Synthesis and characterization of multiwall carbon nanotubes/Cu composites with improved physical and tribological properties

Abstract

An ultra-low electric resistive nanocomposite based on aligned, ballistic conducting multiwall carbon nanotubes (CNTs) reinforcing Cu matrix has been produced through hot-press sintering and unidirectional cold rolling process. The electrical, thermal and tribological property analyses have shown that a small amount of CNTs addition (0.1 wt%) resulted in exceptional results. The Cu-0.1CNT nanocomposite have shown the exceptional electrical conductivity (EC) of 63.38 MS⸳m⁻¹ and ultra-low coefficient of thermal expansion (CTE) of 1.50 × 10⁻⁶ K⁻¹, which are ∼3 % and ∼77 % improvements benchmarked with Cu. Furthermore, coefficient of friction (COF) and specific wear rate, under 10 N load at room temperature are 0.13 and 2.20 × 10⁻⁴ mm³⸳N⁻¹⸳m⁻¹, a notable improvement of ∼79 % and ∼53.5 % against Cu prepared under identical conditions. Polarized Raman investigations have confirmed that rolling has aligned the CNTs in the matrix along the rolling direction. The main mechanism behind the enhancement in electrical and thermal properties was attributed to microstructural changes resulting from the incorporation of CNTs and subsequent unidirectional cold rolling treatment. CNTs also facilitated self-lubricating film formation and prevented metal oxide formation within the worn track of the Cu-0.1CNT composite, leading to superior frictional and wear performance to Cu. This study offers a new approach to producing high-performance materials that excel in conducting electricity, withstanding heat, lubricious, and resisting wear. These properties make them suitable for various applications where electric function and durability are crucial.