Development of phosphocalcic bioceramics from natural phosphate
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Date
2021
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Publisher
Université de M'sila
Abstract
In this work, the sintering behavior 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 sintered 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 phases, 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 formation of carbonated HAp in the in-vitro test " immersion
in SBF" confirms that we have bioactive materials. In the second part, the alumina-fluorapatite composites' sintering
behaviour from alumina and Algerian natural phosphate was investigated using the conventional sintering method from
1000 to 1600 ° C. Besides; we were studying the effect of titanium oxide (0, 1, 3, 5, and 10%) on these composites'
Physico-chemical properties. Sintered samples were examined in terms of formed phases by X-ray diffraction, shrinkage
rate, bulk density, open porosity ratio, Vickers microhardness, Tensile strength, and SEM's morphological structure.
The results indicated that the addition of titanium oxide effectively improved samples' density, especially those
containing 3 and 5%, reaching a value of 3.22 g/cm3, and the percentage of open porosity reached 0,94 and 0,64%,
respectively. Also, this study found that titanium oxide has a clear and good effect on microhardness, reached to 13.65
GPa and a Hight fracture strength of about 140 MPa, and using large proportions of additives adversely affects the
properties of these composites.
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Keywords
Natural phosphate, fluoropatite, quartz, alumina, biomaterials, mechanical properties.