检索结果-南通市图书馆

Structure,nitridation efficiency and magnetic properties of SmFe powders and its nitrides

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第6期42卷 1983-1988页

作者： Xiao-Xia Chen Yang Luo Zhou Hu Wen-Long Yan ning-tao quan Shuo Lu Dun-Bo Yu Jia-Jun Xie National Engineering Research Center for Rare Earth Grirem Advanced Materials Co.Ltd.Beijing100088China

The effect of annealing temperature(TA) at600-900℃ on structure and magnetic properties of the melt-spun Sm_(8.6)Fe_(85.9)Co_(4.3)Zr_(1.2) alloys and its nitrides was investigated.Results show that the melt-spun powder is TbCu7-type SmFe_(9) single phase.X-ray diffractometer(XRD) Rietveld refinement shows that the lattice parameter a increases,c and c/a decrease with the increase in T_(A) at600-700℃.This is due to the tendency of nitrogen entering into the 3f site(1/2,0,0) during the nitridation process,which is good for the magnetic properties.The phase transforms from TbCu7-type SmFe_(9) to Th_(2)Zn_(17)-type Sm_(2)Fe_(17) at above 800 0C.Scanning electron microscopy(SEM) images show that the amount of surface defects of melt-spun powder which are harmful for magnetic properties decreases at first and then increases as TA increases.The coercivity(H_(cj)) and maximum magnetic energy product((BH)_(max)) of its nitrides increase first and then decrease as a function of TA.And the remanence(B_(r))always shows a decrease.The optimal magnetic properties of H_(cj)=748 kA·m^(-1),B_(r)=0.92 T,(BH)_(max)=118 kJ·m^(-3) are obtained by annealing at 675℃ for 2 h and then nitriding at 460℃ for 10 h.

关键词： Melt-spun alloy Annealing temperature Magnetic property XRD Rietveld refinement

Hard magnetic properties of melt-spun nanocomposite Y_(16)Fe_(78)B_(6)ribbons

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第2期42卷 602-605页

作者： Liang Sun Kuo-She Li Hong-Wei Li Dun-Bo Yu Yang Luo Jin-Ling Jin Shuo Lu ning-tao quan GRIREM Advanced Materials Ltd General Research Institute for Nonferrous MetalsBeijing100088China

Melt-spun Y_(16)Fe_(78)B_(6)ribbons were prepared by the melt-spinning technique with pure elements Y,Fe and Fe-B alloy n argon.The ribbons are mainly composed of Y_(2)Fe_(14)B,YFe_(2)andα-Fe phases.Amorphous phase appears at the wheel velocity of>35 m·s^(-1).For the ribbons prepared at optimum wheel velocity and heat treatments,the coercivity,remanence and maximum energy product are239.5 kA·m^(-1),0.61 T and 32.7 kJ·m-3,respectively.By an investigation of Henkel plots of ribbons,it is found that intergrain exchange coupling leads to the enhancement of remanence.The coercivity mechanism of ribbons prepared at 35 m·s^(-1)is mainly controlled by inhomogeneous pinning of domain walls.The phase component and magnetic properties change with annealing temperature and time.The optimum magnetic properties are obtained with the ribbon quenched at 35 m·s^(-1)and annealed at 700℃for10 min.

关键词： Melt spinning Permanent magnets Y-Fe-B alloys Magnetic hardening

Coercivity enhancement of hot-deformed NdFeB permanent magnets with AlCuZn eutectic alloy grain boundary diffusion

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2022年第1期41卷 226-231页

作者： Ye-Qi Yu Kuo-She Li Hai-Jun Peng Xin-Yuan Bai ning-tao quan Kai-Wen Wu Yang Luo Dun-Bo Yu National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsBeijing 100088China GRIREM Advanced Materials Co.Ltd.Beijing 100088China

It is approved that grain boundary diffusion is an effective method to increase the coercivity of hot-deformed NdFeB magnet.In this paper,a new rare earth-free grain boundary diffusion source of hot-deformed magnet was studied.AlCuZn powders blended with commercial NdFeB powders were hot-compacted to obtain fully dense magnets,hot-deformed into anisotropic magnets and finally annealed to gain better homogeneity.Initially,the influences of annealing temperature and time on the magnetic properties of the specimens were studied and the optimal parameters of 600℃ and 60 min were achieved.Then,by changing the proportions of AlCuZn grain boundary diffusion,the coercivity,remanence and maximum energy product of the hot-deformed NdFeB magnets were examined.The result showed that with 1.0 wt%AlCuZn grain boundary diffusion and annealing at 600℃ for 60 min,the coercivity rose from 828 to 987 kA·m^(-1) without deteriorating the remanence.Microstructural analysis confirmed that AlCuZn diffused into the intergranular boundaries and the magnet diffused with AlCuZn possessed finer grains than that of without AlCuZn grain boundary diffusion.

关键词： AlCuZn Grain boundary diffusion Hotdeformed Coercivity enhancement

Permanent magnetic properties of Nd-Fe-B melt-spun ribbons with Y substitution

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2020年第1期39卷 55-61页

作者： Cao-Huan Zhang Yang Luo Dun-Bo Yu ning-tao quan Gui-Yong Wu Ya-Kun Dou Zhou Hu Zi-Long Wang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsBeijing100088China Grirem Advanced Materials Co.Ltd Beijing100088China

Phase constituents,microstructures and magnetic properties of melt-spun Nd12-xYxFe81B6 Nb ribbons were investigated systematically.The influence of Y substitution for Nd on the phase stability,grain size and magnetic exchange coupling was analyzed.It is found that all the ribbons crystallize in the tetragonal 2:14:1 structure,i.e.,with single hard magnetic phase at the roll speed of25 m s-1.With the increase in Y doping,Curie temperature(Tc)increases,while the coercivity decreases monoclinic ally.However,remanence magnetization(Br)and maximum energy product((BH)max)fluctuate and the maximum value is obtained at certain amount of Y.The optimum magnetic properties of intrinsic coercivity of intrinsic coercivity(Hcj)=908.2 kA·m-1 and(BH)max=118.52 kJ·m-3 are achieved when x=1.0.It can be attributed to the strengthened exchange coupling between the neighboring nanograins in Nd-Y-Fe-B meltspun powder based on the Henkel curves.Furthermore,Y substitution also significantly improves the temperature stability of magnetic performance.The coercivity temperature coefficient ofβ=-0.157%·℃-1 and remanence temperature coefficient ofα=-0.32%·℃-1 are gained,which are greatly reduced compared with those of the undoped Nd-Fe-B compounds.

关键词： Rapid quenching (Nd,Y)-Fe-B alloy Exchange coupling Thermal stability

Structure and magnetic properties of TbCu_7-type melt-spun Sm–Fe–B alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2019年第2期38卷 151-156页

作者： Chuan-Jiang Zheng Yang Luo Dun-Bo Yu Wen-Long Yan Hong-Wei Li Yong-Jun Mao Shuo Lu ning-tao quan National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd.

The melt-spun SmFe_(12)B_x(x = 0, 0.50, 0.75,1.00, 1.25 and 1.50) ribbons were prepared at 40 m·s^(-1),and their structure and magnetic properties were studied by powder X-ray diffraction(XRD), vibrating sample magnetometer(VSM) and transmission electron microscopy(TEM). XRD results indicate that SmFe_(12)B_x alloys with 0.50 ≤ x ≤ 1.00 are composed of single-phase TbCu_7-type structure. Moreover, it is found that the boron addition can inhibit the emergence of soft magnetic phase a-Fe and result in the increase in the axial ratio c/a. After annealing at 650 ℃ for 0.5 h, the metastable phase TbCu_7 initially decomposes into the stable phase Sm_2Fe_(14)B(Nd_2Fe_(14)B-type) and a-Fe. The value of magnetic moment per Fe atom increases slightly from 1.75 uB for boron-free sample to 1.80 uB for the x = 0.75 sample and then decreases again.In addition, the best magnetic properties of maximum energy product [(BH)_(max)] of 14.56 kJ·m^(-3), coercivity(H_(cj))of 172.6 kA·m^(-1) and remanence(B_r) of 0.45 T are obtained for the SmFe_(12)B_(1.00) alloy. Based on transmission electron microscopy(TEM) results, the average size of grains is around 197 nm for B-free sample and decreases to 95 nm for x = 1.00 sample, indicating that the addition of boron can refine grains.

关键词： TbCu7-type structure Sm-Fe-B ribbons Phase formation Magnetic moment Microstructure

Magnetic properties optimization of nanocomposite Nd_9Fe_(85)B_6 magnets by controlling microstructure of as-quenched ribbons

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2014年第3期33卷 299-303页

作者： Yu-Chao Liu Hong-Wei Li Kuo-She Li Dun-Bo Yu Jin-Ling Jin Yang Luo Liang Sun ning-tao quan National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals

To optimize the magnetic properties of nanocomposite Nd9Fe85B6 magnets, the as-quenched ribbons with different microstructures were prepared at six wheel velocities from 10 to 30 m s^-1through rapid quenching,followed by a series of annealing treatments at 550-800 °C for 5-10 min. It is found that both the large initial grains at low cooling rate and high content of amorphous phase at high cooling rate cause a-Fe grains coarsening, which leads to a decline in the strength of exchange coupling interaction and the deterioration of magnetic properties. In order to optimize the magnetic properties, the as-quenched ribbons should be chosen with relatively small initial grains as well as a small amount of amorphous phase. For nanocomposite Nd9Fe85B6 materials, the optimized magnetic properties of Hcj= 446 kA m^-1, Br= 0.86 T,（BH）max=80 kJ m^-3are obtained for ribbons prepared at 18 m s-1after annealing at 620 °C for 5 min.

关键词： Nanocomposite Rapid quenching Microstructure Grain sizes

Structure and magnetic properties of melt-spun Sm-Fe-Nb ribbons and their nitrides

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2018年第3期37卷 232-236页

作者： Wen-Long Yan Yang Luo Dun-Bo Yu Gui-Yong Wu ning-tao quan Yuan-Fei Yang Hai-Jun Peng Zi-Long Wang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co. Ltd.

SmFe（10-x）Nbx（x = 0, 0.1, 0.2, 0.3） ribbons and their nitrides were prepared by melt-spinning, followed by annealing and subsequent nitriding. The structure and magnetic properties were investigated by means of X-ray diffraction（XRD） using the Rietveld method, vibrating sample magnetometer（VSM）, transmission electron microscope（TEM） and Mossbauer spectroscopy. XRD analysis shows that the addition of Nb can impede the precipitation of Sm2 Fe（17） and a-Fe phases and the Nb atoms occupy 2 e site in the alloys. At 300 K, the mean hyperfine fields of 2 e site are 29.58 T with Nb doping at x = 0.1 and the corresponding Curie temperature is 552 K. The optimal properties of remanence of Br = 0.9 T, intrinsic coercivity of H（cj）= 741.5 kA·m^-1, and maximum magnetic energy product of（BH）（max）= 124.2 kJ·m-（-3） are gained at x = 0.10 in the nitrides.

关键词： Melt-spinning SmFe10-xNbx powders Magnetic properties XRD Rietveld Mssbauer spectroscopy

Resveratrol combats chronic diseases through enhancing mitochondrial quality

在线全文

学校读者我要写书评

暂无评论

Food Science and Human Wellness 2024年第2期13卷 597-610页

作者： Weichu tao Hu Zhang Xia Jiang ning Chen Tianjiu Research and Development Center for Exercise Nutrition and Foods Hubei Key Laboratory of Exercise Training and MonitoringCollege of Sports MedicineWuhan Sports UniversityWuhan 430079China The University Hospital of Wuhan Sports University Wuhan 430079China

Resveratrol(RSV),as a functional food component extracted from natural plants,has been widely studied and recognized in preventing and treating various diseases,with major mechanisms including executing anti-inflammation and anti-oxidation functions,and improving mitochondrial quality.Chronic diseases as non-communicable diseases are mainly caused by multiple factors,such as physiological decline and dysfunction in the body,and have become a significant challenge on public health worldwide.It is worth noting that chronic diseases such as Alzheimer's disease(AD),Parkinson's disease(PD),muscle atrophy,cardiovascular disease,obesity,and cancer are accompanied by abnormal mitochondrial function.Therefore,targeted regulation of mitochondria may be a meaningful way to prevent and treat chronic diseases.Increasing evidence has confirmed that RSV is actively involved in regulating mitochondria,and it has become an essential consideration to prevent and treat chronic diseases through targeting mitochondria and improving corresponding functions.In this article,current studies on RSV to optimize mitochondrial quality for preventing and alleviating chronic disease are systematically summarized,which can provide a theoretical reference for the development of functional foods or drugs to combat chronic diseases.

关键词： Resveratrol Functional food Mitochondrial quality Chronic disease Anti-inflammation Anti-oxidation

Editable semiconductor photo-electrodes for sustainable ammonia synthesis

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第4期17卷 3107-3112页

作者： ning Lan Kun Du Erling Zhao Wei Zhao tao Ling Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education Institute of New-EnergySchool of Materials Science and EngineeringTianjin UniversityTianjin 300072China School of Materials Science and Engineering Tianjin Chengjian UniversityTianjin 300384China

Powered by an inexhaustible supply of solar energy,photoelectrochemical(PEC)nitrogen reduction reaction(NRR)provides an ideal solution for the synthesis of green ammonia(NH_(3)).Although great efforts have been made in the past decades,there are still significant challenges in increasing the NH_(3) yields of the PEC-NRR devices.In addition to the issues of low activity and selectivity similar to electrochemical NRR,the progress of PEC-NRR is also impeded by the limited increase in NH_(3) yields as the electrode is enlarged.Here,we propose an editable electrode design strategy that parallels unit photo-electrodes to achieve a linear increase in NH_(3) yields with electrode active area.We demonstrate that the editable electrode design strategy minimizes the electrode charge transfer resistance,allowing more photo-generated carriers to reach the electrode surface and promote the catalytic reaction.We believe that this editable electrode design strategy provides an avenue to achieve sustainable PEC NH_(3) production.

关键词： editable electrode photoelectrochemical nitrogen reduction reaction parallel electrode ZnSe