添加元素Dy对Nd—Fe—B永磁合金性能的影响

由于氢化制粉制备的ＮｄＦｅＢ粉末制品烧结时磁体中的晶粒异常长大,使合金的矫顽力降低。通过在ＮｄＦｅＢ合金中加入少量Ｄｙ２Ｏ３,能有效地抑制合金高温烧结时的晶粒长大,增加了各向异性很高的（Ｎｄ,Ｄｙ）２Ｆｅ１４Ｂ相,从而使合金的矫顽力得到提高,当Ｄｙ的加入量超过（摩尔分数）４％时,Ｄｙ在富Ｎｄ相晶界中分布比在基体相Ｎｄ２Ｆｅ１４Ｂ中高。     

交换耦合双层膜NiO/Ni81Fe19的基片温度效应研究

用射频磁控溅射方法在不同基片温度下玻璃基片上分别制备NiO单层膜、NiFe单层膜和NiO／NiFe双层膜,研究了不同基片温度对膜的磁性能的影响．用振动样品磁强计（VSM）分析了膜的磁特性,结果表明：基片温度260℃时淀积的NiFe膜矫顽力Hc为184A·m^－1,小于室温淀积NiFe膜的H_c（584A·m^－1）,且磁滞回线的矩形度更好．室温下淀积NiO（50nm）／NiFe（15nm）双层膜的Hc为4000A·m^－1,交换耦会场（H_EX）仅为1600A·m^－1,磁滞回线的短形度很差,而260℃时淀积的双层膜的Hc下降到3120A·m^－1,H_EX却增大为4640A·m^－1,同时磁滞回线的矩形度也得到改善,其截止温度T_B高达230℃．X射线衍射（XRD）分析了膜的织构,结果表明：室温下淀积NiO膜呈现（220）织构,而260℃时淀积NiO膜呈现（111）织构;室温和260℃淀积的NiFe膜都呈（111）织构,但后者晶粒比前者大．     

多元磁化肥的开发与生产

简要报道多元磁化肥的应用效果,强调对提高化肥利用率的作用,其中磁化肥中氮素利用率可提高５个百分点。讨论多元磁化肥的生产工艺和性能指标,给出描述磁性能的剩磁和矫顽力２个参数,并作了机理探讨。     

化学镀Fe—TM—B（TM=Sn,W,Mo—W）合金的磁性研究

利用化学镀方法首次成功地制备了Ｆｅ－ＴＭ－Ｂ（ＴＭ＝Ｓｎ,Ｗ,Ｍｏ－Ｗ）合金,采用ＶＳＭ研究了合金施镀态和热处理后的磁性。结果表明：随镀层中Ｆｅ含量的增加和热处理温度的降低,镀层饱和磁化强度出现增加趋势,在Ｂ含量分别为１４．９ａｔ％和９．３ａｔ％时,Ｆｅ－Ｓｎ－Ｂ和Ｆｅ－Ｗ－Ｂ镀层的矫顽力出现极小值;Ｆｅ－Ｍｏ－Ｗ－Ｂ镀层矫顽力随退火温度的提高而连续增加。Ｆｅ－Ｓｎ－Ｂ和Ｆｅ－Ｗ－Ｂ镀层的剩磁比不     

Structural and magnetic properties of Sm（Co0.7Fe0.1Ni0.12Zr0.04B0.047.5） melt spun isotropic and anisotropic ribbons

We investigated the structural and magnetic properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun ribbons. Samples were arc melted then melt spun at 37 m/s up to 55 m/s to obtain ribbon for powdering. Annealing was performed in argon atmosphere for 30- 75 min at 600-870 oC. In as-spun ribbons the hexagonal SmCo7 (TbCu7-type of structure) of crystal structure was determined from x-ray diffraction patterns, while fcc-Co has been identified as a secondary phase. After annealing, the 1:7 phase of the as-spun ribbons transformed into 2:17 and 1:5 phases. X-ray patterns for as-milled powders exhibited very broad peaks making it difficult to identify a precise structure but repre-sented the 1:7 structure after annealing at low temperature (650 oC). TEM analysis showed a homogeneous nanocrystalline microstructure with average grain size of 30-80 nm. Coercivity values of 15-27 kOe were obtained from hysteresis loops traced up to a field of 5 T. The co-ercivity decreased as temperature increases, but it maintained values higher than 5 kOe at 380 oC. The maximum energy product at room temperature increased, as high as 7.2 MGOe, for melt-spun isotropic ribbons produced at higher wheel speeds. Anisotropic ribbons had a maximum energy product close to 12 MGOe.     

基于ARM的矫顽磁力仪的研制

设计了一种基于ARM的全自动矫顽磁力检测仪.该仪器以S3C2410为处理器,采用12位精度的串行AD TLV2544进行数据采集.将嵌入式Web服务器移植到ARM上,具有在线数据传输和远程故障诊断功能.同时采用了数控恒流源和开关电源退磁技术.该仪器检测精度高,测试样品体积大,温度适应性强,是一款适用于磁性材料矫顽力快速、准确检测的工业自动化仪器.     

Effect of film thickness on magnetic properties of Cr/SmCo/Cr films

Cr/SmCo/Cr films with different SmCo thickness were deposited on glass substrates by magnetron sputtering,followed by an annealing process at 550 °C for 20 min.Experimental results showed that the SmCo film of 30 nm exhibited two-phase behavior in the demagnetization process,the obvious kink was observed near zero.For the SmCo film of 50 nm,the kink was invisible,and a single phase like behavior was obtained in the demagnetization process.The reversal behavior became consistent in the thicker films.Moreover,the coercivity reduced and the saturated magnetization increased obviously with the increasing thickness.X-ray diffraction results indicated that the average grain size of SmCo 5 in the thicker films were almost 30 nm,but the quantity of SmCo 5 grains increased with the increasing thickness,which enhanced the intergrain exchange coupling(IEC) of the SmCo 5 hard phases.The increase of IEC improved the magnetic properties of SmCo films with increasing thickness.     

超高矫顽力NdFeB磁体研究

为制备超高矫顽力的烧结钕铁硼磁体,设计了材料配方(PrNd)23.5Dy8.7FebalAl0.7Nb0.6Cu0.02B1.05,采用了先进的工艺技术,包括片铸、氢爆碎(HD)、高纯氮气流磨制粉、高取向度密封成型、冷等静压、高温高真空烧结等.实验结果表明,由该工艺制备的粉末平均粒度为 4.5μm;磁体晶粒细小均匀,富钕相弥散分布在Nd2Fe14B主相周围.磁体的剩余磁通密度为1.12T,内禀矫顽力达到2430.2kA/m,最大磁能积达到了246.0kJ/m.     

纳米硬磁晶粒间的交换耦合相互作用和有效各向异性

以纳米Nd2Fe14B永磁材料为例,研究了硬磁晶粒间交换耦合相互作用对磁体有效各向异性的影响。结果表明晶粒间交换耦合相互作用随晶粒尺寸的减小而增强,材料的有效各向异性常数Keff随晶粒尺寸的减小而逐渐下降,Keff随晶粒尺寸的变化与矫顽力的变化规律相似。纳米单相永磁材料有效各向异性的减小是矫顽力降低的主要原因,交换耦合系数口aex实际上是各向异性的减小量。为保证纳米Nd2Fe14B材料具有较高的各向异性和矫顽力,晶粒尺寸应不小于30nm。     

Effect of Ti cap layer thickness on microstructures and magnetic properties of Ti/Ni/Ti films

Nanogranular Ti(3 nm)/Ni(30 nm)/Ti(t nm )(t=1,3,5,7,10) films were prepared by facing magnetron sputtering from Ti and Ni onto glass substrates at room temperature.The structural and magnetic properties of films strongly depended on the Ti layer thickness.X-ray diffraction(XRD) patterns of all as-deposited films showed strong FCC Ni(111) peak.Vibrating sample magnetometer(VSM) measurements indicated that the perpendicular coercivity of the Ti(3 nm)/Ni(30 nm)/Ti(3 nm) film reached about 36 kA/m.With the increase of Co layer thickness,coercivity(Hc) first increased and then decreased.The grain size and magnetic clusters slightly increased and the value of roughness(Ra) was smallest at t=3 nm.