Formation and characterisation of nanoporous TiO2 layers on microroughened titanium surfaces by electrochemical anodisation

Nanoporous titanium dioxide (TiO2) layers were successfully formed by an electrochemical anodisation method on microroughened titanium (Ti) surfaces in fluoride containing aqueous electrolyte. Microroughened Ti surfaces were produced by sandblasting with Al2O3 particles of 50 μm in diameter and acid-etching in a blend of HCl/H2SO4 solution. The surface morphology, topography and chemical composition of the specimens were analysed by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The surface roughness and the wettability of treated Ti surfaces were measured using profilometry and a contact angle measurement system, respectively. With anodising of sandblasted-/acid etched surfaces, micrometre- and nanometre-scale textures on titanium specimens were created. Results showed that these developed nanoporous-microroughened surfaces exhibited lower contact angle values than the other treated Ti surfaces. The sandblasted/acid-etched/anodised Ti specimen had a surface morphology with distinctively formed hills and valleys and higher surface roughness than the other anodised specimens. This study indicated that nanoporous TiO2 structures fabricated on microroughened Ti can be an effective way to modify the titanium surfaces for the future development of implant applications.BAP (Department of Scientific Research Projects) 2011.KB.FEN.029; EMUM (Center for Fabrication and Application of Electronic Materials) in Dokuz Eylul Universit

Temperature-dependent growth of ZnO structures by thermal oxidation of Zn coatings electrodeposited on steel substrates and their photocatalytic activities

In this work, zinc oxide (ZnO) nanostructures were successfully synthesized by thermal oxidation of zinc (Zn) coated steel substrates. Zn coatings were electrodeposited on the mild carbon steel sheet in the sulfate bath by DC current. The zinc coated samples were oxidized in air at distinct annealing temperatures between 400 degrees C and 800 degrees C. The phase structure and surface morphology of the ZnO films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photocatalytic activity of these ZnO layers was examined by means of decomposition of methylene blue (MB) aqueous solutions under DV lamp irradiation for various duration. The findings illustrated that annealing temperatures had a big effect on the morphology and structure of the ZnO layers. The annealed layers showed significantly enhanced photoactivity activity than the pure Zn layer under UV-irradiation. The sample with ZnO nanostructures oxidized at 800 degrees C exhibited a better photocatalytic degradation of MB than the other samples. This paper can provide an important contribution to the development of efficient photocatalysts for the solution of the environmental pollution problems

Mechanical and structural properties of electrodeposited Zn-Ni-Co ternary alloy coating on steel

Bu çalışmanın amacı, çelik malzeme yüzeyine elektrolitik yöntemle kaplanan Zn-Ni-Co (çinko-nikel-kobalt) alaşımlı kaplamanın mekanik ve yapısal özelliklerinin araştırılmasıdır. Akım yoğunluğu, pH ve sıcaklık gibi banyo değişkenlerinin kaplamanın yüzey morfolojisi ve kimyasal kompozisyonu üzerindeki etkisi belirlenmiştir. Farklı akım yoğunluğunda ve değişen kalınlıklarda çökertilen Zn-Ni-Co alaşımlı kaplamaların mekanik ve yapısal özellikleri incelenmiştir. Zn-Ni-Co alaşımlı kaplamanın yüzey görüntüsünün ve mekanik özelliklerinin Zn-Ni ve Zn-Co alaşımlı kaplamaya göre daha iyi olduğu gözlemlenmiştir. Aynı zamanda, Ni-Co alaşımlı kaplamanın mekanik özellikler açısından diğer kaplamalara göre daha iyi bir performansa sahip olduğu görülmüştür. Anahtar sözcükler: Zn-Ni-Co alaşımlı kaplama, mekanik ve yapısal özellikler, yüzey morfolojisi, Zn-Ni, Zn-Co ve Ni-Co alaşımlı kaplama The main purpose of this study is to investigate the mechanical and structural properties of electrodeposited Zn-Ni-Co (zinc-nickel-cobalt) ternary alloy coating on steel substrates. The influence of bath variables such as pH, current density and temperature on the surface morphology and chemical composition of coatings was determined. Microstructural and mechanical properties of Zn-Ni-Co ternary alloy coatings deposited at different current densities and various thickness were investigated. It was observed that the Zn-Ni-Co ternary alloy coatings exhibited more preferred surface appearence and mechanical properties as compared to Zn-Ni and Zn-Co alloy coatings electroplated at the same conditions. In addition, it was indicated that Ni-Co alloy coating showed greater mechanical performance than other alloy coatings. Keywords: Zn-Ni-Co alloy coating, mechanic and structural properties, surface morphology, Zn-Ni, Zn-Co ve Ni-Co alloys coatin