Slip Casting of Silicon Nitride and Mechanical Properties of Sintered Body (Part 1)

• Published in: Journal of the Ceramic Society of Japan Vol. 100; no. 1161; p. 714
• Main Authors: ODA, Kiichi, MIZUTA, Hiroyuki, SHIBASAKI, Yasuo, OHSHIMA, Kazuyuki
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 01.01.1992
• ISSN: 1882-0743; 1348-6535

To develop a complicated shape forming method for the fabrication of Si3N4 engineering ceramic parts slip casting was studied. As the powder characteristics, the isoelectric points of α-Si3N4 (by direct nitridation, median particle size=1.56μm), α-Al2O3 and Y2O3 were determined from zeta-potential measurement to pH=4.9, 8.33 and 9.55, respectively. The preparation conditions of well-dispersed slurries were determined for the solid (92wt%α-Si3N4, 4wt%α-Al2O3, 4wt% Y2O3) by using an organic polymer deflocculant. High-density green body (density=1.95-2.18g/cm3) was prepared from the slurry (75-80wt%solid) by vacuum filtration with a porous resin mold. Fully densified specimens were obtained by gas pressure sintering (at 1770°C for 4h at a N2 pressure of about 0.9MPa). The flexural strength and weibull modulus of the specimen decreased from 726 to 611MPa and from 14.8 to 6.5 with increasing amount of binder from 0 to 4wt%.