Influence of grain size of calcium silicate ceramics on hydroxyapatite precipitation in sbf solution

摘要

CaSiO_3 ceramics were prepared from coprecipitated powders using NaOH as precipitant with different washing treatments. The as-prepared ceramics differed in their Na content and Si/Ca ratio, which was reflected in their different microtextures. The grain size of the CaSiO_3 and the thickness of glassy phase at the grain boundaries increased with increasing Na content. These CaSiO_3 ceramics were soaked in a simulated body fluid (SBF) at 36.5 deg C for various periods of time. Precipitation of hydroxyapatite was observed as ball-like particles on surfaces of all the ceramics, but with different formation rates. The ceramics with smaller grain size showed a faster hydroxyapatite precipitation because the smaller CaSiO_3 grains easily dissolve, allowing the Ca~(2+) ion concentration and pH of the SBF to rapidly approach the suitable condition for precipitation of hydroxyapatite.