Mechanical and thermal properties of spark plasma sintered Alumina-MWCNTs nanocomposites prepared via improvised colloidal route

Multi-walled carbon nanotubes (MWCNTs)-reinforced ceramic nanocomposites for aerospace applications: a review

“…According to Ramachandran et al, the twirled structure of the MWCNTs incorporated into the alumina matrix may block the travelling phonons. This leads to the reduction in thermal conductivity along with agglomeration of MWCNTs onto the matrix could reduce the phonon scattering due to Van der Waals forces of attraction between the MWCNTs which was also observed by Hazel et al [33,114]. In contrast, Kumari et al stated that the uniform dispersion of the MWCNTs onto the ceramic matrix could be reason for the increase in thermal conductivity [111].…”

“…The common CNTs processing techniques include sol-gel, powder metallurgy and in situ growth techniques. However, a colloidal route is also being followed by researchers around the world which is cheaper and time efficient compared to other processing techniques [33].…”

“…Kumari et al prepared CNTs-alumina composites at varying composition and sintering temperatures and reported that the diffusivity of the material increased by 60% compared to monolithic alumina with 7.39 wt.% of the composites for samples sintered at 1550 °C [111]. However, Ramachandran et al reported a reduction of the diffusivity value with increase in CNT content with 1 wt.% showing the highest diffusivity value compared to the monolithic alumina fabricated via same technique [33]. Both research teams prepared the composites through SPS process with sintering temperature and dwell time playing a huge role in determining the diffusivity of the composites.…”

“…CNTs are one such reinforcement which could be used to enhance the fracture toughness of the ceramics. Several literature studies have focused on the effect of CNTs on the mechanical properties of ceramics and it has been determined that appropriate CNTs compositions, densification techniques and homogenous distribution of CNTs onto the ceramic matrix are required to enhance the properties of the composites [31][32][33]. However, there have been also anomalies in mechanical properties noted by various researchers which highlights the importance of CNT/ceramic composition.…”

“…Various research has been conducted to enhance the fracture toughness of the ceramics by reinforcing them with various materials including metal and ceramic additives. Although with the potential of CNTs being a suitable reinforcement material, research work on incorporating CNTs has proved to be effective to ceramics composites as studies have demonstrated enhancement in fracture behaviour [31][32][33].…”