The effect of skull-pin insertion on cerebrospinal fluid pressure and cerebral perfusion pressure: influence of sufentanil and fentanyl

Directed delivery and distribution of anaesthetics (novocaine, lidocaine, trimecaine) immobilized on finely dispersed iron powders under the influence of an external magnetic field in body tissues of test animals have been studied. The data of emission spectral analysis relating to concentration of iron in soft and bone tissues of animals influenced by constant and alternating magnetic field on front and reverse sides over a period from 0 to 180 min are given.     

Thermal stability of finely dispersed ferromagnetic powders

The oxidation mechanism and kinetics have been examined for finely dispersed powders of iron and compounds containing it and noble and platinum metals; these powders were made by a thermochemical method and examined at 20–400°C. The powders do not change in composition and magnetic characteristics up to 110°C because the surfaces of the particles are protected by iron oxides and carbide. This allows the powders to be used to make materials for medical purposes, since they can be sterilized at that temperature. Translated from Poroshkovaya Metallurgiya, Nos. 5–6(413), pp. 1–4, May–June, 2000.     

Influence of the electrolysis temperature on the formation, composition, structure, and magnetic properties of highly dispersed iron and iron-nickel alloy powders

The influence of the electrolysis temperature on the formation, chemical and phase composition, structure, and magnetic properties of highly dispersed iron and iron-nickel (50∶50) powders is investigated. The optimal thermal conditions are determined for the production of powders with micron-sized particles in a two-layer electrolytic bath from concentrated solutions of electrolytes. Institute of Colloid Chemistry and Water Chemistry, UkranianAcademy of Sciences Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5/6(395), pp. 37–42, May–June, 1997.     

粉末冶金工艺对纯铁软磁材料性能的影响

利用粉末冶金技术制备纯铁软磁材料,在不同温度和压力下将不同粒径铁粉压制成生坯,并在保护气氛下进行烧结。结果表明:不同粒径铁粉混合有助于压坯密度的增加,适宜的压制温度可以有效地促进粉末流动,避免大尺寸孔洞的形成,优化组织。140℃、800 MPa温压条件下雾化铁粉压坯密度最高可达7.35 g·cm-3。对比常温压制,温压压坯烧结后孔洞分布均匀。烧结体密度随温度的升高而上升,雾化铁粉压坯在1250℃烧结后密度最高可达7.47 g·cm-3。在一定范围内,软磁材料磁性能与密度成正比,混粉压制试样的密度接近理论值,但在混合铁粉中,较细的铁粉夹杂于粗粉中,阻碍磁畴壁移动,造成饱和磁化强度（M_s）偏小、矫顽力（H_c）偏大的现象,M_s为205.51 emu·g-1,Hc为7.9780 Oe。     

Highly dispersed composite iron—Copper powders obtained from oxalates by a thermochemical method

The preparation of highly dispersed composite iron—copper powders with various concentrations of copper from mixed iron and copper oxalates was studied. The physico-chemical properties of the powders were determined. The powders were corrosion resistant, hydrophilic, practically monodispersed, bacteriocidal and tolerated the sterilization at elevated temperatures. Their magnetic properties could be regulated in the process of forming the initial components. Such powders can be useful in medicine, biology and technology. Institute of Colloid and Water Chemistry, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(402), pp. 1–4, July–August, 1998.     

Manufacture of magnetic cores from various iron powders

Conclusions Coercive force measurements were made on grades PZh4M3, PZhCh3SV, PZhCh3MV, NC 100.24, PZhR(0) and PZhÉ iron powders and magnetic cores heat treated in the temperature range 750–1200°C. Iron powders of large specific surface are characterized by greater coercive forces compared with powders of small specific surface. Grades PZhCh3SV, PZhCh3MV, NC 100.24, and PZhR(0) iron powders are suitable for the manufacture of magnetic cores after they have been alloyed with elements decreasing internal stresses in alloys. Sintered magnetic cores from PZhÉ electrolytic iron powder meet all the requirements of TU 16-538.225-74 without alloying. The properties of grades EMP300M, PM282N, KiP 270.MS, and SC 100.26 iron powders were assessed. KiP 270.MS and SC 100.26 powders possess the same properties as PZhCh3SV, PZhCh3MV, and NC 100.24 powders, but in grade SC 100.26 powder high oxygen contents are not permissible. Consequently, magnetic cores made from this powder will exhibit high coercivity. Grades EMP300M and PZhR(0) iron powders are similar in all their properties, and the magnetic characteristics of cores made from them will therefore also be comparable. Grade PM282N iron powder is produced by the electrolysis of solutions and characterized by a dendritic particle shape. Owing to the large specific surface of the particles of this powder, its coercive force will be 25–30 A/m greater than that of PZhÉ. In the manufacture of magnetic cores from this powder recourse must therefore be had to alloying with silicon in order to decrease their coercivity.Translated from Poroshkovaya Metallurgiya, No. 6(234), pp. 73–78, June, 1982.     

微细铁颗粒的单体解离特性和选择性回收工艺

研究了直接还原熟料中微细铁颗粒的赋存形式和选择性回收工艺.发现尾渣中铁的赋存形态主要为微细粒的单质铁;直接还原熟料中小于5μm的细连生体和铁颗粒很难通过磁选回收,但大于10μm的粗铁颗粒可以回收.为了兼顾粉末铁的品位与回收率,需要对不同赋存状态的铁颗粒进行选择性回收.提高粗连生体的单体解离度,有针对性地回收其中的铁颗粒,是提高粉末铁回收指标的关键.提高磁选场强可提高粉末铁回收率,但降低粉末铁品质.利用正交试验对工艺参数进行了优化,在优化条件下粉末铁中TFe质量分数和铁回收率分别为92.91%和92.03%.      

Hot Pressing Technology to Produce Wear-Resistant P/M Structural Materials with Dispersed Solid Inclusions

We have examined the possibility of milling iron, nickel, chromium, high-speed steel, and titanium carbide powders in an attritor (attrition mill) for use in producing carbide steel. The powders were milled to a particle size of 1–3 μm for TiC and 10 μm for metal components. As a rule, such powders and mixture of powders do not flow or form, which makes it impossible to produce blanks for hot pressing by the traditional die pressing method. Shells pressed from iron powders are proposed for forming a blank. We tested techniques for hot pressing dispersed powders into such envelopes. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 43–50, July–August, 2005.     

掺杂异物铁精粉的鉴别

烧结球团矿作为炼铁生产过程中的主要原料广泛使用经磁选的铁精粉,由于资源、价格、成本等原因,原料市场出现了掺入铁屑、磨床屑、氧化铁皮等异物提高铁精粉中全铁含量的假铁精粉,烧结过程中一旦使用这些假铁精粉,严重影响生产。针对外购进厂铁精粉是否为掺杂异物的铁精粉,通过检查外观特征是否有白色石灰颗粒,通过检查气味是否有臭皮蛋、氨气味道,再通过测定水化后pH值是否呈碱性以及检测铁精粉中的磁性铁和金属铁含量,可以快速简单鉴定该铁精粉是否由铁屑、硫酸渣、氧化铁皮等外来含铁物质配矿而成。     

DISPERSION-STRENGTHENED IRON BY GEL PRECIPITATION

Abstract

Metastable iron oxide particles containing calcium, magnesium, or zirconium in solid solution were produced by the gel precipitation method. These were reduced to metal with hydrogen/nitrogen mixtures in a fluidized-bed furnace at 800°C to yield iron powders containing dispersed oxide phases within each iron particle. The oxide phases were either 2CaO.Fe₂O₃, a solid solution of MgO and FeO, or ZrO₂, which appeared to be free from iron. Consolidation by compacting the powders into cans, sealing under vacuum, and hot extrusion yielded bars in which the oxide particles were dispersed. Hardness and tensile-test data for material heated to 1000°C for up to 100 h suggest that the oxides containing iron coarsen rapidly and contribute to strengthening only by maintaining a small matrix grain size. The iron-free ZrO₂ appears to be a true dispersion hardener and to restrain grain growth more than do the other oxides investigated.     

粉末冶金铜铁合金的组织与性能

分别以元素混合粉、机械合金化粉和水气联合雾化合金粉为原料,结合冷等静压成形、烧结及轧制工艺制备了Cu?5％Fe合金(质量分数),对比了三种原料粉的铜铁合金粉末形貌、微观组织、力学性能及物理性能.结果表明,铁颗粒分布均匀,元素混合、机械合金化和水气联合雾化法粉末烧结体中铁颗粒平均尺寸分别为9.4μm、1.2μm、3.5μ...     

Permanent magnets from fine iron and iron-cobalt alloy powders

Conclusions It has been established that, to obtain the optimum, magnetic properties in isotropic materials from fine iron and iron-cobalt alloy powders, the powders should be heat-treated for 4 h at a temperature of 280°C and compacted under a pressure of 15–16 kbar. Heat treatment tends to destroy dendritic axes of the second and third orders on the powder particles, heal structural defects, and increase the flowability of particles during pressing, thereby ultimately improving the magnetic properties of the resultant components. The maximum magnetic energy is 4.6 kJ/m³ for isotropic magnets from iron powders and 8.6 kJ/m³ for magnets from iron-cobalt alloy powders.Translated from Poroshkovaya Metallurgiya, No. 10 (142), pp. 61–63, October, 1974.     

Preparation and Properties of Iron Powder Plated with Nickel and Cobalt

The magnetic properties (magnetic induction and coercive force) of iron powder coated with nickel and cobalt as a result of chemical deposition from hypophosphite electrolytes are studied. Thermogravimetry, differential thermal and x-ray phase analyses are used to study in detail the kinetics and mechanism of high-temperature oxidation in air (up to 1200°C) for the original and coated powders. The phase composition of oxide films on specimens annealed at all temperatures of the DTA-curve peaks is determined. The possibility of increasing the high-temperature oxidation resistance of iron powder coated with nickel or cobalt is demonstrated.     

Enhanced magnetic properties of anisotropic Nd-Fe-B nanocomposites by Fe(C)coating

Nanostructured anisotropic Nd-Fe-B/Fe(C) composite powders were prepared by coating Fe(C) softmagnetic nanoparticles on HDDR Nd-Fe-B hard magnetic powders using iron pentacarbonyl Fe(CO)_5 as soft-phase precursor.The effect of Fe(CO)_5-loading amount on soft-phase purity,coating morphology and magnetic properties of the composite powders was investigated.Dense and continuous Fe(C) softphase coatings with average particle sizes of 58-68 nm are obtained at Fe(CO)_5 loading amounts of x 12 wt%,leading to enhanced remanence and improved energy product of the coated powders.Positive value in δM-plots and single-phase-like demagnetization curves are observed in the Nd-Fe-B/Fe(C) composite powders,indicating the exchange coupling effect between the coated Fe(C) soft phases and the Nd-Fe-B hard phase.     

铜包铁粉的应用及制备

铜包铁粉是一种将铜包在铁粉表面形成包覆层的复合粉末,被用来改善铜铁混合粉末组织不均、成分偏析等问题。本文综述了铜包铁粉的应用及制备方法,介绍了机械球磨涂覆法、置换镀铜法、化学镀铜法等铜包铁粉制备技术的基本原理及研究进展,总结了铜包铁粉制备过程中存在的问题,并展望了铜包铁粉的发展方向。     

Finely dispersed composite iron—Silver powders

A thermochemical method has been used to make finely dispersed iron-silver composite powders for medical purposes. The physicochemical and biomedical properties have been examined. These Fe’MAg powders have been made with silver mass contents of 0.1, 1, 5, and 10%, and they have been found to be resistant to corrosion, nonpyrophoric, and bactericidal, and to have hydrophilic surfaces and to allow of thermal sterilization; during the formation of the powders, the behavior can be traced from the magnetic characteristics can be controlled depending on subsequent use. The powders can be used in medicine for example for the treatment of suppurating wounds, trophic ulcers, and so on.     

Development of materials with low,precise values of magnetic permeability for reference standards

Summary A procedure has been developed for producing reference standards with low, precise values of magnetic permeability from mixed copper and iron powders by the powder metallurgy technique. A set of standards for seven different values of magnetic permeability was made for serial instruments. The first set of instruments using metal powder reference standards is already in operation.     

Finely dispersed composite iron-platinum and iron-gold powders

The physicochemical laws of the formation of Fe−Pt and Fe−Au oxalates have been determined. For the first time finely dispersed Fe−Pt and Fe−Au composite powders have been fabricated by thermal reduction. The physicochemical and biomedical properties of such powders are investigated. We show that the powders are corrosion-resistant, are almost monodisperse, have a hydrophilic surface, are nonpyrophoric, are harmless, are bactericidal, and withstand sterilization temperatures. Their magnetic properties can be controlled during formation. Colloid Chemistry and Water Chemistry Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 3-4(400), pp. 1–6, March–April, 1997.     

Recovery of iron and copper from copper tailings by coal-based direct reduction and magnetic separation

A technique comprising coal-based direct reduction followed by magnetic separation was presented to recover iron and copper from copper slag flotation tailings. Optimal process parameters, such as reductant and additive ratios, reduction temperature, and reduction time, were experimentally determined and found to be as follows: a limestone ratio of 25%, a bitumite ratio of 30%, and reduction roasting at 1473 K for 90 min. Under these conditions, copper-bearing iron powders (CIP) with an iron content of 90.11% and copper content of 0.86%, indicating iron and copper recoveries of 87.25% and 83.44% respectively, were effectively obtained. Scanning electron microscopy and energy dispersive spectroscopy of the CIP revealed that some tiny copper particles were embedded in metal iron and some copper formed alloy with iron, which was difficult to achieve the separation of these two metals. Thus, the copper went into magnetic products by magnetic separation. Adding copper into the steel can produce weathering steel. Therefore, the CIP can be used as an inexpensive raw material for weathering steel.     

铁粉压缩性的研究

根据Konopicky理论,铁粉在2-8tf/cm2范围内压制时,单位压力P与相对密度Rp有如下关系:P=Aln$\frac{{1-{\rm{Ro}}}}{{1-{\rm{Rp}}}}$。本文用该理论对编号为AS、AG、CD、TJ、YQ不同厂家铁粉的压缩性进行了研究。定了铁粉的粒度及其组成、松装密度、流动性,计算了铁粉退火前后A值及Ro值的变化。并以此对铁粉的压缩性进行了讨论。通过对等密度线的测定,查明了不同粒度铁粉的压坯密度变化,以及在不同压力下压坯密度变化的规律。
本工作说明,铁粉的筛分和合批对改善铁粉性能、扩大铁粉品种是有利的。而铁粉的还原退火对改善铁粉的压缩性,获得中、高密度压件是必要的。