High‐Strength Mica‐Containing Glass‐Ceramics

Glass‐ceramics containing barium–mica in the system Ba 0.5 Mg 3 (Si 3 AIO 10 )F 2 –2MgO · 2Al 2 O 3 · 5SiO 2 –Ca 3 (PO 4 ) 2 are two to three times stronger than conventional mica‐containing glass‐ceramics. Moreover, the barium‐mica glass‐ceramics are easier to machine, as confirmed by a drilling test using conventional steel tools. Such mechanical properties are attributable to the microstructure of the barium–mica glass‐ceramics. Very fine, interlocking mica crystals are precipitated in the glass, and a crack‐deflection mechanism is observed by scanning electron microscopy.