金属粉末在药型罩中的应用

药型罩材料的性能直接影响着聚能效应的发挥。本文综合近年来国内外粉末药型罩的研究发展情况 ,详细介绍了铜、钨、钼、钽、铋等金属粉末在药型罩中的应用     

VIBRATORY COMPACTING OF METAL POWDERS

Abstract

The vibratory compacting of copper powder has been studied using a mechanical vibrator. The major factors influencing the green density of the compacts were the amplitude and frequency of vibration, and the applied pressure. A minimum time of 10 sec on the vibrator was necessary to achieve the maximum density value. Other factors examined were the effects of vibration on blended powders with constituents of widely different densities, and the suitability of this method to compact various materials. Vibratory compacting produced compacts of improved uniformity and green density.     

THE HOT EXTRUSION OF METAL POWDERS

Abstract

The procedure of consolidating metal powders by isostatic compaction, canning, and hot extrusion is described. The properties of a number of nickel. base alloys and stainless steels prepared by this method are given.

It is concluded that, even when no precautions are taken to eliminate air (oxygen) from the canned billet, the resulting oxide content of the extruded bar is insufficient to exert a serious influence on the mechanical properties. The corrosion-resistances of certain stainless-steel samples, extruded from powders, were found to be somewhat lower than the corrosion-resistance of equivalent conventionally wrought products.     

金属粉末表面稳定化处理的研究

研究了几种钝化剂对金属粉末表面的稳定化处理工艺，分析了其钝化机理。经钝化处理后的粉末，其抗氧化性显著提高，而其他物理性能及化学组成基本保持不变。稳定化处理对金属粉末的生产具有很重要的意义。     

不同类型金属粉末的温压行为

研究了铝粉、铜粉、钨粉的温压压制行为,并与铁粉的温压过程进行了对比。实验发现,温压无论对塑性粉末还是脆性粉末均有效果。温压压制可提高粉末压坯密度,降低压坯脱模压力和弹性后效     

THE COMPACTING OF METAL POWDERS BY EXPLOSIVES

Abstract

The paper describes a technique developed for compacting metal powders by the use of detonating explosives under controlled conditions. Aluminium, iron, copper, and steel powders were originally compacted by this means into solid cylinders. Graphite and other non-metal powders have recently been compacted, and modifications have been introduced whereby annular cylinders may be formed. This novel technique may find application in cases where existing mechanical methods of powder compacting are not adequate.     

超细金属粉制备新工艺研究

介绍了利用废镍网边角料制备成超细高纯镍粉的新工艺。该工艺通过适当添加磁场激发剂和纯化剂,并调整其它工艺参数,能使废镍网片迅速熔化,使原镍含量从≤90%提高至>99.8%的超细高纯镍粉。     

ON THERMAL ACTIVATION DURING EXTRUSION OF METAL POWDERS

Abstract

Four aluminium alloy powders were extruded in the temperature range 250–550° C and the strain-rate/flow-stress/temperature relationship analysed in terms of exponential functions. The results of ～400 experimental runs indicate that the powder process is less strain-rate sensitive than is its conventional counterpart. The process is thermally activated and it appears that the rate-controlling mechanism is the climb of edge dislocations or the migration of jogged screw dislocations.     

PRODUCTION OF SOME METAL POWDERS BY HYDROMETALLURGICAL PROCESSES

Abstract

Nickel, cobalt, copper, and iron powders can be manufactured by hydrometallurgical processes. It is possible to use a wide variety of materials, including waste solutions, as the metal-containing feed. Estimates of the capital cost of reduction autoclaves and ancillary equipment show the advantage of increasing the scale of the operation from 2 to 50 tons of metal produced per day.

A major factor in the economics of producing the powders is the cost of purifying the solutions to give a liquor from which metal of the desired purity can be precipitated. Liquid–liquid extraction does not appear to have been used so far in a refinery in which metal is precipitated by hydrogen. The possible application of the technique is examined briefly.

Metal powders can be precipitated directly by reducing with hydrogen some organic phases produced by liquid–liquid extraction of aqueous solutions containing several metals. A suitable solvent mixture is acarboxylic acid with hydrocarbon diluent. The total pressure necessary for reduction is lower than that required when water is the solvent.

An important factor in considering the use of hydrometallurgical methods for producing metal powders is that in some cases the cost of obtaining metal is competitive with any other kind of process, and the fact that it is formed as powder is an added advantage. Also it is possible to make powders with physical characteristics that can be controlled withinnarrow limits over a very wide range.     

THE PRODUCTION OF METAL POWDERS FROM AQUEOUS SOLUTIONS

Abstract

The principles involved in producing metal powders by hydrogen reduction of metal ions in aqueous solutions are discussed from the thermo-dynamic and the kinetic standpoint. The influence of nuclei and of surface-active agents on the nature of the powders are considered in relation to the production of nickel, cobalt, and copper.

A survey is made of the scale and technology of current processes and the uses to which metal powders may be put are described, with particular reference to the manufacture of metal strip and plates, dispersion-hardened nickel, and composites.

The practicability of controlling the conditions of reduction to yield powders with widely varying combinations of properties is a most valuable attribute of hydrometallurgical methods.     

金属锰粉生产中的若干问题

简要地阐述金属锰粉生产中的若干问题，针对金属锰粉的特性，对设备进行了技术改造，采取了一些措施后，试验产品均达到了用户的要求．     

DEFORMATION AND DENSIFICATION DURING THE ROLLING OF METAL POWDERS

Abstract

The deformation of particles and the general process of densification during the roll-compacting of strip from metal powder have been determined by photomicrographic and QTM studies. Observations were made on the expansion of the compacted strip after it had passed the plane joining the roll axes. The effect was related to elastic recovery of the material and the expansion of gases entrapped in the pores between the particles.

The production of satisfactory green strip was found to be restricted to a range of thicknesses obtained between certain maximum and minimum roll gaps. These limits were related to roll pressure and strip density. It was also restricted by a maximum rolling speed that was governed by powder flow to the compaction zone.

Density variations that occurred across the width and through the thickness of green strip were also determined.     

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.     

AN ASSESSMENT OF GLASS-CERAMIC AS AN INSERT MATERIAL FOR DIE COMPACTION OF METAL POWDERS

Abstract

Glass-ceramic inserts have been made and shrink-fitted into steel bolsters to assess the feasibility of glass-ceramic as a die material for the die-compaction of lubricated and unlubricated iron powder. Measurements of compacting pressures and ejection stresses were lower for the glass-ceramic die compared with those for a standard tool-steel die in lubricated conditions, while in unlubricated conditions ejection stresses were appreciably higher, with scoring and brittle fracture of the insert. The results indicate that possibilities may lie in the further development of ceramics as inexpensive die materials for powder compaction in which die-wall friction could be significantly reduced.