Gelcasting and sintering of hydroxyapatite materials: Effect of particle size and Ca/P ratio on microstructural, mechanical and biological properties
| Autor: | Jean Marc Christian Tulliani, Paola Palmero, Mehdi Mohammadi, Laura Montanaro |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
In-vitro bioactivity Ca/P ratio Sintering Mechanical properties Apatite Hydroxyapatite Phase decomposition chemistry.chemical_compound Materials Chemistry Particle size-density relationship ttcp Tetracalcium phosphate Microstructure Grain growth Calcium phosphates Chemical engineering chemistry visual_art Particle-size distribution Ceramics and Composites visual_art.visual_art_medium Particle size |
| Zdroj: | Journal of the European Ceramic Society. 41:7301-7310 |
| ISSN: | 0955-2219 |
| DOI: | 10.1016/j.jeurceramsoc.2021.07.025 |
| Popis: | The sintering behaviour and microstructural evolution of two batches of a commercial calcium-deficient hydroxyapatite powder were investigated. First, the sintered density as a function of the starting particle size distribution was studied, and the minimum particle size to get the desired target density was determined. Then, as the two batches were characterized by a slight difference in Ca/P ratio, the role of such ratio on phase and microstructural evolutions during sintering, as well as on mechanical and biological properties was investigated. It was observed that the powder with lower Ca/P ratio underwent significant hydroxyapatite (HA) to β-tricalcium phosphate (β-TCP) decomposition, with a simultaneous formation of tetracalcium phosphate (TTCP). The microstructure of sintered gelcast samples evolved during isothermal sintering at 1300 °C, moving from a starting homogeneous and narrow grain size distribution to a bimodal distribution after 3 h sintering. In fact, over time, large grains decomposed into smaller ones, finally providing a microstructure composed of coarse grains surrounded by plenty of ultra-fine grains. On the contrary, the powder with the higher Ca/P ratio provided a limited HA to β-TCP transformation, and normal grain growth by increasing the sintering time. Such differences lead to different mechanical properties for gelcast samples produced by the two powder batches, as the material with the lower Ca/P ratio affected by lower mechanical strength. Finally, sintered samples from both powders showed in-vitro bioactivity, with a larger surface coverage observed for the lower Ca/P ratio material. The morphology of the apatite layer seemed to be affected by the material composition, too, showing flake-like and needle-like morphologies depending on the Ca/P ratio of the starting powder. |
| Databáze: | OpenAIRE |
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