MULLITE FABRICATION FROM FUMED SILICA AND BOEHMITE SOL PRECURSORS

A particular combination of commercially available silica and alumina precursors (fumed silica nanopowders and a boehmite sol) have been use d to prepare mullite ceramics using colloidal processing and transient viscous sintering. The simple pressureless sintering route employed p roduced dense monolithic mullite samples at temperatures much lower th an those used in other studies. A very homogeneous and fine microstruc ture (grain size approximate to 0.8 mu m) was achieved by firing cold- isostatically pressed ''green'' compacts for 2 h at 1200 degrees C fol lowed by 5 h at 1350 degrees C.