Development of sol-gel derived hydroxyapatite-titania coatings

Download

index.pdf

Date

2008

Author

Ün, Nusret Serhat

Metadata

Show full item record

Item Usage Stats

32
views

28
downloads

A processing route for development of hydroxyapatite (Ca10(PO4)6(OH)2 or HAp)-titania (TiO2) hybrid coatings on titanium alloy (Ti6Al4V) has been established. HAp powders of different size and morphology were synthesized by aqueous precipitation techniques using different precursor couples and XRD, SEM and FTIR were performed for complete characterization. Hybrid coatings were then prepared via sol-gel by incorporating presynthesized HAp powders into a titanium-alkoxide dip coating solution. Titania network is formed by hydrolysis and condensation of Ti-isopropoxide (Ti[OCH(CH3)2]4) based sols. The effect of titania sol formulation, specifically the effect of organic solvents on the microstructure of the dip coated films calcined at 500 ºC has been investigated. The coatings exhibit higher tendency for cracking when a high vapor pressure solvent, such as ethanol (C2H5OH) is used causing development of higher macroscopic stresses during evaporation of the sol. Titania sol formulations replacing the solvent with n-propanol (CH3(CH2)2OH) and acetly-acetone (C5H8O) combinations enhanced the microstructural integrity of the coating during evaporation and calcination treatments. Sol-gel processing parameters such as multilayer coating application and withdrawal rate can be employed to change the titania thickness in the range of 0.120 - 1.1 microns and to control the microstructure of HAp-titania hybrid coatings. Slower withdraw rates and multi-layer dip coating lead to coatings more vulnerable to cracking. A high calcination temperature in the range of 400 ºC-600 ºC lead to more cracking due to combined effect of densification originated stresses and thermal stresses upon cooling.

Subject Keywords

Metallurgy., Biochemistry.

URI

http://etd.lib.metu.edu.tr/upload/12609449/index.pdf
https://hdl.handle.net/11511/17653

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Optimization of silver nanowire networks for polymer light emitting diode electrodes Coskun, Sahin; Ates, Elif Selen; Ünalan, Hüsnü Emrah (IOP Publishing, 2013-03-29) Silver nanowire (Ag NW) networks are promising candidates for replacement of indium tin oxide (ITO). However, transparent conductors based on Ag NW networks often suffer from 'haziness' resulting from surface roughness. Thus, in addition to achieving suitable transparency and conductivity, surface roughness must be minimized if realistic implementation of Ag NW networks as transparent conductors is to be realized. In this work, we have reduced the surface roughness of Ag NW networks to below 5 nm as compare...
Quantum Transport Mode in Graphene Nanoribbon Based Transistor Hedayat, Sayed Norollah; Ahmadi, Mohammad Taghi; Sedghi, Hassan; Goudarzi, Hadi; Moradi, Shahram (American Scientific Publishers, 2017-09-01) Graphene has incredible carrier transport property with high application opportunity at single molecule level, which composes it as promising materials on nano electronic application. In order to develop the new device such as graphene nanoribbon transistor, Carbon Nanotube Field Effect Transistor (CNTFET) and nanowire based devices, it is essential to investigate the quantum limit in low dimensional systems. In this paper transmission coefficient of the schottky structure in the graphene based transistor i...
Design and implementation of a current source converter based active power filter for medium voltage applications Terciyanlı, Alper; Ermiş, Muammer; Department of Electrical and Electronics Engineering (2010) This research work is devoted to the design, development and implementation of a Current Source Converter (CSC) based Active Power Filter (APF) for Medium Voltage (MV) applications. A new approach has been proposed to the design of the CSC based APF for reducing the converter kVA rating considerably. This design approach is called the Selective Harmonic Amplification Method (SHAM), and is based on the amplification of some selected harmoniccurrent components of the CSC by the input filter, and the CSC contr...
Design of Carbon Nanotube Modified Conducting Polymer for Biosensing Applications Ozdemir, Caglar; Tuncagil, Sevinc; ODACI DEMİRKOL, DİLEK; TİMUR, SUNA; Toppare, Levent Kamil (2011-01-01) An electrochemical biosensor with improved performance was designed through the immobilization of glucose oxidase (GOx) onto conducting polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine (SNS-NH2) modified with carbon nanotubes (CNTs). For the optimization and characterization of the biosensor, pH profile, enzyme loading, reproducibility, operational stability experiments were carried out. It was found that the use of CNTs in a biosensing system enhanced the biosensor response. The linear relati...
Study of high radio frequency plasma discharge effects on carbon fiber using Raman spectroscopy Akbar, D.; Erözbek Güngör, Ümmügül (Elsevier BV, 2014-02-15) The goal of this research is to evaluate the potential of single and dual high RF reactors for the treatment of carbon fiber by Raman and FT-IR spectroscopies. Unsized poly-acrylonitrile (PAN) carbon fiber was treated with single high frequency (40.68 MHz) and double radio frequency capacitively coupled plasma (RF-CCP) discharge reactor (40.68/2.1 MHz) using pure nitrogen gas. The changes in the structure of the carbon fiber surfaces due to the variations of the D and G band intensity ratio (I-D/I-G), cryst...

Citation Formats

N. S. Ün, “Development of sol-gel derived hydroxyapatite-titania coatings,” M.S. - Master of Science, Middle East Technical University, 2008.