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以粒度为80μm的粉煤灰为增强相,粒度为30μm的铝粉为基体,采用粉末冶金法成功制备了粉煤灰颗粒增强铝基复合材料。经SEM、金相显微镜等分析手段对制备的复合材料进行组织观察,并对其进行耐磨性测试。结果表明,粉煤灰含量为20%,烧结温度为650℃时,相对损率最小为0.1590%。随着粉煤灰含量和保压时间的增加,试样的耐磨性逐渐升高,随着烧结温度升高,试样的耐磨性呈现出先升高后降低的趋势。 相似文献
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Gustavo A. Mansilla 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
This paper reports the global response of the mid high and low latitude ionosphere in four longitudinal sectors to two moderate geomagnetic storms that occurred during 2007 (the more intense storms occurred that year). The results obtained during these storms show that the ionospheric effects in general are not moderate in magnitude, showing an important degree of complexity as during intense storms. The outstanding features produced during the storms are significant positive storm effects at mid-high latitudes during the main phase/first part of the recovery, positive effects after the onset of the storm followed by negatives effects at middle latitudes and delayed positive effects during the night-time hours in the trough of the equatorial anomaly (“dusk” effect). Possible physical mechanisms for controlling the morphology of the ionosphere during these events are considered. 相似文献
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寇鸿飞 《民用飞机设计与研究》2014,(3):77-80
对新型灭火剂研究背景和种类进行了简要介绍,对具有开发潜力的新型灭火剂的理化性能、毒性、腐蚀性、灭火性能、环保性能进行深入分析与研究。通过对新型灭火剂性能的研究,得出每种灭火剂的优缺点,筛选出适用于现代民机灭火系统的灭火剂。 相似文献
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Single track and single layer formation in selective laser melting of niobium solid solution alloy 总被引:1,自引:2,他引:1
Selective laser melting (SLM) was employed to fabricate Nb-37Ti-13Cr-2Al-1Si (at%) alloy, using pre-alloyed powders prepared by plasma rotating electrode processing (PREP). A series of single tracks and single layers under different processing parameters was manufactured to evaluate the processing feasibility by SLM, including laser power, scanning speed, and hatch distance. Results showed that continuous single tracks could be fabricated using proper laser powers and scanning velocities. Both the width of a single track and its penetration depth into a substrate increased with an increase of the linear laser beam energy density (LED), i.e., an increase of the laser power and a decrease of the scanning speed. Nb, Ti, Si, Cr, and Al elements distributed heterogeneously over the melt pool in the form of swirl-like patterns. An excess of the hatch distance was not able to interconnect neighboring tracks. Under improper processing parameters, a balling phenomenon occurred, but could be eliminated with an increased LED. This work testified the SLM-processing feasibility of Nb-based alloy and promoted the application of SLM to the manufacture of niobium-based alloys. 相似文献