软磁铁氧体材料

总结了近几十年来软磁铁氧体材料的发展过程，评述了国内软磁铁氧体材料及器件的发展现状、应用和市场，并对其中的锰锌系和镍锌系两大类型的软磁铁氧体材料做了重点介绍，指出了在其广泛的应用领域内，软磁铁氧体将进一步向高频、高磁导率和低损耗方向发展，以适应由新科技新设备的不断推出所带来的其产品如电感、线圈等器件向小型化片式化的发展要求．     

软磁材料锰锌铁氧体共沉粉料的研制

本文研究了碳酸盐—氢氧化物法共同沉淀Ｆｅ２＋、Ｍｎ２＋、Ｚｎ２＋时，反应最终ｐＨ值、沉淀温度、加料方式、加料速度及搅拌强度等因素对恒定共沉粉Ｆｅ２Ｏ３、ＭｎＯ及ＺｎＯｍｏｌ％组成、粒度和颗粒形状的影响，并进一步考查了共沉粉组成与软磁材料性能的关系。在研究基础上确定生产高频低功耗锰锌铁氧体材料Ｈ７２４（ＰＣ４０）和高磁导率锰锌铁氧体材料Ｈ５Ｃ２（μｉ＝１００００±３０％）共沉粉合成的最宜条件。     

用共沉淀法制备尖晶石型锰锌铁氧体粉体

以硫酸锰、硫酸锌和硫酸亚铁为原料，草酸铵为沉淀剂，采用共沉淀法制备了晶石型锰锌铁氧体粉体，利用XRD，SEM，IR等技术考察了原料中金属离子配比、共沉淀前驱体煅烧温度和添加剂等因素对产物的晶形、纯度和结晶性的影响，对不同条件下制得的粉体进行了磁性能测定，实验结果表明：原料中锰、锌、铁离子的量比对产物的物相影响很大，当Zn^2 ,Mn^2 ,Fe^2 的量比为1.0:1.5:6.0，且共沉淀有添加剂CH3COONa时，所得产物为单相的尖晶石型锰锌铁氧体，其晶形为规整的立方体；用化学共沉淀法制备锰锌铁氧体粉体，工艺简单，成本低，易实现工业化生产。     

软磁Mn—Zn铁氧体纳米晶的低温自蔓延合成及表征

采用低温自蔓延方法合成了Mn-Zn铁氧体纳米晶，对其进行了Z射线衍射（XRD），X射线能谱（EDS），电子自旋共振波谱（ESR）和透射电镜（TEM）等测试。研究结果表明，铁氧化化学式为（MnZn)0.5Fe2O4，铁氧体结晶状况良好；铁氧体的g值为9.956O；铁氧体纳米晶粒径度较均匀，为10～20nm，与Scherrer公式计算所得晶粒尺寸（19.6nm）相符；合成铁氧体的g值远大于自由电子的g值（ge=2.0023),初步推断是Mn^2 ，Fe^3 的3d^5半充满价电子层结构和它们在尖晶石型晶胞（MnZn）0.5Fe2O4中的磁矩偶合作用所致。     

低温燃烧合成法研究进展

低温燃烧合成(LCS法是相对于自蔓延高温合成而提出的一种新型材料制备技术,以其高效、节能、快速的突出特点而备受各国研究者青睐.本文从方法概述、基本原理、工艺影响因素、研究进展等几方面对LCS法进行了综述.     

利用废旧干电池制备Mn-Zn铁氧体前躯体的研究

采用酸溶解法将废旧电池作溶解处理以获得含有锰、锌、铁、铜和镍等金属离子的混合溶液，并通过添加铁粉以除去混合溶液中的铜、镍，以及汞杂质，获得了锰、锌和铁的混合溶液．根据锰锌铁氧体的组成对所得溶液进行调整，采用共沉淀的方法合成了锰锌铁氧体的前躯体．研究表明：利用该方法无需将干电池中的各种金属离子分离，通过调整直接合成锰锌铁氧体的前躯体，从而在解决目前大量废旧电池回收后的再利用问题、实现废旧电池无害化和资源化的同时，为铁氧体的生产提供了一个新的原料来源，具有较好的应用前景．     

熔盐合成法制备CaTiO3粉体的研究

以TiO2及CaCO3为原料，CaCl2为反应介质，对熔盐合成法制备CaTiO3粉体进行研究，并与固相合成法进行比较。结果表明，熔盐合成法可将纯相CaTiO3的合成温度从固相合成法所需的1400℃降至800℃，熔盐法合成的CaTiO3粉末粒度较小（〈0．5μm），分布均匀，且具有很高的分散性。在熔盐合成法中由于Ca—CO3及TiO2在熔融CaCl2中有较高的溶解度，两者可在其中通过“溶解析出”机理进行反应，从而在较低的温度下生成单一相的CaTiO3。     

镁锌铁氧体粉末的水热法合成及其矫顽力机理

采用水热法合成名义成分为Mg1-xZnxFe2O4(x=0,0.2,0.4,0.6和0.8)的铁氧体粉末样品,采用X射线衍射仪、扫描电镜和振动样品磁强计等对其结构和矫顽力机理进行研究。结果表明:Zn含量增加有利于(Mg,Zn)Fe2O4铁氧体的成相,晶格常数也随着x的增加而增加;与x=0的样品相比,普通软磁材料矫顽力较大,其他样品的矫顽力呈现典型的软磁铁氧体值,且随着x的增大矫顽力呈逐渐减小的趋势,这与晶粒大小有密切关系;样品中微米级的大颗粒是纳米级小晶粒的聚集体。     

Bonding characteristics of the Al2O3-metal composite coating fabricated onto carbon steel by combustion synthesis

The fabrication of an alumina-metal composite coating onto a carbon steel substrate by using a self-propagating high-temperature synthesis technique was demonstrated. The effects of the type and thickness of the pre-coated layer on the binding structure and surface qual- ity of the coating were systematically investigated. The macrostructure, phase composition, and bonding interface between the coating and the substrate were investigated by scanning electronic microscopy （SEM）, X-ray diffraction （XRD）, and energy-dispersive X-ray spectrometry （EDS）. The diffraction patterns indicated that the coating essentially consisted of α-Al2O3, Fe（Cr）, and FeO-Al2O3. With an increase in the thickness of the pre-coated working layer, the coating became more smooth and compact. The transition layer played an important role in enhancing the binding between the coating and the substmte. When the pre-coated working layer was 10 mm and the pre-coated transition layer was 1 ram, a compact structure and metallurgical bonding with the substrate were obtained. Thermal shock test results indicated that the ceramic coating exhibited good thermal shock resistance when the sample was rapidly quenched from 800℃ to room temperature by plunging into water.     

Combustion Synthesis of TiB2 Ceramics Powder from B2O3-TiO2-Mg System in Air Atmosphere

TiB2 ceramics powder was syuthesized from B2O3 - TiO2 - Mg system. The effects of TiB2 addition as diluent on the conbustion synthesis process were investigated. The results of thermodynanmic calculation and experiments stow that the increase of TiBz content ranging from 0 to 20wt% can reduce the adiabatic temperature Tad from 3100 Kto 2896 K and combustion temperature T,. from 2139 K to 1621 K respectively. The particle size and half width of the particle distributhm are also increased with the addition of TiB2 increasing from 0 to 20wt% . The combustion product is a mixture of TiB2 , MgO , and other intermediate phases. The leached produet contains mairdy TiBz, TiOz and TiN, and its oxygen content is 7.77wt% .     

制备条件对锰锌铁氧体微粒磁性能的影响

采用化学共沉淀法制备MnZnFe2O4纳米磁性微粒，并利用振动样品磁强计对其磁性能进行测量，探讨了反应温度、反应时间和碱的加入量对MnZnFe2O4纳米磁性微粒磁性能的影响。     

MnZnFe2O4磁性纳米添加剂抗磨减磨及自修复效应研究

利用四球和立式万能摩擦磨损试验机考察了MnZnFe2O4纳米磁性微粒作为润滑油添加剂抗磨减摩性能及对磨损表面的修复作用,并用扫描电子显微镜观察分析了磨斑表面形貌.结果表明,MnZnFe2O4纳米微粒添加剂能显著提高润滑油的承载能力,且减小磨斑直径,减小磨损表面犁沟.但MnZnFe2O4纳米微粒添加剂对润滑油的抗磨减磨效果受加载载荷影响：低载时,添加MnZnFe2O4纳米微粒润滑油的摩擦系数与基础油相比无明显改善;高载时,摩擦系数至少降低16%.这表明高载有利于MnZnFe2O4纳米微粒在摩擦表面沉积并在接触区的高温高压作用下熔融铺展,形成低剪切强度的表面膜,并对磨损表面具有一定的修复作用.     

Combustion Synthesis of TiB_2 Ceramics Powder from B_2O_3-TiO_2-Mg System in Air Atmosphere

1Introduction Titaniumdiborideisanincreasingimportantceramic materialbecauseofitschemicalstability,highwearresis tance,andsuperiorelectricalandthermalconductivities,whichmakeTiB2ceramicsidealforapplicationsincutting tools,armormaterials,wearresistantcoati…     

自蔓延高温合成镍铜锌铁氧体粉体研究

为了研究低成本大批量生产制备NiCuZn铁氧体的方法,采用自蔓延高温合成(SHS)工艺制备了Ni0.25Cu0.25zn0.5Fe1.96O3.94粉体,将铁氧体粉体分别在800℃、850℃、900℃进行热处理.以XRD、SEM、TG-DSc、振动样品磁强计(VSM)等手段分别对产物的物相、微观结构和磁性能进行研究.结果表明,SHS制备的NiCuZn铁氧体粉体经900℃热处理后可以转变成单一的尖晶石相,所得铁氧体粉体结构完整,矫顽力达到最小值,Hc=72.3Oe,同时饱和磁化强度达到最大值,Ms=68.34emu/g.     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅｓｂａｓｅｄｏｎＴｉＡｌｈａｖｅｅｘｃｅｌ ｌｅｎｔｐｏｔｅｎｔｉａｌｔｏｔａｋｅｔｈｅｐｌａｃｅｏｆｃｏｎｖｅｎｔｉｏｎａｌｔｉｔａｎｉ ｕｍａｎｄｎｉｃｋｅｌａｌｌｏｙｓｉｎａｄｖａｎｃｅｄｓｐａｃｅｃｒａｆｔｄｕｅｔｏｔｈｅｉｒｌｏｗｄｅｎｓｉｔｙ ,ｇｏｏｄｅｌｅｖａｔｅｄ ｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈａｎｄｈｉｇｈｒｅｓｉｓｔａｎｃｅｔｏｏｘｉｄａｔｉｏｎ[1～ 3] .Ｈｏｗｅｖｅｒ ,ｔｈｅｗａｙｔｏｐｒａｃｔｉｃａｌａｐｐ…     

Combustion Synthesis and Densification of NiAl／TiB2 Composites

A suitable combustion synthesis and densification process was designed to fabricate dense NiAl/TiB2 composites from Ni-Al-Ti-B system. Combustion synthesis processing and microstructure characteristies of products were studied in detail. The results show that the amount of TiB2 ceramics has a great influence on the combustion synthesis processing and microstructure; with the increase of the amount of TiB2 ceramics, the combus-tion temperature and combustion velocity increase rapidly. The volume of synthesized products and the grain size of ceramics particle size are also affected by the amount of TiB2 ceramics. TiB2 ceramics fiber can be produced in this synthesis system. The dense NiAl/TiB2 composites with residual porosity of no more than 1% are fabricated by the combustion synthesis and hot pressing, the mechanical properties of the dense NiAl/TiB2 composites increase with increase of the amount of TiB2 ceramics.     

TiC/Ti-Al基复合材料的燃烧合成

为了改善Ti-Al金属间化合物的脆性,利用SHS/PHIP工艺制备了TiC/Ti-Al基复合材料.理论分析表明,绝热温度随C质量分数的增加而呈升高趋势,当体系中碳的质量分数≥2%时,该体系能完成自蔓延过程.采用电子扫描显微镜,X射线衍射仪对合成产物进行了分析.结果表明,合成产物中除存在基体相Ti3Al和TiAl和增强相TiC外,还存在许多三元相Ti3AlC和Ti2AlC相;随着Al质量分数的增加,增强相的形貌由颗粒状逐渐变成棒状或片状;复合材料的硬度和压缩强度随C质量分数的增加逐渐增加,但密度及相对密度随C质量分数的增加呈先增加后降低的趋势.当C的质量分数达到4%时,其实际密度和相对密度均达到最大.     

Co-precipitation/hydrothermal synthesis of BiFeO<Subscript>3</Subscript> powder

A coprecipitation/hydrothermal route was utilized to fabricate pure phase BiFeO3 powders using FeCl3·6H2O and Bi（NO3）3·5H2O as starting materials, ammonia as precipitant and NaOH as mineralizer. The synthesized powders were characterized by XRD, SEM and DSC-TG analysis. In the process, single-phase BiFeO3 powders could be obtained at a hydrothermal reaction temperature of 180 ℃, with NaOH of 0.15 mol/L, in contrast to 200 ℃ and 4 mol/L for conventional hydrothermal route. Meanwhile, the micro-morphology of synthesized BiFeO3 powders changed with different reaction temperatures and concentrations of NaOH. The N6el temperature, Curie temperature and decomposition temperature of the synthesized BiFeO3 powders were detected to be 301 ℃, 828 ℃ and 964 ℃, respectively. The hydrothermal reactions mechanism to fabricate BiFeO3 powders were discussed based on the in-situ transformation process.