Influence of powder state and rheology on sintering behaviour of SiC

Abstract The influence of conditioning state of a nano-SiC powder on its spark plasma sintering behaviour and microstructural properties is discussed. The powders were firstly deeply characterized by means of SEM, X-ray diffraction, specific surface area measurements and rheological behaviour determination. We found that even if the initial particles are the same, the conditioning state plays a crucial role on the development of the ceramic. Granulated SiC powder exhibits the highest ability of rearrangement and compaction leading to a better green density. This specificity allows the development of the densest ceramic with the lowest grain size. Moreover, this ceramic showed no evidence of phase transition during sintering, with a pure cubic SiC phase. We conclude that the powder state and the storage conditions of the ceramic powder has an impact on the overall powder process and finally influences not only the final density and grain size but also the phase composition.