Nanoparticle-enabled increase of energy efficiency during laser metal additive manufacturing
Nanoparticle-enabled increase of energy efficiency during laser metal additive manufacturing
复制标题
DOI：
10.1016/j.addma.2022.103242
复制
发表时间：
2022-10
影响因子：
11
通讯作者：
Minglei Qu;Qilin Guo;Luis I. Escano;Ali Nabaa;K. Fezzaa;Lianyi Chen
中科院分区：
文献类型：
--
作者：
Minglei Qu;Qilin Guo;Luis I. Escano;Ali Nabaa;K. Fezzaa;Lianyi Chen
激光金属添加剂制造(AM)工艺的低能效是大规模工业生产潜在的可持续性问题。要明确研究激光熔化的能量效率，需要直接表征熔池尺寸和蒸汽抑制，但由于金属熔体的不透明性质，这是非常困难的。本文报道了用高速高能X射线原位成像技术直接观察和定量研究TiC纳米颗粒对Al6061激光粉床熔化(LPBF)过程中蒸汽抑制和熔池形成的影响。在量化结果的基础上，我们计算了Al6061激光熔化能量效率(这里定义为熔化材料所需的能量与激光传输的能量之比)，在Al6061的LPBF过程中，使用和不使用TiC纳米粒子。结果表明，在Al6061中加入TiC纳米颗粒后，激光熔化能量效率显著提高(在312W激光功率、0.4m/S扫描速度下，激光熔化能量效率平均提高114%、521%)。系统的性能测量、模拟和X射线成像研究首次使我们能够确定三种机制共同作用来提高激光熔化的能量效率：(1)添加TiC纳米颗粒提高吸收率；(2)添加TiC纳米颗粒降低导热系数；(3)添加TiC纳米颗粒能够在较低的激光功率下引发蒸汽抑制和多次反射(即降低激光打孔的功率阈值)。本文报道的利用TiC纳米颗粒提高激光熔化能量效率的方法和机理，对开发更节能的激光金属AM材料具有指导意义。
The low energy efficiency of the laser metal additive manufacturing (AM) process is a potential sustainability concern for large-scale industrial production. Explicit investigation of the energy efficiency for laser melting requires the direct characterization of melt pool dimension and vapor depression, which is very difficult due to the opaque nature of the molten metal. Here we report the direct observation and quantification of effects of the TiC nanoparticles on the vapor depression and melt pool formation during laser powder bed fusion (LPBF) of Al6061 by in-situ high-speed high-energy x-ray imaging. Based on the quantification results, we calculated the laser melting energy efficiency (defined here as the ratio of the energy needed to melt the material to the energy delivered by the laser beam) with and without TiC nanoparticles during LPBF of Al6061. The results show that adding TiC nanoparticles into Al6061 leads to a significant increase of laser melting energy efficiency (114% increase on average, 521% increase under 312 W laser power, 0.4 m/s scan speed). Systematic property measurement, simulation, and x-ray imaging studies enable us, for the first time, to identify that three mechanisms work together to enhance the laser melting energy efficiency: (1) adding TiC nanoparticles increases the absorptivity; (2) adding TiC nanoparticles decreases the thermal conductivity, and (3) adding TiC nanoparticles enables the initiation of vapor depression and multiple reflection at lower laser power (i.e., lowers the laser power threshold for keyholing). The method and mechanisms of using TiC nanoparticles to increase the laser melting energy efficiency during LPBF of Al6061 we reported here may guide the development of feedstock materials for more energy efficient laser metal AM.