Fundamental principles of spark plasma sintering of metals: Part II – about the existence or non-existence of the ‘spark plasma effect’
Fundamental principles of spark plasma sintering of metals: Part II – about the existence or non-existence of the ‘spark plasma effect’
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DOI：
10.1080/00325899.2020.1829349
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发表时间：
2020-10
影响因子：
1.4
通讯作者：
J. Trapp;A. Semenov;O. Eberhardt;M. Nöthe;T. Wallmersperger;B. Kieback
中科院分区：
文献类型：
--
作者：
J. Trapp;A. Semenov;O. Eberhardt;M. Nöthe;T. Wallmersperger;B. Kieback
针对两种球形金属粉末颗粒的模型系统，对放电等离子烧结（SPS）中的致密化机制进行了分析和数值研究。根据微观温度分布，分析了不同粒径、接触几何形状、材料和电力负载下颗粒-颗粒接触发生微观局部过热的可能性。结果表明，对于尺寸低于一毫米的颗粒，局部过热低于一开尔文。随后，通过分析计算和有限元模拟获得的微观场分布推导了由表面曲率和外部压力驱动的热迁移、电迁移和扩散的材料传输。结果表明，虽然机械压力使材料传输加速了几个数量级，但电流和温度梯度却没有。还表明脉冲电流对致密化速率没有显着影响。
The mechanisms of densification in spark plasma sintering (SPS) were investigated both analytically and numerically for a model system of two spherical metallic powder particles. From the microscopic temperature distribution, the possibility of a micro-local overheating of the particle–particle contacts was analysed for different particle sizes, contact geometries, materials, and electrical loads. It is shown that, for particles below the size of one millimetre, local overheating is below one Kelvin. Subsequently, the material transport by thermomigration, electromigration, and diffusion driven by surface curvature and external pressure was derived from microscopic field distributions obtained from analytical calculations and finite-element simulations. The results show that, while the mechanical pressure accelerates material transport by orders of magnitude, the electrical current and the temperature gradients do not. It is also shown that pulsing the current has no significant influence on the densification rate.