Effect of multiwalled carbon nanotubes (MWCNTs) distribution on physiomechancal characteristics of alumina (Al2O3) matrix nanocomposite

This paper describes the dispersion of multiwalled carbon nanotubes (MWCNTs) in alumina (Al2O3) matrix for effective fabrication of structural ceramics by a novel combination of gas purging sonication (GPS) and pressure-less sintering technique. Mechanical testing was performed on fabricated samples to check the effectiveness of MWCNTs additions in alumina matrix. As compared to pure alumina, all the mechanical properties except hardness were significantly enhanced at relatively low addition of MWCNTs. Maximum enhancement in Youngs modulus, fracture toughness and flexural strength was 7.2 %, 22 % and 20.2 % as compared to pure alumina at 1 wt% MWCNTs concentration. Microstructural investigations were performed through field emission scanning electron microscopy (FE-SEM) to study underlying high strength mechanism of fabricated sample. Fractography was also carried out on tested sample using stereomicroscope to examine the failure mechanism. Results shows that at higher concentration of MWCNTs (>1 wt%), the mechanical properties significantly decreased due to agglomeration of MWCNTs leading to porosity and reduced density of the nanocomposites as compared to pure alumina.