Role of deflocculants on the rheological properties of boehmite sol

• Published in: Materials letters Vol. 58; no. 10; pp. 1576 - 1581
• Main Authors: Vishista, K, Gnanam, F.D
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2004
• Subjects: Alumina; Boehmite; Ceramics; Sol–gel preparation; Viscosity; Viscosity; Sol–gel preparation; Boehmite; Ceramics; Alumina
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/j.matlet.2003.10.029

The colloidal boehmite precipitate prepared at pH=8.5 was dispersed in aqueous suspensions containing varying concentrations of deflocculants, namely, ammonium citrate, ammonium tartarate, citric acid, acrylic acid, ammonium polyacrylate, polyethylene amine, ammonium carbonate, and polyaminobenzoic acid. The viscosity measurements for the suspensions containing 5–20 wt.% solids loading were carried out. The effect of pH and viscosity was studied. The sedimentation characteristics of the suspensions in the presence of the dispersants were also studied, keeping the solids loading at 20 wt.% and surfactant concentration at 0.1 wt.%. The stability of the suspensions was observed over a period of 72 h. Suspensions with polyaminobenzoic acid, ammonium polyacrylate, and acrylic acid showed good stability and better rheological properties compared to other deflocculants. The viscosity measurements indicated that the addition of polyaminobenzoic acid to the suspension showed minimum viscosity and citric acid exhibited maximum viscosity.