Effect of graphene and CNFs addition on the mechanical and electrical properties of dense alumina-toughened zirconia composites

Fully dense carbon/alumina-toughened zirconia composites were prepared by using a combination of aqueous colloidal powder processing and spark plasma sintering technique (SPS). Various carbon elements were introduced in alumina-toughened zirconia matrix (ZA) as filler; carbon nanofibers (CNFs) and graphene oxide (GO). The influence of the addition of different carbon forms on the microstructure and on the mechanical and electrical properties was investigated. In the case of the ZAGO composites, the SPS technique allowed, in one-step, the in situ reduction of the graphene oxide during the sintering process. The fracture toughness increases for ZAGO composites in comparison to the ZA material while the hardness decreases slightly with carbon elements addition. The electrical conductivity of the ZA composite drastically increased with the addition of graphene oxide, and it reached 10 Ω cm at 2 vol%.A. Borrell acknowledges the Spanish Ministry of Economy and Competitiveness for her Juan de la Cierva contract (JCI-2011-10498) and the Generalitat Valenciana by the financial support for the GV/2014/009 project. M.D. Salvador thanks to CAPES – Programa Ciências sem Fronteiras (Brazil) for the concession of a PVE project No. A086/2013. A.S.A. Chinelatto thanks to CAPES for the concession of a post-doctoral fellowship in ICV-CSIC.Peer Reviewe