Improvement of electrical conductivity of silicon nitride/carbon nano-fibers composite using magnesium silicon nitride and ytterbium oxide as sintering additives

摘要

In order to find out the influence of sintering additives on the electrical conductivity of Si_3N_4-based ceramics composites with dispersed carbon nano-fibers (CNFs) two different mixtures of sintering additives were tested - Al_2O_3/Yb_2O_3 and MgSiN_2/Yb_2O_3, respectively. Optimization of hot-pressing conditions was performed for each mixture. The results show that the electrical conductivity can be effectively increased up to 1315 S/m by replacement of traditional sintering aid - alumina, with magnesium silicon nitride, while the mechanical properties remained on the same level. Other advantages of using MgSiN_2 instead of alumina are the preservation of higher amounts of CNFs in the ceramic composite and lower densification temperature (1500 °C) compared to samples sintered with alumina-based sintering aids (1550 °C).