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Tailoring of the Wetting Behavior of Alumina Dispersions on Polymer Foams by Methylcellulose Addition: A Route Toward Mechanically Stable Ceramic Replica Foams

Polyurethane (PU) foams with open porosity and a pore count of 20 ppi are used as templates for the preparation of open‐porous alumina foams by the replica method. The effect of methylcellulose addition on the rheological properties of the aqueous alumina dispersions is investigated. Methylcellulose leads to an increased viscosity of the dispersions and is effective in increasing the yield strength. The compressive strength and the structural parameters of replica foams made by the respective dispersions are correlated with the rheology of the alumina dispersions used in foam manufacturing. An increased viscosity leads to an improved wetting behavior of the PU template and a more uniform coating with the alumina dispersion. The presence of methylcellulose also has the effect that it increases the adhesion of the coating dispersion on the PU template and causes a more homogenous coating, especially at the sharp edges of the templates' struts. As a consequence, the compressive strength of the sintered foams is significantly increased from 0.4 to 1.1 MPa at the same relative density level.