Multi-walled carbon nanotube–Al2O3 composites: Covalent or non-covalent functionalization for mechanical reinforcement

Abstract

International audienceMulti-walled carbon nanotube–Al2O3 composites are prepared using carbon nanotubes (8 walls, 1.5 lm long or 20 walls, 10 lm long) previously submitted to either covalent or non-covalent functionalization. High-energy sonication mixing, freeze-drying and spark plasma sintering lead to dense composites. The shorter CNTs are better dispersed than the longer ones, whatever the functionalization. Crack-bridging by CNTs is evidenced only when non-covalent functionalization is used and is correlated with a high fracture toughness for composites with the longer CNTs

Double-walled carbon nanotube/zirconia composites: Preparation by spark plasma sintering, electrical conductivity and mechanical properties

“…Crack-bridging is observed in DWCNT/YSZ composites but it is not as homogeneous as that evidenced in DWCNT/MgO composites [35], probably because mainly of damaged DWCNTs. Non-covalent functionalized DWCNTs [51] could be less prone to be damaged during the SPS treatment in the YSZ matrix than the covalent-functionalized DWCNTs used in the present work. Thus, the use of low contents of DWCNTs remains promising for the reinforcement of CNT/YSZ composites.…”

“…It leads to a loss of cohesion of the grain boundaries, which could decrease both the fracture strength and the fracture toughness. It remains to be tested if non-covalent functionalized DWCNTs [51] could be less prone to be damaged during the SPS treatment in the YSZ matrix than the covalent-functionalized DWCNTs used in the present work. The lower matrix grain size in the composites compared to the YSZ sample (135 nm vs 195 nm) could also inhibit the reinforcement mechanisms operating in the YSZ sample.…”

Fabrication, Composition, Properties and Application of the AlMg1SiCu Aluminium Alloy Matrix Composite Materials Reinforced with Halloysite or Carbon Nanotubes

“…The bending strength of the materials went up by 25%, while crack resistance by 45% vis-à-vis aluminium oxide without a fraction of carbon nanotubes. In the publication [40], the authors focused on investigating how the structure of functionalised carbon nanotubes (length and diameter) influences the degree of dispersion of nanofibers in an aluminium oxide matrix. The material was produced by spark plasma sintering (SPS).…”

Effects of processing conditions on microstructure, electrical conductivity and mechanical properties of MWCNT/alumina composites prepared by flocculation

“…The colloidal method is considered one of the most effective means of dispersing CNTs, and though this usually involves heterocoagulation [20][21][22][23], surfactants are often used. Up to now, however, there have been no systematic studies into surfactant removal or the effects of residual surfactant on the properties of CNT/alumina composites prepared by heterocoagulation.…”