ZOU Nan ^{1, 2}, QIN Zixuan ^{1, 2}, ZHANG Mu ^{1, 2}, SUN Xudong ^{1, 2, 3}
(1. Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, Liaoning, China; 2. School of Material Science and Engineering, Northeastern University, Shenyang 110819, Liaoning, China;
3. Foshan Graduate School of Innovation, Northeastern University, Foshan 528311, Guangdong, China)

Abstract: Utilizing a novel non-toxic isobutylene anhydride maleic copolymer, silicon nitride ceramics were fabricated by using the gel-casting method. Isobams with different molecular weights were employed as dispersants and gelling agents to study their effects on Zeta potential and rheological properties, while their dispersion and gelation principles explored. This novel system, in comparison with traditional acrylamide systems, is non-toxic and more environmentally friendly, requiring a lower addition level of less than 1 wt.% of the original powder. Consequently, organic compounds can be eliminated during the sintering process without the need for a specific degassing regime, thus simplifying the process. Dense sintered bodies could be readily obtained after pressure sintering at 1760 ℃ for 2 h, with a mutually interlocking microstructure formed by β-Si₃N₄. With increasing content dispersant, density, porosity, and flexural strength of the sintered bodies showed minimal variation. With 40 vol.% solid content and 0.3 wt.% Isobam 600, the density reached 2.9 g·cm⁻³, with a flexural strength of 454 MPa. Increasing the solid content to 45 vol.% yielded a density of 3.0 g·cm⁻³.

Key words: gelcasting; silicon nitride; Isobam; dispersion; suspension