SURFACE-ROUGHNESS OF POROUS MATERIALS AND ITS CHARACTERIZATION BY X-RAY ABSORPTION-MEASUREMENTS

A geometrical model for the surface microstructure of random porous materials is proposed. The bulk structure of the material is analytically described by means of methods of the stochastic geometry. The surface region is simulated by a random variable generating an exponential decrease of the mean packing fraction of the material in the surface region. The depth profile of the surface depends both on the bulk properties of the porous material and a well-defined surface roughness parameter. An experimental procedure for the determination of the surface roughness parameter is proposed. It is based on the analysis of the absorption of X-rays diffracted by the material.