The purpose of this study is to perform laser direct and serial joining of alumina particles as the minimum unit of additive shaping and to obtain fundamentals of the joining process for achieving both the satisfactory state of bonding and the high degree of flexibility of shaping. In the experiments, spherical alumina particles were manipulated in three-dimensional space using needles and a CO laser beam was directed at the contact point between the particles. Direct joining was achieved under the laser power appropriate to control the melting zone. The results of cross-sectional observation and shear test for the welded joints showed that excessive laser power forms large cavities in the joints and reduces bonding strength. Nanoindentation hardness testing and Raman spectroscopic analysis revealed almost no change in microstructure of the alumina particles after joining. Serial joining of 15 particles shaped a linear chain structure with little difference in length from the estimated dimension. For fabricating fine structures with additively joined particles under the suitable laser conditions, this study provides the fundamentals of laser welding of ceramics, especially about the solidification process that critically affects joining shapes and strength.

中文翻译：

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CO2激光直接连续连接球形氧化铝颗粒的基础研究

本研究的目的是对作为增材成形最小单元的氧化铝颗粒进行激光直接和串行连接，并获得连接过程的基础知识，以实现令人满意的接合状态和高度的成形灵活性。在实验中，使用针在三维空间中操纵球形氧化铝颗粒，并将 CO 激光束引导到颗粒之间的接触点。在适当控制熔化区域的激光功率下实现了直接接合。焊接接头的截面观察和剪切试验结果表明，过高的激光功率会在接头中形成较大的空洞，降低结合强度。纳米压痕硬度测试和拉曼光谱分析表明，加入后氧化铝颗粒的微观结构几乎没有变化。15 个颗粒的串联连接形成了线性链结构，长度与估计尺寸相差不大。为了在合适的激光条件下制造具有附加连接颗粒的精细结构，本研究提供了陶瓷激光焊接的基础知识，特别是关于对连接形状和强度产生关键影响的凝固过程。