Graphene oxide versus reduced graphene oxide versus multi‐walled carbon nanotube as reinforcement for wear resistant ceramics

Abstract

Abstract The present work investigates the relative effectiveness of “nanoplatelet”‐type graphenic carbons [viz., graphene oxide (GO), reduced graphene oxide (rGO)] and “nanofiber”‐type multi‐walled carbon nanotube (MWCNT) as reinforcement in ceramic matrix. The implications of possible departure in effective reinforcement content from the desired amount during processing of GO‐incorporated composites and the relative influences of geometry/morphology of rGO versus MWCNT reinforcements have been revealed here. Monolithic and GO/rGO/MWCNT‐reinforced aluminoborosilicate (ABS) glass‐ceramics, having the same initial reinforcement content (i.e., prior to processing), have been prepared and their mechanical/tribological properties have been examined. The results indicate that removal of non‐carbonaceous constituents of GO during calcination/sintering step (due to in‐situ GO → rGO conversion) of GO‐reinforced composite lowers the effective reinforcement content by ∼50% of the intended value; unlike when pre‐reduced/exfoliated rGO is incorporated. Therefore, ABS‐GO composite exhibits only modest improvement in wear resistance (by ∼20% w.r.t. ABS), as compared to ∼33% and ∼45% improvements for ABS‐MWCNT and ABS‐rGO, respectively. Furthermore, the superior performance of ABS‐rGO versus ABS‐MWCNT is attributed to the greater specific surface area and 2D‐morphology of rGO, accruing tribo‐surface coverage and crack‐bridging. These findings address the debates concerning the respective reinforcing efficacies and highlight rGO's potential as a cost‐effective‐cum‐superior reinforcement for developing wear‐resistant ceramics.