Tsai Song-Ling, Liu Yi-Kai, Pan Heng, Liu Chien-Hung, Lee Ming-Tsang
Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA.
Nanomaterials (Basel). 2016 Jan 8;6(1):12. doi: 10.3390/nano6010012.
The Laser Direct Synthesis and Patterning (LDSP) technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication.
与基于纳米材料的激光增材微制造工艺相比，激光直接合成与图案化（LDSP）技术在加工时间和成本方面具有优势。在LDSP工艺中，基板表面的扫描激光会在反应性液体溶液中引发化学反应，并以预选图案选择性地在基板上沉积目标材料。在本研究中，我们通过实验研究了加工参数以及添加剂溶剂的类型和浓度对采用这种LDSP技术制备的金属薄膜的性能和生长速率的影响。结果表明，具有较高粘度的反应性金属离子溶液能够产生具有优异物理性能的金属薄膜。我们还首次进行了数值分析，以研究光热流体耦合传输现象及其对金属薄膜生长速率的影响。为完成模拟，我们测量了不同厚度的LDSP沉积金属薄膜的光学特性。讨论了与移动热源相关的温度场特性和热致流动。结果表明，LDSP的加工温度范围为330至390K。基于这些结果，开发了一个用于估算该工艺金属薄膜生长速率的半经验模型。从实验和数值结果可以看出，由于银膜厚度增加时反射率提高，生长速率从初始时的约40nm逐渐降低至十次扫描后每次激光扫描10nm。LDSP工艺的这种自控制效应可控制薄膜厚度并提高所制备金属薄膜的均匀性。金属薄膜的生长速率和最终厚度也可通过调整加工参数来调节，因此可用于可控的增材纳米/微制造。
