共查询到18条相似文献,搜索用时 109 毫秒
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钼细晶材料制备工艺研究 总被引:1,自引:0,他引:1
通过改善原料活性,降低还原温度,制备出粒度小于1.0μm的钼粉。由于超细钼粉具有低温活化烧结的特性,由其压制的坯料在烧结过程中烧结温度低,烧结时间短,生产成本低,且烧结钼板坯的晶粒细小均匀。 相似文献
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不同粒度钼粉对板材组织的影响 总被引:1,自引:0,他引:1
通过将不同粒度及形貌的钼粉进行压制烧结成为板坯,再进行轧制加工及不同温度的退火处理观察其显微组织后发现:在同样的烧结工艺下,大粒度钼粉及小粒度钼粉烧结组织的晶粒较大,普通粒度钼粉烧结组织的晶粒细小;在同样的加工工艺下,普通粒度钼粉制备的板坯组织粗大,大粒度钼粉制备的板坯组织较细,小粒度钼粉制备的板坯组织最细小;在1 150~1 200℃退火时,普通粒度钼粉制备板坯的再结晶晶粒数少而晶粒粗大,大粒度钼粉板坯的再结晶晶粒数次之,小粒度钼粉板坯的再结晶晶粒最小;1 300℃时小粒度钼粉板坯的晶粒长大速度最快,而普通粒度钼粉板坯次之,大粒度钼粉板坯最慢。 相似文献
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以同批次二氧化钼为对象,在第二段还原过程中通过对还原温度、料层厚度、装料方式等的不同设置生产出不同形貌特征的钼粉,并通过扫描电子显微图像(SEM)分析对钼粉形貌特征进行了表征,分析总结并系统研究了还原温度梯度、料层厚度、料舟装料方法对钼粉形貌特征的影响。在第二段还原反应中,过低的低温区温度会致使大量细小颗粒出现,而主要还原反应的高温区温度适当降低,却能有效平缓钼粉的生长速度,减少烧结颈及异形颗粒的出现;适当降低料层厚度可以有效改善钼粉团聚现象;钼粉平整装入料舟后,轻整抹平钼粉表面,可以有效降低同料舟的上下层还原条件差,从而使钼粉颗粒更为均匀。 相似文献
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电火花等离子体烧结(SPS)系一种可在短时间内加速低温烧结的合成加工方法。这种SPS烧结方法尤其适用于钼粉加工,因为即便在低温下,其烧结密度也会明显增大。例如,若在1673K温度下仅烧结5s后,其密度陡增;烧结300s后,则粉坯烧结密度达94.1%,为此随烧结进程而促进晶粒长大。这种SPS烧结钼粉固结用激活能量为173kJ·mol-1,低于钼的自蔓延激活能量(424kJ·mol-1)。由此表明,钼粉的SPS烧结进程不仅是通过表面扩散、而且也是通过体积扩散,晶界扩散以及钼原子的粘滞流动或塑性流动而… 相似文献
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Rapid grain growth accompanies the enhanced sintering of molybdenum treated with nickel additions. Grain growth is detrimental
to sintering kinetics and mechanical properties. A sintering model is developed to illustrate that reducing grain boundary
mobility is a means to increase the densification rate. A fine silica dispersion is added to molybdenum powder which is activated
by the addition of nickel. This powder exhibits a long term sintering benefit due to retarded grain growth which is attributed
to dispersoid drag effects on grain boundaries. These experimental powders are further analyzed through precision dilatometry,
showing a characteristic shift in shrinkage rate during constant heating rate experiments. The shrinkage rate of molybdenum
is increased by a factor of 10 at 1000°C when activated with 0.37 pct Ni. The shrinkage rate of nickel activated molybdenum
is further increased by 67 pct with 1400 ppm silica dispersed at the interparticle grain boundaries.
This paper is based on a presentation delivered at the symposium “Activated and Liquid Phase Sintering of Refractory Metals
and Their Compounds” held at the annual meeting of the AIME in Atlanta, Georgia on March 9, 1983, under the sponsorship of
the TMS Refractory Metals Committee of AIME.
Formerly Research Assistant in the Rensselaer Polytechnic Institute, Materials Engineering Department 相似文献
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研究用少量钴、镍和Co-Ni化学沉积的钼粉的烧结特性,比较了钼和Mo-Co、Mo-Ni-Co系的烧结特性,测算了其活化能,结果表明:镍、钴和Ni-Co的添加均改善了其烧结性能,镍比钴的效果好,而Mo-Ni-Co系的活化烧结效果最好。 相似文献
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试验研究了掺杂La2O3、Y2O3、CeO2稀土氧化物颗粒对钼合金的粉末物性、烧结进程、制品的烧结致密度及压力加工丝材的室温力学性能的影响规律。试验结果表明,掺杂稀土氧化物粒子细化了钼粉的粒度,降低了松装密度和粒度分布范围,同时导致粉末团聚现象增多;稀土氧化物粒子延迟了钼合金的烧结进程,降低了烧结制品的致密度,同时细化了烧结体晶粒尺寸。稀土氧化物粒子以弥散强化和细晶强化的形式,提高了钼合金丝的室温强度。CeO2显著提高了钼合金丝的室温韧性,La2O3、Y2O3则降低了钼合金丝的室温韧性。 相似文献
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Deborah C. Blaine John D. Gurosik Seong Jin Park Randall M. German Donald F. Heaney 《Metallurgical and Materials Transactions A》2006,37(3):715-720
Sintering experiments with various molybdenum powders are rationalized using a master sintering curve concept that collapses
density, grain size, or other parameters onto a single curve. In this case, the integral work of sintering is developed and
customized for different green densities. Construction of the master sintering curve is described to show how the curve can
be normalized with respect to green density effects. Various grades of molybdenum for metal injection molding and die compaction
are included in the analysis, processed over a range of heating cycles. Die-compacted samples of varying green densities are
used to illustrate the efficacy of the new, normalized master sintering curve concept. Sintering cycle optimization is one
possible outcome from this analysis. 相似文献
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高温钼粉的性能对其成形及烧结的影响 总被引:1,自引:0,他引:1
对高温钼(又称掺杂钼)粉制备过程中的还原温度对粉末性能的影响进行了描述,并对粉末特性对随后的冷等静压成形和烧结,如冷等静压成形能力、压坯密度、烧结坯密度、线收缩、去氧情况、断裂形式、晶粒度等的影响进行了简要的讨论。 相似文献