树脂基稀土-铁系超磁致伸缩复合材料的制备与压应力效应研究

采用粉末粘结-磁场成型法制备了树脂基稀土-铁系超磁致伸缩复合材料(Giant magnetostrictive particle composite,GMPC),并对样品在不同压应力下的磁致伸缩系数进行了测量,当样品中的TeDyFe合金颗粒尺寸为0~200μm、质量分数为90%时,其磁致伸缩系数于外加磁场达到266 kA.m-1时即已趋近饱和,饱和磁致伸缩系数达623×10-6;当施加在样品纵向方向上的预压应力为5 MPa时,此时样品的饱和磁致伸缩系数最高,为662×10-6,比未加预压应力时样品的饱和磁致伸缩系数高39×10-6,表明所制得的实验样品具有一定的压应力效应,并且压应力效应在较低压力下起积极作用,在较大压力下则产生消极作用。     

速凝成晶-粘结法制备稀土磁致伸缩材料TbDyFe的研究

采用速凝成晶技术,制备了具有<112>和<110>择优取向的Tb0.27Dy0.73Fe1.95速凝片.研究发现,速凝片的择优取向和显微组织与冷却速度密切相关.随着冷却速度的增加,其择优取向从<112>向<110>变化,显微组织由枝状晶向胞枝晶转变.研究了由速凝片制备的稀土粘结磁致伸缩样品的性能.结果表明,当粉末粒度≤(100～150)μm时材料性能较好,具有<112择优取向的样品性能高于<110>择优取向的样品,磁场取向成型有利于材料性能的改善.获得了性能良好的粘结磁致伸缩材料,在238.8 kA·m-1时磁致伸缩系数达到740×10-6.     

硼和铟掺杂对Fe81Ga19快淬薄带的微结构、磁致伸缩性能及磁性的影响

通过甩带快淬法制备三元合金（Fe_0.81Ga_0.19）_100-xB_x （Fe-Ga-B）和（Fe_0.81Ga_0.19）_100-xIn_x （Fe-Ga-In）薄带样品,并对Fe-Ga-B合金样品进行热处理。通过高分辨X射线衍射（HRXRD）和扩展X射线吸收精细结构谱（EXAFS）技术表征薄带的微观结构,利用振动样品磁强计和标准电阻应变仪测量了样品的磁性及饱和磁致伸缩系数。研究表明,有序的L1₂相降低了（Fe_0.81Ga_0.19）₉₈B₂样品的磁致伸缩系数。B原子添加形成的Fe₂B相和modified-DO₃相有利于提高Fe-Ga合金的磁致伸缩系数。但Fe₂B相的饱和磁化强度小于A₂相,饱和磁场却远大于A₂相,因此随着B含量的增加,Fe-Ga-B薄带的饱和磁化强度逐渐减小,矫顽力逐渐增加。合金中形成的非磁性富In相使得In掺杂Fe-Ga-In合金的磁致伸缩系数和饱和磁化强度均减小。非磁性富In相使晶格产生畸变,减弱了磁弹性效应,并且抑制了磁畴的运动,从而明显地减小了Fe-Ga带材样品的磁致伸缩系数以及饱和磁化强度,提高了Fe-Ga合金的矫顽力。     

Fe-Ga磁致伸缩合金相结构及其制备工艺研究进展

与已商业化的Terfenol-D磁致伸缩材料相比,新型磁致伸缩Fe-Ga合金以其高强度、良好韧性、低磁场高磁致伸缩和低成本等优势成为目前凝聚态物理和材料科学领域的研究热点。Fe-Ga合金的磁致伸缩性能取决于合金的微结构,特别是该类合金的相结构。而Fe-Ga合金的微结构又密切相关于合金的制备工艺。从Fe-Ga二元合金的基本相结构出发,在详细分析平衡态和亚稳态Fe-Ga二元合金相图的基础上,重点综述了Fe-Ga合金的相结构对其磁致伸缩性能的影响;之后,详细综述了各种制备工艺下Fe-Ga合金的相结构和磁致伸缩性能;最后展望了该类合金未来发展方向。     

磁场热处理和预压力对Tb0.3Dy0.7Fe1.95合金磁致伸缩"跳跃"效应的影响

研究了磁场热处理对<110>取向Tb0.3Dy0.7Fe1.95多晶合金磁致伸缩"跳跃"效应的影响.在真空超导体强磁场装置中,将经定向凝固的<110>取向Tb0.3Dy0.7Fe1.95多晶合金棒,沿垂直轴向施加强度为1 T的磁场,加热到623 和723 K下,保温5 min后随炉冷却.研究结果表明,磁场热处理增强预压力下的"跳跃"效应,提高不同预压力下的饱和磁致伸缩系数λs,其中623 K磁场热处理样品在8.1 MPa下的λs达到1950×10-6.磁场热处理提高预压力(8.1 MPa)下的动态磁致伸缩系数最大值dmax33,但同时增大dmax33对应的磁场.     

粉末冶金法制备稀土超磁致伸缩材料的研究

介绍了一种粉末冶金制备稀土磁致伸缩材料的方法,该方法包括铸造Tb0.30Dy0.70Fe1.80合金锭、制粉、磁场取向、压制成型和烧结工序。实验结果表明:粒度小于0.147 mm的Tb0.30Dy0.70Fe1.80合金粉末,经磁场取向后压制成型,在1200℃烧结2 h,并在950℃热处理24 h,当磁场强度为240 kA.m-1,预应力为8 MPa时,材料的磁致伸缩系数达到1.613×10-3。     

Zn_xCoFe_2O_4的制备及磁性能和磁致伸缩性能的研究

本实验采用溶胶—凝胶自蔓延的方法,将富含Co元素的废旧锂电池加工成一系列的含锌量不同的钴铁氧体样品,并对不同锌含量样品的形貌、结构、磁性能和磁致伸缩性能进行研究。实验结果表明:含锌的钴铁氧体是尖晶石结构的晶体,与Co Fe_2O_4相比,微观结构和形貌发生了变化,因此,性质发生了明显的变化。随着锌含量的增加,样品的饱和磁化强度先增加后减小;最大磁致伸缩系数整体递减;磁致伸缩应变导数的最大值整体递增,该值对应的磁场强度逐渐降低。研究表明:Zn~(2+)含量为0.4时,样品的最大磁致伸缩系数,最大应变导数及其对应的场强分别是-134.8 ppm,-2.12×10~(-9)A~(-1)m和20.0KA·m~(-1),即应变导数在较低的磁场强度下取得最大值,使用该样品制备而成的器件在非接触式传感器和执行器方面的应用中可能更具优势。     

Pr_(0.15)Tb_(0.85)Fe_(1.9)B_x内禀磁致伸缩的测量与分析

利用电弧熔炼法制备了Pr_(0.15)Tb_(0.85)Fe_(1.9)B_x系列样品,通过X射线衍射法对粉末样品的(440)衍射峰进行精细步进扫描并拟合数据,分析获得样品的内禀磁致伸缩λ_(111),通过电阻应变片法测得块状样品在外加磁场下的磁致伸缩值变化趋势,外推得到宏观饱和磁致伸缩值λ_s,并从Laves相晶体结构特性出发对两者进行详细比较对照和进一步深化分析.结果表明,常温下Pr在Laves相化合物中对磁致伸缩具有较大的贡献,适量B的掺入可以增加Pr在Laves相化合物中的含量且不降低材料的磁致伸缩性能.     

定向凝固法制备稀土超磁致伸缩材料

对Ｔｂ０３Ｄｙ０７Ｆｅ１９５超磁致伸缩材料定向凝固过程进行了研究和分析，结合ＴｂＤｙＦｅ合金凝固特性，研究了凝固参数（包括定向凝固速率Ｖ和固液界面温度梯度Ｇ）、样品尺寸及起始晶粒取向三个主要因素对ＴｂＤｙＦｅ合金样品轴向取向的影响。当定向凝固参数（Ｇ／Ｖ）控制在适当范围，有利于保持平直的固液界面，因此有利于形成轴向＜１１２＞取向；当Ｖ增大或Ｇ减小，固液界面出现下凹，将影响择优取向的形成。样品尺寸与Ｇ和Ｖ应该相匹配，样品直径太大不利于保持平直的固液界面，因此不利于形成轴向＜１１２＞取向。采用＜１１２＞取向的晶粒作籽晶可以加快晶粒的择优竞争生长过程，有利于形成轴向完全＜１１２＞取向。这些因素的恰当控制，制备出了轴向具有完全＜１１２＞取向的Ｔｂ０３Ｄｙ０７Ｆｅ１９５合金样品，对样品进行高温退火处理，磁致伸缩性能达到了近１７００×１０－６。     

Pr0.15TbxDy0.85-xFe2 内禀磁致伸缩的测量

对稀土金属间Laves相赝二元化合物进行X射线衍射分析。其(440)峰出现劈裂，由(440)峰劈裂的程度可以确定内禀磁致伸缩的大小。本文采用X射线衍射的方法对Pr0．15TbxDy0．85-xFe2系列粉末样品的(440)峰步进扫描，并对扫描结果进行拟合，对拟合得到的两组双线峰之间的间距计算得到内禀磁致伸缩λ111,拟合曲线与实验点符合很好，结果表明Pr0．15TbxDy0．85-xFe2的内禀磁致伸缩随Tb含量的增加而增加，并且用0．15的Pr替代Dy后，在x=0．3时，Pr0．15TbxDy0．85-xFe2的内禀磁致伸缩λ111比Tb0.27Dy0.73Fe2的内禀磁致伸缩λ1ll大。     

Microstructure analysis of magnetostrictive composites

To understand the mechanism and the dependency between magnetostrictive composite performance and the orientation of the magnetic field, composites with 30% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin matrix under various orientation fields. Their static and dynamic magnetostriction was tested without pre-stress at room temperature. The results indicate there is a positive correlation between magnetostrictive property and the orientation field. This study used scanning electron microscopy to observe the material longitudinal microstructures followed by a statistical analysis to evaluate the angle distribution between the major axis of the particles and the orientation field in different composites. In summary, this method can be used to elucidate the microstructure of the composites directly: the higher the orientation field, the closer the microstructure to 1–3 structure. As a result, the static and dynamic magnetostriction is increased as the orientation field increases.     

Tb_1-_xDy_x(Fe_1-_yMn_y)_(1.95)合金的磁致伸缩和声学性质及在水声换能器中的应用

研究了Ｔｂ１－ｘＤｙｘ（Ｆｅ１－ｙＭｎｙ）１．９５合金的磁致伸缩、声学等性质及其在水声换能器中的应用。当外加的磁场强度≥８００ｋＡ·ｍ－１时,磁致伸缩系数值在（１３００～１８００）×１０－６范围,有效机电偶合系数值０８４～０９３,声速为２１６８～２８５６ｍ·ｓ－１,杨氏模量为（５０６～７２６）×１０１０Ｎ·ｍ－２;用合金棒材研制水声换能器,该换能器总长３００ｍｍ,总重２ｋｇ,其共振频率为２４ｋＨｚ,发射电流响应１７３ｄＢ,频宽１ｋＨｚ,电声效率４５％     

Magnetostriction in electroplated CoFe alloys

The phenomenon of magnetostriction can wirelessly couple external magnetic fields to generate structural motion. This is an attractive solution for remote delivery of power to microactuators in constrained environments. This study discusses the magnetostriction of electrosynthesized CoFe thin film microactuators. Electrodeposition is commonly employed for the fabrication of metallic thin films, however the magnetostriction of such films has been rarely investigated. In particular, the magnetostrictive behavior of electroplated CoFe films is poorly understood, despite the high magnetostriction capabilities of CoFe alloys. In this work, uniformly thick and smooth Co_0.65Fe_0.35 thin films were electrochemically grown on commercially available micron-scale cantilevers. The CoFe thin films were characterized for their morphology, composition, crystal structure, and magnetic properties. The AC magnetostrictive response of the cantilevers was measured interferometrically and the actuator exhibited a maximum expected displacement of 86 nm.     

稀土改性MoO3／SiO2催化剂上丙烯的歧化

本文系统考察了镧系14种稀土氧化物对烯烃歧化催化剂MoO_3/SiO_2的影响,发现其中多数均可使催化剂的寿命延长,并以Tb及Pr的效果最佳,其稳定时间可达未改性时的1.6倍。主要原因是稀土添加剂有抑制积炭的能力和缩短催化剂的增活期(为未改性的40％～75％)。通过ESR表征,从本质上阐明了Tb_4O_7的作用在于促进了歧化活性中心——挠动四棱锥结构的Mo~(5 )值的增长。在增活期过程中,活性物种前体的减少服从一级反应力学规律。     

Electronic influences on 3J(C,H) coupling constants via -S-, -S(O)- and -SO2-: their determination, calculation and comparison of detection methods

3J(C,H) coupling constants via a sulfur atom in two series of compounds, both including a sulfide, a sulfoxide and a sulfone, were detected experimentally and calculated by quantum mechanical methods. In the first series (1-3) the coupling between a hydrogen, bonded to an sp3 carbon, and an sp2 carbon is treated; the second series (4-6) deals with the coupling between a hydrogen, bonded to an sp3 carbon, and an sp3 carbon. Different pulse sequences (broadband HMBC, SelJres, 1D HSQMBC, J-HMBC-2, selective J-resolved long-range experiment and IMPEACH-MBC) proved to be useful in determining the long-range 3J(C,H) coupling constants. However, the dynamic behaviour of two of the compounds (4 and 6) led to weighted averages of the two coupling constants expected (concerning equatorial and axial positions of the corresponding hydrogens). DFT calculations proved to be useful to calculate not only the 3J(C,H) coupling constants but also the different contributions of FC, PSO, DSO and SD terms; the calculation of the Fermi contact term (FC) was found to be sufficient for the correct estimation of 3J(C,H) coupling constants.     

聚硫橡胶对环氧胶粘剂的增韧作用研究

环氧树脂以其优良的粘接性、化学稳定性、工艺性等性能,在粘接、涂料、机械、电子、国防等领域有广泛的应用[1].环氧树脂改性及工艺研究的相关报道较多[2-9].环氧树脂固化后有脆性大的缺点,在一定程度上限制了环氧树脂的应用.采用液体橡胶增韧环氧胶是改善环氧胶脆性的有效途径.本文介绍了采用聚硫橡胶增韧环氧胶的方法,并且研究了增韧后环氧胶的力学性能.     

稀土超磁致伸缩材料表面离子渗氮研究

采用辉光放电离子渗氮方法研究了表面氮化对（Tb,Dy）Fe2稀土超磁致伸缩材料的耐腐性能、表面机械性能及磁致伸缩性能的影响。结果发现：通过表面离子渗氮处理,可显著改善材料耐腐性能,材料表面硬度由587 HV提高到622 HV,耐磨性能也大幅提高,并且材料磁致伸缩性能几乎未受影响。研究表明,表面离子渗氮是一种适用于稀土超磁致伸缩材料表面改性的方法。     

High impact resistance epoxy resins by incorporation of quadruply hydrogen bonded supramolecular polymers

A bisphenol A based epoxy was incorporated with a quadruply hydrogen bonded supramolecular polymer as a toughening agent to prepare a composite epoxy resin with higher impact resistance. The supramolecular polymer comprising poly-(propylene glycol) bis(2-aminopropyl) ether chains and 2-ureido-4[1H]-pyrimidinone moieties (UPy) self-assembled into spherical domains with sizes of 300 nm to 600 nm in diameter by micro phase separation in bulk epoxy matrixes. A significant improvement of 300% in impact resistance of the supramolecular polymer incorporated epoxy resin was obtained when the content of supramolecular polymer was 10 wt%. Tensile tests showed that the mechanical properties of the modified epoxy resin containing the hydrogen-bonded supramolecular polymers are also improved compared with those of the neat epoxy resin.