Browsing by Author "Aksakal, B."

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Bone Mineral Density Assessment by Dual Energy X-Ray Absorbtiometry as Multiple or Single Assessment of Rat Bones Causes Discrepancy
(2012) Koc, Z.P.; Balci, T.A.; Say, Y.; Aksakal, B.; Güler, A.
Corrosion Protection of Aa6061-T4 Alloy by Sol-Gel Derived Micro and Nano-Scale Hydroxyapatite (Ha) Coating
(Springer, 2012) Sonmez, S.; Aksakal, B.; Dikici, B.
Micron and nano-scale hydroxyapatite (HA) were coated successfully on AA6061-T4 substrates by sol-gel method. Besides, the effects of coating thickness on adhesion strength and corrosion behaviour of the coatings were studied. Corrosion resistance was measured by potentiodynamic polarization test using a potentiostat under in vitro conditions. The coatings before and after corrosion tests were characterized by adhesion tests, a scanning electron microscopy attached with EDS and X-ray diffraction analysis. The results revealed that all the coatings exhibit a passive behaviour in Ringer's solution. Specimens coated with nano-scale HA had the higher corrosion resistance than micro-scale coatings. The highest corrosion resistance appeared to be for the similar to 30 mu m nano-scale HA coated substrates. However, for micro-scale HA coatings, the highest adhesion resistance was obtained at similar to 30 mu m film thickness.
The Effect of Coating Thickness on Corrosion Resistance of Hydroxyapatite Coated Ti6al4v and 316l Ss Implants
(Springer, 2010) Aksakal, B.; Gavgali, M.; Dikici, B.
Hydroxyapatite (HAP) has been coated onto Ti6Al4V and 316L SS substrates by sol-gel method. The coating thicknesses for the analysis were about 40 and 72 mu m. Adhesion and corrosion tests have been conducted on uncoated and HAP-coated substrates. The coatings were characterized by XRD, SEM, and adhesion analysis. The corrosion resistance was examined in vitro by potentiodynamic polarization technique in Ringer's solution at room temperature. Electrochemical analysis indicated that the highest corrosion susceptibility was found on 72-mu m-coated 316L SS, and the 40-mu m HAP-coated Ti6Al4V showed the highest corrosion resistance. It was observed that the coating thickness was an effective parameter on both adhesion and corrosion resistance. It was shown that adhesion and corrosion resistance decreased with increasing coating thickness on both substrates.
Influence of Hydroxyapatite Coating Thickness and Powder Particle Size on Corrosion Performance of Ma8m Magnesium Alloy
(Elsevier Science Sa, 2014) Sonmez, S.; Aksakal, B.; Dikici, B.
To improve the corrosion resistance of MA8M magnesium alloy, sol-gel derived coatings of micron and nano-scale hydroxyapatite (HA) were coated successfully on MA8M magnesium alloy substrates. The effects of coating thickness and HA powder particle size on the adhesion strength and corrosion resistance on magnesium alloy was investigated. Potentiodynamic polarization (PDS) tests were performed in a Ringer solution. The coatings before and after corrosion tests were characterized by adhesion tests, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The results show that the micro-scale-HA coated Mg substrates were more corrosion resistant than the nano-scale-HA coatings. Corrosion susceptibilities of the nano-scale-HA coated samples were influenced inversely. The anodic activity of the micro-scale-HA coatings increased with increased coating thickness. The coated film provided good barrier characteristics and achieved good corrosion protection for Mg substrates when compared to substrates without any coatings. The best corrosion resistance was obtained at 30 mu m film thickness for micro-scale-HA coatings. (C) 2014 Elsevier B. V. All rights reserved.
Production Technique–structure Relationship in Bioceramic-Coated Scaffold Applications
(Elsevier, 2023) Aslan, N.; Topuz, M.; Aksakal, B.; Dikici, B.
It is well known that the surface of metal-based implants is very resistive in aggressive body environments due to the noble oxide layer naturally formed on their surfaces. However, their osseointegration properties are very low. By the way, specific cells attached are desired on the implant surface when the surface of an implant connects with tissue in many circumstances. Thus in parallel with technological developments, biomedical engineering focuses on the growth of new tissue on the implant surface or in the porosities of the implant. The bulk properties of metallic scaffolds, especially Young’s modulus, can be controlled by the porosity ratio of the scaffold but cannot form a bond between the implant and tissue interfaces. Thus the coating of scaffold walls with a bioactive material is required. In this chapter, bioceramic coating techniques of scaffolds, mechanical and corrosion behavior, biocompatibility, and interactions of surface/tissue interface, especially considering the last published reports, were reviewed, in detail. © 2023 Elsevier Ltd. All rights reserved.
Synthesis and Characterization of Hydroxyapatite/Tio2 Coatings on the Β-Type Titanium Alloys With Different Sintering Parameters Using Sol-Gel Method
(Maik Nauka/interperiodica/springer, 2018) Dikici, B.; Niinomi, M.; Topuz, M.; Say, Y.; Aksakal, B.; Yilmazer, H.; Nakai, M.
In this study, hydroxyapatite (HA) based composite films were successfully syntheses on the beta-type Ti29Nb13Ta4.6Zr (TNTZ). The solutionized TNTZ substrates coated with HA and HA/Titania (TiO2) bioactive composite coatings by sol-gel method under various sintering parameters related to sintering temperatures and heating ramp rates. Microstructural observations of the coatings revealed that apatite was formed on the substrates. The hardness values of the coatings increase with increasing both the sintering temperature and the TiO2 concentration in the coatings layer. However, it was found that the heating ramp rate of the sintering was not affecting the hardness values so much. Also, the hardness values of the HA/TiO2 composite coatings at all sintering temperatures were higher than only HA coated TNTZ samples due to the existence TiO2 phases in the HA matrix. Results indicating that the doping of HA with TiO2, improve the physical consistency between the coating layer and the substrates and provide a better inter-particle bonding due to the existence TiO2 phases in the HA.