Preparation of Si_3N_4 Ceramics by Aligning α-Si_3N_4 Whiskers

摘要

In this paper, silicon nitride (Si_3N_4) ceramics by aligning α-Si_3N_4 whiskers were prepared via tape casting, hot-press sintering technique using Y_2O_3 and MgO as sintering additives. Aligned α-Si_3N_4 whiskers were realized by modifying the tape casting technique. After tape casting, Si_3N_4 tape with good flexibility and uniform pores can be obtained. Microstructures of the tape, green body and sintered sample were observed by SEM images. The results show α-Si_3N_4 whiskers in Si_3N_4 tape and green body were aligned preferentially along the tape casting direction. Si_3N_4 ceramics with aligned elongated grains are developed by hot-press sintering technique based on the reaction between Si_3N_4 and the sintering additives which lead to the liquid phase.