In vitro bioactivity investigation of alkali treated Ti6Al7Nb alloy foams

Butev, Ezgi
Bor, Sakir
Biocompatible Ti6Al7Nb alloy foams with 70% porosity manufactured by space holder method were activated via alkali treatment using 5 M NaOH solution at 60 degrees C. The interconnected pore structures enabled formation of homogenous sodium rich coating on the foam surfaces by allowing penetration of alkali solution throughout the pores which had average size of 200 mu m. The resulted coating layer having 500 nm thickness exhibited porous network morphology with 100 nm pore size. On the other hand, heat treatment conducted subsequent to alkali treatment at 600 degrees C in air transformed sodium rich coating into crystalline bioactive sodium titanate phases. Although the coatings obtained by additional heat treatment were mechanically stable and preserved their morphology, oxidation of the samples deteriorated the compressive strength significantly without affecting the elastic modulus. However, heat treated samples revealed better hydroxyapatite formation when soaked in simulated body fluid (SBF) compared to alkali treated foams. On the other hand, untreated surfaces containing bioactive TiO2 layer were observed to comprise of Ca and P rich precipitates only rather than hydroxyapatite within 15 days. The apatite formed on the treated porous surfaces was observed to have flower-like structure with Ca/P ratio around 1.5 close to that of natural bone.


Characterization of Ti6Al7Nb alloy foams surface treated in aqueous NaOH and CaCl2 solutions
Butev, Ezgi; ESEN, ZİYA; Bor, Sakir (2016-07-01)
Ti6Al7Nb alloy foams having 53-73% porosity were manufactured via evaporation of magnesium space holders. A bioactive 1 mu m thick sodium hydrogel titanate layer, NaxH2-xTiyO2y+1., formed after 5 M NaOH treatment, was converted to crystalline sodium titanate, Na2TiyO2y+1, as a result of post-heat treatment. On the other hand, subsequent CaCl2 treatment of NaOH treated specimens induced calcium titanate formation. However, heat treatment of NaOH-CaCl2 treated specimens led to the loss of calcium and disappea...
Enhanced capacitive behaviour of graphene based electrochemical double layer capacitors by etheric substitution on ionic liquids
Siyahjani, Shirin; Oner, Saliha; Diker, Halide; GÜLTEKİN, BURAK; Varlikli, Canan (Elsevier BV, 2020-08-01)
In this study, we report the effect of etheric substituents in imidazolium and ammonium based ionic liquids (IL) on the performance of electrochemical double layer capacitors (EDLC) consisted of gel polymer electrolyte (GPE) and reduced graphene oxide (RGO) electrode. GPEs contain poly (vinylidene fluoride-hexafluompropylene) (PVDF-HFP) and the ILs. Ammonium and imidazolium based ionic liquids (ILs) differ by their length of etheric groups and etheric group contents, respectively. According to the cyclic vo...
Characterization of Ti-6Al-4V alloy foams synthesized by space holder technique
ESEN, ZİYA; Bor, Sakir (2011-03-25)
Ti-6Al-4V foams, biomedical candidate materials, were synthesized by powder metallurgical space holder technique as a result of evaporation of magnesium to achieve desired porosity content. Final products contained porosities in the range similar to 43-64% with an average macropore size between 485 and 572 mu m and a lamellar type Widmanstatten microstructure composed of alpha-platelets and beta-laths. Unlike the case of bulk Ti-6Al-4V alloy tested under compression loading, compression stress-strain curves...
Surface characteristics and in-vitro behavior of chemically treated bulk Ti6Al7Nb alloys
ESEN, ZİYA; Ocal, Ezgi Butev (2017-01-15)
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...
A mechanism for the enhanced attachment and proliferation of fibroblasts on anodized 316L stainless steel with nano-pit arrays
Ni, Siyu; Sun, Linlin; Ercan, Batur; Liu, Luting; Ziemer, Katherine; Webster, Thomas J. (Wiley, 2014-08-01)
In this study, 316L stainless steel with tunable nanometer pit sizes (0, 25, 50, and 60 nm) were fabricated by an anodization procedure in an ethylene glycol electrolyte solution containing 5 vol % perchloric acid. The surface morphology and elemental composition of the 316L stainless steel were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The nano-pit arrays on all of the 316L stainless steel samples were in a regular arrang...
Citation Formats
E. Butev, Z. ESEN, and S. Bor, “In vitro bioactivity investigation of alkali treated Ti6Al7Nb alloy foams,” APPLIED SURFACE SCIENCE, pp. 437–443, 2015, Accessed: 00, 2020. [Online]. Available: