具有优异高频特性非晶磁粉芯的制备及磁性能研究

通过水雾化法制备了Fe74Cr1Si9B10P4C2非晶合金粉末,该成分合金过冷液相区可达35 K,具有良好的大块非晶形成能力,粒径在100 μm左右的粉末依然为非晶态.同时该成分非晶合金还具有优异的软磁性能,其饱和磁感Bs可达1.3T,矫顽力Hc=4.6 A/m.通过对非晶粉末表面进行钝化绝缘处理可极大提高非晶磁粉芯的高频特性,粉芯磁导率在10 MHz左右依然保持稳定,同时磁心损耗也极大降低,在Bm=100 mT,f=100 kHz测试条件下,其损耗Pcv=592.9 kW/m3.     

机械合金化制备Zr50Cu40Ai10非晶合金粉末及其晶化研究

以金属Zr、Cu和Al为原料,通过真空熔炼和气体雾化制备Zr-Cu-Al合金粉末,再经高能球磨得到Zr50Cu40Al10非晶合金粉末。采用氮/氧分析仪、X射线衍射仪(XRD)、扫描电镜(SEM)和热分析仪(DSC)对其非晶形成能力及晶化行为进行研究。结果表明,球磨120h后可获得Zr50Cu40Al10非晶合金粉末,且随球磨时间增加,粉末的颗粒尺寸逐渐减小,90h后达到亚微米级。球磨过程中由于铁的增加,使合金的结构"混乱度"增加、负混合热增大,因而热稳定性增强,其过冷区间ΔTx为62K,约为雾化法制备的非晶合金粉末的2倍。此外,采用非等温晶化方法,用KISSINGER方程计算出机械合金化Zr50Cu40Al10非晶合金的玻璃转变和初始晶化的表观激活能分别为152.6kJ/mol和172.4kJ/mol,远小于相应的气体雾化法制备的Zr50Cu40Al10非晶合金粉末表观激活能,其原因是粉末中氧含量和体系自由能较高。     

Mg-Zn粉末机械合金化非晶转变

采用纯金属镁粉和锌粉为原料,通过机械合金化制取了Mg-Zn非晶合金粉末。借助扫描电镜(SEM)、透射电镜(TEM)、X-射线衍射仪、能谱分析仪等手段研究了Mg_(50)Zn_(50)粉末的机械合金化非晶转变过程。本实验证明了镁基合金在负值混合焓较小的条件下,可以通过机械驱动力的作用而发生MA非晶反应,且非晶反应能力很强,Mg_(50)Zn_(50)在50h内完成了非晶转变。非晶反应可能与颗粒的变形细化过程有关,原子的界面扩散在非晶反应过程中起重要作用。     

用机械球磨法制备FeSiAl非晶粉末的Mossbauer研究

本文通过对机械球磨方法制备的ＦｅＳｉＡｌ非昌粉末进行Ｍｏｓｓｂａｕｒ谱分析，研究非晶的形成过程。经１２小时球磨后，基体组织中非晶含量达８０％以上，将其非晶粉末压退火后仍为原来的ＤＯ３结构。     

低损耗FeSiBPC非晶磁粉芯的制备及磁性能研究

采用高压水雾化方法制备了成分为(Fe0.76Si0.09B0.10P0.05)98C2的非晶粉末,由该成分非晶粉末制备出的磁粉芯具有较高的抗直流偏置性能及优异的损耗特性.研究了制备工艺对样品磁性能的影响.研究结果表明,非晶磁粉芯压制后的去应力退火处理能够有效的提高磁导率和降低损耗,过高的热处理温度会使非晶粉末晶化,导致涡流损耗急剧升高,恶化磁性能,最佳的退火温度为693K,绝缘包覆是制备高性能磁粉芯的必备工艺,通过最优化工艺制备的磁粉芯,其损耗为Pcv =320 kW/m3(f=100 kHz,Bm=0.1 T),抗直流偏置性能为:在H=100 Oe(1 Oe=7.9578×10A/m)外加磁场下,磁导率μa=60的磁粉芯样品对应电感下降为原感值的60％.通过与同规格其他类型磁粉芯的对比,发现FeSiBPC非晶磁粉芯具有极低的损耗及优异的高频磁性能.     

水雾化制备Fe-Si-B-C非晶软磁粉末及其晶化过程的研究

采用水雾化方法制备了Fe-Si-B-C四元非晶合金粉末。研究了粉末的粒度分布、相结构、微观形貌、热稳定性以及基本软磁性能,并通过Kissinger峰移法计算了其晶化时所需的激活能。结果表明,通过水雾化方法制备的Fe-Si-B-C四元软磁粉末的粒度分布合理;粒径小于38μm的粉末为完全非晶结构,且粉末表面光滑,内部成分均匀;非晶粉末的初始结晶温度为542.15℃,且升温过程中存在2个晶化放热峰;2个晶化反应对应的晶化激活能分别为463.92 k J/mol和910.21 k J/mol;粉末的饱和磁感应强度和矫顽力分别为1.08 T和111.4 A/m。     

非晶薄带厚度控制研究进展

从纵向厚度和横向厚度两个角度介绍了非晶薄带厚度控制研究情况。纵向厚度方面,喷嘴间隙、冷却辊转速、辊嘴间距等工艺参数是主要影响因素,对各种厚度控制的经验公式进行了比较;实际生产中,纵向厚度控制主要是对辊嘴间距的控制。相对于纵向厚度控制,横向厚度控制更为复杂,主要分析了喷嘴横向形状、熔潭稳定性、冷却辊辊型三个主要因素对横向厚度的影响。非晶薄带厚度控制还必须结合相关制带工艺的研究,与带材厚度检测相结合,实现非晶带材厚度的自动闭环控制,才能进一步提高厚度控制水平。     

机械合金化制备Co80Zr20非晶合金粉末

采用行星式高能球磨机，通过室温下球磨纯元素混合粉末制备出原子数分数比为Co80Zr20的非晶合金粉末。应用X射线衍射（XRD）、差示扫描量热分析仪（DSC）、扫描电镜及透射电镜对不同球磨时间的混合粉末进行了研究。结果发现，球磨时间对混合粉末的结构及颗粒形貌存在显著影响。原始混合粉末由密排六方的β-Co和α—Zr组成，经过0．5h球磨，β—Co转变为同素异构的面心立方的α—Co，随着球磨时间的增加，Co、Zr颗粒都发生严重塑性变形，并且通过冷焊团聚起来，形成具有层状结构的复合颗粒。球磨导致基体元素Co品格中的晶体缺陷密度大大增加，使得合金元素Zr原子向Co品格中扩散迁移，扩散迁移到Co晶格中的Zr原子数量随球磨时间的增加而增加，导致Co元素的品格常数单调增大。当球磨时间达到8h时，形成Co80Zr20固溶体，继续球磨至10～20h，固溶体转变为非晶。球磨20h得到的非晶粉末的玻璃化转变温度为759K，它可以在840K通过单一放热过程或者继续球磨至40h而发生晶化反应，这两种不同晶化工艺所得到的晶化产物完全相同，均为面心立方的Co23Zr6。     

水雾化Fe69Ni5Al4Sn2P10C2B4Si4非晶合金粉末及其磁粉芯的性能

 Fe69Ni5Al4Sn2P10C2B4Si4合金具有强的非晶形成能力，可以通过水雾化方法获得粒度小于75 μm的非晶态合金粉末。用粒度45~75 μm的水雾化粉末制备的磁粉芯具有优异的磁性能，磁导率大于60，良好的频率特性、高的品质因数和低的损耗。该磁粉芯与磁导率相等的韩国MPP磁粉芯产品相比，其综合性能更优越。     

Fe-Cr-P-Ti非晶态合金粉末的制备、性能及其在金刚石磨轮上的应用

用高压水雾化方法制得Fe-Cr.P-Ti非晶态合金粉末,并对其粉末特性做了研究,同时对其在金刚石磨轮上的应用也作了简单介绍.     

THE PROPERTIES OF 18Ni 350 MARAGING STEEL PRODUCED FROM ELEMENTAL AND PREALLOYED POWDERS

Abstract

The strength of extruded and heat-treated bar of 18Ni 350 maraging steel produced from prealloyed powder has been found to be comparable to that of conventional, wrought 18Ni 350 maraging steel. Impact toughness was considerably higher. In contrast, properties of bar Obtained from an elemental powder mix were markedly inferior to wrought 18Ni 350 maraging steel. The high toughness of Charpy V-notch specimens produced from prealloyed powder was partly attributed to the presence of continuous, aluminium-rich stringers.This resulted in delamination of the specimens during testing and led to a fibrous fracture. Charpy V-notch specimens produced from the elemental powders also contained stringers. However, these were not continuous and therefore did not cause delamination. The resulting fracture surface was flat and relatively featureless. Electron-microprobe analysis has shown that the morphology of the stringers is largely determined by their composition and the composition at the stringer/matrix interface.     

THE PROPERTIES AND SOME APPLICATIONS OF CARBONYL-NICKEL POWDERS

Abstract

Nickel carbonyl, formed by the reaction of carbon monoxide with a nickel concentrate, can be decomposed in a heated space to produce pure nickel in powder form. By varying the decomposition conditions it is possible to achieve a wide range of powders, differing in particle shape and size distribution.

The properties of carbonyl-nickel powders now commercially available or in an advanced stage of development are discussed, and it is shown how such powders can be used for some applications in which specific properties are required.     

THE PRESSING AND SINTERING PROPERTIES OF IRON POWDERS

Abstract

Some twenty different iron powders are available in Europe for the manufacture of sintered bearings and structural parts. These powders can be grouped under four headings: reduced, atomized, comminuted, and electrolytic. Details are given of the experience gained in testing these types of powder by the methods in common use in the metal-powder industry.

The influence of the data thus obtained on the processing, in particular the pressing and sintering conditions, of iron powders is discussed in detail. Consideration is given to the way in which the properties of the powders affect their sinterability, the pressing operation and tool design, and also the physical characteristics of the finished product.     

湿化学法制备纳米粉的热力学条件

阐明了湿化学制备纳米粉的热力学条件以及如何借助于材料的腐蚀状态图（Ｅ－ｐＨ图）确定沉淀成胶条件。实验结果证明，这种方法具有简单，直观，快捷等优点，不但可以方便地确定单组分沉淀成胶条件，而且对多组分分共沉淀条件的确定具有更显著的优越性。     

A MODEL SYSTEM FOR THE STUDY OF THE SURFACE PROPERTIES OF METAL POWDERS

Abstract

The specimen in a field-ion microscope is in the form of a fine wire,elcctropolished to a sharp point. The observed end region of the specimen is roughly hemispherical, with a radius of curvature in the range 200–1500 Å. The end region may be considered as a model of a single (small) particle of a metal powder. This can be cleaned, contaminated with various gases, oxidized, heat-treated, or coated with another metal, as desired. The resulting changes in surface morphology, the occurrence of surface reactions, and the nature of surface-transport processes can be studied at the atomic level. Examples of this approach are drawn from the authors’ work on tungsten, rhenium, iridium, and iron. The effects of oxygen, hydrogen, and carbon on these materials are described. A pronounced surface reaction when a tungsten specimen is coated with approximately one monolayer of nickel is reported. This is believed to be related to the phenomenon of the nickel-activated sintering of tungsten.     

THE ROLLING OF COPPER STRIP FROM HYDROGEN-REDUCED AND OTHER POWDERS

Abstract

Copper powders were rolled to form strip in a normal two-high mill. Satisfactory green strip was obtained from the low-density powder produced by hydrogen reduction from aqueous solution, provided that a mechanical method was used to feed the powder into the rolls. All the types of powder investigated required considerable further rolling after compaction, with at least two heat-treatments, to produce normal mechanical properties.     

RELATIONSHIP BETWEEN THE PROPERTIES OF TANTALUM AND NIOBIUM POWDERS AND THEIR SINTERING BEHAVIOUR

Abstract

Experiments have been carried out to determine the relationship between the properties of tantalum powder and its compressibility, and to examine the effect of carbon and niobium on the hardness and tensile and electrical properties of semi-manufactured products of tantalum. The influence of the particle-size distribution of niobium powder upon the properties of sintered bars has also been studied, with particular reference to the problem of swelling of the bars during sintering.     

PHYSICAL METHODS FOR INVESTIGATING THE PROPERTIES OF OXIDE POWDERS IN RELATION TO SINTERING

Abstract

By the application of several modern techniques, a fairly thorough characterization of even the finest oxide powders with respect to particle and crystallite size and shape may be obtained. The application of these techniques is discussed with particular reference to the characterization of a sample of Mg(OH₂) and the oxides prepared from it by calcination in vacuo. The techniques described are, however, exacting and time consuming and whilst invaluable for any basic study cannot, in general, be considered practicable in routine work. For this reason a final section is devoted to a discussion of attempts to “calibrate” the results from conventional techniques in terms of the more fundamental parameters of powder characterization.     

非晶态纳米Co-Si-B合金粉末的制备及性能研究

用NaBH4化学还原CoCl2·6H2O和NaSiF6的混合水溶液,首次成功地制备出了非晶态Co-Si-B三元纳米合金粉末.通过电感耦合等离子体发射光谱(ICP)、X射线衍射(XRD)、透射电子显微镜(TEM)等方法分析了样品的成分、结构和磁性能.结果发现,所制备的粉末为非晶态半硬磁合金,颗粒呈球形,粒径在20～50nm之间.该非晶粉末的晶化是通过三个放热反应完成的,DSC曲线上没有明显的玻璃化转变,也不存在过冷液相区.