Processing of copper–carbon nanotube composites by vacuum hot pressing technique

Copper (Cu) matrix composites reinforced with 0.2, 5 and 10 vol% single wall carbon nanotubes (SWCNT) and 5 and 10 vol% multi-wall carbon nanotubes (MWCNT) were processed by high energy milling of pure copper powder with carbon nanotubes (CNTs) and subsequent consolidation by vacuum hot pressing. Microstructural observations of the sintered composites revealed equiaxed twinned microstructure for 0.2 vol% SWCNT composite and elongated grain structure, with CNT layers in between, in composites having higher CNTs content. The porosity in the composites was associated with CNT layers. The distribution of CNTs was found to be different in axial and transverse directions. Significant improvement in hardness of Cu–SWCNT composite was observed with increase in CNTs content. Whereas, in case of MWCNT composite, hardness reduced for 10 vol% CNT composites. Compression strength of the SWCNT samples was found to be higher than the MWCNT reinforced samples.