Hydroxyapatite Introduction
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FINAL YEAR PROJECT 1 (Semester2, Academic Year 2007/2008)
Title :
Sintering Behaviour of Cerium-doped Hydroxyapatite Bioceramics Prepared by:
KELVIN HOH CHEE WAI (ME075719) Project Supervisor: Assoc. Prof. Ir. Dr. Ramesh Singh
Department of Mechanical Engineering Universiti Tenaga Nasional (UNITEN)
OBJECTIVE
To investigate the effects of adding small amounts of Cerium Oxide (CeO 2 ) on the sinterability of nanocrystalline HA powder.
METHODOLOGY Literature Review
FYP 1
Preparation of Cerium-doped HA powder Powder Characterization Body Preparation Consolidation Process Mechanical Testing & Evaluation Report preparation & presentation
FYP 2
INTRODUCTION •What is Hydroxyapatite? It is the most suitable ceramic material for hard tissue replacement implant from the point of view of Biocompatibility. It has the chemical similarity with the mineral portions of hard tissue. (e.g. Calcium + Phosphorus) Chemical formula:
Ca10(PO4)6(OH)2
•Why Hydroxyapatite is being developed? Metallic materials have various problems to be used as implant. (e.g. negative tissue reaction, wear and corrosion.) Zirconia (ZrO2) and Alumina (Al2O3) belong to Bioinert materials.
Table 1 : Typical Properties of Bioceramics
The Limitation of Hydroxyapatite
How to improve the Hydroxyapatite?
Control of sintering temperature & atmosphere.
Manipulation of processing parameters.
Addition of additives (dopants) into the HA powder.
Ideal Sintering Additive (dopant)
Aid densification of HA without decomposition.
No effect on Biocompatibility & Bioactive phases.
Control of grain size.
Improve the mechanical properties.
X-ray Diffractometer (XRD) 1250C
-TCP
1400C
1450C
TTCP
-TCP
CaO
Scanning Electron Microscope (SEM)
Y O
ky d
Hall-Petch Equation
Where, ky óo d óy
= = = =
material constant starting stress for dislocation movement grain diameter (m) Fracture strength
Fracture Toughness vs Porosity
Vickers Hardness vs Sintering Temperature
CONCLUSIONS Hydroxyapatite is suitable for fabricating the artificial teeth & bone due to its excellent biocompatibility. Improvement on Fracture Toughness & Young’s Modulus is needed. Cerium was found that it decreases the crystal’s size of the HA.
Stoichiometric
The stoichiometric Ca/P ratio of HA
:
1.67
Calcium Oxide (CaO) forms if Ca/P
:
>1.67
-TCP and -TCP forms (Tricalcium Phosphate)
:
<1.67
Title :
Sintering Behaviour of Cerium-doped Hydroxyapatite Bioceramics Prepared by:
KELVIN HOH CHEE WAI (ME075719) Project Supervisor: Assoc. Prof. Ir. Dr. Ramesh Singh
Department of Mechanical Engineering Universiti Tenaga Nasional (UNITEN)
OBJECTIVE
To investigate the effects of adding small amounts of Cerium Oxide (CeO 2 ) on the sinterability of nanocrystalline HA powder.
METHODOLOGY Literature Review
FYP 1
Preparation of Cerium-doped HA powder Powder Characterization Body Preparation Consolidation Process Mechanical Testing & Evaluation Report preparation & presentation
FYP 2
INTRODUCTION •What is Hydroxyapatite? It is the most suitable ceramic material for hard tissue replacement implant from the point of view of Biocompatibility. It has the chemical similarity with the mineral portions of hard tissue. (e.g. Calcium + Phosphorus) Chemical formula:
Ca10(PO4)6(OH)2
•Why Hydroxyapatite is being developed? Metallic materials have various problems to be used as implant. (e.g. negative tissue reaction, wear and corrosion.) Zirconia (ZrO2) and Alumina (Al2O3) belong to Bioinert materials.
Table 1 : Typical Properties of Bioceramics
The Limitation of Hydroxyapatite
How to improve the Hydroxyapatite?
Control of sintering temperature & atmosphere.
Manipulation of processing parameters.
Addition of additives (dopants) into the HA powder.
Ideal Sintering Additive (dopant)
Aid densification of HA without decomposition.
No effect on Biocompatibility & Bioactive phases.
Control of grain size.
Improve the mechanical properties.
X-ray Diffractometer (XRD) 1250C
-TCP
1400C
1450C
TTCP
-TCP
CaO
Scanning Electron Microscope (SEM)
Y O
ky d
Hall-Petch Equation
Where, ky óo d óy
= = = =
material constant starting stress for dislocation movement grain diameter (m) Fracture strength
Fracture Toughness vs Porosity
Vickers Hardness vs Sintering Temperature
CONCLUSIONS Hydroxyapatite is suitable for fabricating the artificial teeth & bone due to its excellent biocompatibility. Improvement on Fracture Toughness & Young’s Modulus is needed. Cerium was found that it decreases the crystal’s size of the HA.
Stoichiometric
The stoichiometric Ca/P ratio of HA
:
1.67
Calcium Oxide (CaO) forms if Ca/P
:
>1.67
-TCP and -TCP forms (Tricalcium Phosphate)
:
<1.67
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