The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composit...The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composition,elemental distribution and corrosion resistance of the coatings were extensively investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),energy-dispersive X-ray spectrometry(EDX)and electrochemical workstation.The results showed that ultrasound improved the homogeneous distribution of micro-porous structure.The coatings were mainly composed of MgO ceramic and small amount of calcium and phosphorus with porous structure.The Ca/P ratio of the coatings increased when 60 W ultrasonic was used.The corrosion potential in simulated body fluid(SBF)changed from1.583 V of bare magnesium alloy to -0.353 V of magnesium alloy coated under 60 W ultrasonic.The corrosion resistance of UMAO coatings was better than that of MAO coatings.展开更多
Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing(PEC)with micro-arc oxidation(MAO)to further enhance the anti-corrosion property in this paper.Scanning electron micros...Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing(PEC)with micro-arc oxidation(MAO)to further enhance the anti-corrosion property in this paper.Scanning electron microscopy(SEM)was used to observe the microstructure of the coatings,meanwhile,energy dispersive spectrometry(EDS)and X-ray diffraction(XRD)were separately used to investigate the elemental as well as phase compositions of the coatings.The anti-corrosion property of the coatings was evaluated by potentiodynamic polarization curves as well as electrochemical impedance spectroscopy(EIS).The results show that PEC process is closely related with the effects of adsorption as well as diffusion of the activated carbon atoms,and it can provide a favorable pretreatment surface with predesigned chemical composition to obtain a new kind of phase,namely Si C with superior corrosion resistance and chemical stability,in the following PEC+MAO hybrid coatings.Meanwhile,PEC preprocessing also can afford an excellent micro-structure to increase the coating thickness as well as to improve the compactness of the PEC+MAO hybrid coatings.During the fabrication process of the PEC+MAO hybrid coatings,an overlapping phenomenon in regard to coating thickness can be observed instead of heaping up layer by layer.Compared with both single PEC surface modification layers as well as single MAO coatings,the PEC+MAO hybrid coatings exhibit more superior anti-corrosion property.Especially,the EIS data reveal that the PEC+MAO hybrid coatings can act as an effective protection system to provide relatively excellent long-range anti-corrosion protection.Note also that employing same MAO technique for both single MAO treatment as well as PEC+MAO combining procedure is the key to this research.展开更多
Poor corrosion resistance is one of the main disadvantages for biodegradable magnesium-based metals,especially applied for bone fixation,where there is a high demand of bio-mechanical strength and stability.Surface co...Poor corrosion resistance is one of the main disadvantages for biodegradable magnesium-based metals,especially applied for bone fixation,where there is a high demand of bio-mechanical strength and stability.Surface coating has been proved as an effective method to control the in vivo degradation.In this study a Ca-P self-sealing micro-arc oxidation(MAO)coating was studied to verify its efficacy and biological properties by in vitro and in vivo tests.It was found that the MAO coating could effectively retard the degradation according to immersion and electrochemical tests as well as 3D reconstruction by X-ray tomography after implantation.The MAO coating exhibited no toxicity and could stimulate the new bone formation.Therefore,the Ca-P self-sealing MAO coating could be a potential candidate for application of biodegradable Mg-based implant in bone fixations.展开更多
基金The authors are grateful for the supports from the National Natural Science Foundation of China(No.31070859)the Natural Science Foundation of Heilongjiang Province(No.ZD201008).
文摘The ultrasonic micro-arc oxidation(UMAO)was used to fabricate ceramic coatings on magnesium alloy.UMAO coatings were produced at 60 W input ultrasonic.The effects of the ultrasound on the microstructure,phase composition,elemental distribution and corrosion resistance of the coatings were extensively investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD),energy-dispersive X-ray spectrometry(EDX)and electrochemical workstation.The results showed that ultrasound improved the homogeneous distribution of micro-porous structure.The coatings were mainly composed of MgO ceramic and small amount of calcium and phosphorus with porous structure.The Ca/P ratio of the coatings increased when 60 W ultrasonic was used.The corrosion potential in simulated body fluid(SBF)changed from1.583 V of bare magnesium alloy to -0.353 V of magnesium alloy coated under 60 W ultrasonic.The corrosion resistance of UMAO coatings was better than that of MAO coatings.
基金financially supported by the Creative Research Group Fund Grant of Gansu Province,China(1111RJDA011)。
文摘Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing(PEC)with micro-arc oxidation(MAO)to further enhance the anti-corrosion property in this paper.Scanning electron microscopy(SEM)was used to observe the microstructure of the coatings,meanwhile,energy dispersive spectrometry(EDS)and X-ray diffraction(XRD)were separately used to investigate the elemental as well as phase compositions of the coatings.The anti-corrosion property of the coatings was evaluated by potentiodynamic polarization curves as well as electrochemical impedance spectroscopy(EIS).The results show that PEC process is closely related with the effects of adsorption as well as diffusion of the activated carbon atoms,and it can provide a favorable pretreatment surface with predesigned chemical composition to obtain a new kind of phase,namely Si C with superior corrosion resistance and chemical stability,in the following PEC+MAO hybrid coatings.Meanwhile,PEC preprocessing also can afford an excellent micro-structure to increase the coating thickness as well as to improve the compactness of the PEC+MAO hybrid coatings.During the fabrication process of the PEC+MAO hybrid coatings,an overlapping phenomenon in regard to coating thickness can be observed instead of heaping up layer by layer.Compared with both single PEC surface modification layers as well as single MAO coatings,the PEC+MAO hybrid coatings exhibit more superior anti-corrosion property.Especially,the EIS data reveal that the PEC+MAO hybrid coatings can act as an effective protection system to provide relatively excellent long-range anti-corrosion protection.Note also that employing same MAO technique for both single MAO treatment as well as PEC+MAO combining procedure is the key to this research.
基金This work was financially supported by National Basic Research program of China(973 program,No.2012CB619101)Innovative R&D Team of Biodegradable Magnesium Alloy and Related Implanted Device(No.201001C0104669453).
文摘Poor corrosion resistance is one of the main disadvantages for biodegradable magnesium-based metals,especially applied for bone fixation,where there is a high demand of bio-mechanical strength and stability.Surface coating has been proved as an effective method to control the in vivo degradation.In this study a Ca-P self-sealing micro-arc oxidation(MAO)coating was studied to verify its efficacy and biological properties by in vitro and in vivo tests.It was found that the MAO coating could effectively retard the degradation according to immersion and electrochemical tests as well as 3D reconstruction by X-ray tomography after implantation.The MAO coating exhibited no toxicity and could stimulate the new bone formation.Therefore,the Ca-P self-sealing MAO coating could be a potential candidate for application of biodegradable Mg-based implant in bone fixations.
