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纳米Ni0.5Zn0.5Fe2O4铁氧体的制备及电磁损耗特性研究 总被引:10,自引:0,他引:10
采用NH4 HCO3与FeCl3·6H2O、Zn(NO3)2·6H2O、Ni(NO3)2·6H2O进行室温固相反应制得Fe(OH)3、Zn3(OH)4CO3·H2O、Ni3(OH)4CO3·4H2O混合前驱物,先经微波加热,再热分解制得纳米粉体.利用激光粒度分析仪、XRD、SEM和TEM对分解产物进行了表征,获得了形貌为球形、颗粒分布均匀、平均粒度为62nm、尖晶石结构的纳米Ni0.5Zn0.5Fe2O4复合铁氧体粉体.经测试样品的相对介电常数和相对磁导率后,发现该纳米铁氧体粉体在100~1800MHz内具有良好的电损耗和磁损耗性能. 相似文献
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采用固相反应法合成了(1-x)CaTiO3/xNi0.5Zn0.5Fe2O4(0≤x≤1.0)复合材料,并研究了复合材料的物相、微观结构、介电性能和磁性能。结果表明:样品中仅含有钙钛矿型CaTiO3和尖晶石型Ni0.5Zn0.5Fe2O4。1260℃保温3h,样品相对密度达到98.91%,颗粒尺寸约为2μm。样品介电常数随Ni0.5Zn0.5Fe2O4含量(x)增加而增大。当x=0.7、测试频率为103 Hz时,样品介电常数(εr)和介电损耗(tanδ)分别为2629.18和1.74。(1-x)CaTiO3/xNi0.5Zn0.5Fe2O4复合材料显示磁性。其中x=0.7时,样品饱和磁化强度(Ms)达到49.07A·m2/kg;这归因于Ni0.5Zn0.5Fe2O4具有优异的磁性能。 相似文献
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Fe3O4/羧基改性壳聚糖复合纳米粒子的制备、表征及生物学应用 总被引:2,自引:0,他引:2
采用氧化水热法,以H2O2为氧化剂制备了磁性Fe3O4纳米颗粒.以磁性Fe3O4为核,通过反相悬浮聚合法对Fe3O4颗粒表面进行改性,在碳二亚胺的活化作用下,与壳聚糖衍生物-α-酮戊二酸缩壳聚糖(KCTS)反应制备了表面含有一定羧基的磁性Fe3O4/KCTS纳米粒子.经XRD、TEM、VSM、IR、TGA等手段对复合材料进行了表征及性能研究.结果表明,该磁性Fe3O4/KCTS纳米粒子的平均粒径为26nm,比饱和磁化强度为24.8A·m2/kg.其性能优良,具备超顺磁性,能很好的应用于生物分离,蛋白吸附等领域. 相似文献
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采用分析纯CoCl2·6H2O、ZnCl2·6H2O、FeCl3·6H2O和NaOH为主要原料,控制反应物摩尔比,利用低温固相反应法制备了尖晶石型CoFe2O4、ZnFe2O4和Co0.5Zn0.5Fe2O4纳米粒子.采用X射线衍射、透射电子显微镜对样品的结构、形貌进行表征.在室温下采用振动样品磁强计对其磁性能进行了测定.结果表明:反尖晶石型CoFe2O4纳米粒子的饱和磁化强度为64.28A·m2/kg,呈亚铁磁性;正尖晶石型ZnFe2O4纳米粒子的饱和磁化强度为7.27A·m2/kg,表现出与块体的反铁磁性不同的超顺磁性;而Zn2+替代反尖晶石型CoFe2O4中的一部分磁性离子Co2+形成的复合铁氧体Co0.5Zn0.5Fe2O4的饱和磁化强度为35.06A·m2/kg,呈亚铁磁性.最后,对3种铁氧体的磁性来源进行了探究. 相似文献
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通过FeCl2.4H2O和FeCl3.6H2O混合共沉淀,合成平均粒径为6 nm和10 nm的Fe3O4纳米粒子。然后将两种Fe3O4纳米粒子分别与经HNO3氧化处理的多壁碳纳米管(MWCNTs)置于乙醇水溶液(水和乙醇的体积比为1∶1)中,在超声波作用下制备Fe3O4/MWCNT复合材料。用高分辨透射电子显微镜、X-射线光电子能谱、振动样品磁强计、X射线衍射仪、热重分析仪对所制备的Fe3O4/MWCNT复合材料进行表征。结果表明:由6 nm和10 nm Fe3O4纳米粒子所制备的Fe3O4/MWCNT复合材料中,Fe3O4的质量分数分别为26.65%和29.3%,相应的磁饱和强度分别为16.5 emug-1和7.5 emug-1。 相似文献
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在没有加酸并含有阳离子表面活性剂十六烷基三甲基溴化铵的Fe3O4纳米粒子悬浮液中,采用原位化学氧化聚合法制备了聚苯胺/Fe3O4纳米复合材料,并用高分辨透射电镜(HRTEM)、红外(FT-IR)、X射线衍射(XRD)、振动样品磁强计等对此纳米复合材料的形貌、结构和电磁性能进行了研究,对此纳米复合材料的形成机理也作了分析.研究结果表明Fe3O4纳米粒子被聚苯胺所包覆.Fe3O4纳米粒子和聚苯胺之间存在着一定的相互作用,以利于Fe3O4纳米粒子被聚苯胺所包覆.此纳米复合材料兼具导电性和磁性,Fe3O4的含量对其电磁性能影响很大,随着Fe3O4含量的增加,其室温电导率随之降低,而其饱和磁化强度则随之增加. 相似文献
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《化工新型材料》2015,(4)
采用化学共沉淀法经过硅烷偶联剂改性制备纳米四氧化三铁粒子(纳米Fe3O4),再通过不同的制备工艺与天然胶乳(NR)共混,制备纳米Fe3O4/天然橡胶复合材料(纳米Fe3O4/NR)。利用马尔文MS2000激光粒度仪、X射线衍射仪(XRD)和扫描电子显微镜(SEM)等分析仪器分别对所制备样品的形貌、成分及结构进行表征。结果表明:化学共沉淀法制备的纳米Fe3O4粒子为结晶态,粒径约为47nm。硅烷偶联剂可有效地对纳米Fe3O4表面进行改性;改性后的纳米Fe3O4粒子,增强了纳米Fe3O4/NR复合材料的界面作用,提高了纳米Fe3O4粒子在NR中的分散性,改善了复合材料的结构和性能。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献