Browsing by Author "Ocal, Ezgi Butev"

Now showing 1 - 2 of 2

Citation - WoS: 55
Citation - Scopus: 56
Comparison of the Short and Long-Term Degradation Behaviors of As-Cast Pure Mg, Az91 and We43 Alloys
(Elsevier Science Sa, 2020) Ocal, Ezgi Butev; Esen, Ziya; Esen, Ziya; Aydinol, Kadri; Dericioglu, Arcan F.; 52373; Ortak Dersler Bölümü
The corrosion behaviors of pure magnesium, AZ91, and WE43 alloys have been evaluated by weight loss, hydrogen evolution rate, pH change measurements and potentiodynamic polarization as well as electrochemical impedance spectroscopy (EIS) methods. Main corrosion product formed on the surface of Mg/Mg-alloys after immersion of 24 h was Mg(OH)(2) on the other hand, at the end of the 20 days additional CaCO3 which was found to display a critical role in degradation characteristics of the samples, was found. Examination in the cross section of the polished surfaces revealed that protective layers became thicker and corrosion rate of the samples decreased possibly due to increased protective abilities of the surfaces. Intermetallics in AZ91 and WE43 alloys acted as cathodic centers and induced micro galvanic corrosion. Undermining of intermetallics in WE43 alloy intensified the corrosion rate. AZ91 alloy exhibited the lowest corrosion rate among the samples when tested in simulated body fluid (SBF).
Citation - WoS: 5
Citation - Scopus: 6
Surface characteristics and in-vitro behavior of chemically treated bulk Ti6Al7Nb alloys
(Elsevier Science Sa, 2017) Esen, Ziya; Esen, Ziya; Ocal, Ezgi Butev; 52373; Ortak Dersler Bölümü
The effect of various treatments on surface chemical composition and structure, and bioactivity of Ti6Al7Nb bulk alloys has been investigated. The alloys were treated employing aqueous solutions of NaOH and CaCl2 separately, and also by subsequent CaCl2 treatment after NaOH treatment (NaOH-CaCl2 treatment) which were followed by heat treatment. NaOH treatment was observed to be effective in enrichment of surface layer with Na. On the other hand, Na+ ions were mostly replaced by Ca2+ ions as a result of NaOH-CaCl2 treatment, while single step CaCl2 treatment was less effective in Ca incorporation. Additionally, porous network surface structure seen in NaOH and NaOH-CaCl2 treated samples was completely different than globular morphology detected in CaCl2-treated samples in single step. Subsequent heat treatments caused coarsening of surface structure and loss of some Na+ and Ca2+ ions. NaOH and NaOH-heat treated samples did not exhibit apatite formation within 15 days immersion in simulated body fluid (SBF). On the other hand, NaOH-CaCl2 samples had the highest apatite formation; however, NaOH-CaCl2-heat treated samples did not display any mineralization. Conversely, CaCl2 treated samples allowed apatite formation after heat treatment. (C) 2016 Elsevier B.V. All rights reserved.