Creating anisotropic properties in conductive ceramics by incorporating hBN flakes

Tailoring physical properties in conductive ceramics is difficult, which is dominated by the continuous ceramic matrix. In this study, tunable anisotropic physical and mechanical properties in conductive ceramics were successfully realized by incorporating hexagonal boron nitride (hBN) flakes in their matrices. Two conductive TiB2-AlN-hBN ceramics (TAB) with different hBN contents were fabricated by spark plasma sintering using powder mixtures containing TiN, Al, boron and hBN. Perpendicular to the load direction, flexural strength, fracture toughness, electrical conductivity and thermal conductivity of TiB2-AlN-60 vol% hBN composites at room temperature were 151 +/- 6.34 MPa, 2.62 +/- 0.31 MPa m1/2, 5.3 x 10(5) S m(-1) and 77.87 W m(-)1 K-1. Whilst electrical conductivity and thermal conductivity decreased to 2.0 x 10(5) S m(-1) and 32.25 W m(-1) K-1 at the direction parallel to the load. These differences were created just by incorporating small amounts of extra aligned hBN flakes in the conductive matrix, providing new opportunities to material selection and design.

Automated summary

Tunable anisotropic physical and mechanical properties were achieved in conductive ceramics by incorporating hBN flakes, providing new opportunities for material selection and design.