Control of Structural-Mechanical Properties of Pseudoboehmite Pastes by Changing the Plasticizing Agent

Abstract

The study of the influence the type of plasticizing organic/inorganic agents on structural-mechanical properties (plastic strength, molding pressure, limit shear stress, greatest plastic viscosity, plasticity and etc.) of the pseudoboehmite pastes is presented. Samples of the pastes were prepared using plasticizing agents of organic nature (acetic, malic, tartaric, oxalic and citric acids and diethyelen glycol) and inorganic nature such as nitric and phosphoric acids, aqueous ammonia solution and ammonium hydrocarbonate. Our results suggest the pastes plasticized with nitric/phosphoric acids or with diethylene glycol demonstrate the highest plastic strength in the set. Plastic strength values were found to correlate well with the molding pressure necessary for the paste shaping through a piston extruder. The structural-mechanical type of paste was determined using a modulus of elasticity, viscosity and limit shear stress. All pastes were found to be suitable for extrusion molding and did not belong to SMT types 0 and III. The plasticizing agent was found to affect SMT type of paste. Paste types I, II, IV, and V were obtained by changing the plasticizing agent. Alumina granules without visible defects and with sufficient crush strength value were prepared using the investigated pastes. This allows them to be used as supports/adsorbents/catalysts for industrial processes.