| Ceramic foams with porosity 95% or above could be prepared by controlling slurry rheology through additives in direct casting route. The additives used to control slurry rheology included sucrose and two different dispersants, Darvan 821 A (ammonium polyacrylate) and DBAC (dibasic ammonium citrate). In addition, slurry rheology could also be varied through variation in ceramic loading. Slurry rheology had a significant influence on the foaming behaviour resulting in sintered foams with varying microstructure and total porosity. Lower viscosity slurries foamed to a greater extent, leading to higher porosity in foams. DBAC based slurries foamed to greater extent, resulting in thinner cell walls and increased number of interconnections between the cells. Use of sucrose helped in strengthening of green ceramic foams enabling ease in handling and machining. |
