Processing of porous ceramics from highly concentrated suspensions by foaming, in situ polymerization and burn-out of polylactide fibers

Abstract The paper presents the preparation of porous alumina samples by two techniques. The first one is based on the in situ polymerization of the foamed slurries. The second method is based on the gelcasting of slurries containing polylactide fibers (PLA) and subsequent bun-out of these pore-formers. Foaming has been done in air and nitrogen in order to analyze the influence of the oxygen inhibition on the properties of obtained samples. The prepared slurries were characterized by high concentration of alumina powder (50 and 55  vol %) in order to obtain well densified walls between the pores and as a result high compressive strength of obtained samples. DTA/TG analysis coupled with mass spectrometry allowed to identify the type of gases released to the atmosphere during the thermal decomposition of the PLA fibers and the surfactant Tergitol used in the research. The application of the PLA fibers allows to design the shape of pores; moreover, fibers are well replicated in the ceramic bodies and the burn-out of these pore-formers is not harmful for the environment.