氮化铁磁流体的制备

对以气相液相反应法制备氮化铁磁流体进行了探索,并摸索到制备氮化铁磁流体的工艺流程,所研制的氮化铁磁流体磁饱和强度达到0.05T(脓缩前),并将其应用在静态密封上,成功地研制出磁流体密封安全阀.     

转炉烟尘制备氮化铁磁粉的研究

转炉烟尘通过湿法(硫酸和氨水)冶金提纯净化、高能球磨处理后,在NH3/H2气氛下进行还原氮化,以穆斯堡尔谱学、X光衍射等方法对处理试样进行物相分析.结果表明,Ar气氛下球磨2h后,经550℃/2h还原、550℃/3h氮化(NH3/H2=3/4,降温时NH3/H2=1/6)处理,γ'-Fe4N 的生成量≥91%.     

硅粉在高氮压下氮化的研究

本文对三种不同纯度的硅粉在加压氮气(～1MPa)中进行氮化研究。实验表明:在1250～1370℃1h 内硅粉可快速氮化反应生成氮化硅,主要晶相为β-Si_3N_4。硅粉快速氮化时,存在一个临界氮气压力,临界压力大小与硅粉本身表面特性有关,采用适当的工艺参数可快速制备高质量的α-SiN_4粉末。     

高密度磁记录材料——纳米磁性团簇研究进展

报导有关纳米磁性团簇的一些最新研究成果。根据团簇组成成分的不同，将其分为铁磁金属团簇铁磁合金团族、铁磁化合物团簇及嵌埋式铁磁团簇四大类，分别就其制备方法、磁性能及应用前景等进行了综述。对各类团簇的优缺点进行了评述。     

球磨技术制备铁的氮化物及性能研究

本实验通过球磨α－Ｆｅ和脲的混合粉末,制得α’－Ｆｅ（Ｎ）超细粉末,Ｎ原子含量为８．８％（原子分数）,饱和磁化强度σｓ为２４２．７ｅｍｕ／ｇ。样品径１６０℃真空退火４ｈ,α－Ｆｅ’（Ｎ）相部分转变为α”－Ｆｅ１６Ｎ２相,此时样品的饱和磁化强度σｓ提高到２５２．０ｅｍｕ／ｇ,样品中α”－Ｆｅ１６Ｎ２相含量约２１％（质量分数）,其σｓ为２８７．０ｅｍｕ／ｇ。样分析表明,在１５０￣２００℃,α’－Ｆｅ（     

新型超硬材料—氮化碳薄膜研究新进展

概述了新型超硬材料－氮化碳的晶体结构和合成Ｃ３Ｎ４的实验方法，以及Ｃ３Ｎ４薄膜的ＴＥＤ，ＸＲＤ，ＸＰＳ，ＦＴＩＲ，Ｒａｍａｎ和Ｈｖ的测试结果。     

H_2 H_2O还原法制备超细金属磁记录粉

采用Ｈ２＋Ｈ２Ｏ还原法，通过控制Ｈ２Ｏ／Ｈ２比可改善粉体晶粒链状结构的晶间界面结构，采用ＸＲＤ、ＴＥＭ、ＶＳＭ等方法测试粉体的晶体结构、粒子形貌和磁性能．结果为金属磁粉的矫顽力提高；粒子形状均匀，表面平滑，毛刺少；４６０℃时Ｈ２＋Ｈ２Ｏ还原金属磁粉的矫顽力为１５２０Ｏｅ，比传统氢还原工艺矫顽力１４４０Ｏｅ提高５．６％．采用流化床反应器，具有温度均匀，气固接触充分，可防止颗粒烧结等优点，工业应用前景广阔．     

H2+H2O还原法制备超细金属磁记录粉

采用H2＋H2O还原法,通过控制H2O／H2比可改善粉体晶粒链状结构的晶间界面结构,采用XRD、TEM、VSM等方法测试粉体的晶体结构、粒子形貌和磁性能,结果为金属磁偻的矫顽力提高;粒子形状均匀,表面平滑,毛刺少;460℃时H2＋H2O还原金属磁粉的矫顽力为1520Oe,比传统氢还原工艺矫顽力1440Oe提高5.6%。采用流化床反应器,具有温度均匀,气固接触充分,可防止颗粒烧结等优点,工业应用前景广阔。     

高能球磨制备镍铝合金粉的工艺研究

本文以高能球磨制备镍铝合金扮为例，基于合金化进程的快慢以及出粉率的高低考虑，详细讨论了工艺参数的制定过程。实验中采用QM-3SP4行星式球磨机，主要考察的工艺参数有球料比．工艺控制剂乙醇的用量、球磨时间。结果表明，在转速500rad／min下，采用20：1的球料此，乙醇添加量为合金粉之质量的8％，可以在较短的时间内得到合金粉，且出粉率接近100％，并基于实验提出了一个估算工艺控制剂乙醇用量的方法，为后续高能球磨贵金属合金粉提供了重要的参考依据。     

Particulate magnetic recording media: a review

After describing briefly the principles of magnetic recording and the manufacture of media, the author reviews the history, characteristics, and development trends of the most important particulate magnetic recording materials. These are acicular iron oxides, chromium dioxide, cobalt-modified iron oxides, acicular metal particles, and barium ferrite. A trend common to most of the materials is particle size reduction     

Localized electro-thermal processing: a new route to the patterning of magnetic recording media

Previous reports have detailed the fabrication of media able to support high density magnetic recording in both longitudinal and perpendicular formats by the global rapid thermal processing of sputtered non-magnetic precursor films. During processing in this manner a magnetic element is released from its nitride and agglomerates to form a random near mono-dispersion of magnetic nano-particles. Here we explore, primarily through modelling and simulation, the feasibility of processing similarly formulated precursor media not globally but locally. We investigate the potential of using conducting nano-probe tips to produce, via electro-thermal (Joule) heating, a nano-patterned recording medium in the form of regular arrays of magnetic islands in a non-magnetic host. In the first instance we concentrate on the simplest cobalt based precursor medium for which both initial simulation and experimental studies indicate the formation of magnetic islands with dimensions of the order of the tip diameter; this is relatively straightforward. The results signify that if practical production scenarios can be devised to produce technologically significant areas of recording media by the rapid multi-probe repetition of this technique, then processing in this manner offers a promising route to areal recording densities of perhaps 5 Terabit/in(2) even with the simplest cobalt media. We also note that the electro-thermal processing method is potentially extendable to the production of a wide variety of magnetic materials (e.g.?PtCo, FeCo, NiFe alloys) and, applied via electrical nano-imprinting type techniques, to the production of a wide variety of patterned structures.     

转炉烟尘制备氮化铁磁性材料及其性能的研究

在NH3/H2气氛下对转炉烟尘进行了还原与氮化的连续处理,以穆斯堡尔谱学结合X光衍射方法对处理试样进行物相分析.实验结果表明,氮化温度为560℃,NH3/H2比小于11时,γ-Fe4N的含量超过70%,处理试样的比饱和磁化强度σs高达140emu/g,较原始样品的有明显增加.     

Cobalt chromium perpendicular magnetic recording media: a corrosionstudy

An electrochemical and environmental chamber study of the effects of corrosion on the magnetic properties of various cobalt chromium thin-film compositions is reported. The propensity of these various materials towards corrosion is delineated, with suggestions for an optimum composition with respect to corrosion resistance. The effects of the presence of a titanium seed layer and those of a soft nickel/iron keeper layer on the corrosion resistance of the recording medium are studied     

Perpendicular magnetic recording performance of double-layer media

Perpendicular magnetic recording performance for double-layer (Co-Cr,Ni-Fe) media was analyzed, with a simple magnetization model, in comparison with single-layer media. The calculated output voltage from a ring-shaped reproducing head shows good agreement with experimental data. It is shown theoretically and empirically that the Co-Cr layer thickness can be reduced without sacrificing the output amplitude, if the Ni-Fe layer is placed underneath it to perform as a "flux sink" to extinguish the rear surface charge on the Co-Cr layer.     

Wear properties of perpendicular magnetic recording media

Wear properties of sputtered Co-Cr/permalloy double layer on flexible substrate with and without an inorganic protective top layer were studied under simulated tribological conditions. A soft head slider (ex. glass) gave even severer damage to media than the hard one (ex. Al2O3-TiC), and a 200 Å thin inorganic protective top layer was effective enough to enhance resistance against wear. Read-write experiments were also done with use of the double layer flexible media with the protective top layer (200 Å in thickness) by running them on a specially designed driver unit with an Al2O3.TiC spherical SPT head. An out-put signal loss was no more than 3dB even after 10 million times of the head passes.     

Nanocomposite magnetic films for high-density perpendicular magnetic recording media

Multi-layer nanocomposite structures of Ta/Ru/CoCr₁/FeCoTaCr(soft magnetic layer)/CoCr₂/CoCrPt-SiO₂(hard magnetic layer or recording layer)/C and Ta/Ru/CoCr₁/CoCrPt-SiO₂/CoCr₂/FeCoTaCr/C were proposed. This exchange coupled composite (ECC) media consisting of hard/soft stacked magnetic layers were promising in improving the writability of perpendicular magnetic recording media. A small CoCrPt c-axis orientation dispersion of about 3° was achieved with the optimized sputter conditions. The CoCrPt-SiO₂ grains were well segregated by SiO₂ at grain boundaries. The macro-magnetic properties showed that the stacked magnetic grains switched in a coherent mode and that switching field decreased with increasing the thickness of the soft magnetic layer.     

Fabrication of magnetic nanodot arrays for patterned magnetic recording media

Fabrication processes of arrayed magnetic nanodots for the use of patterned magnetic recording media were reviewed. One candidate for the patterned media is ordered assemble of magnetic nanoparticles, and the other is patterned magnetic thin films fabricated using various micro/nano scale machining processes. For the formation of patterned masks and molds, lithography processes as well as self-organized pattern formation are utilized. For the deposition processes of magnetic dots, electrochemical deposition processes were widely used. These fabrication processes are reviewed mainly from recent reports. The recording systems for the patterned media including probe-type-recording are also overviewed.