基于同步辐射CT技术表征3D打印用气雾化TC4粉末的研究

Characterization of Gas-Atomized TC4 Powders for 3D Printing Based on Synchrotron Radiation CT Technique

摘要:

本研究利用气雾化技术制备球形TC4合金粉末,作者利用SEM、同步辐射CT扫描-三维重建等分析手段对异常颗粒粉体以及不同粒径的TC4合金粉末表面和内部的孔缺陷进行了表征。实验结果表明,本研究制备的TC4合金粉末随着粉末粒径减小,粉体表面由凸凹不平的冷凝收缩痕迹渐变为光滑表面,粉体内部的孔隙逐渐减少,且孔隙尺寸也随之减小；经分析,由于雾化过程中凝固与球化时间的差异及飞行轨迹的不同等原因导致了包裹式、连体式、椭球形、卫星粉等异常粉末颗粒的生成；同步辐射CT扫描-三维重建表明,粉末内部的孔隙率和孔隙尺寸随着粉末粒度的增大而增大；作者认为通过调整雾化工艺,使金属熔滴在未开始冷却凝固前彻底雾化破碎,从而能有效解决粉末内部孔隙缺陷的问题。

Abstract:

In this study, spherical TC4 alloy powders were prepared by gas atomization. The surface and internal pore defects of TC4 alloy powders with different particle sizes were characterized by SEM, synchrotron radiation CT scanning and three-dimensional reconstruction. The experimental results show that the surface of the powder gradually changes from the condensed shrinkage trace to smooth surface with the decrease of particle size. The number and size of pores in powders also gradually decrease with decreasing the particle size. The formation of anomalous powders with the morphologies of wrapping, conjoined, ellipsoid and satellite is resulted from the difference of coagulation and spheroidization time and the different flight trajectories during the atomization process. The results of three-dimensional reconstruction by synchrotron radiation CT scanning show that the porosity and pore size of the powder increase with the increase of its particle size. The authors propose that if the metal droplet could be completely broken into tiny droplets during atomizing prior to its solidification by tailoring the atomizing parameters, internal porosity defects would be effectively minimized.