Densification and crystallization of glass powder compacts during constant heating rate sintering

Heating microscopy was used to study the interaction between the processes of densification and crystallization of glass powder compacts under constant heating rate sintering conditions without the application of external loads. For barium magnesium aluminosilicate (BMAS) glass powder compacts sintered between 800-1100 degrees C, it has been shown that the relative rates of crystallization and densification can be controlled by changing the heating rate. Samples sintered at a high heating rate of 15 K min(-1) could be fully densified in the amorphous state, delaying the onset of crystallization. In the samples sintered at a low heating rate of 1 K min(-1), the onset of crystallization coincided with the termination of densification at approximate to 1000 degrees C. Since the experiments were performed without an application of external loads, the results are applicable for the manufacturing of dense BMAS glass-ceramics via a pressureless sintering route.