Electrical performance of orthotropic and isotropic 3YTZP composites with graphene fillers. Issue 4 (April 2023) - López-Pernía, C.
Abstract: 3 mol% yttria tetragonal zirconia polycrystal (3YTZP) composites with orthotropic or isotropic microstructures were obtained incorporating few layer graphene (FLG) or exfoliated graphene nanoplatelets (e-GNP) as fillers. Electrical conductivity was studied in a wide range of contents in two configurations: perpendicular (σꓕ ) and parallel (σ// ) to the pressing axis during spark plasma sintering (SPS). Isotropic e-GNP composites presented excellent electrical conductivity for high e-GNP contents (σꓕ ∼ 3200 S/m and σ// ∼ 1900 S/m for 20 vol% e-GNP), consequence of their misoriented distribution throughout the matrix. Optimum electrical performance was achieved in the highly anisotropic FLG composites, with high electrical conductivity for low contents (σꓕ ∼ 680 S/m for 5 vol%), percolation threshold below 2.5 vol% FLG and outstanding electrical conductivity for high contents (σꓕ ∼ 4000 S/m for 20 vol%), result of the high aspect ratio and low thickness of FLG. Highlights: Significantly different electrical performance of orthotropic/isotropic composites. Significantly higher σ// for e-GNP vs FLG composites for 10 and 20 GBN vol%. Highest values of σ⊥ and lowest percolation threshold in anisotropic FLG composites. Excellent electrical performance for isotropic composites with 10 and 20 e-GNP vol%. GBN aspect ratio, thickness and defects determine composite electrical conductivity.