Characterization of reticulated ceramic foams with mercury intrusion porosimetry and mercury probe atomic force microscopy

Abstract This study addresses the question of whether mercury intrusion porosimetry is an appropriate measurement devise for the porosity characterization of reticulated ceramic foams which features three kinds of pores: functional pores, material pores and strut cavities remaining after decomposition of the polymeric foam. Reticulated ceramic foam samples made of Al 2 O 3 and Al 2 O 3 -C and with functional pore sizes between 10 and 60 ppi (pores per inch) were investigated. The results show that it is feasible to measure the strut cavities and the entryways of the material pores with the help of the mercury intrusion porosimeter. The results for the strut cavity diameter depends strongly on the ppi number of the polyurethane foam used for the preparation of the ceramic foam. For the reticulated Al 2 O 3 -C foam samples no extrusion of the mercury is observed. Reasons for the missing extrusion of mercury are discussed. Furthermore, atomic force microscopy (AFM) measurements on Al 2 O 3 and Al 2 O 3 -C samples are carried out using a recent AFM method to examine interactions between a mercury droplet and rough surfaces. Factors like approach/retrace speed, reproducibility and applied force are investigated. It is seen that for Al 2 O 3 larger attractive forces are measured than for Al 2 O 3 -C.