Park Janghan, Ye Zefang, Celio Hugo, Wang Yaguo
J. Mike Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, USA.
Texas Materials Institute, The University of Texas at Austin, Austin, Texas, USA.
3D Print Addit Manuf. 2024 Apr 1;11(2):e896-e905. doi: 10.1089/3dp.2022.0229. Epub 2024 Apr 16.
As a branch of laser powder bed fusion, selective laser sintering (SLS) with femtosecond (fs) lasers and metal nanoparticles (NPs) can achieve high precision and dense submicron features with reduced residual stress, due to the extremely short pulse duration. Successful sintering of metal NPs with fs laser is challenging due to the ablation caused by hot electron effects. In this study, a double-pulse sintering strategy with a pair of time-delayed fs-laser pulses is proposed for controlling the electron temperature while still maintaining a high enough lattice temperature. We demonstrate that when delay time is slightly longer than the electron-phonon coupling time of Cu NPs, the ablation area was drastically reduced and the power window for successful sintering was extended by about two times. Simultaneously, the heat-affected zone can be reduced by 66% (area). This new strategy can be adopted for all the SLS processes with fs laser and unlock the power of SLS with fs lasers for future applications.
作为激光粉末床熔融的一个分支，使用飞秒（fs）激光和金属纳米颗粒（NP）的选择性激光烧结（SLS）能够实现高精度和致密的亚微米特征，且由于脉冲持续时间极短，残余应力得以降低。由于热电子效应导致的烧蚀，用飞秒激光成功烧结金属纳米颗粒具有挑战性。在本研究中，提出了一种具有一对延时飞秒激光脉冲的双脉冲烧结策略，用于控制电子温度，同时仍保持足够高的晶格温度。我们证明，当延迟时间略长于铜纳米颗粒的电子 - 声子耦合时间时，烧蚀面积大幅减小，成功烧结的功率窗口扩大了约两倍。同时，热影响区面积可减少66%。这种新策略可应用于所有使用飞秒激光的选择性激光烧结工艺，并为未来应用释放飞秒激光选择性激光烧结的能量。
