Preparation method of submicrometer-sized alpha-alumina by surface modification of gamma-alumina with alumina sol

A method is introduced to prepare almost-spherical submicrometer-sized or-a lumina via surface modification of gamma-alumina with an alumina sol, Mille d gamma-alumina, in the presence of 3 wt% of alpha-alumina with a median pa rticle size (d(50)) of 0.32 mu m (AKP-30), produced irregularly shaped alph a-alumina with d(50) approximate to 0.3 mu m after heat treatment at 1100 d egrees C for 1 h. gamma-alumina that had been surface-modified by milling i n the presence of 3 wt% of the alumina sol resulted in almost-monosized, sp herical a-alumina similar to 0.3 mu m in size after heat treatment at 1100 degrees C for 1 h, Furthermore, almost-spherical or-alumina 0.1-0.2 mu m in size was obtained by milling gamma-alumina with 3 wt% of AKP-30 alumina in the presence of 3 wt% of the alumina sol, followed by heat treatment at 11 00 degrees C for 1 h, The alumina sol that has been introduced in this work seems to act as a dispersant, in addition to helping to form a spherical s hape.