Freeze casting of aqueous alumina slurries with glycerol for porous ceramics

Freeze‐cast yttria‐stabilized zirconia pore networks: Effects of alcohol additives

“…13 Studies have also shown that addition of alcohols (ethanol and IPA) or glycerol to aqueous slurries also increases viscosity. 10,14 Despite that the liquid in the slurries were at a higher temperature than the equilibrium freezing temperature of the solution according to the phase diagrams, upon visual inspection the slurries appeared to freeze completely and did not melt or deform during demolding. The contrast between the water-alcohol phase diagrams and the observations made in the current study suggest that other interactions occurred to make the slurries behave as though they were completely frozen.…”

“…[6][7][8] For example, numerous studies observed smaller pores and increased connectivity between walls in ceramic samples cast from aqueous slurries with glycerol. [9][10][11] The hydrogen bonds that form between water and glycerol inhibit complete ice crystallization, limiting ice crystal size and decreasing resulting pore size. Addition of glycerol also reduced volumetric expansion of water upon solidification, likely increasing the amount of micro-porosity within the ceramic walls that were removed during sintering to give denser ceramic walls.…”

“…Addition of glycerol also reduced volumetric expansion of water upon solidification, likely increasing the amount of micro-porosity within the ceramic walls that were removed during sintering to give denser ceramic walls. 10 Only a few freeze casting studies have explored the use of alcohols such as ethanol, tert-butyl alcohol (TBA), or isopropyl alcohol (IPA) as additives and their effects on pore network characteristics. Munch et al used 4 wt.% ethanol in aqueous alumina slurries and saw a bimodal pore width distribution in the lamellar structures and the appearance of "pocket-like dendrites" on the lamellae surfaces.…”

Ceramic macromembrane for tangento-axial micro- and ultrafiltration water systems

“…It should be noted that ceramic membranes allow conditions of use at high temperatures (above 200˚C) as well as cleaning processes in extreme pH conditions (<3 and/or >12) to which organic filters cannot stand. Hence, they have higher levels of use and durability than those of organic filters [2,3].…”

The influence of Fe2O3 doping on the pore structure and mechanical strength of TiO2-containing alumina obtained by freeze-casting

“…Hence, the structural development of alumina based freeze casting has been reported based on controlling the lamellar pore structure [24] by symmetrical channel arrangements along the radial axis [25]. Furthermore, a number of solvents have been investigated towards freeze casting structure formation in addition to water, including tert-butanol [4], naphthalene [26], polyether glycol [27], glycerol [28] and camphene [29,30] among many other examples. 4 The mechanical properties of porous alumina substrates are also important and doping with different metal oxides is a strategy employed accordingly.…”