Reducing the density deviation in alumina by pressure-vacuum hybrid slip casting by employing powders with different particle sizes

• Published in: Journal of Asian Ceramic Societies Vol. 8; no. 2; pp. 407 - 415
• Main Authors: Cho, Kyeong-Sik, Min, Jae-Hong, Lee, Hyun-Kwuon, Kim, Hai-Doo
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 02.04.2020; Taylor & Francis Group
• Subjects: al2o3; density deviation; green density; Slip casting
• ISSN: 2187-0764; 2187-0764
• DOI: 10.1080/21870764.2020.1749372

We reduced the density variation in Al 2 O 3 fabricated by pressure-vacuum hybrid slip casting (PVHSC) by adding small powders to large particles. In PVHSC, consolidation occurs not only by compression of the slip in the casting chamber but also by suction of the dispersion medium from the chamber. Three powders with particles of different sizes [the host powder (H), octahedral-void-filling powder (O), and tetrahedral-void-filling powder (T)] were prepared by milling commercial Al 2 O 3 powders to control the particle size. Slips were prepared using three powder batches: H powder only, a mixture of H and O powders, or a mixture of all three powders. The solid cast green body fabricated from the powder batches including fine powder showed longer constant drying rate periods and drying completion times compared to a batch of the host powder. The green density of Al 2 O 3 made from the mixture of all three powders was 59.4 ± 0.3%, and the density distribution was uniform along the thickness direction. After sintering at 1650°C, the Al 2 O 3 bodies also exhibited the uniform density distribution and higher densities when the powder including fine powder were used.