Influence of multi-walled carbon nanotubes reinforcements on hardness and abrasion behaviour of porous Al-matrix composite processed by cold pressing and sintering

Abstract

Carbon nanotubes (CNTs) are normally used as reinforcements in metallic matrix composites due to their ultrahigh elastic modulus and ultrahigh strength combined with low weight. In the present study, porous Al matrix composites were fabricated using different concentrations (0.1, 0.25, 0.5, 1 and 2 wt%) of multi-walled carbon nanotubes (MWCNTs) in pure aluminum by ultrasonic mixing, cold pressing and sintering. The microstructures were analyzed by optical microscopy, scanning electron microscopy (SEM) and Raman spectroscopy. Vickers hardness was performed in order to check the effect of the MWCNTs on the strength of the composite. Also, abrasion tests were carried out in order to qualitatively check the correlation with hardness measurements. It was found a good correlation between both properties and it was evidenced the optimized value of MWCNTs is 0.25 wt% for this type of porous composite processing. Above this concentration, hardness and abrasion resistance tend to decrease due to processing difficulty.