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This work investigated two titanium-based alloys with a constant tantalum content and variable contents of alloy additives – niobium and zirconium. The Ti-30Ta-10Zr-20Nb (wt.%) and Ti-30Ta-20Zr-10Nb (wt.%) alloys were obtained using a combination of powder metallurgy and arc melting methods. The influence of alloying additives on the structure and properties of the Ti-Ta-Nb-Zr system was studied using, among others: X-ray diffraction and scanning electron microscopy. The X-ray diffraction confirmed the single-β-phase structure of both alloys. In addition, the microscopic analysis revealed that a higher amount of zirconium favoured the formation of larger grains. However, the microhardness analysis indicated that the alloy with the higher niobium content had the higher microhardness. Importantly, the in vitro corrosion study revealed that the addition of niobium promoted the better corrosion resistance of the investigated alloy. [ABSTRACT FROM AUTHOR]

This work reports on determination of the influence of passivation type of Ti15wt.%Mo implant alloy surface on its corrosion resistance in simulated body fluids. The alloy under investigation was subjected to natural self-passivation in air, and forced passivation by autoclaving in steam, boiling in 30 % solution of H2O2, and electrochemical passivation in 0.9 % NaCl solution. Resistance of the passivated Ti15Mo alloy to pitting corrosion was studied at 37ºC in 0.9 % NaCl solution using open circuit potential method, anodic polarization curves, and electrochemical impedance spectroscopy (EIS). Comparative estimation of the determined parameters of corrosion resistance revealed that the obtained passive layers improve anticorrosive properties of the tested alloy. Surface of the alloy subjected to passivation in steam autoclave reveals the highest protection against pitting corrosion. Anodic potentiodynamic curves showed that the Ti15Mo alloy after different passivation types of the surface is characterized by a lack of susceptibility to pitting corrosion up to potential of 9 V. Based on the EIS investigations, the thickness of the formed oxide layers (TiO2, anatase) was determined to be in the range from 2.0 to 7.8 nm in dependence on the applied type of passivation. It was ascertained that electrochemical properties of the Ti15Mo alloy and possibility of its surface passivation using simple methods, make it an attractive material for use in biomedicine for long-term implants.

W pracy przedstawiono badania woltamperometryczne procesu elektroosadzania cyrkonu z roztworu DMSO na różnych podłożach. Stwierdzono, że jest to procees wieloelektronowy zachodzący w kilku etapach. Ponadto otrzymano warstwy cyrkonu na tytanie, miedzi, stali kwasoodpornej i niklu. Wytworzony osad katodowy miał formę białego proszku, na skutek natychmiastowego utlenienia cyrkonu w kontakcie z powietrzem.

Scientists and medics are still searching for new metallic materials that can be used in medicine, e.g., as material for implants. The following article proposes materials based on titanium with vital elements prepared by combined powder metallurgy and arc melting methods. Four compositions of Ti-28Ta-9Nb, Ti-28Ta-19Nb, Ti-28Ta-9Zr and Ti-28Ta-19Zr (wt.%) have been prepared. The tested material was thoroughly analyzed by X-ray diffraction and scanning electron microscopy. Qualitative phase analysis using X-ray diffraction showed the presence of two phases, a' and ß titanium. In addition, a microhardness test was conducted, and the material was characterized in terms of corrosion properties. It was found that the corrosion resistance decreases with an increase of the ß phase presence. [ABSTRACT FROM AUTHOR]

This work investigated two titanium-based alloys with a constant tantalum content and variable contents of alloy additives - niobium and zirconium. The Ti-30Ta-10Zr-20Nb (wt.%) and Ti-30Ta-20Zr-10Nb (wt.%) alloys were obtained using a combination of powder metallurgy and arc melting methods. The influence of alloying additives on the structure and properties of the Ti-Ta-Nb-Zr system was studied using, among others: X-ray diffraction and scanning electron microscopy. The X-ray diffraction confirmed the single-ß-phase structure of both alloys. In addition, the microscopic analysis revealed that a higher amount of zirconium favoured the formation of larger grains. However, the microhardness analysis indicated that the alloy with the higher niobium content had the higher microhardness. Importantly, the in vitro corrosion study revealed that the addition of niobium promoted the better corrosion resistance of the investigated alloy. [ABSTRACT FROM AUTHOR]

Dental/osseous implants manufactured of titanium (Ti) have become a routine and affordable method in medical practice. To increase the overall safety and longtime stability of the implants further, the sophisticated approaches have been investigated in order to supply the implants with the bioactive surface layers. They have to serve two purposes: to increase the osseointegration capacity of the implants and to reduce the chances of bacterial growth and formation of bacterial biofilms leading to periimplantitis. Plasma electrolytic oxidation (PEO) is becoming a promising method to introduce functionalized surface layers on a metal substrate. Various PEO protocols have been suggested in order to achieve better biocompatibility of the dental implants and to increase their resistance to bacterial infections. It was also suggested that the PEO layers could increase resistance to corrosion on the surfaces of metallic implants. The dynamic processes running on the surface of Ti during the PEO processing still require efforts to fully understand the molecular mechanisms of the formation of hard and porous oxide surface layers. We and others have already shown that addition of a chelating agent to the bath electrolyte leads to better outcomes in the morphology and functional characteristics of the implants. Here we report in depth characterization of the PEO parameters and the produced PEO surface layers using the bath electrolyte containing another widely used chelating agent, nitrilotriacetic acid (NTA) along with potassium phosphate and calcium formate. The results will contribute to further understanding the mechanisms of the PEO process and to establishing routine protocols for commercial exploitation of the PEO method. [ABSTRACT FROM AUTHOR]

The paper presents the results on biofilm formation induced by pure Desulfovibrio desulfuricans strains and its effect on corrosion behaviour of 2205 duplex stainless steel (DSS). Biofilm formation and damage process stimulated by D. desulfuricans strains are analysed with reference to their metabolic activity and to the surface characterisation of structure and configuration of the biofilm. Electrochemical techniques are applied to monitor bacterial attachment to the steel surface and to determine the influence of bacteria on the passivity and corrosion resistance of 2205 DSS. The obtained results prove that 2205 DSS is rapidly colonised by D. desulfuricans and that the biofilms formed affect its corrosion resistance. Bacterial activity leads to the more noble corrosion potential values and to the increased current densities on the potentiodynamic polarisation curves. SEM observations reveal micropits as well as signs of crevice attack on the steel surface. [ABSTRACT FROM AUTHOR]

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Hydrothermal synthesis of hydroxyapatite (HA) is a method which is relatively easy to apply and enables HA precipitation on substrates of various shapes, which is vital to endoprostheses fabrication. Anodic oxidation facilitates HA precipitation, making the coating thicker and more uniform. In this paper the influence of anodic oxidation of titanium substrates on HA precipitation in hydrothermal synthesis is discussed. To determine chemical composition and coating uniformity of anodised and polished Ti substrates the Raman microspectroscopy was employed. The composition was also confirmed using X-ray diffraction method. HA coatings on Ti after anodic oxidation exhibit higher uniformity in comparison to untreated Ti. The X-ray diffraction patterns showed that the HA coating was partly amorphous. Also influence of additional treatment (soaking in NaOH and/or HBSS) after anodic oxidation is discussed in the present paper. It seems that pretreatment may be favourable in some cases, but if the anodic oxidation was conducted in the presence of calcium phosphates the pretreatment seems to prevent the HA precipitation. [ABSTRACT FROM AUTHOR]

Abstract: Conversion coatings on the magnesium alloy AZ81 were prepared using the phosphate–permanganate baths differing in composition. The corrosion behavior of the coated and uncoated alloys has been investigated by electrochemical impedance spectroscopy (EIS) and linear polarization methods. The choice of proper electric equivalent circuit (EEC) is discussed. The effect of temperature, bath composition and time of conversion as well as etching in acids before application on the corrosion resistance of the coated alloy has been evaluated. The best corrosion resistance was obtained for the samples coated in the bath containing 25g KMnO4, 150g Na2HPO4 and 50ml H3PO4 in 1 dcm3, applied at 80°C. Differences in the morphology and composition of coated surfaces were investigated by the scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques and correlated with the corrosion resistance of the samples. [Copyright &y& Elsevier]