Microstructure of Mica‐Based Nanocomposite Glass‐Ceramics

A high-strength machinable glass-ceramic was prepared by controlling the crystallization of ZrO[sub 2]-containing Ca[sub 0.43]K[sub 0.14]Mg[sub 3] (Si[sub 3]AlO[sub 10])F[sub 2] glass. A unique microstructure of the glass-ceramic was observed, using transmission electron microscopy (TEM): zirconia particles of nanometer size, 20-50 nm, were embedded in calcium mica crystal. After zirconia particles grew in nanometer size, the mica crystals were precipitated to embed the particles. The particles were identified as transformable tetragonal zirconia crystals. This texture leads to high strength (500 MPa in bending) and good machinability.