Abstract
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−1 and 663 cm−1. There are vibration modes of SiC at peaks of 618 cm−1, 779 cm−1 and 973 cm−1. The experimental observation proves chemical reactions and the formation of Si3N4 and SiC by laser irradiation.
Highlights
The discovery of carbon nanotubes (CNTs) in 1991 [1] has attracted tremendous attention
Due to the moderate temperature, the mobility of irradiation defects leads to C–C bond breaks in various layers of multi-walled carbon nanotubes (MWCNTs) [18]
W/cm this study, we investigate the morphologies of MWCNTs on silicon substrate after 6 s, 8 s, 10 s and irradiation is 3 s and
Summary
The discovery of carbon nanotubes (CNTs) in 1991 [1] has attracted tremendous attention Due to their superior electrical, mechanical, and thermal properties [2,3], CNTs are unique building blocks for many novel functional materials, which gives CNTs enormous commercial potential in applications including energy storage [4] and biotechnology [5]. A continuous fiber laser is used to irradiate MWCNTs on different substrate (silicon and silica) surfaces. The experiments demonstrate that: (1) substrates strongly affect the welding process of MWCNTs; (2) more irradiation time is needed to weld MWCNTs on a silicon surface due its higher thermal conductivity; (3) by prolonging. Nanomaterials 2016, 6, 36 laser irradiation time, the chemical reaction products Si3 N4 and SiC are created during the welding processing between MWCNTs and silicon. New chemical bonds of Si–N and Si–C make the welding between MWCNTs and silicon successful
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