Effects of ball milling on the densification behavior, microstructure, and mechanical properties of TiB2–SiC ceramics

Abstract

High-performance and fine-grained TiB2–SiC composite ceramics were fabricated via hot pressing with ball-milled TiB2 powder doped with SiC. The final product was densified at a relatively low sintering temperature of 1850 °C and brief soaking time of 30 min. The effects of ball milling on TiB2 powder composition and densification behavior, mechanical properties, and microstructures of the ceramic composites were investigated. TiO2 and B2O3 in the raw material were converted to SiO2 via reactions with SiC and Si3N4, thereby forming liquid phases to promote densification. A longer milling time resulted in a small TiB2 grain size. The relative density, Vickers hardness, flexural strength, and fracture toughness of the fabricated TiB2–SiC composites reached 99.0% ± 0.3%, 24.25 ± 1.10 GPa, 647 ± 30 MPa, and 6.43 ± 0.15 MPa m1/2, respectively. The primary toughening mechanisms in the composites were crack deflection, partial crack branching, and crack bridging.