Nanocrystalline NdFeB film was fabricated onto the copper substrate through direct current electroplating method,and characterized by scanning electron microscope(SEM) coupled with energy dispersive X-ray spectroscope...Nanocrystalline NdFeB film was fabricated onto the copper substrate through direct current electroplating method,and characterized by scanning electron microscope(SEM) coupled with energy dispersive X-ray spectroscope(EDS),vibrating sample magnetometer and potentiodynamic polarization techniques.The initial electroplating behavior was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) techniques.Results revealed that the corrosion resistance of the NdFeB film was better than that of the traditional sintered NdFeB magnet.The depositing process of the NdFeB film followed the three-dimensional nucleation and subsequent grain growth mechanism,and was controlled by charger transfer.With the increase of the negative potential bias,the deposition mechanism of NdFeB film changed from heterogeneous to homogeneous nucleation/growth,which consequently resulted in the decrease of charge-transfer-resistance.展开更多
CoNiFe,CoNiFeB and CoNiFeP soft magnetic thin films were prepared by cyclic voltammetry method.The morphologies,composition and structures were characterized by scanning electron microscope（SEM）,energy-dispersive X-...CoNiFe,CoNiFeB and CoNiFeP soft magnetic thin films were prepared by cyclic voltammetry method.The morphologies,composition and structures were characterized by scanning electron microscope（SEM）,energy-dispersive X-ray spectroscope（EDS） and X-ray diffractometer（XRD）.The soft magnetic properties were investigated through vibrating sample magnetometer（VSM）.The corrosion resistance was investigated through Tafel polarization and electrochemical impedance spectroscopic（EIS）.The results show that all the electrodeposited CoNiFe,CoNiFeB and CoNiFeP films are mixtures of crystalline and amorphous phases,and high amount of boron/phosphorus-containing additives favors the formation of amorphous state.Nanostructure is obtained in CoNiFe and CoNiFeB films.The inclusion of boron causes the film more dense and also increases its corrosion resistance.Meanwhile,the inclusion of boron lowers its coercivity（Hc） from 851.48 A/m to 604.79 A/m,but the saturation magnetic flux density（Bs） is almost unchanged.However,the addition of phosphorus greatly increases the film particle size and decreases its corrosion stability.The coercivity（Hc） of CoNiFeP film is also highly increased to 12485.79 A/m,and its saturation magnetic flux density（Bs） is greatly decreased to 1.25 T.展开更多
Copper is susceptible to producing corrosion problems in corrosive environments, which leads to serious safety problems. Thus, investigating the corrosion behavior of copper is of great significance. The effects of ro...Copper is susceptible to producing corrosion problems in corrosive environments, which leads to serious safety problems. Thus, investigating the corrosion behavior of copper is of great significance. The effects of rotating electromagnetic field on corrosion behavior of T2 copper in 3.5% sodium chloride solution with electrochemical measurements were investigated. The results showed that rotating electromagnetic field changed properties of 3.5% sodium chloride solution by increasing the values of temperature and pH and decreasing the values of conductivity and dissolved oxygen. The rotating electromagnetic field improved the corrosion resistance of T2 copper. The corrosion products of T2 copper in treated 3.5% sodium chloride solution were composed of Cu20 and CuCl. The low corrosion rate of T2 copper was resulted from the decrease of dissolved oxygen in 3.5% sodium chloride solution treated by rotating electromagnetic field.展开更多
Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding perfo...Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding performance.The research process ofMg-Li alloys is reviewed and three main problems are pointed out.Aimed at the poor corrosion resistance of Mg-Li alloys,thecorrosion behavior is mainly summarized.The surface treatment technologies,including electroplating,electroless plating,plasmaspraying,molten salt replacement,conversion coating,anodizing,micro-arc oxidation,organic coating,and organic-inorganic hybridcoating,are introduced in detail.Finally,the future development of corrosion and protection of Mg?Li alloys is discussed.展开更多
The effects of applying an electromagnetic interaction of low intensity (EMILI) on the microstructure and corrosion resistance of 7075-T651 Al alloy plates (13 mm in thickness) during modified indirect electric arc (M...The effects of applying an electromagnetic interaction of low intensity (EMILI) on the microstructure and corrosion resistance of 7075-T651 Al alloy plates (13 mm in thickness) during modified indirect electric arc (MIEA) welding were investigated. The welding process was conducted in a single pass with a heat input of ~1.5 kJ/mm. The microstructural observations of the welds were correlated with the effect of EMILI on the local mechanical properties and the corrosion resistance in natural seawater by means of microhardness measurements and electrochemical impedance spectroscopy, respectively. Microstructural characterization of the welds revealed a grain refinement in the weld metal due to the electromagnetic stirring induced by EMILI of 3 mT during welding. In addition, observations in the scanning electron microscope showed that the precipitation of Cu-rich phases and segregation of eutectics were reduced in the heat affected zone (HAZ) also as an effect of EMILI. The high corrosion dissolution of the 7075-T651 welds in natural seawater and the extent of overaging in the HAZ were reduced when welding with EMILI of 3 mT. Thus, EMILI along with the MIEA technique may lead to welded joints with better microstructural characteristics, improved mechanical properties in the HAZ and reduced electrochemical activity.展开更多
基金Project(2008BS04030)supported by Research Award Fund for Outstanding Young Scientists in Shandong Province,China
文摘Nanocrystalline NdFeB film was fabricated onto the copper substrate through direct current electroplating method,and characterized by scanning electron microscope(SEM) coupled with energy dispersive X-ray spectroscope(EDS),vibrating sample magnetometer and potentiodynamic polarization techniques.The initial electroplating behavior was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) techniques.Results revealed that the corrosion resistance of the NdFeB film was better than that of the traditional sintered NdFeB magnet.The depositing process of the NdFeB film followed the three-dimensional nucleation and subsequent grain growth mechanism,and was controlled by charger transfer.With the increase of the negative potential bias,the deposition mechanism of NdFeB film changed from heterogeneous to homogeneous nucleation/growth,which consequently resulted in the decrease of charge-transfer-resistance.
基金Projects(50771092,21073162) supported by the National Natural Science Foundation of ChinaProject(2005DKA10400-Z15) supported by the Ministry of Science and Technology of China
文摘CoNiFe,CoNiFeB and CoNiFeP soft magnetic thin films were prepared by cyclic voltammetry method.The morphologies,composition and structures were characterized by scanning electron microscope（SEM）,energy-dispersive X-ray spectroscope（EDS） and X-ray diffractometer（XRD）.The soft magnetic properties were investigated through vibrating sample magnetometer（VSM）.The corrosion resistance was investigated through Tafel polarization and electrochemical impedance spectroscopic（EIS）.The results show that all the electrodeposited CoNiFe,CoNiFeB and CoNiFeP films are mixtures of crystalline and amorphous phases,and high amount of boron/phosphorus-containing additives favors the formation of amorphous state.Nanostructure is obtained in CoNiFe and CoNiFeB films.The inclusion of boron causes the film more dense and also increases its corrosion resistance.Meanwhile,the inclusion of boron lowers its coercivity（Hc） from 851.48 A/m to 604.79 A/m,but the saturation magnetic flux density（Bs） is almost unchanged.However,the addition of phosphorus greatly increases the film particle size and decreases its corrosion stability.The coercivity（Hc） of CoNiFeP film is also highly increased to 12485.79 A/m,and its saturation magnetic flux density（Bs） is greatly decreased to 1.25 T.
基金Projects(51207031,51177022)supported by the National Natural Science Foundation of ChinaProject(2013M541368)supported by the China Postdoctoral Science Foundation+1 种基金Project(BS2011NJ002)supported by the Promotive Research Fund for Excellent Young and Middle-Aged Scientists of Shandong Province,ChinaProject(2008DFR60340)supported by the International Science and Technology Cooperation of China
文摘Copper is susceptible to producing corrosion problems in corrosive environments, which leads to serious safety problems. Thus, investigating the corrosion behavior of copper is of great significance. The effects of rotating electromagnetic field on corrosion behavior of T2 copper in 3.5% sodium chloride solution with electrochemical measurements were investigated. The results showed that rotating electromagnetic field changed properties of 3.5% sodium chloride solution by increasing the values of temperature and pH and decreasing the values of conductivity and dissolved oxygen. The rotating electromagnetic field improved the corrosion resistance of T2 copper. The corrosion products of T2 copper in treated 3.5% sodium chloride solution were composed of Cu20 and CuCl. The low corrosion rate of T2 copper was resulted from the decrease of dissolved oxygen in 3.5% sodium chloride solution treated by rotating electromagnetic field.
基金Project(2017zzts005) supported by the Fundamental Research Funds for the Central Universities of Central South University
文摘Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding performance.The research process ofMg-Li alloys is reviewed and three main problems are pointed out.Aimed at the poor corrosion resistance of Mg-Li alloys,thecorrosion behavior is mainly summarized.The surface treatment technologies,including electroplating,electroless plating,plasmaspraying,molten salt replacement,conversion coating,anodizing,micro-arc oxidation,organic coating,and organic-inorganic hybridcoating,are introduced in detail.Finally,the future development of corrosion and protection of Mg?Li alloys is discussed.
文摘The effects of applying an electromagnetic interaction of low intensity (EMILI) on the microstructure and corrosion resistance of 7075-T651 Al alloy plates (13 mm in thickness) during modified indirect electric arc (MIEA) welding were investigated. The welding process was conducted in a single pass with a heat input of ~1.5 kJ/mm. The microstructural observations of the welds were correlated with the effect of EMILI on the local mechanical properties and the corrosion resistance in natural seawater by means of microhardness measurements and electrochemical impedance spectroscopy, respectively. Microstructural characterization of the welds revealed a grain refinement in the weld metal due to the electromagnetic stirring induced by EMILI of 3 mT during welding. In addition, observations in the scanning electron microscope showed that the precipitation of Cu-rich phases and segregation of eutectics were reduced in the heat affected zone (HAZ) also as an effect of EMILI. The high corrosion dissolution of the 7075-T651 welds in natural seawater and the extent of overaging in the HAZ were reduced when welding with EMILI of 3 mT. Thus, EMILI along with the MIEA technique may lead to welded joints with better microstructural characteristics, improved mechanical properties in the HAZ and reduced electrochemical activity.
