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Research progress of permanent ferrite magnet materials
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作者 XU Bin CHEN Yu-feng +3 位作者 ZHOU Yu-juan LUO Bi-yun ZHONG Shou-guo LIU Xing-ao 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期1723-1762,共40页
Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a... Permanent ferrite magnet materials are extensively employed due to their exceptional magnetic properties and cost-effectiveness.The fast development in electromobile and household appliance industries contributes to a new progress in permanent ferrite materials.This paper reviews the deveolpement and progress of permanent ferrite magnet industry in recent years.The emergence of new raw material,the advancement of perparation methods and manufacturing techniques,and the potential applications of permanent ferrite materials are introduced and discussed.Specifically,nanocrystallization plays a crucial role in achieving high performance at a low cost and reducing reliance on rare earth resources,and therefore it could be a promising development trendency. 展开更多
关键词 permanent ferrite magnetic materials HIGH-PERFORMANCE nanosizing
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Recent progress in high temperature permanent magnetic materials 被引量:22
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作者 Cheng-Bao Jiang Shi-Zhong An 《Rare Metals》 SCIE EI CAS CSCD 2013年第5期431-440,共10页
Permanent magnetic materials capable of operating at high temperature up to 500℃ have wide potential applications in fields such as aeronautics, space, and electronic cars. SmCo alloys are candidates for high tempera... Permanent magnetic materials capable of operating at high temperature up to 500℃ have wide potential applications in fields such as aeronautics, space, and electronic cars. SmCo alloys are candidates for high temperature applications, since they have large magnetocrystalline anisotropy field (6-30 T), high Curie temperature (720-920℃), and large energy product (〉200 kJ.m-3) at room temperature. However, the highest service temperature of commercial 2:17 type SmCo magnets is only 300℃, and many efforts have been devoted to develop novel high temperature permanent magnets. This review focuses on the development of three kinds of SmCo based magnets: 2:17 type SmCo magnets, nanocrystalline SmCo magnets, and nanocomposite SmCo magnets. The oxidation protection, including alloying and surface modification, of high temperature permanent magnets is discussed as well. 展开更多
关键词 Magnetic materials Sm-Co alloys permanent magnets High temperature
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A simple permanent deformation model of rockfill materials 被引量:4
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作者 De-gao Zou Jing-mao Liu +2 位作者 Xian-jing Kong Chen-guang Zhou Qing-po Yang 《Water Science and Engineering》 EI CAS CSCD 2018年第4期302-309,共8页
Existing experimental results have shown that using a semi-log linear relationship between the permanent volumetric strain and cyclic number underestimates the volumetric deformation of rockfill materials with a large... Existing experimental results have shown that using a semi-log linear relationship between the permanent volumetric strain and cyclic number underestimates the volumetric deformation of rockfill materials with a large cyclic number, and that the error increases with the confining pressure. The existing permanent deformation models are not suitable for the seismic safety analysis of high dams during strong earthquakes. In this study, a series of large-scale triaxial cyclic loading tests of rockfill materials were performed, and a new permanent deformation model of rockfill materials was developed and validated with three kinds of rockfill materials. The results show that the proposed model can properly reflect the general features of the permanent deformation of rockfill materials. The main features of the model are as follows:(1) relations between the cyclic number and permanent volumetric/shear strain are described by hyperbolic functions, which can avoid underestimating the volumetric deformation occurring during strong earthquakes;(2) the model can capture the effect of the mean effective stress on the permanent volumetric strain, with greater confining pressure correlating to greater permanent volumetric deformation, and the permanent volumetric strain under low confining pressure near the dam crest can be well represented; and(3) the model can reflect the effect of the consolidation stress ratio on the permanent shear strain. 展开更多
关键词 Rockfill materials permanent deformation Triaxial test Cyclic loading Consolidation stress ratio
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New shakedown criterion and permanent deformation properties of unbound granular materials 被引量:3
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作者 Ali Alnedawi Kali Prasad Nepal Riyadh Al-Ameri 《Journal of Modern Transportation》 2019年第2期108-119,共12页
Unbound granular material specifications for road pavements in Australia are primarily based on physical material specification rather than mechanical characterisation. This simplified approach does not reflect the ac... Unbound granular material specifications for road pavements in Australia are primarily based on physical material specification rather than mechanical characterisation. This simplified approach does not reflect the actual material performance under repeated dynamic traffic loads. There is a little information available on the influence of the local crushed rock properties and compacted layer properties on permanent deformation (PD). This study aims to characterise the local unbound granular materials in Victoria according to their PD behaviour under repeated loads and to develop a suitable shakedown criterion that could describe the PD of the tested materials to simplify the flexible pavement design. Repeated-load triaxial tests were conducted over several samples with a range of moisture contents, gradations, densities, and stress conditions. The laboratory test results showed that PD behaviour was influenced by several factors. In addition, the tested subbase-specified unbound granular materials reflect high PD resistance that is almost equivalent to basequality unbound granular materials. This may indicate that current requirements for the subbase-quality unbound granular materials are over-prescribe. Moreover, as the existing shakedown criterion was not applicable for the multi-stage repeated-load triaxial test and the local tested materials, a new shakedown criterion and new boundaries are proposed based on the PD behaviour. In the proposed criterion, the shakedown ranges are identified based on the curve angle of the PD vs. logarithm of the number of loading cycles, and this new criterion was validated using several materials from existing literature. The local tested base and subbase materials can be assigned as Range A when PD\1%, Range B when 1%\PD\3%, and Range C when PD[3%. The proposed criterion could provide a useful and quick approach to assess the PD of the unbound granular materials with both single and multistages of stresses. 展开更多
关键词 Flexible PAVEMENT Unbound GRANULAR materials Repeated load TRIAXIAL test permanent deformation SHAKEDOWN theory
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Neural network-based model for prediction of permanent deformation of unbound granular materials
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作者 Ali Alnedawi Riyadh Al-Ameri Kali Prasad Nepal 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2019年第6期1231-1242,共12页
Several available mechanistic-empirical pavement design methods fail to include predictive model for permanent deformation(PD)of unbound granular materials(UGMs),which make these methods more conservative.In addition,... Several available mechanistic-empirical pavement design methods fail to include predictive model for permanent deformation(PD)of unbound granular materials(UGMs),which make these methods more conservative.In addition,there are limited regression models capable of predicting the PD under multistress levels,and these models have regression limitations and generally fail to cover the complexity of UGM behaviour.Recent researches are focused on using new methods of computational intelligence systems to address the problems,such as artificial neural network(ANN).In this context,we aim to develop an artificial neural model to predict the PD of UGMs exposed to repeated loads.Extensive repeated load triaxial tests(RLTTs)were conducted on base and subbase materials locally available in Victoria,Australia to investigate the PD properties of the tested materials and to prepare the database of the neural networks.Specimens were prepared over different moisture contents and gradations to cover a wide testing matrix.The ANN model consists of one input layer with five neurons,one hidden layer with twelve neurons,and one output layer with one neuron.The five inputs were the number of load cycles,deviatoric stress,moisture content,coefficient of uniformity,and coefficient of curvature.The sensitivity analysis showed that the most important indicator that impacts PD is the number of load cycles with influence factor of 41%.It shows that the ANN method is rapid and efficient to predict the PD,which could be implemented in the Austroads pavement design method. 展开更多
关键词 Flexible PAVEMENT design Unbound GRANULAR materials permanent deformation (PD) Repeated load TRIAXIAL test (RLTT) PREDICTION models Artificial neural network (ANN)
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The Production Management Improvement Model of Small and Medium-sized Permanent Magnetic Materials Manufacturing Companies
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作者 TIAN Zhong-qu ZHANG Shu-juan +2 位作者 JIN Ya-juan REN Miao AN Pei 《International Journal of Plant Engineering and Management》 2016年第3期150-159,共10页
An integrated production planning and control model based on MRPⅡand JIT is put forward through analyzing the characteristics of magnetic materials manufacturing companies. Master Production Schedule with limited cap... An integrated production planning and control model based on MRPⅡand JIT is put forward through analyzing the characteristics of magnetic materials manufacturing companies. Master Production Schedule with limited capacity and operational plan in workshop level based on the basic data of flow chart are formulated by this model which applied JIT idea and based on customer order demand. Push production is adapted during execution phase combined with process flow cards. The model is helpful to reduce inventory,keep certain flexbility of production and improve continuity and equilibrium of manufacturing process. 展开更多
关键词 permanent magnetic materials manufacturing MRP II JIT production management
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Design and Performance Analysis of Permanent Magnet Claw Pole Machine with Hybrid Cores 被引量:1
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作者 Chengcheng Liu Zheng Chao +1 位作者 Shaopeng Wang Youhua Wang 《CES Transactions on Electrical Machines and Systems》 CSCD 2023年第3期275-283,共9页
Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for hi... Permanent magnet claw pole machine(PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material(SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet-SMC cores and amorphous alloy-SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM. 展开更多
关键词 permanent magnet claw pole machine(PMCPM) Soft magnetic materials(SMC) Hybrid cores Eddy current loss
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Advance in the chemical synthesis and magnetic properties of nanostructured rare-earth-based permanent magnets 被引量:13
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作者 Ce Yang Yang-Long Hou 《Rare Metals》 SCIE EI CAS CSCD 2013年第2期105-112,共8页
Rare-earth-based permanent magnets are one of the most important magnets in both scientific and industrial fields. With the development of technology, nanostructured rarearth-based permanent magnets with high energy p... Rare-earth-based permanent magnets are one of the most important magnets in both scientific and industrial fields. With the development of technology, nanostructured rarearth-based permanent magnets with high energy products are highly required. In this article, we will review the progress in chemical synthetic strategies of nanostructured rare-earth-based permanent magnets. 展开更多
关键词 rare-earth permanent magnets Chemicalsynthesis
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Computational Design of Rare-Earth Reduced Permanent Magnets 被引量:1
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作者 Alexander Kovacs Johann Fischbacher +6 位作者 Markus Gusenbauer Harald Oezelt Heike C.Herper Olga Yu.Vekilova Pablo Nieves Sergiu Arapan Thomas Schrefl 《Engineering》 SCIE EI 2020年第2期148-153,共6页
Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive fie... Multiscale simulation is a key research tool in the quest for new permanent magnets.Starting with first principles methods,a sequence of simulation methods can be applied to calculate the maximum possible coercive field and expected energy density product of a magnet made from a novel magnetic material composition.Iron(Fe)-rich magnetic phases suitable for permanent magnets can be found by means of adaptive genetic algorithms.The intrinsic properties computed by ab initio simulations are used as input for micromagnetic simulations of the hysteresis properties of permanent magnets with a realistic structure.Using machine learning techniques,the magnet’s structure can be optimized so that the upper limits for coercivity and energy density product for a given phase can be estimated.Structure property relations of synthetic permanent magnets were computed for several candidate hard magnetic phases.The following pairs(coercive field(T),energy density product(kJ·m^-3))were obtained for iron-tin-antimony(Fe3Sn0.75Sb0.25):(0.49,290),L10-ordered iron-nickel(L10 FeNi):(1,400),cobalt-iron-tantalum(CoFe6Ta):(0.87,425),and manganese-aluminum(MnAl):(0.53,80). 展开更多
关键词 rare-earth permanent MAGNETS MICROMAGNETICS
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Design and Optimization of Line-Start Rare-Earth Permanent Magnetic Synchronous Motor Basing on FEM
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作者 Shang Jing Hu Jianhui Zou Jibin 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第z1期107-111,共5页
The 2D transient FEM was used to analyze the starting process of the three phase rare-earth LS-PMSM.By verifying the simulation result with the experiment one, we get the conclusion that it is consistent with the expe... The 2D transient FEM was used to analyze the starting process of the three phase rare-earth LS-PMSM.By verifying the simulation result with the experiment one, we get the conclusion that it is consistent with the experiment result very well.At the same time, by analyzing the situation of the magnetic bridge, we also get the result that the amplitude of EMF waves are changing with the situation of the magnetic poles and we can optimize the motor's structure at the same time. 展开更多
关键词 LINE-START permanent magnetic SYNCHRONOUS MOTOR rare-earth MAGNET
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Effective model for rare-earth Kitaev materials and its classical Monte Carlo simulation
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作者 Mengjie Sun Huihang Lin +9 位作者 Zheng Zhang Yanzhen Cai Wei Ren Jing Kang Jianting Ji Feng Jin Xiaoqun Wang Rong Yu Qingming Zhang Zhengxin Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第8期509-517,共9页
Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamil... Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamiltonian consistent with the symmetry group of the crystal structure.Then we apply classical Monte Carlo simulations to preliminarily study the model and establish a phase diagram.When approaching to the low temperature limit,several magnetic long range orders are observed,including the stripe,the zigzag,the antiferromagnetic(AFM),the ferromagnetic(FM),the incommensurate spiral(IS),the multi-Q,and the 120°ones.We further calculate the thermodynamic properties of the system,such as the temperature dependence of the magnetic susceptibility and the heat capacity.The ordering transition temperatures reflected in the two quantities agree with each other.For most interaction regions,the system is magnetically more susceptible in the ab-plane than in the c-direction.The stripe phase is special,where the susceptibility is fairly isotropic in the whole temperature region.These features provide useful information to understand the magnetic properties of related materials. 展开更多
关键词 Monte Carlo methods Kitaev materials quantum spin liquids rare-earth ions DM interaction
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Permanent Rare-Earth Magnets—The Need to Protect Them against Corrosion
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作者 Célia Aparecida Lino dos Santos Zehbour Panossian 《Materials Sciences and Applications》 2019年第4期317-327,共11页
The RE-Fe-B permanent magnets have a complex microstructure and they are susceptible to corrosion process. In this paper, the commercial nickel coatings adhesion was investigated. The microstructure of the RE-Fe-B wit... The RE-Fe-B permanent magnets have a complex microstructure and they are susceptible to corrosion process. In this paper, the commercial nickel coatings adhesion was investigated. The microstructure of the RE-Fe-B without coating was analyzed by scanning electronic microscopy and electrochemical techniques. The interface magnet/coating was studied by scanning electron microscopy and the nickel-plated Nd-Fe-B commercial magnets were tested in a salt spray chamber. The ferromagnetic and RE-rich phases were observed. After the anodic polarization curve, a strong intergranular corrosion was observed and the RE-rich phase was preferentially attacked. The interface magnet/Ni coating presented inter-granular corrosion that can affect the nickel coating adherence. This attack had probably occurred during the electrodeposition process. Not all the samples suffered localized corrosion during the salt spray tests and the Ni triple-layer coating presented a few corrosion points. RE-Fe-B alloy magnets need to be protected with appropriate coatings to each environment to which they will be exposed and the protective coating must not be damaged. 展开更多
关键词 permanent Magnet rare-earth CORROSION Protection against CORROSION
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An Empirical Study of CAPM’s Applicability to Rare Earth Permanent Magnet Material Stocks
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作者 Angela Zhao 《Proceedings of Business and Economic Studies》 2022年第2期36-42,共7页
China has the world’s largest reserves of rare earth elements.Rare earth permanent magnet material has always been one of the popular industries in the investment market.CAPM is the basic asset-pricing model in finan... China has the world’s largest reserves of rare earth elements.Rare earth permanent magnet material has always been one of the popular industries in the investment market.CAPM is the basic asset-pricing model in financial economics.There are a number of studies conducted to examine the applicability of CAPM to stock markets in different industries and to investigate the modification method to improve the model’s prediction accuracy.In this study,seven leading enterprises in China’s rare earth permanent magnet material industry listed on the A-share market were selected as the research subjects.Based on CAPM,regression analysis was conducted on the monthly data from March 2016 to February 2022.The results demonstrated that using the β coefficient to explain the risk of China’s rare earth permanent magnet industry is ineffective.The ultimate benefit was less affected by market indexes but mainly by non-systematic risks.CAPM has low applicability to China’s rare earth permanent magnet material industry and requires further improvement.Nevertheless,CAPM still has some guiding significance in making enterprise comparisons and investment decisions. 展开更多
关键词 CAPM Rare earth permanent magnet material INVESTMENT Stock market Systematic risk
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Research progress in rare earths and their composites based electrode materials for supercapacitors 被引量:4
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作者 Subasri Arunachalam Balakrishnan Kirubasankar +4 位作者 Duo Pan Hu Liu Chao Yan Zhanhu Guo Subramania Angaiah 《Green Energy & Environment》 SCIE CSCD 2020年第3期259-273,共15页
Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting po... Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting polymers and transition metal oxide/hydroxide based electrode materials have been made to show a remarkable electrochemical performance.Rare-earth materials have attracted significant research attention as an electrode material for supercapacitor applications based on their physicochemical properties.In this review,rare earth metals,rare earth metal oxides/hydroxides,rare-earth metal chalcogenides,rare-earth metal/carbon composites and rare-earth metal/metal oxide composites based electrode materials are discussed for supercapacitors.We also discuss the energy chemistry of rare-earth metal-based materials.Besides the factors that affect the performance of the electrode materials,their evaluation methods and supercapacitor performances are discussed in details.Finally,the future outlook in rare-earth-based electrode materials is revealed towards its current developments for supercapacitor applications. 展开更多
关键词 rare-earth metals rare-earth metal oxides Rare earth metal hydroxides SUPERCAPACITOR Electrode materials
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Effect of vertical stress rest period on deformation behaviour of unbound granular materials:Experimental and numerical investigations 被引量:2
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作者 Ali Alnedawi Kali Prasad Nepal +1 位作者 Riyadh Al-Ameri Mohanad Alabdullah 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2019年第1期172-180,共9页
Repeated load triaxial test is used to assess the deformation behaviour of unbound granular materials(UGMs) in flexible road pavements. Repeated load pulse characteristics(i.e. shape, loading period and rest period) a... Repeated load triaxial test is used to assess the deformation behaviour of unbound granular materials(UGMs) in flexible road pavements. Repeated load pulse characteristics(i.e. shape, loading period and rest period) are the stress configurations used in the experimental set-up to simulate the passing axle loads. Some researchers and standard testing protocols suggest a rest period of varying durations after a loading phase. A thorough review of existing literature and practises has revealed that there is no agreement about the effect of the rest period of vertical stress pulse on the deformation behaviour of the UGMs. Therefore,the main objective of this study is to investigate the effect of repeated stress rest period on the deformation behaviour of UGMs experimentally. Experiments are conducted, both with and without rest period, using basalt and granite crushed rocks from Victoria, Australia. Furthermore, in order to gain insight into the effect of the rest period, finite element modelling is also developed. Both the experimental and modelling results show that the rest period has a noticeable effect on both resilient and permanent deformation behaviours of UGMs. It is, therefore, recommended to take extra precautions while adopting a particular standard testing protocol and to supplement the results by additional tests with different loading configurations. 展开更多
关键词 Flexible PAVEMENT Unbound GRANULAR materials(UGMs) Repeated load TRIAXIAL test Resilient MODULUS permanent deformation Finite element modelling
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Critical Materials Institute develops new acid-free magnet recycling process 被引量:1
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《China Rare Earth Information》 2017年第9期7-8,共2页
A new rare-earth magnet recycling process developed by researchers at the Critical Materials Institute (CMI) dissolves magnets in an acid-free solution and recovers high purity rare earth elements. For shredded magnet... A new rare-earth magnet recycling process developed by researchers at the Critical Materials Institute (CMI) dissolves magnets in an acid-free solution and recovers high purity rare earth elements. For shredded magnet-containing electronic wastes, the process does not require pre-processing such as pre-sorting or demagnetization of the electronic waste. 展开更多
关键词 A NEW rare-earth MAGNET recycling process developed by researchers at the CRITICAL materials Institute (CMI)
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A Study of Two-Phase Nanocrystalline Nd_(8.5)Fe_(75)Co_5Cu_1Zr_3Nb_1B_(6.5)Permanent Magnet
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作者 倪建森 徐晖 +3 位作者 朱明原 李强 周邦新 董远达 《Journal of Rare Earths》 SCIE EI CAS CSCD 2003年第4期401-403,共3页
Nanocrystalline Nd 8.5 Fe 75 Co 5Cu 1Zr 3Nb 1B 6.5 ribbons were prepared by melt spun (18 m·s -1 ) and subsequent heat treatment (670 ℃/4 min). Excellent magnetic properties of the bonded m... Nanocrystalline Nd 8.5 Fe 75 Co 5Cu 1Zr 3Nb 1B 6.5 ribbons were prepared by melt spun (18 m·s -1 ) and subsequent heat treatment (670 ℃/4 min). Excellent magnetic properties of the bonded magnet were achieved as follows: B r=0.68 T (6 8 kGs), J H c=620.3 kA·m -1 (7.8 kOe), ( BH ) max =74 kJ·m -3 (9 3 MGOe). The results of TEM photomicrographs confirm that the appearance of α Fe phase is earlier than that of Nd 2Fe 14 B phase during crystallization process. The addition of Cu and Zr elements shows to be advantageous to the improvement of an intrinsic coercivity and squareness of hysteresis loop, as well as energy product. 展开更多
关键词 metal materials exchange coupled two phase nanocrystalline bonded permanent magnet rare earths
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Development of Strip Casting Technology in Rare Earth Permanent Magnet Alloys and Hydrogen Storage Alloys in China
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作者 韩卫平 郭炳麟 +2 位作者 喻晓军 祝景汉 程星华 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第S2期297-302,共6页
The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in r... The SC technique is now being applied widely in material preparation, especially in rare earth functional materials in virtue of its advanced process and high performance product. The applications of SC technique in rare earth permanent magnet alloys and hydrogen storage alloys were analyzed integrative, on the basis of summary of SC technique development in this paper. The paper mainly includes development history of SC technology, effect of SC technology on alloy microstructure, application of SC technology in RE storage hydrogen alloy and sintered Nd-Fe-B alloy, development of SC equipment and SC product industry. At the same time, the paper points out the existing problem of SC products. 展开更多
关键词 strip casting technique rare earth permanent magnet material rare earth hydrogen storage alloy columnar crystal
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Mn-based permanent magnets
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作者 Jinbo Yang Wenyun Yang +4 位作者 Zhuyin Shao Dong Liang Hui Zhao Yuanhua Xia Yunbo Yang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第11期55-70,共16页
Mn-based intermetallic compounds have attracted much attention due to their fascinating structural and physical properties,especially their interesting hard magnetic properties.In this paper,we have summarized the mag... Mn-based intermetallic compounds have attracted much attention due to their fascinating structural and physical properties,especially their interesting hard magnetic properties.In this paper,we have summarized the magnetic and structural properties of Mn-based intermetallic compounds(Mn X,where X=Al,Bi,and Ga).Various methods for synthesizing single phases of MnAl,MnBi,and Mnx Ga were developed in our lab.A very high saturation magnetization of 125 emu/g,coercivity of 5 kOe,and maximum energy product(BH)_(max)of 3.1 MG·Oe were achieved at room temperature for the pureτ-Mn–Al magnetic phase without carbon doping and the extrusion process.Low temperature phase(LTP)MnBi with a purity above 95 wt.%can be synthesized.An abnormal temperature coefficient of the coercivity was observed for the LTP MnBi magnet.Its coercivity increased with temperature from 100 K to 540 K,reached a maximum of 2.5 T at about540 K,and then decreased slowly to 1.8 T at 610 K.The positive temperature coefficient of the coercivity is related to the evolution of the structure and magnetocrystalline anisotropy field of the LTP MnBi phase with temperature.The LTP MnBi bonded magnets show maximum energy products(BH)_(max)of 8.9 MG·Oe(70 kJ/m^(3))and 5.0 MG·Oe(40 k J/m^(3))at room temperature and 400 K,respectively.Ferrimagnetic Mn_(x)Ga phases with L10 structures(x〈2.0)and D0_(22)structures(x〉2.0)were obtained.All of the above structures can be described by a D0_(22)supercell model in which 2 a-Ga and 2 b-Mn are simultaneously substituted.The tetragonal D0_(22)phases of the Mn_(x)Ga show high coercivities ranging from 7.2 kOe for low Mn content x=1.8 to 18.2 kOe for high Mn content x=3 at room temperature.The Mn_(1.2)Ga sample exhibits a room temperature magnetization value of 80 emu/g.The hard magnetic properties of coercivityiH_(c)=3.5 kOe,remanence M_(r)=43.6 emu/g,and(BH)_(max)=2.5 MG·Oe were obtained at room temperature.Based on the above studies,we believe that Mn-based magnetic materials could be promising candidates for rare earth free permanent magnets exhibiting a high Curie temperature,high magnetocrystalline anisotropy,and very high coercivity. 展开更多
关键词 permanent magnetic materials magnetic properties manganese alloys magnetic structure COERCIVITY MAGNETIZATION neutron diffraction
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MTA与iRoot BP Plus行直接盖髓术治疗龋源性露髓恒磨牙临床疗效分析
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作者 孙琼 沈正焱 +3 位作者 李朋 余兴亚 蔡寅寅 邢田 《中国美容医学》 CAS 2024年第2期118-122,共5页
目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4... 目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4月-2019年10月就诊于笔者科室符合纳入标准的53例患者,共53颗患牙,随机分为M组和B组,分别使用MTA与iRoot BP Plus行直接盖髓术,术后定期复查,比较两组的临床疗效。结果:共计45例患者(45颗患牙)完成2年随访,总体成功率84.4%;M组和B组分别为85.7%、83.3%,两组比较差异无统计学意义(P>0.05)。性别、年龄、露髓孔大小等因素对疗效均无显著影响(P>0.05)。结论:成熟恒磨牙术中露髓时使用MTA或iRoot BP Plus行直接盖髓术均可获得良好疗效;相较于性别、年龄、露髓孔大小等因素,如何简单准确评判牙髓状态及避免龈下微渗漏更加值得关注。 展开更多
关键词 牙髓暴露 直接盖髓术 成熟恒磨牙 生物活性材料 微渗漏
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