Spark plasma sintering and mechanical properties of compounds in TiB2-SiC pseudo-diagram

Abstract

The influence of spark plasma sintering (SPS) parameters (temperature, time, pressure) and the role of particle size on densification, microstructure and mechanical properties of commercial additive-free TiB2, SiC and composites thereof were studied by X-ray diffraction, scanning electron microscopy, the ultrasonic method and indentation. Three particle sizes of SiC and 2 of TiB2 were processed. An optimal cycle was found for TiB2 and SiC: 2000 °C, 3 min dwell time, and 100 MPa applied at 600 °C. The relative density of pure SiC increases linearly from 70% to 90% when the initial particle size decreases from 1.75 µm to 0.5 µm. Pure TiB2 was densified up to 87%. Using 2.5 wt% SiC in TiB2, the relative density increases to 97%. Young's modulus and the hardness of all samples were measured, with results discussed. The higher properties were obtained for additive-free TiB2–5%SiC with a relative density of 97% and with the Young's modulus and Vickers hardness values being close to 378 GPa and 23 GPa, respectively.