Production of bioactive dense hydroxyapatite using egg shell derived powder /
In this work, hydroxyapatite powder is synthesized via a novel hydrothermal process from a biogenic source of calcium phosphate, hen's eggshell. Dense hydroxyapatite bodies are prepared via uniaxial pressing of circular disc shape of 1:4 height-todiameter ratio at various compaction pressures....
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur :
Kulliyyah of Engineering, International Islamic University Malaysia,
2012
|
| Subjects: | |
| Online Access: | Click here to view 1st 24 pages of the thesis. Members can view fulltext at the specified PCs in the library. |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | In this work, hydroxyapatite powder is synthesized via a novel hydrothermal process from a biogenic source of calcium phosphate, hen's eggshell. Dense hydroxyapatite bodies are prepared via uniaxial pressing of circular disc shape of 1:4 height-todiameter ratio at various compaction pressures. This is followed by a pressureless sintering at various sintering temperatures. The effect of different compaction pressures and sintering temperatures on the phase behaviour of the synthesized powder and mechanical properties of the dense bodies are investigated. Synthesis of hydroxyapatite powder from eggshell as the calcium precursor was proved successful by phase analysis. XRD and FTIR reveals phases of calcium phosphate from pure hydroxyapatite to existence of β-TCP and calcium pyro phosphate (CPP) at elevated temperature, as well as better crystallinity as indicated by narrower peak of XRD. The microstructural development of all sintered hydroxyapatite is found to be affected by compaction pressure and sintering temperature. Density and average grain size increase sharply at sintering temperature of 1100ºC and improve gradually with the increasing compaction pressure. Mechanical properties of dense bodies are measured by a diametrical compression test whereby compressive strength increases almost linearly at increasing temperature until the maximum temperature of 1100oC, where the strength declines at a higher temperature believed to be due to the appearance of second phase in sintered hydroxyapatite. The highest compressive strength achieved is 15.5 MPa. Meanwhile increase of compaction pressure of up to 21 MPa reveals a linear increase of compressive strength. Similarly, Vickers' hardness test shows the same effect of sintering temperature, obtaining a maximum hardness value of 8.94 GPa at 1100oC before declining rapidly at higher temperatures. In a nutshell, sintering condition can be manipulated to achieve required mechanical strength, with caution taken for the maximum sintering temperature, as exaggerated grain growth accompanied by grain coalescence promotes weak mechanical strength and increases brittleness. |
|---|---|
| Item Description: | Abstracts in English and Arabic. "A dissertation submitted in fulfilment of the requirement for the degree of Master of Science in Materials Engineering."--On t.p. |
| Physical Description: | xiii, 95 leaves : ill. ; 30cm. |
| Bibliography: | Includes bibliographical references (leaves 86-94). |