Preparation of Refractory Nozzle by Gelcasting of Zirconia Suspensions with Coarse Particles

Zirconia suspensions with coarse particles were prepared and the rheogical behavior and sediment stability of such suspensions with different dispersants were studied. It was found that ZrO2 suspension stabilized with TAC (tri-ammonium citrate) has an obvious shear-thinning behavior and rapid settlement; In contrast, the suspension stabilized with arabic gum shows a shear-thickening behavior and hardly any settlement. Considering both fluidity and settlement stability, APA (ammonium-polyacrylate) was chosen as the dispersant to increase the solid volume fraction of ZrO2 suspension. Utilizing the above suspension, a kind of refractory nozzle for precision casting of a Cu-Cr alloy was prepared by gelcasting. Such nozzle has a very good resistance to thermal shock and flux scouring.