Spark Plasma Sintering and Microstructural Characterization of Additive-Free Polycrystalline β-SiC

Additive-free -SiC powders were sintered by means of Spark Plasma Sintering System. Experiments were performed in the temperature range from 1650°C to 2200°C, 3 to 10 min holding time and pressure from 50 until 150 MPa. In order to favour sinterization, the starting powder was mechanically activated: defect concentration was increased by centrifugal ball milling. Applied temperature, holding time and/or pressure were varied to analyze their effect on the densification and grain growth kinetics. The full sinterization of the material was obtained for temperatures as high as 1900°C and over. The relative density of the obtained material was high, up to 97.0  0.6 % the theoretical density for 2200°C sintering temperature. An intense grain growth took place while sintering. The final microstructure exhibited a grain size distribution range from 1.0 to 2.5 m, depending on the sintering conditions. Such grain growth strongly depends on the sintering time, not so much on the sintering temperature.