Pressureless sintering and characterization of Al2O3-platelet-reinforced barium-magnesium aluminosilicate glass-ceramic composites

The fabrication of Al2O3-platelet-reinforced (BMAS) glass-ceramics via a low-cost pressureless sintering route has been considered. Two new compaction techniques were introduced for the fabrication of this type of composite: pressure filtration and rotary forging. For comparison, conventional processing using uniaxial and isostatic die cold-pressing was considered also. Pressure filtration did not yield improved results in comparison with dry compaction techniques in terms of final density. Rotary forging, on the contrary, was shown to be an attractive compaction technique since it allows the fabrication of nearly fully dense composites using forming pressures 10 times lower than those employed using conventional die-pressing. Composites containing up to 20 vol% of platelets could be densified fully under pressureless conditions at temperatures of 980 degrees C by exploiting the viscous flow of the amorphous matrix. (C) 1997 Elsevier Science Limited.