Incorporation of Mullite as a Second Phase into Alumina by an Infiltration Technique

A process has been developed for incorporating mullite into alumina by infiltrating partially sintered (porous) alumina bodies with a prehydrolyzed ethyl silicate solution. The technique allows for the incorporation of mullite into only the surface (partial infiltration) or throughout the alumina body (complete infiltration). Sintering infiltrated bodies at 1600°C for 12 h yielded specimens with relative densities >98% in which only mullite and alumina were detected by X-Ray diffraction analysis. The presence of mullite significantly limited grain growth in alumina.