Effects of solid loading and calcination temperature on microstructure and properties of porous Si3N4 ceramics by aqueous gelcasting using DMAA system

摘要: Abstract Herein, a low–toxic N, N–dimethylacrylamide (DMAA) system was used in preparation of porous Si3N4 ceramics by aqueous gelcasting, and variations microstructure properties with solid loading calcination temperature were systematically investigated. In the considered range 28–44 vol%, all slurries exhibited superior rheological (≤145 mPa⋅s at 95.40 s−1 for 44 vol% loading) perfectly suitable casting. With increasing loading, decreased bulk density (1.71–1.69 g/cm3), volume shrinkage (37.73–13.77%) flexural strength (46.56–26.75 MPa) green bodies obtained, exhibiting better mechanical than those derived from conventional acrylamide (AM) system. Regarding various loadings, increase favored phase transformation α→β–Si3N4 β–Si3N4 growth, however, increased an inhibiting effect on since mass transport gas blocked due to disruption pore connectivity. The resulting changes imparted (110.36–367.88 MPa), fracture toughness (2.54–5.03 MPa⋅m1/2), as well decreasing porosity (54.21–41.05%) size (0.38–0.33 μm). This work demonstrates potential research value DMAA preparing high–performance through gelcasting technique.