Investigation of the electrochemical behaviour of TiMo alloys in simulated physiological solutions

This paper addresses on the electrochemical behaviour of three TiMo alloys exposed to simulated physiological environments. Their stability and corrosion resistance was characterized in order to explore the potential application for the manufacturing of implant materials. Ringer’s solution together with an acidic modification of the Ringer’s solution (pH = 3.1) at room temperature were considered. Both electrochemical methods (namely, potentiodynamic polarization curves and electrochemical impedance spectroscopy, EIS), and spatially-resolved scanning electrochemical microscopy (SECM), were used. Additionally, surface characterization was made employing optical microscopy and scanning electron microscopy (SEM). The oxide films formed on the TiMo alloys in neutral and acidic Ringer’s solutions effectively protect the metal from dissolution in this environment, and no breakdown of the passive layer occurs in the potential range up to +1.00 V vs. SCE. SEM micrographs of retrieved samples do not show corrosion pits, cracks, or any other defects despite the rather high positive potential values reached during the potential excursion. EIS data reveal that two-layer oxide films are formed, consisting of a porous outer layer and a compact inner layer (approximately 5-6 nm thick), the latter accounting almost completely for the corrosion resistance of the materials. The corrosion resistance of the inner compact film towards metal dissolution is smaller in the acidic environment, whereas it increases with higher Mo contents in the alloy. The passive oxide films exhibit dielectric characteristics towards charge transfer, and they are imaged as insulators by scanning electrochemical microscop

Investigation of processing effects on the corrosion resistance of Ti20Mo alloy in saline solutions

The electrochemical properties of Ti20Mo alloys prepared using different fabrication procedures, namely cold crucible levitation melting (CCLM) and powder sintering, were investigated using linear potentiodynamic polarization and EIS measurements. The surface condition was established using AFM, with the observation of a more porous surface finish in the case of powder sintering. A major effect of surface conditioning on the corrosion resistance of Ti20Mo alloys was observed, where the compact finish exhibits a superior corrosion resistance in chloride-containing saline solutions. Less insulating surfaces towards electron exchange resulted for the more porous finish as revealed by scanning electrochemical microscopy (SECM

‘Sissi’ - culoare şi parfum în colecţia de trandafiri de la USAMV Iaşi, România

In the current paper are presented the resultsregarding behaviour of ‘Sissi’roses in cropping conditions of roses collection from UASVM Iaşi, Romania. During vegetation period were monitoring the following features: bush form, bush vigour, aspect of leafage, resistance at pathogen agents attack, rod and floral peduncle, flowering intensity, rosebud shape, shape of opened flowers, flower’s durability, colour of petals at opening, colour of petals at flowering, falling mode of petals, flowers’ perfume, other aspects (adaptability at cropping conditions). At the end of research was observed that ‘Sissi’roses had a very good adaptation at cropping conditions from the NE area of Romania, decorating from spring till late in autumn with flowers which had a delicate and tender perfume

Metastable beta Ti-Nb-Mo alloys with improved corrosion resistance in saline solution

The present study explores the microstructural characteristics and electrochemical responses of four metastable beta Ti-Nb-Mo alloys for biomedical implantation. They were synthesized by the cold crucible levitation melting technique, and compositions were selected to keep the molybdenum equivalency close to 12 wt% Moeq. For the sake of comparison, Ti12Mo was also investigated. Microstructural characterization reveals that all the alloys are β (body-centred cubic structure), and the surface is composed by β equiaxial grains with dimensions in the range of tens to hundreds μm. The corrosion resistance (potentiodynamic polarization and electrochemical impedance spectroscopy) of the alloys was determined in 0.9 wt% NaCl saline solution at 25 ºC. The materials spontaneously form a passivating oxide film on their surface, and they are stable for polarizations up to +1.0 VSCE. No evidence of localized breakdown of the oxide layers is found for polarizations more positive than those encountered in the human body. The passive layers show dielectric characteristics, and the wide frequency ranges displaying capacitive characteristics occur for both higher niobium contents in the alloy and longer exposures to the saline solution. The insulating characteristics of the oxide-covered surfaces were investigated by scanning electrochemical microscopy operated in the feedback mode, using ferrocene-methanol as redox mediator. Both z-approach curves and amperometric images were taken over the surface of the samples both at their open circuit potential and polarized. It has been found that Ti8Nb10Mo and Ti16Nb8Mo exhibit the lowest activity towards electron transfer. The new Ti-Nb-Mo ternary alloys are regarded to be potential candidates for biomedical application on the basis of both their microstructural characteristics and their corrosion resistance in saline solution with chloride content equivalent to body fluid

Corrosion behaviour of new quaternary ZrNbTiAl alloys in simulated physiological solution using electrochemical techniques and surface analysis methods

The potential biomedical application of three new quaternary Zr alloys, namely Zr6Ti15Nb4Al, Zr32Ti15Nb4Al, and Zr49Ti15Nb4Al, was evaluated in vitro using electrochemical methods complemented with surface analysis of corrosion resistance. Cyclic potentiodynamic polarization (CCP) and electrochemical impedance spectroscopy (EIS) tests were performed in Ringer’s solution at 37 ºC. The electrochemical behavior of the ZrTiNbAl quaternary alloys was consistent with the formation of passivating oxide films on the surfaces of these materials. Localized breakdown of the oxide layer occurred on Zr6Ti15Nb4Al and Zr32Ti15Nb4Al alloys subjected to positive anodic polarization, a feature confirmed by scanning electron microscopy (SEM) on retrieved samples. The Zr49Ti15Nb4Al alloy, which had the highest titanium (49 wt.%) content, exhibited a larger passive range in the polarization curve and was immune to localized corrosion breakdown in a simulated physiological solution for the range of polarizations that can occur in the human bod

The structural analysis of composite materials reinforced with SI-C particles

The composite materials with particles consisting of a basic material (matrix) embedded particles of one or more materials. The particles can be metallic or nonmetallic, as the matrix can be, metalic or non metalic. Like a first step the composite mixing involves the embedded process analysis of SiC particles in molten metal. The main issues considered relate to some aspects of embedding additional material in molten metal and methods of achieving the best possible including it. From this point of view was used the overheat of metalic matrix. The experimental plan was followed by Taguchi and structural analysis made was focus on four from 16 completed experimental researches. Six parameters were used each one has two levels. Also the micrographs corresponding experimental tests are presented

Evaluating electrochemical behaviour of recrystallized titanium alloys in Ringer's solution

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