Glass Cristallization-controlled Pore Retantion in Calsium-phosphate Glassceramics from Powder Sintering of CaO-P2O5-B2O3-Al2O3-TiO2-ZrO2статья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 23 ноября 2017 г.
Аннотация:The formation of a porous structure plays a key role in the synthesis of calcium-phosphate biomaterials for bone
implantology and endoprosthesis, since it determines both bioactivity and mechanical strength of the final material.
The results of the present investigation demonstrate the feasibility of a crystallization-controlled design of
material porosity, without pore-former addition, through a low-cost glass powder sintering process. The method
takes advantage of the partial crystallization of glass withmolar composition 45P2O5–50СаО–5Al2O3, with added
5B2O3, 5ZrO2, and 5TiO2, for achieving controlled pore retention and mechanical strength. The investigation —
comprising differential thermal analysis, X-ray diffraction, scanning electron microscopy, viscosity, density, flexural
and compressive strength measurements — gives a quantitative description of how the pore retention is
driven by the systemviscosity and by the formation of a reinforcing framework of precipitated crystals, the latter
ones preventing the collapse into a vitrified non-porous material. The final porosity turns out to be describable by
amodified Frenkel's model accounting for the crystallization constraints to the liquid flow. As a result, the present
study demonstrates the possibility of obtaining calcium-phosphate glassceramicswith 70% of crystal fraction,
flexural strength 25 MPa, compressive strength 40 MPa, and a final porosity of 25% with pore sizes selectable
from 10 to 180 μm from the starting grain size. Importantly, bioactivity tests show good bio-integration and
pore filling with neogenic bone tissue and blood vessels, without toxicity, opening the way to possible applications
in small-bone implantology