was investigated. The corrosion behavior of the coated samples was studied.T...The phosphated zinc layer was post-sealed with molybdate to obtain the composite coating without pores.The composition of the formed coating was investigated. The corrosion behavior of the coated samples was studied.The coated samples were first scratched and subsequently corroded in a neutral salt spray( NSS) chamber for 2-72 h; the microstructure of the corrosion products was analyzed via SEM and EDS; and the self-healing performance was discussed. The coating obtained contains Zn_3( PO_4)_2· 4H_2 O,Mo_2O_3 and MoO_4^(2-). The electrochemical impedance first increases and then decreases with the immersion time. However,after immersion for 6 days,it remains at about 10 kΩ·cm^2,much higher than the value for the single-treated samples without corrosion. Micro structural observations show that the corrosion products in scratch increase in size and finally cover the whole scratch completely. The initial corrosion products have high P,Mo and O contents but almost no Cl,while in later stages the first three components decrease and Cl increases. The corrosion products form a compact mass of needle-like crystals,effectively inhibiting zinc corrosion. The composite coating exhibits good self-healing.展开更多
Polystyrene(PS) fibers with core-shell structures were fabricated by coaxial electrostatic spinning,[10_TD$IF]in which there are liquid epoxy or curing agent as the core and PS as the shell. Scanning electron microsco...Polystyrene(PS) fibers with core-shell structures were fabricated by coaxial electrostatic spinning,[10_TD$IF]in which there are liquid epoxy or curing agent as the core and PS as the shell. Scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectra and optical microscope were utilized for charactering the morphology and composition of the fibers. Composite coatings embedded with the healant-loaded coreshell fibers have been prepared and the self-healing of the scratch on the coatings has been revealed.展开更多
Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-si...Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-situ polymerization. The main objective of this study was to model and optimize the microen- capsulation process. Five-level central composite design was used to design, model, and optimize the microencapsulation process. A quadratic model was constructed to show the dependency of the per- centage of encapsulated linseed oil and capsule size, as model responses, on the studied independent variables （the rotational speed of the agitator and the power and duration of sonication）. Analysis of vari- ance showed that all of the variables have significant effects on the encapsulated linseed oil percentage, while the rotational speed of the agitator and sonication time is effective variables for controlling the capsule size. Under the determined optimum conditions, a maximum encapsulated linseed oil percentage （ELO%） of 93.9% and a minimum micro/nanocapsule size of 0.574 μm were achieved at 594 rpm agitation, 350 W sonication power, and 3 min sonication time. Validation of the model was performed. The percent- age relative errors between the predicted and experimental values of the ELO% and micro/nanocapsule size are 1.28% and 3.66%, respectively. The efficacy of the optimum micro/nanocapsules in healing cracks in a glass flake epoxy paint and corrosion protection was investigated by the salt spray test and Tafel polarization technique.展开更多
A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane...A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane foam coating is applied on the inside of a fabric substrate, which closes the fissure if the membrane is punctured with a spike. Experimental tests are carried out with a purpose built setup by measuring the air mass flow through a leak in a damaged membrane sample. It is shown that the weight per unit area of the self-repairing foam as well as the curing of the two component PU-foam under an overpressure influence the repair efficiency. Curing the foam under overpressure affects the relative density as well as the microstructure of the foam coatings. Maximal median repair efficiencies of 0.999 have been obtained with 0.16 g.cm 2 foam cured at 1 bar overpressure. These results suggest that the bio-inspired technique has the potential to extend the functional integrity of injured inflatable structures dramatically.展开更多
Polymeric coatings are susceptible to microdefects that are difficult to detect thus leading to premature failure of metallic components or even catastrophic accidents.Although obtaining considerable progress in damag...Polymeric coatings are susceptible to microdefects that are difficult to detect thus leading to premature failure of metallic components or even catastrophic accidents.Although obtaining considerable progress in damage healing and detecting,it is still challenging for anticorrosion coating to realize warning the damage generation and tracing the healing process simultaneously.This article validates a robust strategy based on damage-induced fluorescence enhancement effect to visualize dynamic damage-healing processes in anticorrosion coatings on magnesium alloy AZ31.Through embedding fluorescent poly-dopamine nanoparticles into thermo-responsive epoxy resin,immediate fluorescence was intensified at coating damages.Localized electrochemical impedance and salt spray results proved that the prepared coating possessed pronounced healing and corrosion protection capability with near-infrared irradiation.Notably,the healing behavior can be traced and visualized based on the decrease in fluorescence intensity.This work opens a new avenue to monitor the failure and self-healing mechanism of anticorrosion coatings,providing guideline for engineering of next generation smart protection materials.展开更多
基金Funded by the National Natural Science Foundation(No.501408517)the Natural Science Foundation of Fujian Province(No.2012J05099)the Pre-research Project of National Natural Science Fund of Xiamen University of Technology(No.XYK201410)
文摘The phosphated and cerium nitrate post-sealed galvanized steel was firstly scratched to expose zinc layer and then placed in neutral salt spray （NSS） chamber for different durations. The microstructure and compositions of the scratches were investigated using SEM and EDS. The phases of the corrosion products were examined through XRD. The self-healing mechanism of the composite coatings was discussed. The experimental results show that the composite coatings have an excellent corrosion resistance. The corrosion products increase with corrosion time and finally cover the whole scratch. They contain phosphorous, cerium, oxygen, chloride and zinc, and are fine needle and exceedingly compact. The composite coatings are favorable self-healing. During corrosion, the self-healing ions such as Ce3＋, Ce4＋, PO43-, Zn2＋ in the composite coatings were dissolved, migrated, recombined, and covered the exposed zinc, impeding zinc corrosion. The self-healing process of the scratches on the composite coatings can be divided into three stages, about 2 h, 4 h, and 24 h, respectively.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51408517 and 51578255)the Natural Science Foundation of Fujian Province(Grant No.2017J01489)
文摘The phosphated zinc layer was post-sealed with molybdate to obtain the composite coating without pores.The composition of the formed coating was investigated. The corrosion behavior of the coated samples was studied.The coated samples were first scratched and subsequently corroded in a neutral salt spray( NSS) chamber for 2-72 h; the microstructure of the corrosion products was analyzed via SEM and EDS; and the self-healing performance was discussed. The coating obtained contains Zn_3( PO_4)_2· 4H_2 O,Mo_2O_3 and MoO_4^(2-). The electrochemical impedance first increases and then decreases with the immersion time. However,after immersion for 6 days,it remains at about 10 kΩ·cm^2,much higher than the value for the single-treated samples without corrosion. Micro structural observations show that the corrosion products in scratch increase in size and finally cover the whole scratch completely. The initial corrosion products have high P,Mo and O contents but almost no Cl,while in later stages the first three components decrease and Cl increases. The corrosion products form a compact mass of needle-like crystals,effectively inhibiting zinc corrosion. The composite coating exhibits good self-healing.
基金financially supported by the MOS of China (No. 2017YFB0703300)the National Natural Science Foundation ofChina (No. 51673117)the Science and Technology Innovation Commission of Shenzhen (Nos. JSGG20160226201833790, JCYJ20150625102750478)
文摘Polystyrene(PS) fibers with core-shell structures were fabricated by coaxial electrostatic spinning,[10_TD$IF]in which there are liquid epoxy or curing agent as the core and PS as the shell. Scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectra and optical microscope were utilized for charactering the morphology and composition of the fibers. Composite coatings embedded with the healant-loaded coreshell fibers have been prepared and the self-healing of the scratch on the coatings has been revealed.
文摘Micro/nanocapsules of urea-formaldehyde resin loaded with linseed oil, which are a self-healing agent in glass flake epoxy anti-corrosion paint, were prepared using a combination of ultrasonic homogenization and in-situ polymerization. The main objective of this study was to model and optimize the microen- capsulation process. Five-level central composite design was used to design, model, and optimize the microencapsulation process. A quadratic model was constructed to show the dependency of the per- centage of encapsulated linseed oil and capsule size, as model responses, on the studied independent variables （the rotational speed of the agitator and the power and duration of sonication）. Analysis of vari- ance showed that all of the variables have significant effects on the encapsulated linseed oil percentage, while the rotational speed of the agitator and sonication time is effective variables for controlling the capsule size. Under the determined optimum conditions, a maximum encapsulated linseed oil percentage （ELO%） of 93.9% and a minimum micro/nanocapsule size of 0.574 μm were achieved at 594 rpm agitation, 350 W sonication power, and 3 min sonication time. Validation of the model was performed. The percent- age relative errors between the predicted and experimental values of the ELO% and micro/nanocapsule size are 1.28% and 3.66%, respectively. The efficacy of the optimum micro/nanocapsules in healing cracks in a glass flake epoxy paint and corrosion protection was investigated by the salt spray test and Tafel polarization technique.
文摘A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane foam coating is applied on the inside of a fabric substrate, which closes the fissure if the membrane is punctured with a spike. Experimental tests are carried out with a purpose built setup by measuring the air mass flow through a leak in a damaged membrane sample. It is shown that the weight per unit area of the self-repairing foam as well as the curing of the two component PU-foam under an overpressure influence the repair efficiency. Curing the foam under overpressure affects the relative density as well as the microstructure of the foam coatings. Maximal median repair efficiencies of 0.999 have been obtained with 0.16 g.cm 2 foam cured at 1 bar overpressure. These results suggest that the bio-inspired technique has the potential to extend the functional integrity of injured inflatable structures dramatically.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.52201077)the Natural Science Foundation of Shandong Province(Grant No.ZR2022QE191)+2 种基金Elite Scheme of Shandong University of Science and Technology(Grant No.0104060541123)Talent introduction and Research Start-up Fund of Shandong University of Science and Technology(Grant No.0104060510124)Shandong Province Higher Educational Program for Young Innovation Talents and experimental support by the State Key Laboratory of Marine Coatings,Marine Chemical Research Institute Co.,Ltd.We thank Prof.Xiaobo Chen for the help in polishing the language of this paper.
文摘Polymeric coatings are susceptible to microdefects that are difficult to detect thus leading to premature failure of metallic components or even catastrophic accidents.Although obtaining considerable progress in damage healing and detecting,it is still challenging for anticorrosion coating to realize warning the damage generation and tracing the healing process simultaneously.This article validates a robust strategy based on damage-induced fluorescence enhancement effect to visualize dynamic damage-healing processes in anticorrosion coatings on magnesium alloy AZ31.Through embedding fluorescent poly-dopamine nanoparticles into thermo-responsive epoxy resin,immediate fluorescence was intensified at coating damages.Localized electrochemical impedance and salt spray results proved that the prepared coating possessed pronounced healing and corrosion protection capability with near-infrared irradiation.Notably,the healing behavior can be traced and visualized based on the decrease in fluorescence intensity.This work opens a new avenue to monitor the failure and self-healing mechanism of anticorrosion coatings,providing guideline for engineering of next generation smart protection materials.
