Role of impurities on the spark plasma sintering of ZrCx–ZrB2 composites

The study of the spark plasma sintering (SPS) of ZrCx and ZrCx–ZrB2 composites was carried out considering the effect of experimental parameters such as the applied load, the temperature and the heating time. In addition, the role of the main impurities, detected in the raw materials, on the sintering behaviour has been explored by Transmission Electron Microscopy (TEM). The analyses of monoliths and composites showed up the liquid phase formation from silica impurities and the complete structural reorganisation of free carbon into the graphite form during the sintering treatment. It is also shown that within composites, the plastic strain is preferentially accommodated by ZrB2 crystals.