Effect of nanograghite addition on the densification of ZrB2-SiC composites fabricated by spark plasma sintering

Abstract Ultrahigh temperature ZrB2-SiC composites reinforced with different amount of nano-graphite (0, 2.5, 5, 7.5 and 10 wt%) were fabricated by spark plasma sintering process. The effect of graphite nano-flake on the densification behavior of the mentioned composites were investigated. Spark plasma sintering was carried out at a temperature of 1900 °C for a dwell time of 7 min under an applied pressure of 40 MPa. A fully dense ZrB2-SiC composite (with relative density of 100.6%) was obtained by the addition of 5 wt% nano-graphite. Elimination of oxide impurities through the chemical reactions with graphite as well as formation of sub-micron phases caused to an enhancement in the densification. In addition, the in-situ formed ZrC phase was one of the reasons behind the increasing of relative density. Keywords: spark plasma sintering, ultrahigh temperature composites, densification behavior, nano-graphite, ZrB2-SiC composites Keywords: spark plasma sintering, ultrahigh temperature composites, densification behavior, nano-graphite, ZrB2-SiC composites