Fe-6.5Si soft magnetic composites(SMCs)with hybrid phosphate-silica insulation coatings have been designed to improve their comprehensive property via chemical coating combining sol-gel method in this work.The microst...Fe-6.5Si soft magnetic composites(SMCs)with hybrid phosphate-silica insulation coatings have been designed to improve their comprehensive property via chemical coating combining sol-gel method in this work.The microstructure and magnetic performance of the Fe-6.5Si SMCs with hybrid phosphate-silica insulation coatings were investigated.The hybrid phosphate-silica coatings with high heat resistance and high withstand pressure,formed on the surface of the Fe-6.5Si ferromagnetic powders,were found stable in the composites.Compared with Fe-6.5Si SMCs coated by single phosphate or single silica,Fe-6.5Si SMCs with hybrid phosphate-silica show much higher permeability and lower core loss.The work provides a new way to optimize the magnetic performance of soft magnetic composites.展开更多
Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion re...Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion resistance.This article reports the detrimental impact of diamond magnetism on the composites microstructure and gives explanations.Microstructure differences between composites that,respectively,contained no-further-treated diamond,magnetism-strengthening treated diamond and magnetism weakening treated diamond were carefully observed.It is shown that diamond magnetization treatment drastically harms the composite microstructure(e.g.,roughening the coating surface,coarsening the matrix grain,and more seriously,reducing the mechanical retention of diamond grains in the matrix) while demagnetization treatment does the opposite.All the observed facts could be explained by the electromagnetic interaction between magnetic fields produced by magnetic diamond grains and electric current(moving cations) during the electrodeposition process.展开更多
Magnetic Fe3 O4@Cu/Ce microspheres were successfully prepared by one-step solvothermal approach and further utilized to remediate toxic arsenic(As(Ⅲ)) pollution. The effects of Cu/Ce elements co-doping on the crystal...Magnetic Fe3 O4@Cu/Ce microspheres were successfully prepared by one-step solvothermal approach and further utilized to remediate toxic arsenic(As(Ⅲ)) pollution. The effects of Cu/Ce elements co-doping on the crystal structure, catalytic oxidation and adsorption behaviors of magnetic microspheres were researched systematically. The results showed that with the aid of Cu/Ce elements, the grain size reduced, lattice defects increased, and the oxygen vacancies and surface hydroxyl groups were improved. Therefore, Cu/Ce elements endowed magnetic Fe3 O4@Cu/Ce microspheres with excellent As(III) removal performance, whose maximum adsorption capacity reached 139.19 mg/g. The adsorption mechanism mainly involved catalytic oxidant co-adsorption. This research developed a feasible strategy for the preparation of high efficiency magnetic adsorbent to enhance the removal of As(Ⅲ).展开更多
The dispersion of magnetic nanoparticles in matrix is crucial to ensure optimum performance of the composite.The difficulty level of achieving good dispersion is further increase when a multi-phases of matrix is prese...The dispersion of magnetic nanoparticles in matrix is crucial to ensure optimum performance of the composite.The difficulty level of achieving good dispersion is further increase when a multi-phases of matrix is present.A pre-coating technique of magnetic nanoparticles with polypropylene using ball-mill prior to melt-blending process was employed to prepare a multi-phases thermoplastic natural rubber composite.The effect of filler loading(2 wt%-10 wt%) on morphology,structure,magnetic properties,thermal stability and dynamic mechanical properties of the composites were investigated.It was found that the NiZn ferrite nanoparticles act as nucleating agent to form beta isostatic polypropylene thermoplastic composites.The composites’ magnetic properties are directly dependent on the filler concentration.The dispersion of magnetic fillers in polymer matrix plays role in affecting the magnetic properties and thermal stability.The preference of filler to locate at amorphous phase has distorted the chain orientation of natural rubber and polypropylene.Hence,the polymorphism and crystallinity of the matrix varied as the filler loading increased,affecting the dynamic mechanical properties.It was found that 8 wt% NiZn nanocomposite exhibits highest E’ and tanδ,indicating the dynamic mechanical properties of NiZn nanocomposite are affected by β-phase degree.展开更多
By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures w...By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures were characterized by three layers, the middle layer of which reaches 80% thickness and forms the column grain of(Fe,Co) solid with Gd solution. Grain refinement takes place with the increase of the wheel speed. And after 0.5 h heat treatment at 823 K, the ribbon thickness becomes larger and the middle layer of column grain is very orderly perpendicular to the ribbon plane. The coercivity of quenched and annealed Fe63Co32Gd5 ribbons both have the inflection point at the wheel speed of 20 m/s, and the tendency is declining. The heat treatment processing makes the coercivity become lower by improving the order of(Fe,Co)17Gd2 compound. The saturation magnetization of quenched ribbons increases with the enhancement of wheel speed, whereas that of annealed ones decreases firstly and then increases. The minimum coercivity is 5.30×103 A/m and the maximum saturation magnetization is 163.62 A·m2/kg, which is obtained in the conditions of the wheel speed of 35 m/s and 0.5 h heat treatment at the temperature of 823 K.展开更多
软磁复合材料因其突出的高频特性而被广泛用作变压器和电机的铁心材料。为了提高高频磁化下变压器或电机的效率与功率密度,需要提高产品设计阶段铁损的计算精度。该文提出一种基于梯形等效电路与神经网络结合的动态磁滞模型,可用以计算...软磁复合材料因其突出的高频特性而被广泛用作变压器和电机的铁心材料。为了提高高频磁化下变压器或电机的效率与功率密度,需要提高产品设计阶段铁损的计算精度。该文提出一种基于梯形等效电路与神经网络结合的动态磁滞模型,可用以计算高频软磁复合材料铁损。该模型通过非理想电感、恒定电阻和非线性电阻分别计算静态磁滞损耗、涡流损耗和异常损耗;其中,为了提高低磁密下静态磁滞回环的模拟精度,引入能够表征磁化过程的神经网络算法模拟静态磁滞部分;同时,在采用梯形等效电路计算涡流损耗和异常损耗时,考虑趋肤效应对铁损的影响;最后,搭建高频正弦激励下的软磁材料磁特性测试系统,在频率为1 Hz~10 k Hz范围内对软磁复合材料的磁滞回线和铁损进行实验测量,并将铁损计算方法与实测数据进行对比,验证该模型在高频正弦激励下预估损耗的准确性,为变压器和电动机优化设计提供一种模型结构简单、精度较高且工程实用性强的损耗计算方法。展开更多
基金Projects(2020GDSYL-20200402008,2018GDASCX-0117)supported by GDAS’Project of Science and Technology Development,ChinaProjects(2015B010136004,2019A1515010886)supported by Science and Technology Planning Project of Guangdong Province of ChinaProject(1920001001392)supported by Key Technology Project of Foshan,China。
文摘Fe-6.5Si soft magnetic composites(SMCs)with hybrid phosphate-silica insulation coatings have been designed to improve their comprehensive property via chemical coating combining sol-gel method in this work.The microstructure and magnetic performance of the Fe-6.5Si SMCs with hybrid phosphate-silica insulation coatings were investigated.The hybrid phosphate-silica coatings with high heat resistance and high withstand pressure,formed on the surface of the Fe-6.5Si ferromagnetic powders,were found stable in the composites.Compared with Fe-6.5Si SMCs coated by single phosphate or single silica,Fe-6.5Si SMCs with hybrid phosphate-silica show much higher permeability and lower core loss.The work provides a new way to optimize the magnetic performance of soft magnetic composites.
基金This work was supported by Henan Agricultural University,the Natural Science Foundation of Henan Province(0411051300)the Project for Excel-lent University Teachers under the supervision of Henan Provincial Bureau of Education.
文摘Electroformed diamond tools have been used for many years in grinding and cutting fields while electrodeposited diamond composite coatings have been widely studied due to their desirable hardness,wear and corrosion resistance.This article reports the detrimental impact of diamond magnetism on the composites microstructure and gives explanations.Microstructure differences between composites that,respectively,contained no-further-treated diamond,magnetism-strengthening treated diamond and magnetism weakening treated diamond were carefully observed.It is shown that diamond magnetization treatment drastically harms the composite microstructure(e.g.,roughening the coating surface,coarsening the matrix grain,and more seriously,reducing the mechanical retention of diamond grains in the matrix) while demagnetization treatment does the opposite.All the observed facts could be explained by the electromagnetic interaction between magnetic fields produced by magnetic diamond grains and electric current(moving cations) during the electrodeposition process.
基金Project(2018YFC1802204)supported by the National Key R&D Program of ChinaProject(51634010)supported by the Key Project of National Natural Science Foundation of ChinaProject(2018SK2026)supported by the Key R&D Program of Hunan Province,China。
文摘Magnetic Fe3 O4@Cu/Ce microspheres were successfully prepared by one-step solvothermal approach and further utilized to remediate toxic arsenic(As(Ⅲ)) pollution. The effects of Cu/Ce elements co-doping on the crystal structure, catalytic oxidation and adsorption behaviors of magnetic microspheres were researched systematically. The results showed that with the aid of Cu/Ce elements, the grain size reduced, lattice defects increased, and the oxygen vacancies and surface hydroxyl groups were improved. Therefore, Cu/Ce elements endowed magnetic Fe3 O4@Cu/Ce microspheres with excellent As(III) removal performance, whose maximum adsorption capacity reached 139.19 mg/g. The adsorption mechanism mainly involved catalytic oxidant co-adsorption. This research developed a feasible strategy for the preparation of high efficiency magnetic adsorbent to enhance the removal of As(Ⅲ).
基金the support from the National Science Fund(NSF)MOSTI+1 种基金UKMUCSI
文摘The dispersion of magnetic nanoparticles in matrix is crucial to ensure optimum performance of the composite.The difficulty level of achieving good dispersion is further increase when a multi-phases of matrix is present.A pre-coating technique of magnetic nanoparticles with polypropylene using ball-mill prior to melt-blending process was employed to prepare a multi-phases thermoplastic natural rubber composite.The effect of filler loading(2 wt%-10 wt%) on morphology,structure,magnetic properties,thermal stability and dynamic mechanical properties of the composites were investigated.It was found that the NiZn ferrite nanoparticles act as nucleating agent to form beta isostatic polypropylene thermoplastic composites.The composites’ magnetic properties are directly dependent on the filler concentration.The dispersion of magnetic fillers in polymer matrix plays role in affecting the magnetic properties and thermal stability.The preference of filler to locate at amorphous phase has distorted the chain orientation of natural rubber and polypropylene.Hence,the polymorphism and crystallinity of the matrix varied as the filler loading increased,affecting the dynamic mechanical properties.It was found that 8 wt% NiZn nanocomposite exhibits highest E’ and tanδ,indicating the dynamic mechanical properties of NiZn nanocomposite are affected by β-phase degree.
基金Projects(51271149,50901060)supported by the National Natural Science Foundation of ChinaProject(NPU-310201401007JCY01007)supported by the Nothwestern Polytechnical University(NPU)Foundations for Fundamental Research,ChinaProject(2012-0009451)supported by the National Research Foundation of Korea
文摘By using the melt spinning techniques, the Fe63Co32Gd5 alloy ribbons with 15-50 m in thickness and 3-7 mm in width were prepared at the wheel speeds of 15, 20, 25 and 35 m/s. The rapid solidification microstructures were characterized by three layers, the middle layer of which reaches 80% thickness and forms the column grain of(Fe,Co) solid with Gd solution. Grain refinement takes place with the increase of the wheel speed. And after 0.5 h heat treatment at 823 K, the ribbon thickness becomes larger and the middle layer of column grain is very orderly perpendicular to the ribbon plane. The coercivity of quenched and annealed Fe63Co32Gd5 ribbons both have the inflection point at the wheel speed of 20 m/s, and the tendency is declining. The heat treatment processing makes the coercivity become lower by improving the order of(Fe,Co)17Gd2 compound. The saturation magnetization of quenched ribbons increases with the enhancement of wheel speed, whereas that of annealed ones decreases firstly and then increases. The minimum coercivity is 5.30×103 A/m and the maximum saturation magnetization is 163.62 A·m2/kg, which is obtained in the conditions of the wheel speed of 35 m/s and 0.5 h heat treatment at the temperature of 823 K.
文摘软磁复合材料因其突出的高频特性而被广泛用作变压器和电机的铁心材料。为了提高高频磁化下变压器或电机的效率与功率密度,需要提高产品设计阶段铁损的计算精度。该文提出一种基于梯形等效电路与神经网络结合的动态磁滞模型,可用以计算高频软磁复合材料铁损。该模型通过非理想电感、恒定电阻和非线性电阻分别计算静态磁滞损耗、涡流损耗和异常损耗;其中,为了提高低磁密下静态磁滞回环的模拟精度,引入能够表征磁化过程的神经网络算法模拟静态磁滞部分;同时,在采用梯形等效电路计算涡流损耗和异常损耗时,考虑趋肤效应对铁损的影响;最后,搭建高频正弦激励下的软磁材料磁特性测试系统,在频率为1 Hz~10 k Hz范围内对软磁复合材料的磁滞回线和铁损进行实验测量,并将铁损计算方法与实测数据进行对比,验证该模型在高频正弦激励下预估损耗的准确性,为变压器和电动机优化设计提供一种模型结构简单、精度较高且工程实用性强的损耗计算方法。
