Role of hybrid reinforcement of carbon nanotubes and graphene nanoplatelets on the electrical conductivity of plasma sprayed alumina coating

Abstract This article reports the effect of hybrid reinforcement of carbon nanotubes (CNTs) (1 wt%) and graphene nanoplatelets (GNPs) (0.5 wt%) on electrical conductivity of atmospheric plasma sprayed alumina (Al 2 O 3 ) coating. The uniform dispersion of CNTs and GNPs were observed over Al 2 O 3 matrix. Scratch test revealed the improved inter-splat bonding strength with addition of CNTs and GNPs, which could lead to improved electrical conductivity of Al 2 O 3 coating. The electrical conductivity increased from ~5 × 10 –12 to ~0.7 S/m, by the addition of CNTs (1 wt%) and GNPs (0.5 wt%) in Al 2 O 3 coating. A drastic improvement of ~ 12 orders of magnitude in electrical conductivity was observed in Al 2 O 3 − 1 wt% CNT- 0.5 wt% GNP coatings. This improvement in electrical conductivity was majorly attributed to the lower porosity and strong inter-splat bonding. In addition, availability of more numbers of conductive channels as a result of homogeneous distribution of CNTs/GNPs and clean interface with Al 2 O 3 has played the significant role in enhancement of electrical conductivity.