Promotion of the alginate gelling method for preparing Al ₂ O ₃ honeycomb ceramics

In this work, Al2O3 honeycomb ceramics with unidirectionally aligned channels were fabricated by the ionotropic gelation process of alginate/Al2O3 suspensions. By heating the bottom of the suspension container during the gelation step, the heat energy conducted upward from foot to the top surface of the slurry, which has shortened the gelation time from 48 to 10 h and improved efficiency dramatically. Meanwhile, as the heating temperature increased from 25 to 40°C, the porosity of Al2O3 honeycomb ceramics remained unchangeable with the pore size decreasing from 163 to 79 μm for the increasing opportunities for forming capillaries in the primary membrane. By the integrated effect of unidirectional pore channels and dense pore walls, both the compressive strength and water permeability of the sintered samples were higher than those of Al2O3 foam ceramics.