Fabrication and Characterization of Nanostructured Calcium Phosphate and Zirconium Dioxide Composites

الملخص

The aim of this study is to fabricate and characterize ceramic composites made of Ca10(PO4)6(OH)2 and ZrO2 using a simple powder pressing technique and to study the effect of addition of ZrO2 on the biaxial flexural strength (BFS) of the ceramic composites. Various compositions of hydroxyapatite (HAp) Ca10(PO4)6(OH)2 and zirconia powder ZrO2, ranging from 10 to 90 wt% ZrO2, were prepared using a wet mixing process. Ten compacts (13.5mm3mm) were made for each group, pressed and fired in air at sintering (firing) temperatures from 1100 to 1450oC for up to 12 hrs. The bulk density, true porosity, linear shrinkage and BFS were evaluated.
The true porosity reduced and linear shrinkage increased with increasing firing temperature and amounts of zirconia, whereas the firing time had little effect. The highest mean value achieved for the BFS was 269 MPa (20) for a composition of 70% ZrO2 and 30% HAp fired at 1450oC for 6 hrs, however with the hydroxyapatite (HAp) decomposed to -TCP as reported earlier [1].
We conclude that firing temperature and composition affect densification behaviour of calcium phosphate/ZrO2 ceramic composites. The BFS increases with a reduction of porosity and increases with both firing temperature and additions of ZrO2. It was noted that there is considerable scope for improvement in the BFS values by reducing the porosity of these ceramics composite. Further work is needed to examine the crystals structure and to elucidate the microstructural features of the composites.