Granulation of Nano Alumina Powder for Improved Flowability by Spray Drying

This paper reports on the methodology adopted for obtaining near spherical agglomerated Al2O3 powders which enables them to be coated by plasma spray technique on titanium alloys. An attempt was made on spray drying alumina slurries with polyethylene glycol as binder and sodium hexametaphosphate as a dispersant. The effect of pH on the stability and viscosity of the slurry was established and also the rheological behavior of the slurry was studied in detail. Uniform agglomerated particles were obtained by spray drying the slurry containing 22 vol% alumina, 6 wt% polyethylene glycol and 0.02 wt% sodium hexametaphosphate as a dispersant.