Development and characterization of zirconia toughened alumina foam filters based on different zirconium raw material

This study investigated the influence of the zirconium raw material and the forming method on the properties of zirconia toughened alumina bulk and foam samples. As the zirconia toughened alumina foams were intended for the use as metal melt filters, the key property was the thermal shock resistance. The tested compositions showed no increase in the strength after thermal shock whereby bulk and ceramic foam samples were examined. The small detected differences in the residual strengths of the different compositions can be traced back to differences in the initial strength, and therefore the higher residual strengths do not offer any advantages for the application as metal melt filter. For the characterization of the bulk samples, cast and pressed samples were prepared and tested. The cast samples showed typically a lower open porosity and lower shrinkage compared to the pressed samples. The lower open porosity caused a higher strength of the cast bulk samples compared to the pressed samples. It can be concluded that the cast samples showed a better consistency with the results of the ceramic foam samples and so are more suitable for a preselection of compositions.