Aluminum matrix composites reinforced by molybdenum-coated carbon nanotubes

Abstract

To extend the application of carbon nanotubes (CNTs) and explore novel aluminum matrix composites, CNTs were coated by molybdenum layers using metal organic chemical vapor deposition, and then Mo-coated CNT (Mo-CNT)/Al composites were prepared by the combination processes of powder mixing and spark plasma sintering. The influences of powder mixing and Mo-CNT content on the mechanical properties and electrical conductivity of the composites were investigated. The results show that magnetic stirring is better than mechanical milling for mixing the Mo-CNTs and Al powders. The electrical conductivity of the composites decreases with increasing Mo-CNT content. When the Mo-CNT content is 0.5wt%, the tensile strength and hardness of Mo-CNT/Al reach their maximum values. The tensile strength of 0.5wt% Mo-CNT/Al increases by 29.9%, while the electrical conductivity only decreases by 7.1%, relative to sintered pure Al. The phase analysis of Mo-CNT/Al composites reveals that there is no formation of Al carbide in the composites.

Metallurgical Challenges in Carbon Nanotube-Reinforced Metal Matrix Nanocomposites

“…Similarly, it is shown that there is no intermetallic formation in the microstructure of (Mo-coated CNT)-Al nanocomposites [16]. It is attributed to the presence of Mo layer, acting as an appropriate barrier to the interfacial reaction between CNTs and the matrix.…”

“…Moreover, the inhomogeneous dispersion of CNTs gives rise to non-homogeneity and anisotropy in these binary systems. On the other hand, it may impede the full sintering and reduces the relative density, wettability of CNTs, and resultant mechanical properties [16,[33][34][35].…”

“…They reported enhanced hardness and wear resistance in spark plasma sintered CNT-Cu nanocomposites than pure Cu with good CNT/Cu interfacial bonding as well as uniform CNTs distribution in the matrix and high relative density. Metallization of CNTs using chemical vapor deposition (CVD) [16] and electroless coating [95] is one of the effective approaches to achieve a strong metal/CNT interfacial bonding as well as a homogeneous dispersion of CNTs inside the matrix. It can improve the load transfer from matrix to CNTs through the metallic coating.…”

“…To overcome this challenge, a broad spectrum of dispersion methods is developed. Among these techniques, the mechanical methods [15], surface treatment [16], and chemical methods [17] are the most conventional. Each of these techniques has their own advantages and disadvantages, being discussed in the next sections.…”

Influence of the Reinforcement Distribution and Interface on the Electronic Transport Properties of MWCNT‐Reinforced Metal Matrix Composites

“…In an attempt to improve CNT dispersion and interfacial contacts in an Al matrix, Nie et al coated the nanotubes with molybdenum. [8] According to the authors, this did not improve the electrical conductivity of the composites due to low CNT and Mo conductivities (compared to Al) and most probably, due to porosity (up to 5%). In electroless-deposited spark-plasma-sintered (SPS) MWCNT/ Cu composites, the increase in the electrical resistivity was significant.…”