Development of an Electroless Plating Process for Multi-wall Carbon Nanotubes (MWCNTS) to Improve Their Dispersion and Wettability in Molten Aluminum
Embedding CNTs in molten aluminum by mechanical stirring represents one approach of producing Aluminum-Carbon Nanotube (Al-CNT) composites. Molten aluminum is known for its high surface tension with CNTs resulting in extremely poor wettability. One approach to tackle this problem is done by metallizing CNTs via electroless plating . The new interfacial metallic layer on CNTs improves their dispersion and wettability in molten aluminum. One of the challenges, however, is the rapid growth of the plated layer on CNTs during microfiltration of the prepared powder resulting in aggregates of metal-coated CNTs and grown copper crystals. This results in poor dispersion of the powder in molten aluminum making the industrial upscaling of the process not viable. In this work, chemical constraints were put to control electroless plating kinetically. Instead of growing catalytic palladium particles on top of CNTs via what is known as a two-step process sensitization and activation, colloidal ready grown Palladium-tin (Pd-Sn) particles of a fixed size were used to ensure the conformity of the coat, the concentration and volume of the catalytic solution was optimized to ensure the coverage of the surface area of CNTs. After the surface of CNTs was covered with the catalyst, a Copper-Cobalt (Cu-Co) electrolyte of extremely high deposition rate was used to ensure a reaction stopping mechanism before filtering the Copper coated CNTs ensuring that copper does not grow on aggregates of the tubes. Copper coated CNTs of an average size of 85 nm were obtained. Percentages from 0.5 to 2% of the prepared powder (containing less than 0.1% of CNTs for each 2 gm) were dispersed in molten aluminum and casted resulting into 12.2–52.1% increase in the Vickers hardness indicating the effectiveness of the copper coated CNTs in improving the properties of commercial pure aluminum.
KeywordsMetal-matrix composites (MMCs) Carbon nanotubes Electroless copper-cobalt plating Colloidal tin-palladium activation Palladium acceleration Casting
The authors wish to thank EgyptAlum Company in Nagaa Hammady, Egypt for donating the commercial pure aluminum samples for the purpose of research and development.
M. Elsharkawi is grateful for the financial support by the Office of the Dean of Graduate Studies and Research at the American University in Cairo and by Al-Alfi foundation.
- 4.Mallory GO, Hajdu JB (2009) Electroless plating: fundamentals and applications. Am Electroplaters Surf Finish, New YorkGoogle Scholar
- 5.Feng Y, Yuan H (2004) Electroless plating of carbon nanotubes with silver. J Mat Sci 39:3241–3243. https://doi.org/10.1023/b:jmsc.0000025869.05546.94 CrossRefGoogle Scholar
- 8.Shacham-Diamand Y, Sverdlov Y, Friedberg S, Yaverboim A. (2017) Electroless plating and printing technologies, in nanomaterials for 2D and 3D printing. In: S. Magdassi and A. Kamyshny (eds) Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. https://doi.org/10.1002/9783527685790.ch3
- 12.Agarwal A, Bakshi SR, Lahiri D (2011) Processing techniques. Carbon nanotubes: reinforced metal matrix composites. CRC Press-Taylor & Francis, Boca Raton, Florida, pp 30–33Google Scholar