Laser Spot Welding and Electric Contact Points Using Copper/Single-Walled Carbon Nanotube Nanocomposite Synthesized by Laser Surface Implanting

Abstract

In our previous studies, we have developed a wet process, denoted as laser surface implanting (LSI), to synthesize a copper/single-walled carbon nanotube (Cu–SWCNT) metal nanocomposite. The nanostructure of this Cu–SWCNT composite was shown to contain discernable SWCNT clusters in nanosizes inside the copper matrix. Its hardness could achieve up to three times that of pure copper, verified by micro-hardness and nano-hardness tests. A focus ion beam bombardment test and a plane strain compression test show 2.5 times toughness improvement for the Cu-SWCNT composite. Based on these strength improvements, two potential applications for the Cu-SWCNT nanocomposite are proposed and their feasibilities are verified using specially design test rigs. The first application is related to creating long lasting electric contacts. The result shows that the Cu-SWCNT nanocomposite is highly wear-resistant. The contact area of the simulated electric contacts increases after repeated impact loading, which potentially could lower the contact resistance. The second application is to use the Cu-SWCNT implants as high strength spot weld for joining copper foils. A smaller weld with a higher strength reduces the power requirement of the laser and, consequently, the thermal distortion for higher-dimensional precision. The specially designed test rig for the weld strength characterization is a new contribution, providing a new testing capability for small and non-homogeneous samples not suitable for a standard tensile test machine.

A Review on the Recent Trends in Forming Composite Joints Using Spot Welding Variants

“…The use of LSW in joining copper with single-walled carbon nanotubes (SWC-NTs) involved the use of a laser beam to melt the copper. The molten copper mixed with the solution-based SWCNTs and solidified to form joints with the dispersed SWCNTs [113]. The SWCNT nanocomposites were embedded, before welding, into the copper using the laser Surface Implanting (LSI) process.…”

Digital Synthesis of Realistically Clustered Carbon Nanotubes

“…Consider a discrete curve in space illustrated in Figure 3, composed of discrete points represented by the matrix = S which is an m × 3 matrix where m is the number of discrete points that comprise the curve, each point being in three dimensions. The parallel transport of the frames begins with the first derivative computed with respect to the spatial dimensions of the space to obtain the curve's tangent vectors, = T as shown in Equation (7). These are then normalized and are shown in Figure 3 as the set of blue vectors.…”

“…Since their discovery in the early 1990's, carbon nanotubes (CNTs) were expected to revolutionize material properties the way carbon fiber had done in the decades prior. Carbon nanotubes are used in myriad applications such as fuel cells [1][2][3], low power electromagnetic device performance [4,5], metal matrix composites [6,7], and even for realizing practical quantum mechanics technological applications [8,9]. The advancement of carbon nanotube manufacturing now allows for controlling the size and chirality of fabricated carbon nanotubes to a greater degree than before.…”

“…The objective of this paper is to establish enabling tools for generating realistically sized nanotubes and anisotropic nanotube clusters with atomic resolution for exploring new applications using modeling and simulation-based approaches. One targeted area is the use of carbon nanotubes as a reinforcing medium in a metal matrix composite [6,7,15]. While computational resources now exist for molecular dynamics simulations of multibillions of atoms [16], atomically modeling the whole formation process of nanotubes is still not yet tractable.…”