Effect of powder size distribution on densification and microstructural evolution of binder-jet 3D-printed alloy 625
Effect of powder size distribution on densification and microstructural evolution of binder-jet 3D-printed alloy 625
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DOI：
10.1016/j.matdes.2018.11.051
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发表时间：
2019-01-15
影响因子：
8.4
通讯作者：
Chmielus, Markus
中科院分区：
文献类型：
--
作者：
Mostafaei, Amir;De Vecchis, Pierangeli Rodriguez;Chmielus, Markus
粘合剂喷射3D打印是一种粉末床增材制造工艺，其选择性地将粘合剂逐层沉积在粉末床上以制造绿色部件，然后进行烧结步骤以进行致密化。包括16-63 μ m（全）、16-25 μ m（细）和53-63 μ m（粗）粉末的三种不同粉末尺寸分布的气体雾化合金625粉末被3D打印，绿色相对体积密度分别为约52%、45%和48%，随后在1225和1300摄氏度之间的温度下真空烧结4小时。对于粒度分布较窄的细粉和粗粉，在喷射粘结剂过程中可能会形成具有高孔配位数的印刷缺陷，即使在超固相线液相烧结过程中，这些印刷缺陷也无法在最终烧结阶段去除。然而，全粒度分布给出了更高的绿色密度，具有更少的大的、高度协调的孔，因此超固相线液相烧结能够达到接近全密度。此外，细粉末在烧结过程中产生不均匀的各向异性线性收缩，这不利于设计复杂的结构。结果表明，如果打印参数，如层厚度，粘合剂饱和度，打印头粘合剂液滴尺寸和干燥时间是相似的，则粒度分布是超固相线液相烧结，孔去除和最终微观结构的决定因素。(C)2018由Elsevier Ltd.出版
Binder-jet 3D-printing is a powder bed additive manufacturing process that selectively deposits binder on a powder bed layer-by-layer to fabricate a green part followed by a sintering step for densification. Gas-atomized alloy 625 powders of three different powder size distributions including 16-63 pm (full), 16-25 pm (fine) and 53-63 jim (coarse) powders were 3D-printed with green relative bulk densities of about 52%, 45% and 48%, respectively, followed by vacuum-sintering at temperatures between 1225 and 1300 degrees C for 4 h. For the fine and coarse powders with narrow size distribution, printing defects with high pore coordination numbers may form during the binder jetting process which cannot be removed during the final sintering stage even during supersolidus liquid phase sintering. However, the full particle size distribution gave higher green density with fewer large, highly coordinated pores so supersolidus liquid phase sintering was able to reach near-full density. Additionally, the fine powders gave non-uniform, anisotropic linear shrinkage during sintering which is unfavorable for designing complex structures. The results suggest that particle size distribution is a determining factor for supersolidus liquid phase sintering, pore removal and final microstructure, if printing parameters such as layer thickness, binder saturation, printhead binder droplet size and drying time are similar. (C) 2018 Published by Elsevier Ltd.