Sintering behaviour of fluorapatite–silicate composites produced from natural fluorapatite and quartz
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Date
2021
Journal Title
Journal ISSN
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Publisher
Université de M'sila
Abstract
In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable
amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered
in air at temperatures from 1000 ◦C to 1350 ◦C. The effects of temperatures on the densification, phase formation,
chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited
mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite,
wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature.
The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk
density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite
when sintered at 1100 ◦C. The addition of quartz was found to alter the microstructure of the composites, where
it exhibited a rod-like morphology when sintered at 1000 ◦C and a regular rounded grain structure when sintered
at 1350 ◦C. A wetted grain surface was observed for composites containing high quartz content and was believed
to be associated with a transient liquid phase sintering
Description
Keywords
Fluorapatite Quartz Composites Sintering behaviour