Achieving an appropriate dispersion of Carbon Nanotubes (CNTs) within a ceramic matrix should be referred to as the main challenge for the synthesis of CNTs reinforced ceramics with enhanced toughening properties. In the present paper, dispersion of 1 wt% MWCNTs within 3YTZP based ceramics has been investigated through the comparison of three conventional approaches based on using surfactants, functionalization, and planetary milling. Addition of 2 wt% Sodium Dodecyl Sulfate (SDS) as the surfactant material followed by 2 hours ultrasonication was found successful to disperse carbon nanotubes in a water media, while chemical functionalization of the CNTs surface using a mixture of H2SO4/HNO3 (3:1) could result in identical well dispersed powder mixtures. Formation of functional groups on the surface of CNTs was confirmed by FTIR spectroscopy and efficiency of the above methods to result in well dispersed powders was detected using UV-Vis spectroscopy. The surfactant method was, accordingly, found to result in the highest dispersion of nanotubes within the ceramic microstructure. In the planetary milling method, well dispersed CNTs within 3YTZP particles could be attained through the optimization of processing conditions such as 24 h milling time, 250 RPM, and 2 BPR. The accuracy of the above results could be verified by SEM as well as Raman spectroscopy. On the other hand, although the dispersed powders provided through functionalization and planetary milling methods revealed CNTs bundles in few scopes of the SEM results and minor damages were also observed in the Raman spectroscopy report, they were both at acceptable levels.
Additive-free carbon nanotube dispersions, pastes, gels, and doughs in cresols
