Regina Monteiro

Citation:

Lima, M. M. R. A., and R. C. C. Monteiro. "Crystallization of a borosilicate glass during sintering studied by dilatometry and XRD analysis." Materials Science Forum. 455-456 (2004): 212-215.

Abstract:

The crystallization of a borosilicate glass, when compacts of powdered glass were sintered under various conditions, was investigated by dilatometric and XRD analysis. The dilatometry results from non-isothermal sintering experiments until 800°C, performed at different heating rates (1, 2, 5, 8 and 10°C/min), revealed that the compacts started to shrink above ∼ 600°C and that the shrinkage decreased with the increase of the heating rate for temperatures up to ∼750°C. Above this temperature, and specifically when the samples were heated at heating rates < 5°C /min, the shrinkage was hindered, while samples heated at heating rates ≥ 5°C/min showed continuous shrinkage. XRD results showed that the formation of cristobalite had occurred during the sintering at the lowest heating rates and therefore, the presence of this crystalline phase was affecting the shrinkage of the compacts, inhibiting further sintering of the glass. The crystallization of the glass when sintered at a temperature in the range 700-850°C and hold at the selected temperature during various times was also analysed. XRD results showed that both cristobalite and quartz were present in glass compacts sintered under particular conditions (for example, after heating during 24h at 725°C and 765°C). Quartz dissolution took place when the glass samples were sintered at 850°C. At this temperature and whatever the sintering time, cristobalite was the only crystalline phase present in the sintered compacts.

Notes:

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