Sintering behaviour of fluorapatite-silicate composites produced from natural fluorapatite and quartz
Document Type
Article
Publication Date
6-15-2021
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 degrees C to 1350 degrees 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 degrees 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 degrees C and a regular rounded grain structure when sintered at 1350 degrees 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.
Keywords
Fluorapatite, Quartz, Composites, Sintering behaviour
Divisions
mechanical,PHYSICS
Funders
FRGS grant (FP0202018A)
Publication Title
Ceramics International
Volume
47
Issue
12
Publisher
Elsevier
Publisher Location
THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND