Effect of Al₂O₃ on the Process Performance of ZrO₂ Microspheres

Abstract

Al₂O₃-ZrO₂ microspheres were prepared by internal gelation method. The effects of Al³⁺ on the stability of solution and performance of gel spheres were studied. Al³⁺ had a great influence on the stability of the solutions, and the more of the amount of Al³⁺, the shorter of the stabilization time. Because Al³⁺ did not copolymerize with Zr⁴⁺ during the sol-gel transformation, the strength of gel sphere added with Al³⁺ was low and deformed easily as it was squeezed. The results of our experiments well verify Glasser team’s speculation and conclusions. At the same time, based on the experimental results, we prepared Al₂O₃-ZrO₂ composite microspheres with higher content of Al₂O₃ by controlling the pH of the solution. The change curve of viscosity with time and the stabilization time of the solution with different Al³⁺ dosage were given, which could provide references for industrial mass production. Samples without hydrothermal treatment cracked severely, while the samples hydrothermally treated kept structural integrity with no cracks after calcined. Al₂O₃-ZrO₂ microspheres with no segregation and phase separation were prepared and alumina evenly distributed in the zirconia matrix. When the content of Al₂O₃ was low, the tetragonal phase was stable. And the cubic phase was obtained when the content of Al₂O₃ was more.

Keywords

solution stability / gelation time / Al₂O₃-ZrO₂ microspheres