Densification of ultrafine SiC powders

Effects of carbon and oxygen on the spark plasma sintering additive-free densification and on the mechanical properties of nanostructured SiC ceramics

“…Our results are similar to those obtained by Vassen et al [3] on SiC sintered with boron and carbon additives and with a density near 95%TD. The effect of the porosity on the toughness calculated by the Anstis equation is relatively low because the porosity size is low (nanometric).…”

“…The higher coefficients could be caused by the presence of silicon excess which has high oxygen affinity. Lower E ox coefficients (1 to 2.5) were only found for powders showing an excess of carbon [3,30,31]. The E ox coefficient of SiC-C nanopowder (2.2) is similar to the E ox values of those latter powders and suggests that oxygen content is low for such SSA.…”

“…Mechanical characterizations from Vickers indentation made in the center (black area) of the S-SiC sample sintered under 100 MPa show interesting properties with hardness at 2150 Hv and fracture [3,36,37] is not easy because the mechanical properties are very sensitive to the microstructure and to the composition of the SiC samples. Our results are similar to those obtained by Vassen et al [3] on SiC sintered with boron and carbon additives and with a density near 95%TD.…”

“…Using SiC nanopowders could help overcoming these drawbacks, by suppressing or decreasing the need of sintering additives for the densification thanks to the high surface reactivity of the nanoparticles, and by enhancing mechanical properties such as hardness, strength or superplasticity thanks to a nanoscaled microstructure [3,4]. Achieving high density without additives could also be facilitated thanks to innovative sintering technique like spark plasma sintering (SPS).…”

Mechanical properties of nanostructured silicon carbide consolidated by spark plasma sintering

“…As pointed out by several authors, [2][3][4][5][6][7][8][9] another promising way to enhance the mechanical performance might be the reduction of grain size down to the nanosize range. In the light of this, a large amount of works focusing on the synthesis and consolidation of bulk nanostructured silicon carbide was recently performed with regard to the Hall-Petch relation predicting a substantial increase in yield strength and hardness for nanoscaled microstructures.…”