Boehmite modification of nano grade α-alumina and the rheological properties of the modified slurry

The boehmite effect on the modification of the surface of a nano grade α-alumina was studied. The pre-aging process was performed by adding boehmite to a nano grade α-alumina (Nα-A) slurry and adjusting the pH value of the mixed slurry to less than 4. After the pre-aging process, boehmite was coated onto the surface of Nα-A particles to change its zero charged point (PZC) from pH = 6–7 to 9–10, similar to that of the boehmite slurry. Mixed and boehmite slurries show thixotropic behavior if the pre-aging process is adjusted to pH = 1. However, there is no thixotropic behavior if the pre-aging process is adjusted to pH = ∼2. Boehmite degrades to a nano grade sol as the pH of the pre-aging process decreases, especially at pH = ∼1. The rheology and the thixotropic properties of the mixed slurry at different pre-aging conditions are discussed in this article.