Bimetallic diffusion modeling and temperature regulation during ball milling
Bimetallic diffusion modeling and temperature regulation during ball milling
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DOI：
10.1016/j.matdes.2018.05.055
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发表时间：
2018-10
影响因子：
8.4
通讯作者：
M. Aureli;Constantine C. Doumanidis;I. Gunduz;A. Hussien;Y. Liao;Nikolaos Kostoglou;C. Rebholz;C. Doumanidis
中科院分区：
文献类型：
--
作者：
M. Aureli;Constantine C. Doumanidis;I. Gunduz;A. Hussien;Y. Liao;Nikolaos Kostoglou;C. Rebholz;C. Doumanidis
本文建立了球磨双金属Ni-Al颗粒中温度和扩散动力学的高效计算模型。相邻双金属畴之间的机械接触条件和碰撞时产生的温度场决定了通过畴界面的扩散通量。通过定义反映边界扩散阻力条件的镜像，通过格林函数方法研究了浓度分布。通过实验开环扫描电子显微图和稳态x射线衍射谱对模型的预测进行了验证。通过仿真建立了扩散饱和度和内部温度的动态模型，用于闭环控制器的设计。该反馈控制器在实验室设备上实现，配备用于外部瓶温测量的红外测温仪，作为自调谐调节器。控制器采用模型的效率参数作为内部温度和扩散饱和度的实时观测器，这两个参数在处理过程中是物理上无法获得的。利用实验开环结果设定扩散穿透阈值，避免制造过程中发生早期放热反应。通过控制过程持续时间，调节系统成功地再现了开环参考测试的材料组成，以确保期望的球磨产品的热力学特性和操作的安全性。
This work establishes a computationally efficient model of temperature and diffusion dynamics in ball milled bimetallic Ni-Al particulates. Mechanical contact conditions between adjacent bimetallic domains and temperature fields generated upon impact define the diffusive fluxes through the domains' interfaces. The concentration distributions are studied via Green's function methods, by defining mirror images which reflect the boundary diffusive resistance conditions. Predictions of the model are validated against experimental open-loop scanning electron micrographs and X-ray diffraction spectra at steady-state. Dynamic models of diffusion saturation and internal temperature are developed for the design of closed-loop controller via simulation. This feedback controller is implemented on a laboratory device, equipped with infrared thermometry for external vial temperature measurement, as a self-tuning regulator. The controller adapts an efficiency parameter of the model that thus serves as a real-time observer for internal temperature and diffusion saturation, which are physically inaccessible during processing. Experimental open-loop results are employed to set thresholds of diffusion penetration to avoid early exothermic reaction during fabrication. By controlling the process duration, the regulation system successfully reproduces the material composition of the open-loop reference tests, to ensure desired thermodynamic properties of the ball milled products and safety of the operation.