Abstract
In order to explore the possibility of using carbon nanotube (CNT) to introduce and control the temperature coefficient of resistance (TCR) of metal matrix composite, relatively thick and short multi-walled CNTs (MWCNTs) were introduced in the metal matrix with in-situ formation of chromium carbide (Cr7C3) at the CNT/copper (Cu) interface. We demonstrate that incompatible properties such as electrical conductivity and TCR can be achieved simultaneously by introducing MWCNTs in the Cu matrix, with control of the interfacial resistivity using the MWCNT/Cr7C3–Cu system. High electrical conductivity of 94.66 IACS and low TCR of 1,451 10–6 °C−1 are achieved in the 5 vol.% MWCNT–CuCr composite. In-situ formation of Cr7C3 nanostructures at the MWCNT/Cu interface by reaction of diffused Cr atoms and amorphous carbon of MWCNTs would assist in improving the electrical properties of the MWCNT–CuCr composites.
Highlights
We previously showed that chromium (Cr) carbide nanostructures generated in an multiwalled CNTs (MWCNTs)–Cu composite can increase the interfacial bonding strength of MWCNT/Cu without deteriorating the thermal conductivity of the composite[22]
The pristine MWCNTs, with diameters ranging from 20–110 nm and length ranging from 2–15 μm, synthesized by means of chemical vapor deposition followed by high-temperature annealing at 2600 °C 27, were used in this research (Fig. 1)
This process is based on the charge difference between the positively charged Cu particles and the MWCNTs, which are negatively charged by acid treatment in the solvent
Summary
Unlike traditional micrometer sized reinforcements, nanoscale fillers such as graphene and CNT have higher specific surface areas, and as such play crucial roles in determining the electrical properties of the composites because of the greatly increased interface area between the matrix and the CNTs. Successful tailoring of the material system in MMCs, has been rare due to the difficulty of improving what are generally thought to be mutually exclusive properties. To lower the electrical resistivity and the TCR of the Cu composite via in-situ reaction during the spark plasma sintering (SPS) process, we have fabricated Cr carbide nanostructures on thick MWCNTs in an MWCNT– Cu composite; this method is effective for interfacial reaction control due to the relatively short sintering time at low temperature by joule heating, with various vol % of MWCNTs. Resistivity and TCR of the fabricated MWCNT–Cu composite are evaluated and compared with those characteristics of conventional materials
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