Freeze gelcasting of hydrogenated vegetable oil-in-aqueous alumina slurry emulsions for the preparation of macroporous ceramics

摘要

Freeze gelcasting of hydrogenated vegetable oil-in-aqueous alumina slurry (HVO-in-AAS) emulsions has been studied for the preparation of macroporous ceramics. The emulsions with HVO to AAS volume ratios in the range of 1.34—2.69 prepared from a 30 vol.% AAS containing carrageenan using sodium dodecyl sulphate emulsifying agent at 85 °C undergo gelation on cooling to room temperature due to the solidification of HVO and physical cross-linking of carrageenan. Macroporous ceramics obtained by drying, HVO removal followed by sintering at 1500 °C of the gelled emulsion bodies had porosity in the range of 70.7-84% and contain cells of spherical to polygonal shape. The average cell size (13.24-3.6 μm) decreased and the cell interconnectivity increased with an increase in HVO to AAS volume ratio and mixing speed. The macroporous alumina bodies had high compressive strength (6.5-39.6 MPa) and Young's modulus (350-2352 MPa).