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《粉末冶金学》2013,56(19):13-32
AbstractThe effects of compacting pressure and of sintering temperature and time on the properties of porous sintered nickel compacts have been studied, using three carbonyl and two reduced nickel powders. For all five powders, the density of the green compacts and the porosity of the sintered compacts were linearly related to the log compacting pressure. Similar relationships with pressure were observed for strength and electrical conductivity.Photomicrographs of sections through the sintered compacts made from the reduced nickel powders show that there are pores in two different size ranges, originating from the porosity between the original powder particles and the pores within the particles. It is concluded that sintered compacts from all five powders containing 40–50% porosity have adequate strength and conductivity for use in fuel-cell electrodes. 相似文献
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《粉末冶金学》2013,56(32):366-373
AbstractAluminium-tin powder-metallurgy alloys containing 20–40% Sn and 0–3% Cu were prepared by compaction and extrusion of prealloyed atomized powder. The powder-metallurgy (PM) material had a fine distribution of the tin phase and was stronger, with greater fatigue strength than an Al-20% Sn-1 % Cu cast alloy but was harder and less ductile. Heat-treatment reduced the hardness of the PM alloys to values comparable with those of the cast material, whereas the strength, although also reduced, remained superior to that of the cast product. 相似文献
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阐述了用湿法冶金加压氢还原技术制取微细镍粉(0.2-1.0μm)的方法。该法以工业碱式碳酸镍为原料,水为制浆介质,直接进行浆料氢还原。在配制浆料时加入一定量的硫酸,以保证溶液中有足够的初始镍离子浓度,并消除原料组成及原料pH值的波动带来的不稳定因素。同时加入催化剂,以增加固体表面的活性,以此作为缩短或消除反应诱导期的主要手段。并提出,在确定的镍离子还原初始浓度下,可通过控制固体表面的活性来达到控制产品粒度的目的。此外,还从镍颗粒的形貌试论了该还原反应的机理。 相似文献
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本文评述了当前高负载粉末冶金齿轮的发展状况.表明,经选择性表面致密化加工的粉末冶金钢齿轮,其齿的弯曲疲劳强度与接触疲劳强度都和常规钢的相应齿轮相同,完全可替代钢齿轮,如汽车变速器中的钢齿轮.特别是,描述了预成形件的设计与辗压后齿轮中的相应密度分布.最后,表明用选择性表面致密化制造的粉末冶金钢齿轮,既具有相应钢齿轮的使用性能,又具有巨大的节约生产成本的潜力. 相似文献
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还原扩散法直接制造ZrNi合金粉末的研究 总被引:2,自引:0,他引:2
对以Ca作还原剂ZrO粉末和Ni粉末作原料,用还原扩散法直接制造ZrNi合金粉末的过程进行了研究分析,发现Ca不令是ZrO2的还原剂,而且Ni的溶剂和载体,在合金形成过程中,Ni通过在液体Ca中溶解和扩散,到达被还原出出来的金属Zr表面,并与Zr合金化形成ZrNi合金因此Ca的添加量是过程的关键因素。 相似文献
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研究了氢一次还原、平均粒度为6.5—7.5μm的钨粉的烧结特性。得出多孔钨构件的相对密度随烧结温度和时间、粉末粒度、压制件密度而变化的规律。提出了生产相对密度为78—81%、开孔率>95%的多孔钨的生产工艺参数,即:压制件相对密度为60—65%,烧结温度为2100—2250℃、时间为4—8小时。 相似文献
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对两炉型生产的可溶氧化钼性质进行了分析对比,着重从产品颗粒外观形貌分析,找出了反射炉产品均一性及质量稳定性差、在氨浸过程中浸出率低、对水洗工艺适应性差的原因。 相似文献
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叙述了在采用流化床和固定沫热分解与还原钼酸铵过程中控制用粉粒度与形状的两种工艺试验结果,比较了它们的技术经济性能。结果表明,采用流化床热分解与还原工艺,不仅能生产出粒度和形状可控的优质钼粉产品,而且能实现大规模、自动化和连续化生产,经济效益明显。 相似文献
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采用钼混合氧化物直接合金化,可同时采用两种氧化物取代钨铁和钼铁在冶炼合金过程中直接合金化,它节省两种铁合金生产工序,减少合金生产过程中元素损失及环境污染,更是节约能源,降低炼钢成本,增加效益的重要途径,科技实践表明,根据物料平衡需要,钨与钼可以不同比例混合,当钨钼氧化物(W+Mo)元素加入量达4%时与采用铁合金相比冶炼钨钼高速钢,在不增加冶炼时间和用电单耗前提下,钨钼综合回收率达97.66%,各项 相似文献
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《粉末冶金学》2013,56(20):145-155
AbstractThe results are reported of a laboratory investigation aimed at developing a method of recovering machining scrap from zirconium alloys by powder-metallurgy methods. Observations made during the crushing, and sintering of the hydride are described. The mechanical properties obtained before and after heat-treatment are reviewed, together with the resistance to corrosion by carbon dioxide of these alloys at 700°C. In general, the properties of the dense sintered parts arecomparable with those of cast parts, quite apart from the hardening influence of the oxygen content. 相似文献
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