Densification of pure magnesium by spark plasma sintering-discussion of sintering mechanism
Densification of pure magnesium by spark plasma sintering-discussion of sintering mechanism
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放电等离子烧结纯镁致密化-烧结机理探讨
DOI：
10.1016/j.apt.2019.08.012
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发表时间：
2019-11-01
影响因子：
5.2
通讯作者：
Zhang, Tingting
中科院分区：
文献类型：
--
作者：
Liu, Ruifeng;Wang, Wenxian;Zhang, Tingting
本文采用放电等离子烧结法制备了高纯纯镁，并通过数值模拟和同步实验探讨了其烧结致密化机理。结果表明，在放电等离子烧结过程中，镁颗粒表面形成了一层致密的氧化镁膜，由于氧化膜的去除作用，镁颗粒表面的氧化物发生了还原。高能脉冲电流优先流过颗粒接触面，为颗粒间产生微弧提供了条件，颗粒接触点温度可达1979 ℃。在烧结初期气压较低的情况下，微弧诱导的局部高温使材料出现熔化（甚至蒸发）。在相同的烧结温度570 ℃下，抗弯强度的明显差异也证明了放电等离子烧结的重要性。烧结颈的形成过程表明，烧结过程是熔化（甚至蒸发）、扩散和塑性变形的综合反映。为了实现粉末颗粒间的小面积、高质量连接，基于高频脉冲电流的趋肤效应、邻近效应和电弧放电效应的启示，提出了一种创新的高频脉冲电流粉末烧结技术（高频脉冲电流辅助烧结）。该技术对其他合金和工程材料也具有指导意义。(C)2019日本粉末技术学会。由Elsevier B.V.和日本粉末技术协会出版。All rights reserved.
In this study, high-quantity pure magnesium was prepared by SPS, and the sintering densification mechanism was discussed by using numerical simulation and simultaneous experiment. Results show that a layer of dense magnesium oxide was formed at the surface of Mg particles, and the oxide reduction can be observed owing to the effect of oxide film removal in SPS. The high energy pulsed current flows preferentially through particle contact surfaces, which provides the conditions for the generation of micro-arc between particles and the temperature at the particles contact point can be up to 1979 degrees C. With the low pressure at the initial sintering stage, local high temperature induced by micro-arc makes the melting (even evaporation) appearance. At the same sintering temperature of 570 degrees C, the obvious difference in bending strength also demonstrates the significance of spark discharge in SPS. The formation process of sintering neck demonstrates that sintering process is the reflection of melting (even evaporation), diffusion and plastic deformation. In order to realize tiny area and high-quality connection between powder particles, an innovative powder sintering technology using high-frequency pulse electric current (High frequency pulse current assisted sintering) is proposed based on the enlightenment of the skin, proximity and arc discharge effect of high-frequency pulse current. This technology is also instructive for other alloys and engineering materials. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.