Flexible polyurethane foams as templates for cellular glass–ceramics

In this work flexible polyurethane (PU) foams were obtained with varying air permeability, cell diameter and morphology. The addition of up to 1.5 g anti-foamer with a mixing time of 75 s resulted in larger cell diameters, higher air permeability and lower distorted area. PU foams obtained were used as templates to produce glass–ceramic (GC) foams by the replication method. Glass powder of the LZSA (Li2O–ZrO2–SiO2–Al2O3) system was used to infiltrate the PU foams. The retention capacity of the ceramic suspension in PU foam is increased with a reduction of the cell diameter. In contrast, the infiltration capacity increases with raise of the cell diameter. The permeability reduction of GC foams with respect to PU foams varied from 3% to 25% when 2.7 and 0.8.0 mm cell diameters were used, respectively. The results of mechanical characterization were coherent with the morphological characteristics in both PU and GC foams.