DENSIFICATION AND CRYSTALLIZATION OF GLASS POWDER COMPACTS DURING CONSTANT HEATING RATE SINTERING

Heating microscopy was used to study the interaction between the proce sses of densification and crystallization of glass powder compacts und er constant heating rate sintering conditions without the application of external loads. For barium magnesium aluminosilicate (BMAS) glass p owder compacts sintered between 800-1100 degrees C, it has been shown that the relative rates of crystallization and densification can be co ntrolled by changing the heating rate. Samples sintered at a high heat ing rate of 15 K min(-1) could be fully densified in the amorphous sta te, delaying the onset of crystallization. In the samples sintered at a low heating rate of 1 K min(-1), the onset of crystallization coinci ded with the termination of densification at approximate to 1000 degre es C. Since the experiments were performed without an application of e xternal loads, the results are applicable for the manufacturing of den se BMAS glass-ceramics via a pressureless sintering route.