PREPARATION OF HIGH-STRENGTH CALCIUM-MICA-CONTAINING MACHINABLE GLASS-CERAMICS

New machinable glass-ceramics containing fine calcium-mica were prepared by crystallizing glasses in the system CaxK(1-2x)Mg3(Si3AlO10)F2. TEM observation suggested that the host glasses were separated into two fine phases, and the precipitating crystal size decreased with increasing the potassium content. The machinability were improved with increasing the calcium content. The mechanical strength and the machinability of the glass-ceramics depended on both the amount of calcium-mica precipitated and the crystal size. Because of its high bending strength (almost-equal-to 300 MPa) and its hardness compatible with natural teeth, it has great potential for dental prosthetic applications.