Microstructure and properties of nanostructured coating on Ti6Al4V

Implant surface properties of Ti6Al4V alloy that is currently used as a biocompatible material because of a variety of unique properties can be improved by a self-organized TiO2 layer. The TiO2 nanotubes forming on the titanium-based materials is a relatively recent technology for the surface properties modification and represents pronounced potential in promoting cell adhesion, proliferation, and differentiation that facilitate an implant osseointegration. This work focuses on the influence of surface treatment quality and anodic oxidation parameters on the structure features and properties of TiO2 nanotube coatings. The nanotubes were formed on Ti6Al4V alloy substrates by simultaneous surface oxidation and controlled dissolving of an oxide film in the presence of fluorine ions. The anodization process on ground or polished samples was performed at experimental condition of 30 V for 1 h. The selected anodized samples were heat treated for 2 h at 500 degrees C under flowing argon. All samples were characterized by scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy. The corrosion rate in physiological solution reached 0.0043, 0.0182, and 0.0998 mm per year for the samples in polished and not-anodized, as-anodized, and anodized-heat treated conditions, respectively.Web of Science133art. no. 70

Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva

The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing inphosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. Thestructure and composition of the films were investigated using scanning electronicmicroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition ofthe oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zrand O, the layers formed in phosphoric acid contain phosphorus originating from thephosphoric acid. When the phosphoric acid solution contains NaF, fluorine is alsoincorporated into the oxide layer. The oxides formed at a higher voltage have greaterroughness than those formed at 30 V. Anodized samples exhibit smaller current densitiesduring anodic polarization compared to the as-received zirconium covered with native oxide.Fil: Romonti, Daniela E.. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Gomez Sanchez, Andrea Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Milošev, Ingrid. Jožef Stefan Institute; EsloveniaFil: Demetrescu, Ioana. Faculty of Applied Chemistry and Materials Science; RumaniaFil: Ceré, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Anodized aluminium pressure sensitive paint: effect of paint application technique

The porous surface of the Anodized Aluminium Pressure Sensitive Paint (AA-PSP) is what differentiates it from conventional sol–gel based PSPs, leading to a faster response time of the paint. The objective of the current study is to examine the effect of the paint application technique, i.e., whether the AA substrate is dipped or sprayed, on the pressure and temperature sensitivity. A more practical procedure for preparing the AA samples is also presented. Scanning Electron Microscope (SEM) images are acquired together with the calibration of the AA-PSP at various temperatures and pressures to determine the effectiveness of each application technique. The results revealed that the AA sample which was dipped in the PSP solution shows a higher pressure sensitivity than the sprayed one. The SEMs show that spraying leads to the covering up of the micropores created on the surface and undermining the benefit of anodization

Low-cost and low-topography fabrication of multilayer interconnections for microfluidic devices

Multilayer interconnections are needed for microdevices with a large number of independent electrodes. A multi-level photolithographic process is commonly employed to provide multilayer interconnections in integrated circuit (IC) devices, but it is often too expensive for large-area or disposable devices frequently needed for microfluidics. The printed circuit board (PCB) can provide multilayer interconnection at low cost, but its rough topography poses a challenge for small droplets to slide over. Here we report a low-cost fabrication of low-topography multilayer interconnects by selective and controlled anodization of thin-film metal layers. The process utilizes anodization of metal (tantalum in this paper) or, more specifically, repetitions of a partial anodization to form insulation layers between conductive layers and a full anodization to form isolating regions between electrodes, replacing the usual process of depositing, planarizing, and etching insulation layers. After verifying the electric connections and insulations as intended, the developed method is applied to electrowetting-on-dielectric (EWOD), whose complex microfluidic products are currently built on PCB or thin-film transistor (TFT) substrates. To demonstrate the utility, we fabricated a 3 metal-layer EWOD device with steps (surface topography) less than 1 micrometer (vs. > 10 micrometers of PCB EWOD devices) and confirmed basic digital microfluidic operations

Effect of surface modification on the stability of oxide scales formed on TiAl intermetallic alloys at high temperature

TiAl intermetallic alloys have many interesting potential application in the automitive and aerospace industry due to their low density and good mechanical properties. Unfortunately they have a low oxidation resistance at temperature higher than 700 °C and the improvement of their oxidation behavior is still an open issue. In this work the surface of a TiAlCrNB alloy has been modified by means of their anodic coating or cerium converison coating. Afterwards the stability of the oxide scale formed at 900 °C has been studied by analyzing crack formation and porpagatin, which is the phenomenon that con produce scale spallation during the alloy cooling

Electrochemical treatment of aluminium alloy 7075 in aqueous solutions of imidazolium phosphonate and phosphate ionic liquids and scratch resistance of the resultant materials

The abilitiy of 1-ethyl-3-methylimidazolium ethylphosphonate ([ImPhosphonate]) and 1-ethyl-3-methylimidazolium diethylphosphate ([ImPhosphate]) ionic liquids (ILs) to interact with anodized Al7075 T6 aluminium alloy has been studied via electrochemical techniques under different applied potentials, inside and outside the passivation regions. SEM, EDX and XPS analysis have been used to study the composition of the surface coatings. The abrasion resistance after treatment with the ILs has been studied by scratch tests under progressive load, and compared with the performance of the unprotected material and the anodized alloy. While conventional anodization only improves the abrasion resistance of Al7075 in a 30%, the maximum reduction of the penetration depth, 86% with respect to Al7075 and 79% with respect to the anodized alloy, is obtained for the material treated with [ImPhosphonate] at 1 V, in the passivation region. Under these conditions, a phosphorus-containing alumina layer is formed. Applied voltages outside the passivation region for each IL activate the dissolution of the alumina layer and reduce abrasion resistance, not only with respect to the anodized material, but also with respect to the unprotected alloy.This work received the financial support of the Ministerio de Economía y Competitividad (MINECO, Spain) and the EU FEDER Program (Grant MAT2014-55384-P), and the Fundación Séneca, Agencia de Ciencia y Tecnología de la Región de Murcia for a “Ayuda a las Unidades y Grupos de Excelencia Científica de la Región de Murcia (Programa Séneca 2014)” (Grant 19877/GERM/14)

Effect of the anodization voltage on the porewidening rate of nanoporous anodic alumina

A detailed study of the pore-widening rate of nanoporous anodic alumina layers as a function of the anodization voltage was carried out. The study focuses on samples produced under the same electrolyte and concentration but different anodization voltages within the self-ordering regime. By means of ellipsometry-based optical characterization, it is shown that in the porewidening process, the porosity increases at a faster rate for lower anodization voltages. This opens the possibility of obtaining three-dimensional nanostructured nanoporous anodic alumina with controlled thickness and refractive index of each layer, and with a refractive index difference of up to 0.24 between layers, for samples produced with oxalic acid electrolytes

Fabrication and structural characterization of highly ordered sub-100-nm planar magnetic nanodot arrays over 1 cm2 coverage area

Porous alumina masks are fabricated by anodization of aluminum films grown on both semiconducting and insulating substrates. For these self-assembled alumina masks, pore diameters and periodicities within the ranges of 10–130 and 20–200nm, respectively, can be controlled by varying anodization conditions. 20nm periodicities correspond to pore densities in excess of 1012 per square inch, close to the holy grail of media with 1Tbit∕in.2 density. With these alumina masks, ordered sub-100-nm planar ferromagnetic nanodot arrays covering over 1cm2 were fabricated by electron beam evaporation and subsequent mask lift-off. Moreover, exchange-biased bilayer nanodots were fabricated using argon-ion milling. The average dot diameter and periodicity are tuned between 25 and 130nm and between 45 and 200nm, respectively. Quantitative analyses of scanning electron microscopy (SEM) images of pore and dot arrays show a high degree of hexagonal ordering and narrow size distributions. The dot periodicity obtained from grazi..

FESEM and EIS Study of Sealed AA2024 T3 Anodized in Sulfuric Acid Electrolytes: Influence of Tartaric Acid

The present study investigates the effect of tartaric acid on anodic film morphology and on corrosion resistance of hydrothermally sealed anodized AA2024. Anodizing treatment was performed in dilute sulfuric acid electrolyte with or without addition of tartaric acid. Hydrothermal sealing was carried out in boiling water for each anodized specimen. The morphology of the sealed anodic films was examined using field-emission scanning electron microscopy (FESEM). Electrochemical impedance spectroscopy (EIS) was performed to assess sealing quality and corrosion resistance of the anodic films. It was shown that the sealing was more efficient in the case of anodic films formed in tartaric acid electrolyte mainly due to their lower porosity. It was also observed that the properties of the barrier layer were higher when sealing was performed on specimens anodized in the presence of tartaric acid. This suggests a specific role of the species on the barrier layer, which contributes to the enhancement of the performance in terms of corrosion resistance of the sealed anodic films. The present study clearly validates the beneficial role of tartaric acid in anodizing baths for the corrosion protection of AA2024