28 results on '"F. Rosalbino"'
Search Results
2. Influence of corrosion on brazed joints' strength
- Author
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M. Pezzoli, F. Rosalbino, F. ucchi, and Emma Paola Maria Virginia Angelini
- Subjects
Materials science ,Surface Properties ,Bond strength ,Metallurgy ,Alloy ,Saliva, Artificial ,chemistry.chemical_element ,engineering.material ,Ringer's Solution ,Corrosion ,Galvanic corrosion ,Nickel ,chemistry ,Tensile Strength ,Ultimate tensile strength ,engineering ,Brazing ,Stress, Mechanical ,Dental Soldering ,Isotonic Solutions ,General Dentistry ,Base metal ,Dental Alloys - Abstract
The influence of corrosion on the bond strength of different brazed joints commonly used in dentistry has been investigated by means of accelerated immersion tests in artificial saliva buffered at pH 2, and in Ringer's solution, both kept at 37° Two CoCr base metal alloys were brazed with a gold and a non-precious alloy. After 60 days' immersion the tensile strength of the samples brazed with the gold alloy was dramatically reduced because of galvanic corrosion phenomena. The bond strength of the specimens brazed with the non-precious alloy was largely unaffected. Corrosion products rich in nickel were detected. The electrochemical characterization of the base metal alloys and brazing materials was performed by means of polarization curves in the two media investigated. High short circuit currents were only produced with the gold brazing materials.
- Published
- 1991
3. Contributor contact details
- Author
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Philippe Dillmann, Gérard Béranger, Paolo Piccardo, Henning Matthiesen, Christian Degrigny, G. Santarini, Régis Bertholon, D. Neff, E. Vega, P. Dillmann, L. Bellot-Gurlet, M. Descostes, G. Béranger, E. Pons, C. Lemaitre, D. David, D. Crusset, Enrique Vega, Pascal Berger, Philippe Fluzin, Walter-John Chitty, Bruno Huet, Valérie L'Hostis, Hassane Idrissi, L. Maréchal, S. Perrin, Jean-Bernard Memet, Solenn Reguer, François Mirambet, Jean Susini, Marie-Anne Loeper-Attia, E. Angelini, F. Rosalbino, S. Grassini, G.M. Ingo, T. de Caro, François Mathis, Joseph Salomon, Sandrine Pagès-Camagna, Michel Dubus, Dominique Robcis, Marc Aucouturier, Sophie Descamps, Elisabeth Delange, Benoît Mille, Luc Robbiola, Katerina Kreislova, Dagmar Knotkova, Vladimir Cihal, Jiri Had, David Gregory, Birgit Sørensen, Lisbeth Rischel Hilbert, Lena Sjögren, Nathalie Le Bozec, E. Rocca, F. Mirambet, A. Galtayries, A. Mongiatti, P. Marcus, C. Chiavari, C. Dinoi, C. Martini, D. Prandstraller, and G. Poli
- Published
- 2007
4. Simulation of corrosion process of buried archaeological bronze artefacts
- Author
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E. Angelini, F. Rosalbino, S. Grassini, G.M. Ingo, and T. De Caro
- Subjects
corrosion ,materials science ,multidisciplinary investigations ,Ancient metallurgy - Abstract
Research activities regarding the conservation of Cultural Heritage have significantly increased in recent years in every European and Mediterranean country, as artefacts are important remains of our civilisation and valuable signs of how human being evolved in terms of art and history. One major concern of curators and archaeologists is the preservation of archaeological objects taken out of excavations and kept in museums. In the case of bronzes and other copper based alloys, the degradation phenomena occurring during burial or exposure to a museum atmosphere usually initiate by the formation of a cuprite layer, which darkens the surface, and then, depending on the environment surrounding the sample, various corrosion products of copper II can develop, giving either a brown-black colour or a green one to the surface. This process damages the alloys, as the copper required to form the corrosion products comes from the metal core, which can then considerably decrease, indeed disappear, following the corrosion rate. It is therefore crucial to find methods of protection and conservation of these metallic artefacts that prevent them from getting damaged. In this paper, we present analyses carried out on Italian copper-based archaeological value artefacts selected as a function of the archaeological context and of the chemical composition and structure; and on aged copper-based reference alloys of similar composition to that of the ancient alloys, in order to characterise their corrosion products and modelize the mechanism of the degradation process. The archaeological artefacts came from two different sites in Sardinia and the riverbanks of the Tiber. They were analysed by means of optical and scanning electron microscopy, X-ray diffraction and fluorescence performed with portable instrument and glow discharge optical emission spectroscopy. The corrosion layer was also characterised by electrochemical impedance spectroscopy. The reference alloys were produced with the similar composition determined after the analyses of a large selection of artefacts. These analyses gave us either ternary or quaternary alloys of copper, tin, zinc and lead. These alloys were then buried in soils coming from the Sardinian and Roman sites, in presence of water. Ageing tests were run on these samples in a climatic chamber, where the samples were put for 1, 4 and 7 months. The aged samples were characterised by means of the same techniques than those used for the artefacts. The first results obtained on the artefacts show the formation of malachite on samples coming from sites exposed to a marine and chlorinated atmosphere and a partial mineralisation of the alloys due to their interaction with the soils. Cuprite is also detected as a major component of the corrosion layer. For the one-month degraded reference alloys, wide dark red and red spots of cuprite have formed a first thin corrosion layer. Green traces of malachite are also noticeable on samples buried in soils containing higher water content than the field capacity
- Published
- 2007
5. Electrochemical investigation of inorganic thin layers deposited by RF magnetron sputtering
- Author
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E. Angelini, S. Grassini, A. Palma, F. Rosalbino, F. Fracassi, F. Palumbo, and R.dAgostino
- Published
- 2007
6. SiOx thin films deposited in continuous and pulsed plasma: comparison of their corrosion protective properties
- Author
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S. Grassini, E. Angelini, F. Fracassi, S. Laera, A. Palma, F. Rosalbino, and F. Palumbo
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- 2006
7. Study of the corrosion protective properties of PECVD SiOx and SiNx thin films
- Author
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E. Angelini, S. Grassini, F. Rosalbino, F. Fracassi, R. d'Agostino, S. Laera, and F. Palombo
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- 2005
8. Tribological and electrochemical characterisation of pecvd coatings
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E. Angelini, R. dAgostino, F. Fracassi, S. Grassini, S. Laera, F. Palumbo, and F. Rosalbino
- Published
- 2005
9. Trattamenti di modificazione superficiale in plasmi di bassa pressione per la protezione dei materiali metallici dalla corrosione
- Author
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E. Angelini, S. Grassini, A. Palma, F. Rosalbino, F. Fracassi, F. Palumbo, S. Laera, and R. dAgostino
- Published
- 2005
10. Microstructural evolution of Cu-based alloys in Roman mirrors
- Author
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E. Angelini, T. de Caro, S. Grassini, G.M. Ingo, and F. Rosalbino
- Subjects
corrosion ,Roman mirrors ,high tin bronzes ,SEM+EDS - Abstract
Roman mirrors have been characterized by means of different analytical techniques, OM, SEM+EDS, GDOES, XRD. They are made with the classic bronzes used by Romans for manufacturing luxurious mirrors (high tin amount, 27-30%; lead amount, 7-8%); on ancient mirrors the following three intermetallic compounds may be foud:?-Cu6Sn5, 61.5 wt%Sn;?-Cu3Sn, 38.2 wt% Sn; ?-Cu31Sn8, 32.6% Sn. These latter phases and a+d eutectoid may be indentified when deliberate tinning of low tin bronzes or copper is carried out, while the mirrors produced with high tin leaded bronzes are characterised by a more complex microstructure and this is especially true if the alloy has been quenched. The mirrors show a front side, shiny, and a back side, dull. The microstructure of the front side is characterized by the presence of a noticeable surface tin oxide enrichment, by an inner layer with small rounded lead globules dispersed in a very fine homogeneous a+d eutectoid cast structure. The microstructure of the back side is characterised by a homogeneous and mineralised a+d eutectoid ghost structure throughout, with deep corrosion attacks. The Sn surface enrichment seems to be responsible for the dark grey silvery lustrous appearance of the front side of the mirrors still reflecting after more than 2000 years of burial.
- Published
- 2003
11. Protection of Silver-based Alloys from Tarnishing by means of PECVD Coatings
- Author
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S. Grassini, R. d?Agostino, E. Angelini, F. Fracassi, G. M. Ingo, N. Lionetti, F. Palumbo, and F. Rosalbino
- Published
- 2003
12. Innovative conservation treatments for ancient silver objects
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E. Angelini, F. Fracassi, S. Grassini, G.M. Ingo, E. Palumbo, and F. Rosalbino
- Subjects
corrosion ,materials science ,technology, industry, and agriculture ,multidisciplinary investigations ,Ancient metallurgy - Abstract
SiO2-like coatings have been deposited onto silver-based alloys by means of plasma-enhanced chemical vapor deposition (PECVD) fed with a tetraethoxysilane/oxygen mixture in order to study their capability to protect the alloys from tarnishing. Chemical and morphological characterization of the coatings has been carried out by means of X-ray photoelectron spectroscopy (XPS), infrared absorption spectroscopy, and scanning electron microscopy, while tarnishing susceptibility has been evaluated by means of visual inspection after intermittent immersions in Na2S solution at room temperature. It has been found that coatings deposited from oxygen-rich mixtures at high input power are characterized by excellent protective properties.
- Published
- 2003
13. Identification of parameters useful for the identification of fakes of metal artefacts of archaeological interest - Identificazione di osservabili utili all'individuazione di falsi nell'ambito del reperti metallic di interesse archeologico
- Author
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E. Angelini, G. M. Ingo, F. Rosalbino, T. De Caro, and S. Grassini
- Subjects
impedenza elettrochimica ,monete ,falsificazioni ,MO XRD SEM - Abstract
Lo studio verte sull'identificazione di possibili osservabili chimico-fisici quali dati microchimici, elettrochimici, microstrutturali e micromorfologici di superficie, specifici e di riscontro esclusivo o in manufatti metallici originali o in manufatti falsi e/o contraffatti. La presenza di tali osservabili viene identificata e discussa anche in base a considerazioni sulle antiche metodologie di produzione e lavorazione dei metalli oltre che in base a considerazioni storico-archeologiche. La ricerca è finalizzata alla progettazione di un apparato analitico-informatico che permetta l'acquisizione e l'elaborazione di dati utili alla determinazione dell'originalità dei manufatti metallici mediante la scelta delle caratteristiche analitiche e strumentali. Vengono qui di seguito presentati i risultati ottenuti su monete conservate al Museo Nazionale Romano, dove sono presenti oltre alle monete autentiche di età antica, medioevale e moderna, anche riproduzioni di monete di epoca antica e di età moderna.
- Published
- 2003
14. Deposition of SiOx films from hexamethyldisiloxane/oxygen radiofrequency glow discharges: Process optimization by plasma diagnostics
- Author
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E.Angelini, S. Grassini, F. Rosalbino, F. Fracassi, and R. d'Agostino
- Abstract
This paper describes the preliminary results on the utilization of thin film deposited in Plasmas fed with hexamethyldisiloxane-oxygen (HMDSO-O-2) mixture for the corrosion protection of Mg alloys. The corrosion behavior of coated substrates has been evaluated by means of impedance measurements performed in aerated 0.1 M Na2SO4 solution. Interesting and promising results have been obtained when a suitable plasma pretreatment is performed both with hydrogen and CF4 fed plasmas and therefore when the extent of surface oxidation is reduced or when the magnesium surface is fluorinated. As a matter of fact, the charge transfer resistance, R-ct, increases from about 60Omegacm(2) for the uncoated alloy to more than 90 kOmegacm(2) after deposition of a 1300 nm thick SiOx film.
- Published
- 2003
15. Microchemical and microstructural characterization of the corrosion products of copper and bronze artifacts, as Roman mirrors, and of gilded Middle Ages objects
- Author
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E. Angelini, G, Bultrini, I.Caliari, M. Dabalà, T.de Caro, S. Grassini, G.M. Ingo, and F. Rosalbino
- Subjects
Corrosion ,GDOES ,roman mirrors ,gilded artefacts ,bronze - Abstract
With the use of different complementary analytical techniques as SEM+EDS (scanning electron microscopy + energy dispersive spectrometry), GDOES (glow discharge optical emission spectroscopy), OM (optical microscopy), XRD (X-ray diffraction) and electrochemical techniques, as EIS (electrochemical impedance spectroscopy), a microchemical and microstructural characterization of the corrosion products of metallic artefacts of archaeological and artistic interest has been carried out. In particular high tin bronze artefacts, as Roman mirrors, found during archaeological excavation of the Phoenician-Punic and then Roman city of Tharros (north-western Sardinia), have been investigated, together with Roman and middle Ages gilded artefacts.
- Published
- 2002
16. Microstructural and Electrochemical Characterization of Roman Mirrors
- Author
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E.Angelini, I.Calliari, M.Dabalà, T. de Caro, S. Grassini, G.M. Ingo, and F. Rosalbino
- Abstract
Ancient mirrors, made of copper alloys with a high tin amount, up to 24%, are metallic artefacts of noticeable archaeological interest for different reasons: i) for the study of the alloy characteristics, as brittleness, several mirrors crack during the excavation itself; ii) for the study of the complex production techniques; iii) for the study of the deposition techniques of Sn, Au and Ag carried out for increasing the brightness degree; iiii) for the study of the corrosion mechanism and consequently of the selection of the proper restoration and protection methodology. Microstructural and microchemical characterization have been performed by means of OM (optical microscopy), SEM+EDS (scanning electron microscopy + energy dispersive spectrometry) and GDOES (glow discharge optical emission spectroscopy), together with electrochemical tests (impedance measurements, polarization curves), on several fragments of roman mirrors coming from Phoenician-Punic Sardinian excavation sites enhancing, at the end of the study, the common features of these objects, as the alloy composition and the typology of corrosion products. The shiny sides of the mirrors, which have a patina 20-100 mm thick, are generally attached by the aggressive agents (soil, atmosphere) to a lower extent with respect to the dull one, generally covered by wide isles of corrosion products. Both the patina and the corrosion products show a noticeable enrichment in Sn. Phosphorus, carbon and silicon have also been detected, thus indicating a deep interaction between the buried artefacts and the soil.
- Published
- 2001
17. XPS and electrochemical characterisation of tarnish films on dental alloys
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E. Angelini, E. Cordano, S. Kaciulis, G. Mattogno, L. Pandolfi, M.R. Pinasco, and F. Rosalbino
- Subjects
corrosion ,dental alloys ,XPS ,tarnish - Abstract
Three gold resin casting alloys ranging in nobility between 30 and 74 wt.% have been analysed by XPS, SEM plus energy-dispersive spectroscopy (EDS) as well as by L*a*b* colorimetry before and after in vitro tarnishing in 0.1 M Na(2)S solution with a rotating wheel apparatus. The lower the nobility of the alloy, the higher the tarnishing tendency: the alloys appear darker with increased redness and yellowness, as determined by colorimetric analysis. On the three alloys, corrosion products of almost the same chemical composition are detected in different amounts. The products are mainly Cu (53-57 wt,%), S (23-29 wt.%) and Ag (similar to 4 wt.%), as determined by EDS, X-ray photoelectron spectroscopy analysis carried out in the first tarnishing steps indicates more sulphur enrichment on the surfaces of the alloys with the lower nobility. Auger maps of the tarnished surfaces show evidence of the onset of a selective reaction of sulphur with Cu and Ag in the first steps. The electrochemical results are in accordance with the previously exposed data: the polarization curves recorded on alloys with increasing Ag and Cu amounts show higher current density values indicating a worse performance.
- Published
- 2000
18. New chemical treatment for bioactive titanium alloy with high corrosion resistance.
- Author
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S. Spriano, M. Bronzoni, F. Rosalbino, and E. Vern
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TITANIUM ,PHOSPHATE minerals ,MICROALLOYING ,FINISHES & finishing - Abstract
Abstract It was recently claimed that titanium metal and its alloys can bond to the living bone, without being coated by apatite (VPS coatings), but by being chemically and heat-treated. The bioactivity of treated titanium is of interest because of the opportunity to obtain orthopaedic or dental implants presenting, at the same time, high toughness, strength and fatigue resistance as well as bone-bonding ability. The bioactive behaviour of the treated implants is due to the presence of a modified surface, which, during soaking in body fluid, promotes the precipitation of apatite. The apatite formed is strongly bonded to the substrate and promotes living bone bonding. In this work were characterised samples of Ti-6Al-7Nb alloy with surfaces presenting a different chemical and mechanical state. The aim of the research was twofold. The first objective was to characterise chemically and heat-treated samples with different surface topography, in order to define the best conditions for osteogenic integration. The second aim was to assess the corrosion behaviour of the bioactive implants, because they expose a microporous and quite thin modified surface layer. No-treated and passivated samples, with a surface state closed to that nowadays used on implants, were used as reference. The surface structure, morphology, electrochemical behaviour and bioactivity of the different samples were assessed by means of XRD, SEM-EDS, anodic polarizations, open circuit measurements and in-vitro tests. Results evidence that it is possible to modify the surface of the Ti-6Al-7Nb alloy in order to obtain the formation of a bioactive layer and that the substrate roughness influences the characteristics of the surface layer formed. It was also evidenced that the as treated surfaces present inadequate corrosion behaviour, so a new two-step chemical treatment has been developed in order to obtain a bioactive material with good corrosion resistance. [ABSTRACT FROM AUTHOR]
- Published
- 2005
19. A comparative evaluation between new ternary zirconium alloys as alternative metals for orthopedic and dental prosthetic devices.
- Author
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Shyti G, Rosalbino F, Macciò D, Scarabelli L, Quarto R, and Giannoni P
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- Biocompatible Materials chemistry, Biocompatible Materials pharmacology, Corrosion, Dielectric Spectroscopy methods, Humans, Materials Testing methods, Mesenchymal Stem Cells drug effects, Alloys chemistry, Alloys pharmacology, Dental Prosthesis, Orthotic Devices, Titanium chemistry, Titanium pharmacology, Zirconium chemistry, Zirconium pharmacology
- Abstract
Purpose: We assessed in vitro the corrosion behavior and biocompatibility of four Zr-based alloys (Zr97.5 Nb1.5VM1.0 ; VM, valve metal: Ti, Mo, W, Ta; at%) to be used as implant materials, comparing the results with grade-2 titanium, a biocompatible metal standard., Methods: Corrosion resistance was investigated by open circuit potential and electrochemical impedance spectroscopy measurements as a function of exposure time to an artificial physiological environment (Ringer's solution). Human bone marrow stromal cells were used to evaluate biocompatibility of the alloys and their influence on growth kinetics and cell osteogenic differentiation through histochemical and gene expression analyses., Results: Open circuit potential values indicated that Zr-based alloys and grade-2 Ti undergo spontaneous passivation in the simulated aggressive environment. High impedance values for all samples demonstrated improved corrosion resistance of the oxide film, with the best protection characteristics displayed by Zr97.5 Nb1.5Ta1.0. Cells seeded on all surfaces showed the same growth kinetics, although matrix mineralization and alkaline phosphatase activity were maximal on Zr97.5 Nb1.5Mo1.0 and Zr97.5 Nb1.5Ta1.0. Markers of ongoing proliferation, however, such as podocalyxin and CD49f, were still overexpressed on Zr97.5 Nb1.5 Mo1.0 even upon osteoinduction. No relevant effects were noted for the CD146-expressing population of bone progenitors. Nonetheless, the presence of a more differentiated cell population on Zr97.5Nb1.5Ta1.0 samples was inferable by comparing mineralization data and transcript levels of osteogenic markers (osteocalcin, osteopontin, bone sialoprotein, and RUNX2)., Conclusions: The combination of passivation, corrosion resistance and satisfactory biotolerance to bone progenitors make the Zr-based alloys promising implant materials. Among those we tested, Zr97.5Nb1.5Ta1.0 seems to be the most appealing.
- Published
- 2014
- Full Text
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20. Microstructure and in vitro degradation performance of Mg-Zn-Mn alloys for biomedical application.
- Author
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Rosalbino F, De Negri S, Scavino G, and Saccone A
- Subjects
- Corrosion, Potentiometry, X-Ray Absorption Spectroscopy, Alloys chemistry, Magnesium chemistry, Manganese chemistry, Materials Testing, Zinc chemistry
- Abstract
Manganese and zinc were selected as alloying elements to develop a Mg-based ternary alloy for biomedical applications, taking into account the good biocompatibility of these metals. The microstructures of Mg-Zn-Mn alloys containing 0.5 or 1.0 mass% of manganese and 1.0 or 1.5 mass% of zinc were investigated by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Their corrosion properties were assessed by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements performed in Ringer's physiological solution that simulates bodily fluids. All tested samples are two-phase alloys formed by a Mg-based matrix, consisting of a Mg-Zn-Mn solid solution, and a Mg-Zn binary phase. The electrochemical results show an improvement of the corrosion behavior of the investigated alloys with increasing Zn and Mn content. This is attributed to the formation of a partially protective Mg(OH)(2) surface film whose protective capabilities are increased by the alloying elements. The reduced influence of the Mg-Zn intermetallic compound on the corrosion rate of Mg-Zn-Mn alloys in the presence of a partially protective surface layer can be ascribed to an increasing resistance between the Mg-Zn-Mn solid solution and the second phase, thereby decreasing the effective driving force for microgalvanic corrosion. Owing to its highest corrosion protective ability, the Mg-1.5Zn-1Mn alloy is a promising candidate for the development of degradable implants, such as screws, plates, and rods., (Copyright © 2012 Wiley Periodicals, Inc.)
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- 2013
- Full Text
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21. Influence of noble metals alloying additions on the corrosion behaviour of titanium in a fluoride-containing environment.
- Author
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Rosalbino F, Delsante S, Borzone G, and Scavino G
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- Alloys chemical synthesis, Alloys pharmacology, Cariostatic Agents pharmacology, Coated Materials, Biocompatible chemistry, Coated Materials, Biocompatible pharmacology, Coordination Complexes chemical synthesis, Corrosion, Electric Impedance, Environment, Fluoridation, Fluorides chemistry, Gold chemistry, Gold pharmacology, Materials Testing, Palladium chemistry, Palladium pharmacology, Platinum chemistry, Platinum pharmacology, Silver chemistry, Silver pharmacology, Alloys chemistry, Coordination Complexes chemistry, Fluorides pharmacology, Titanium chemistry
- Abstract
Titanium alloys exhibit excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film, and some of these alloys (particularly Ti-6Al-7Nb) have been chosen for surgical and odontological implants for their resistance and biocompatibility. Treatment with fluorides (F(-)) is known to be the main method for preventing plaque formation and dental caries. Toothpastes, mouthwashes, and prophylactic gels can contain from 200 to 20,000 ppm F(-) and can affect the corrosion behaviour of titanium alloy devices present in the oral cavity. In this work, the electrochemical corrosion behaviour of Ti-1M alloys (M = Ag, Au, Pd, Pt) was assessed in artificial saliva of pH = 3.0 containing 910 ppm F(-) (0.05 M NaF) through open circuit potential, E(OC), and electrochemical impedance spectroscopy (EIS) measurements. The corrosion behaviour of the Ti-6Al-7Nb commercial alloy was also evaluated for comparison. E (OC) measurements show an active behaviour for all the titanium alloys in fluoridated acidified saliva due to the presence of significant concentrations of HF and HF(2) (-) species that dissolve the spontaneous air-formed oxide film giving rise to surface activation. However, an increase in stability of the passive oxide layer and consequently a decrease in surface activation is observed for the Ti-1M alloys. This behaviour is confirmed by EIS measurements. In fact, the Ti-6Al-7Nb alloy exhibits lower impedance values as compared with Ti-1M alloys, the highest values being measured for the Ti-1Au alloy. The experimental results show that the corrosion resistance of the studied Ti-1M alloys is similar to or better than that of Ti-6Al-7Nb alloy currently used as biomaterial, suggesting their potential for dental applications.
- Published
- 2012
- Full Text
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22. In vitro corrosion behaviour of Ti-Nb-Sn shape memory alloys in Ringer's physiological solution.
- Author
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Rosalbino F, Macciò D, Scavino G, and Saccone A
- Subjects
- Dielectric Spectroscopy, Ringer's Solution, Corrosion, Dental Alloys chemistry, Isotonic Solutions, Tin chemistry
- Abstract
The nearly equiatomic Ni-Ti alloy (Nitinol) has been widely employed in the medical and dental fields owing to its shape memory or superelastic properties. The main concern about the use of this alloy derives form the fact that it contains a large amount of nickel (55% by mass), which is suspected responsible for allergic, toxic and carcinogenic reactions. In this work, the in vitro corrosion behavior of two Ti-Nb-Sn shape memory alloys, Ti-16Nb-5Sn and Ti-18Nb-4Sn (mass%) has been investigated and compared with that of Nitinol. The in vitro corrosion resistance was assessed in naturally aerated Ringer's physiological solution at 37°C by corrosion potential and electrochemical impedance spectroscopy (EIS) measurements as a function of exposure time, and potentiodynamic polarization curves. Corrosion potential values indicated that both Ni-Ti and Ti-Nb-Sn alloys undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Ti-18Nb-5Sn alloy. Significantly low anodic current density values were obtained from the polarization curves, indicating a typical passive behaviour for all investigated alloys, but Nitinol exhibited breakdown of passivity at potentials above approximately 450 mV(SCE), suggesting lower corrosion protection characteristics of its oxide film compared to the Ti-Nb-Sn alloys. EIS studies showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The obtained EIS spectra were analyzed using an equivalent electrical circuit representing a duplex structure oxide film, composed by an outer and porous layer (low resistance), and an inner barrier layer (high resistance) mainly responsible for the alloys corrosion resistance. The resistance of passive film present on the metals' surface increases with exposure time displaying the highest values to Ti-18Nb-4Sn alloy. All these electrochemical results suggest that Ti-Nb-Sn alloys are promising materials for biomedical applications.
- Published
- 2012
- Full Text
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23. Study of the in vitro corrosion behavior and biocompatibility of Zr-2.5Nb and Zr-1.5Nb-1Ta (at%) crystalline alloys.
- Author
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Rosalbino F, Macciò D, Giannoni P, Quarto R, and Saccone A
- Subjects
- Alloys chemistry, Biocompatible Materials, Bone Marrow Cells cytology, Cell Line, Tumor, Cell Proliferation, Electrochemical Techniques, Humans, Osteosarcoma, Stromal Cells, Niobium chemistry, Tantalum chemistry, Zirconium chemistry
- Abstract
The in vitro corrosion behavior and biocompatibility of two Zr alloys, Zr-2.5Nb, employed for the manufacture of CANDU reactor pressure tubes, and Zr-1.5Nb-1Ta (at%), for use as implant materials have been assessed and compared with those of Grade 2 Ti, which is known to be a highly compatible metallic biomaterial. The in vitro corrosion resistance was investigated by open circuit potential and electrochemical impedance spectroscopy (EIS) measurements, as a function of exposure time to an artificial physiological environment (Ringer's solution). Open circuit potential values indicated that both the Zr alloys and Grade 2 Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Zr-1.5Nb-1Ta alloy and that this oxide has better corrosion protection characteristics than the ones formed on Grade 2 Ti or on the Zr-2.5Nb alloy. EIS study showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film presents on the metals surface, improving their resistance with exposure time, presenting the highest values to the Zr-1.5Nb-1Ta alloy. For the biocompatibility analysis human osteosarcoma cell line (Saos-2) and human primary bone marrow stromal cells (BMSC) were used. Biocompatibility tests showed that Saos-2 cells grow rapidly, independently of the surface, due to reduced dependency from matrix deposition and microenvironment recognition. BMSC instead display a reduced proliferation, possibly caused by a reduced crosstalk with the metal surface microenvironment. However, once the substrate has been colonized, BMSC seem to respond properly to osteoinduction stimuli, thus supporting a substantial equivalence in the biocompatibility among the Zr alloys and Grade 2 titanium. In summary, high in vitro corrosion resistance together with satisfactory biocompatibility make the Zr-2.5Nb and Zr-1.5Nb-1Ta crystalline alloys promising biomaterials for surgical implants.
- Published
- 2011
- Full Text
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24. Bio-corrosion characterization of Mg-Zn-X (X = Ca, Mn, Si) alloys for biomedical applications.
- Author
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Rosalbino F, De Negri S, Saccone A, Angelini E, and Delfino S
- Subjects
- Biocompatible Materials metabolism, Biomedical Technology instrumentation, Biomedical Technology methods, Body Fluids metabolism, Body Fluids physiology, Calcium chemistry, Coated Materials, Biocompatible, Corrosion, Manganese chemistry, Materials Testing, Models, Biological, Prostheses and Implants, Silicon chemistry, Surface Properties, Alloys chemistry, Biocompatible Materials chemistry, Magnesium chemistry, Zinc chemistry
- Abstract
The successful applications of magnesium-based alloys as biodegradable orthopedic implants are mainly inhibited due to their high degradation rates in physiological environment. This study examines the bio-corrosion behaviour of Mg-2Zn-0.2X (X = Ca, Mn, Si) alloys in Ringer's physiological solution that simulates bodily fluids, and compares it with that of AZ91 magnesium alloy. Potentiodynamic polarization and electrochemical impedance spectroscopy results showed a better corrosion behaviour of AZ91 alloy with respect to Mg-2Zn-0.2Ca and Mg-2Zn-0.2Si alloys. On the contrary, enhanced corrosion resistance was observed for Mg-2Zn-0.2Mn alloy compared to the AZ91 one: Mg-2Zn-0.2Mn alloy exhibited a four-fold increase in the polarization resistance than AZ91 alloy after 168 h exposure to the Ringer's physiological solution. The improved corrosion behaviour of the Mg-2Zn-0.2Mn alloy with respect to the AZ91 one can be ascribed to enhanced protective properties of the Mg(OH)(2) surface layer. The present study suggests the Mg-2Zn-0.2Mn alloy as a promising candidate for its applications in degradable orthopedic implants, and is worthwhile to further investigate the in vivo corrosion behaviour as well as assessed the mechanical properties of this alloy.
- Published
- 2010
- Full Text
- View/download PDF
25. New chemical treatment for bioactive titanium alloy with high corrosion resistance.
- Author
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Spriano S, Bronzoni M, Rosalbino F, and Vernè E
- Subjects
- Biocompatible Materials chemistry, Materials Testing, Microscopy, Electron, Scanning, Surface Properties, Corrosion, Prostheses and Implants, Titanium chemistry
- Abstract
It was recently claimed that titanium metal and its alloys can bond to the living bone, without being coated by apatite (VPS coatings), but by being chemically and heat-treated. The bioactivity of treated titanium is of interest because of the opportunity to obtain orthopaedic or dental implants presenting, at the same time, high toughness, strength and fatigue resistance as well as bone-bonding ability. The bioactive behaviour of the treated implants is due to the presence of a modified surface, which, during soaking in body fluid, promotes the precipitation of apatite. The apatite formed is strongly bonded to the substrate and promotes living bone bonding. In this work were characterised samples of Ti-6Al-7Nb alloy with surfaces presenting a different chemical and mechanical state. The aim of the research was twofold. The first objective was to characterise chemically and heat-treated samples with different surface topography, in order to define the best conditions for osteogenic integration. The second aim was to assess the corrosion behaviour of the bioactive implants, because they expose a microporous and quite thin modified surface layer. No-treated and passivated samples, with a surface state closed to that nowadays used on implants, were used as reference. The surface structure, morphology, electrochemical behaviour and bioactivity of the different samples were assessed by means of XRD, SEM-EDS, anodic polarizations, open circuit measurements and in-vitro tests. Results evidence that it is possible to modify the surface of the Ti-6Al-7Nb alloy in order to obtain the formation of a bioactive layer and that the substrate roughness influences the characteristics of the surface layer formed. It was also evidenced that the as treated surfaces present inadequate corrosion behaviour, so a new two-step chemical treatment has been developed in order to obtain a bioactive material with good corrosion resistance.
- Published
- 2005
- Full Text
- View/download PDF
26. Reliability of Pd based dental alloys regarding to corrosion resistance and production processes.
- Author
-
Pinasco MR, Angelini E, Cordano E, Magi E, and Rosalbino F
- Abstract
The knowledge of the relationship among chemical composition, microstructure, productive processes, functional properties, quality and price of the final product is an ever greater requirement for the firms producing dental alloys as well as for the dental laboratories making prosthesis. The present study deals with the evaluation of the corrosion resistance of high-Pd and Pd-Ag alloys by quantification of released ions following the recent European regulations suggested. Moreover the reliability of the alloys as far as concern their corrosion resistance was also investigated in relation to the different steps of alloy industrial production and restoration forming processes as well as after homogenization treatments followed by different cooling rate. The very complex microstructure of both alloys was greatly affected by the different casting conditions, deformation rate and thermal treatments used in alloy industrial production and prosthesis manufacturing. However the corrosion resistance of both alloys remained very good in all metallurgical states. The potentiodynamic tests allowed to distinguish among the structural conditions: the homogenization treatments, eliminating segregation inside the different phases, improved further the corrosion resistance of both alloys., (Copyright 2000 Kluwer Academic Publishers)
- Published
- 2000
- Full Text
- View/download PDF
27. Ni-Zr alloys: relationship between surface characteristics and electrocatalytic behavior
- Author
-
Angelini E, Antonione C, Baricco M, Daolio S, Fabrizio M, and Rosalbino F
- Abstract
A relationship between electrocatalytic activity for the hydrogen evolution reaction and the surface composition of the electrode was established for Ni-Zr crystalline and amorphous alloys by means of secondary ion mass spectrometry (SIMS). Electrocatalytic activity was tested by means of cathodic polarization in 1 M KOH at 25 degrees C and the resulting exchange current density has been taken as a measure of catalytic efficiency. Surface activation treatment involved chemical etching in HF solutions; the consequent morphological and compositional surface changes were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behavior of the pure elements (Ni and Zr) was also considered for comparison. All samples submitted to chemical etching in HF solutions showed an increase in electrocatalytic activity, particularly the alloy with the highest Ni content. The beneficial effect of chemical etching is due to dissolution of the zirconium oxide layer and to the formation of nanocrystalline Ni on the surfaces.
- Published
- 2000
- Full Text
- View/download PDF
28. Influence of corrosion on brazed joints' strength.
- Author
-
Angelini E, Pezzoli M, Rosalbino F, and Zucchi F
- Subjects
- Corrosion, Isotonic Solutions chemistry, Ringer's Solution, Saliva, Artificial chemistry, Stress, Mechanical, Surface Properties, Tensile Strength, Dental Alloys chemistry, Dental Soldering
- Abstract
The influence of corrosion on the bond strength of different brazed joints commonly used in dentistry has been investigated by means of accelerated immersion tests in artificial saliva buffered at pH 2, and in Ringer's solution, both kept at 37 degrees C. Two Co-Cr base metal alloys were brazed with a gold and a non-precious alloy. After 60 days' immersion the tensile strength of the samples brazed with the gold alloy was dramatically reduced because of galvanic corrosion phenomena. The bond strength of the specimens brazed with the non-precious alloy was largely unaffected. Corrosion products rich in nickel were detected. The electrochemical characterization of the base metal alloys and brazing materials was performed by means of polarization curves in the two media investigated. High short circuit currents were only produced with the gold brazing materials.
- Published
- 1991
- Full Text
- View/download PDF
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