Abstract:

Polymeric sponge replication method is one of the common ways for ceramic foam production. The existence of central triangular voids in the struts results in a decrease of mechanical properties limiting their applications. To remove this defect, some additives consisting of Al powder particles and silica sol are added to ceramic slurries consisting of Al₂O₃ and ZrO₂ (partially stabilized zirconia). With increasing temperature for pyrolyzing and sintering of raw materials, first the Al powder and then the glass phase which consisted of melted Al₂O₃, ZrO₂ and SiO₂ was soaked into hollow struts. SEM investigations showed that the center of foam struts were free of hollows. XRD considerations depicted that a ZrO₂ phase with tetragonal crystallographic structure is present in the produced foam which could be the reason of improved toughness and mechanical properties. Compressive strength of foams increased significantly due to the decrease of closed porosity. The Weibull statistical study showed remarkable increasing of the Weibull module and its value for foams with 10, 20 and 30~ppi was 5.91, 6.06 and 6.53 respectively.

Key words: Ceramic foam, Processing, Strut structure, Al₂O₃-ZrO₂, Weibull modulus