Product Code: ICAL06_M1105

Connection of Macro-sized Double-walled Carbon Nanotube Strands by Current-assisted Laser Irradiation
Authors:
Tao Gong, Tsinghua University; Beijing Peoples Republic of China
Yong Zhang, Tsinghua University; Beijing Peoples Republic of China
Dehai Wu, Tsinghua University; Beijing Peoples Republic of China
Kunlin Wang, Tsinghua University; Beijing Peoples Republic of China
Minlin Zhong, Tsinghua University; Beijing Peoples Republic of China
Wenjin Liu, Tsinghua University; Beijing Peoples Republic of China
Presented at ICALEO 2006

Since their discovery in 1991, carbon nanotubes (CNTs) have demonstrated many remarkable mechanical, electrical and thermal properties, showing very attractive potentials in many fields. However, due to the micro size (diameter and length) of most CNT products, they can hardly be used for many predicable applications such as 'space elevator'. Although the production of macro-sized CNTs has been greatly developed in recent years, the macro-sized CNTs are still not long enough and can only form one-dimensional structures. In this paper, we successfully developed a method to connect different macro-sized DWNT (double-walled carbon nanotube) strands by laser irradiation. Before laser processing, the DWNT strands were overlapped for 3~4mm at the joints which were then covered with thin DWNT films through some pretreatment procedures. A 25W CO2 laser (beam diameter is focused to be 2mm) was employed to radiate the strands and at the same time a 20~36V voltage was added on the strands during processing in order to heat the joint to a high temperature for improving the connection. The joints were analyzed by SEM/TEM microstructure observation and Raman analysis. The research approved that laser irradiation did not damage the DWNT structure. The mechanical properties of the strands were remained after connection as the average tensile strength and modulus of the joint were measured to be very close to the original strands. The Resistance-Temperature curve of the joints were also tested and compared with the original strands to express the changes of electrical properties. The result showed that two curves had almost the same unique characteristics such as the conductor-semiconductor transformation at a certain temperature. This strong connection was considered to be realized by a possibly coalescence of DWNTs at the joints under the effect of laser power at high temperature.