The pressure-decay technique for air permeability evaluation of dense refractory ceramics

The development of high-quality ceramic materials depends on the reliable evaluation of their structural, mechanical, thermal and fluid dynamic properties. However, particularly in the case of dense materials, the experimental evaluation of air permeability parameters involves much work and reliable measurements of high pressure and extremely low flow rate values. The objective of this study was to optimize the analytical routine of a new and promising permeametry technique, whose main advantages are its easy operation and fully electronic data acquisition. Tests carried out on a high-alumina ultra-low cement refractory castable sample showed that permeability constants k1 and k2 fitted reliably to Forchheimer's equation only when the original data set was screened at pressure intervals of 0.2 bar. It was also observed that the broader the pressure-drop range used for fitting purposes, the more reliable the resulting k1 and k2 values, even though permeability constants obtained by different techniques were best compared in similar pressure-drop ranges