Sulfanilic acid: A novel consolidation agent for Al₂O ₃ in aqueous media

A new solidifying agent, 4-aminobenzene sulfonic acid (sulfanilic acid), is reported in this paper. The consolidation process and mechanism were followed using on viscoelastic, FTIR, SEM, and Hg porosimetry measurements. It was shown that the Al₂O₃ slurries with PAA-Na as dispersant exhibited a high degree of particle stabilization. After the addition of sulfanilic acid, we observed an exponential increase in the storage modulus (G′) as a function of consolidation time. Correspondingly, Al ₂O₃ slurries exhibited a transition from a viscous to an elastic state (in 62 min). FTIR analysis indicated that the consolidation process might follow two steps: first, the adsorption of sulfanilic acid on the Al₂O₃ particle surface; second, the acid-base interaction between the adsorbed PAA-Na molecules and the sulfanilic acid molecules. This interaction could possibly induce the formation of three-dimensional networks through a bridging or charge neutralization mechanism. The as-consolidated Al₂O₃ green samples were homogeneous, with the relative green density being 54.69%. Results showed that it was feasible to introduce sulfanilic acid for the consolidation of Al₂O₃ slurries in aqueous media.