Fractal Dimension Analysis of Structure and Bending Strength of Porous Alumina Prepared Using Starch and Carbon Fiber as Pore-Forming Agents

Porous alumina was prepared via a sacrificial template method using alumina as the matrix and starch and carbon fibers as the pore-forming agents. After sintering, no residual pore-forming agents were present. The density, porosity, and pore structure of the samples were measured using the Archimedes’ method and mercury intrusion porosimetry (MIP). The results showed that the pore size distribution of porous alumina was double-peak when the content of the pore-forming agent was 20, 30, or 50 vol.%, but was single-peak when the content was 40 vol.%. A fractal model based on the measured MIP data was used to calculate and evaluate the fractal dimension (Ds) of porous alumina. The Ds values decreased with an increase in the pore-forming agent content. Furthermore, Ds was negatively correlated with porosity, most probable pore size, and median pore diameter and positively correlated with the bending strength of porous alumina. Since porous alumina has obvious fractal characteristics, the fractal theory can be used to quantitatively describe its complex distribution.