Impact of carbon binders and carbon fillers on mercury intrusion and extrusion porosimetry of carbon-bonded alumina

Carbon-bonded alumina samples with different compositions and varying mixing and shaping procedures were tested regarding their densities, porosities, and pore entryway diameter distributions by means of helium pycnometry, buoyancy method and mercury intrusion porosimetry, respectively. A majority of the carbonbonded alumina samples showed no release of the mercury from the pores during pressure reduction (extrusion), but a constant cumulative mercury volume. Samples without any carbon binder and uninitiated carbon binder showed an extrusion of mercury causing a hysteresis curve. Further tests yielded a strong adhesion between mercury and coked carbon binder, probably inducing the remainder of the mercury within the pores during the extrusion step. Despite the different sample compositions (due to omission of distinct raw materials) and pronounced differences in grain size, a majority of the measured bulk densities was in a similar range between 1.69 and 1.81 g/cm(3).