POEM法制备微米级Cu球形粒子的传热与凝固行为研究

脉冲微孔喷射法（POEM）制备微米级球形粒子是典型的无容器传热和凝固过程，制备出的球形粒子具有粒径均一、圆整度高、热履历一致等特点，对流和辐射主导的传热机制对其制备工艺、凝固过程和组织控制至关重要。针对脉冲微孔喷射法微米级球形金属粒子的制备过程、冷却传热与凝固特征，本文建立了三维球坐标系下的粒子传热与凝固数值计算模型，考虑纯Cu粒子在无约束凝固过程中的对流和辐射换热特点，采用温度回升法处理纯金属的凝固潜热，计算了金属粒子在凝固过程不同阶段的温度变化与分布特点，考察了粒子凝固进程中的温度梯度、冷却速率、液固界面推进与凝固速度；模拟分析粒子的对流、辐射换热特征及贡献强度，探讨了不同制备工艺对粒子对流换热的影响，为POEM法微米级球形粒子制备工艺的优化和凝固过程调控提供参考。

Heat transfer and solidification behavior of micron-sized Cu spherical particles prepared by Pulsated Orifice Ejection Method

The preparation of micron-sized spherical particles by the Pulsed Orifice Ejection Method (POEM) is a typical unconstrained heat transfer and solidification process, and the prepared spherical particles have the characteristics of uniform particle size, high roundness and consistent thermal history. The heat transfer mechanism dominated by convection and radiation is crucial for the preparation technology, solidification process and microstructure control. According to the preparation process, heat transfer and solidification characteristics of micron-sized spherical metal particles by POEM, a numerical calculation model of heat transfer and solidification in a three-dimensional spherical coordinate system is established in this paper. The proposed model considers the behavior of the convection and radiation heat transfer of pure Cu particles in the unconstrained solidification process, and adopts the temperature recovery method to deal with the latent heat of pure metal solidification. The temperature variation and distribution of spherical particles at different solidification stages are calculated, and the temperature gradient, cooling rate, liquid-solid interface movement and solidification rate during the solidification process are also investigated. In addition, the convective and radiative heat transfer and their contribution are simulated and analyzed, and the effects of different preparation processes on the convective heat transfer of the particles are explored. The results provide references for the optimization of the preparation and the regulation of the solidification process of micron-sized spherical particles by POEM.