Hydrothermal Synthesis of Porous Al2O3/Al Metal Ceramics: III. Effect of the Thermal Dehydration of Bayerite on the Formation of a Porous Al2O3/Al Composite

It was found that the diffusion permeability of a porous cover on aluminum particles increased as a result of the structural transformations of bayerite into active aluminum oxide on the thermal treatment of a porous Al(OH)₃/Al composite. The cyclic treatment (each cycle included a treatment with water at 100°C and a thermal treatment at 550°C) eliminated diffusion limitations and resulted in the formation of porous Al₂O₃/Al metal ceramics with a required set of adsorption–structure and mechanical properties. The following two competing processes were found to affect the formation of the mechanical properties of the synthesized material: the formation of new contacts in the course of the precipitation of aluminum hydroxide and the degradation of old contacts under the action of mechanical stresses that appear in the course of synthesis.