Yuan Yanping, Chen Jimin
Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China.
Beijing Engineering Research Center of 3D Printing for Digital Medical Health, Beijing University of Technology, Beijing 100124, China.
Nanomaterials (Basel). 2016 Feb 24;6(3):36. doi: 10.3390/nano6030036.
In this study, a continuous fiber laser (1064 nm wavelength, 30 W/cm²) is used to irradiate multi-walled carbon nanotubes (MWCNTs) on different substrate surfaces. Effects of substrates on nano-welding of MWCNTs are investigated by scanning electron microscope (SEM). For MWCNTs on silica, after 3 s irradiation, nanoscale welding with good quality can be achieved due to breaking C-C bonds and formation of new graphene layers. While welding junctions can be formed until 10 s for the MWCNTs on silicon, the difference of irradiation time to achieve welding is attributed to the difference of thermal conductivity for silica and silicon. As the irradiation time is prolonged up to 12.5 s, most of the MWCNTs are welded to a silicon substrate, which leads to their frameworks of tube walls on the silicon surface. This is because the accumulation of absorbed energy makes the temperature rise. Then chemical reactions among silicon, carbon and nitrogen occur. New chemical bonds of Si-N and Si-C achieve the welding between the MWCNTs and silicon. Vibration modes of Si₃N₄ appear at peaks of 363 cm and 663 cm. There are vibration modes of SiC at peaks of 618 cm, 779 cm and 973 cm. The experimental observation proves chemical reactions and the formation of Si₃N₄ and SiC by laser irradiation.
在本研究中，使用连续光纤激光器（波长1064 nm，功率30 W/cm²）照射不同基底表面上的多壁碳纳米管（MWCNTs）。通过扫描电子显微镜（SEM）研究基底对MWCNTs纳米焊接的影响。对于二氧化硅上的MWCNTs，照射3 s后，由于C-C键断裂和新石墨烯层的形成，可以实现高质量的纳米级焊接。而对于硅上的MWCNTs，直到照射10 s时才能形成焊接接点，实现焊接的照射时间差异归因于二氧化硅和硅的热导率不同。随着照射时间延长至12.5 s，大多数MWCNTs焊接到硅基底上，这导致它们在硅表面形成管壁框架。这是因为吸收能量的积累使温度升高。然后硅、碳和氮之间发生化学反应。Si-N和Si-C新化学键实现了MWCNTs与硅之间的焊接。Si₃N₄的振动模式出现在363 cm和663 cm的峰值处。SiC的振动模式出现在618 cm、779 cm和973 cm的峰值处。实验观察证明了激光照射引发的化学反应以及Si₃N₄和SiC的形成。
