RWSSCL-X-12型粉末冶金全自动多功能电阻炉

RWSSCL-X-12型电阻炉是一种集粉末冶金烧结、渗碳(或碳氮共渗)、淬火、磷化为一体的专用电阻炉。它可以单独作为烧结炉使用,也可以作为烧结、磷化两用炉或作为渗碳(或碳氮共渗)、淬火、磷化三用炉使用。这种电阻炉生产效率高,能节约工时和能耗,并保证产品质量。     

不同工艺条件对WC-20％Co硬质合金性能的影响

采用高能球磨法制备WC—Co粉末,分别在低压和真空条件下制备WC-20％Co硬质合金,通过对合金性能的检测和金相组织的观察,研究了球磨时间和烧结工艺对硬质合金性能的影响。结果表明,球磨时间对硬质合金性能和组织结构有明显的影响;通过控制适当的球磨时间,町提高硬质合金的硬度和高韧性;通过调节工艺,真空烧结也可以提高合金的性能,低压烧结对粗颗粒WC为原料的合金的综合性能提高不明显。     

WC-(Co-Al)硬质合金的研究

研究采用反应烧结制备以Co3 Al代Co作为粘结金属的硬质合金技术。对制得的硬质合金进行了组织结构的观察及性能测定。结果表明 ,铝的加入有助于烧结过程中WC晶粒的细化和均匀化 ,制得了WC晶粒均匀的超细硬质合金。与相同粘结剂含量的钴粘结硬质合金相比 ,在耐腐蚀和高温抗氧化性方面 ,Co Al硬质合金表现出明显的优异性能。研究发现 ,在烧结中由于发生Co Al的激烈化合反应而导致孔隙的形成。采用低压等静压烧结或烧结后进行低压等静压处理可降低孔隙度提高合金的力学性能     

新型电弧炉炉底用捣打料技术特性和应用

ＨＹＤＬ－８５炉底用捣打料的主要晶相为方镁石,基质胶结相为低熔点过渡型的Ｃ２Ｆ（４ＡＦ）相。在实际应用中Ｃ２Ｆ具有活化晶格加速烧结的作用,且Ｃ２Ｆ分解成氧化铁及ＣａＯ,分别溶入入镁石形成ＲＯ相及反应生成高熔点Ｃ２Ｓ相,有较强的抗蚀性。     

我国矿用硬质合金的发展现状与趋势

通过对我国矿用硬质合金发展历史和现状的分析,指出了我国部分矿用硬质合金生产厂家经过20世纪80年代以来大规模的技术引进和技术改造,其生产技术、工艺装备和产品质量都有较大幅度的提高,部分厂家生产的矿用硬质合金质量已达到世界先进水平。在分析近几年来我国矿用硬质合金理论研究现状的同时,提出了我国矿用硬质合金21世纪的发展趋势:即喷雾制粒、低压烧结等先进的矿用硬质合金生产技术和设备被各生产厂家普遍采用。梯度结构和超细晶粒硬质合金生产将在矿用硬质合金市场上不断推广和应用。矿用硬质合金的强化处理,如热处理、深冷处理、等离子注入等作为提高矿用硬质合金综合机械性能的有效手段,将得到广泛应用。     

Contact precipitation of silver on copper powder

The processing characteristics of articles made from copper powder can be improved by alloying the copper powder with additions of silver (up to 0.2%). The simplest and most economical method is deposition of silver onto copper powder particles by contact exchange. We have studied the effect of different types of electrolytes (nitrate, pyrophosphate, sulfosalicylate, sulfite, ferricyanide, cyanide thiocyanate, and thiocyanate) on the kinetic characteristics of the electrode processes. We have done structural studies of copper powder alloyed with silver. We have determined the bulk (as-poured) density of the powders after cementation, and also the density, shrinkage, electrical resistance, and hardness of specimens prepared by the traditional procedure from the alloyed powders. In most of the studied systems, the cementation process occurs with diffusion control of the cathode reaction. However, this does not lead to visible formation of growths and dendrites of silver on the surface of the copper particles. According to x-ray phase analysis results, during cementation a solid solution of copper in silver is formed on the surface of the particles. After sintering the green compacts, the alloy is homogenized with formation of a solid solution of silver in copper. The nature of the electrolyte markedly affects the properties of the Cu−Ag material. In some cases, the hardness and electrical conductance of the specimens increase simultaneously. Technological and economic considerations lead to choosing cyanide thiocyanate electrolyte as the best for alloying copper powder with silver. Urals State Technical University; Institute of High-Temperature Electrochemistry, Urals Branch, Russian Academy of Sciences, Ekaterinburg. Translated from Poroshkovaya Metallurgiya, Nos. 7–8(408), pp. 22–29, July–August, 1999.     

Fluidized cathode cementation of copper

Copper recovery by cementation using iron nails surrounded by a fluidized bed of spherical copper particles was studied in a laboratory scale drum reactor. The rate of cementation was found to be directly proportional to cupric ion concentration and the surface areas of the nails and fluidized copper particles. The fluidized copper particles served as a cathode for copper cementation and enhanced the cementation rate. The activation energy for the process was found to be 22.0 kJ/mol. The rate controlling process is thought to be diffusion of cupric ion through a solution boundary layer surrounding the copper particles. Granular activated carbon was shown to be effective as a fluidized cathode material, but did not enhance the cementation rate.     

The effect of cyanide and lead ions on the cementation rate,stoichiometry and morphology of silver in cementation from cyanide solutions with zinc powder

The cementation of silver on zinc powder from solutions with a wide concentration range of cyanide has been investigated in the absence and presence of lead ions through stirred reactor batch tests and scanning electron microscopy studies on the cementation product. The concentration of cyanide ions affected the morphology of the product, the nature of cementation reaction and the cementation kinetics. Three cyanide-dependent concentration regimes have been identified: a low cyanide concentration regime in which silver cementation followed an ion-exchange type reaction taking place at the zinc/aqueous solution interface, and the silver deposited around the zinc particle in a uniform growth; a high cyanide concentration regime, as in plant practices, in which the cementation of silver followed an overall chemical reaction involving the evolution of hydrogen and a one-to-one molar silver-to-zinc stoichiometry (In this regime, both the anodic oxidation and the cathodic reduction reactions occurred at distinct interfaces and the silver deposited in a dense-branching morphology.), and an intermediate cyanide concentration regime which is a transition between the two previous regimes. In the low and intermediate regimes, lead and cyanide ions did not affect the morphology of the cemented silver, but increased the silver cementation kinetics owing to Zn(OH)₂ instability. Within the high cyanide concentration regime, lead ions did not appreciably change the cementation kinetics. They modified the pattern of the silver deposit from a dense-branching to a dendritic morphology.     

The effect of certain surfactants on the cementation of nickel from zinc sulphate solutions by suspended zinc particles in the presence of copper

The effect of surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on both nickel-zinc dust cementation kinetics and the structure of obtained deposits was investigated. Experiments were carried out in the presence of copper to increase the low cementation rate of nickel. The reaction of nickel cementation was found not to follow first-order kinetics due to hydrogen evolution which takes place along with the cementation reaction. Two rate regions were observed. Hydrogen evolution in the presence of D1 is lower than with D2, D3 and without surfactants. D1 and D3 decrease but D2 has no effect on nickel cementation. The influence of D1 and D3 is higher at the beginning of the process. Higher temperature improves nickel cementation only in the initial period. The structure of cementation products depends on the temperature. Uniform layers of lamellar crystallites on the surface of zinc particles were observed at 65°C with and without surfactants. At 85°C the morphology changes to massive spheroid formations of lamellar crystallites. The presence of D1 and D3 decreases both the crystallite size and deposit porosity. The lowest porosity was found in the presence of D3. The inhibition effect of D1 on the hydrogen evolution contributes to decrease in zinc consumption during the cementation of nickel.     

炭/炭复合材料MoSi2/SiC抗氧化涂层的研究

采用包埋法制备C／C复合材料抗氧化MoSi2／SiC梯度涂层，同时对抗氧化涂层的形成、组织结构以及抗氧化性能与渗料的关系和抗氧化机理进行了研究。结果表明：采用包埋法制备的C／C复合材料抗氧化MoSi2／SiC梯度涂层致密，但有少量裂纹，涂层有良好的抗氧化效果。当硅与SiC保持一定的比例，渗料中MoSi2的含量为50％时，涂层具有最好的抗氧化效果；当MoSi2与SiC保持一定的比例，渗料中硅的含量为20％时，涂层具有最好的抗氧化效果。     

宽厚板连铸粘结漏钢的原因分析

针对宽厚板连铸机在Q345D和Q345E生产中发生多次粘结报警甚至拉漏的情况,分析了粘结漏钢产生的机理,从宽厚板的现场生产工艺参数、保护渣物理性能及熔化状况等方面,分析了宽厚板连铸产生粘结漏钢的原因。     

乙二胺四乙酸二钠对铜粉置换硫代硫酸盐金的影响

探讨了铜粉置换硫代硫酸盐金时,硫代硫酸盐浸金体系氧化剂二价铜离子对该置换反应的负面影响。结果表明,加入乙二胺四乙酸二钠能消除氧化剂的抑制作用,提高金置换率。比较了硫氰酸盐、硫脲和硫代硫酸盐等浸金体系的氧化剂对置换回收金产生抑制作用的共性原因,分析了克服其负面影响方法的共同特点。     

低压蒸汽锅炉水质控制

从锅炉给水和锅炉炉水2个方面,阐明了如何对低压蒸汽锅炉水质进行控制,从而确保低压蒸汽锅炉的安全、经济运行。     

精矿蒸汽干燥低压节能技术在广西金川公司的应用

广西金川有色金属有限公司冶炼厂精矿干燥系统采用低压蒸汽回转干燥的方式对混合铜精矿进行干燥,主要介绍低压蒸汽回转干燥在广西金川有色金属有限公司冶炼厂开发应用状况、工艺流程、技术改造以及生产实践等。     

Kinetics and deposit morphology of gold cemented on magnesium, aluminum, zinc, iron and copper from ammonium thiosulfate-ammonia solutions

The kinetics of gold cementation by magnesium aluminum, zinc, iron and copper at equal conditions as well as the morphology of cementation products and the dissolution of cementing agents were investigated. Both the effect of cementing agents on gold cementation rate and the dissolution of metals decrease in order Cu > Zn > Mg > Fe > Al. High dissolution of magnesium, zinc, iron and copper per mol deposited gold was found. Zinc is the most efficient cementing agent. Magnesium and iron can be used in gold cementation practice but the extremely slow cementation rate prevents the practical application of aluminum.Significant differences in the morphology of gold deposits on magnesium, aluminum, zinc, iron and copper were found: thick deposit layers with small or large cracks were observed on magnesium or zinc; porous layers of fern leaf-shaped dendrites on copper; compact smooth deposit of fine crystallites on iron and small very rare formations of fine dendrites on aluminum.     

Oedometer Behavior of an Artificial Cemented Highly Collapsible Soil

This study aims at investigating the mechanical behavior and the changes in fabric at various stages of loading and wetting of an artificial cemented highly collapsible geomaterial. The required metastable structure of a collapsible soil was produced by adding particles of expanded polystyrene to a soil-cement mixture. This technique is shown to reproduce main features inherently attributed to collapsible soils under idealized conditions where the effects of void ratio and degree of cementation can be properly isolated and accounted for. Collapse potential was evaluated on samples with and without cementation. From the observed behavior it was possible to identify the initial void ratio, cementation level, initial suction, and stress path as factors controlling the collapse potential of soils.     

Kinetics and deposit morphology of copper cementation onto zinc,iron and aluminium

The kinetics of copper cementation onto iron, zinc and aluminium powders at 60 °C and pH=1 have been examined along with the morphology of the deposited copper. The three reductants cemented copper very differently:

• (a)Aluminium gave substantially slower cementation that either iron or zinc and also dissolved significantly less. This passivity of aluminium is due to the oxide layer on its surface;
• (b)The highest cementation rate was obtained using zinc; however, intensive hydrogen evolution on the deposited copper leads to high consumption of zinc;
• (c)Iron was the best substrate for cementation, it deposited copper at ∼70% the rate of zinc but did not react significantly with the acid leading to only one quarter the consumption of zinc;
• (d)The morphology of copper deposits strongly depends on the cementation agent: a coherent layer of fine-grained crystallites less than 1 μm size was obtained on iron, a dendritic deposit with high porosity was obtained on zinc and globular crystallites 1–4 μm in size were obtained on aluminium.

     

低压饱和蒸汽回收利用技术研究与应用

重点介绍了低压饱和蒸汽回收利用技术的发展应用情况和技术特点,结合工程案例,阐明了低压饱和蒸汽回收利用技术的综合效益和发展前景。     

矿井涌水抛渣注浆封底治理技术

详细介绍了三贵口主井淹井事故处理技术。通过勘测井下涌水,设计堵水方案,堵层厚度计算以及注浆量估算,采取抛渣和注浆封底方法,成功地堵住了涌水。     

Experimental studies of cementation of tin in a dispersed form

Results of experimental studies of the cementation recovery of tin in a dispersed form from sulfuric solutions are presented. The dependence of the steady potential of aluminum on the concentration of chlorine ions in a sulfuric solution of divalent tin is shown. Polarization measurements of electrode processes of the Al-Sn galvanic pair are performed. The dependence of dispersity and bulk density of the tin powder on cementation conditions is established.