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Marcello Gelfi - One of the best experts on this subject based on the ideXlab platform.

  • On the strengthening mechanisms of 18 carat yellow Gold and its mechanical behaviour
    Materials Science and Engineering A, 2008
    Co-Authors: R. Roberti, Giorgio Cornacchia, Michela Faccoli, Marcello Gelfi
    Abstract:

    In order to contribute to a better understanding of the mechanical properties of Gold Alloys this paper investigates the mechanical behaviour of an 18 carat yellow alloy; the strain hardening behaviour during a tensile test was measured in the annealed as well as in different cold-work conditions. In addition, the contribution of different strengthening mechanisms is discussed on the basis of current results and of data reported in literature. In particular, the contributions of grain size refinement and copper solid solution alloying in improving the mechanical strength of Gold Alloys were quantified. © 2007.

R Schaller - One of the best experts on this subject based on the ideXlab platform.

  • mechanical spectroscopy of 18 carat aucupd white Gold Alloys
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
    Co-Authors: I Tkalcec, John Hennig, D Mari, R Schaller
    Abstract:

    The mechanical loss and dynamic modulus temperature spectra of two 18-carat white Gold Alloys, Au58%Cu24%Pd18% without (grade A) and with alloying additions (grade B), were measured in the 400-1000 K temperature range. A peak interpreted as a Zener relaxation peak is found at about 630 K in both Alloys. In the as-quenched state the peak shifts to lower temperatures due to excess vacancies, creating a transient peak at 520 K visible only upon the first heating. In grade A, a relaxation peak is observed at 750 K and is attributed to grain boundary relaxation, since it is absent in monocrystalline sample. in the same temperature region, the grade B features a peak with a large hysteresis between heating and cooling. A sharp peak observed in heating at 830 K is accompanied by a strong modulus decrease. In cooling, we observe a peak at 750 K, below which the mechanical loss abruptly decreases, accompanied by a modulus recovery. The peak hysteresis is interpreted as being due to dissolution or precipitation, respectively. The internal friction spectrum is correlated with the alloy's mechanical properties, namely the hardening of the grade B upon tempering at a temperature below the dissolution peak. (C) 2009 Elsevier B.V. All rights reserved.

Ikuya Watanabe - One of the best experts on this subject based on the ideXlab platform.

  • bond strength of Gold Alloys laser welded to cobalt chromium alloy
    The Open Dentistry Journal, 2008
    Co-Authors: Ikuya Watanabe, Cameron Wallace
    Abstract:

    The objective of this study was to investigate the joint properties between cast Gold Alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of Gold Alloys (Type IV, Type II and low-Gold) and a Co-Cr alloy. Each Gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-Gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-Gold welded to Co-Cr. This study indicated that, of the three Gold Alloys tested, the Type IV Gold alloy was the most suitable alloy for laser-welding to Co-Cr.

  • Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy
    The Open Dentistry Journal, 2008
    Co-Authors: Ikuya Watanabe, Cameron Wallace
    Abstract:

    The objective of this study was to investigate the joint properties between cast Gold Alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of Gold Alloys (Type IV, Type II and low-Gold) and a Co-Cr alloy. Each Gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-Gold and Type II. There was no statistical difference (P

  • Joint properties of cast Fe‐Pt magnetic alloy laser welded to Gold Alloys
    Journal of Biomedical Materials Research Part B, 2006
    Co-Authors: Ikuya Watanabe, Khoi Nguyen, P. Andrew Benson, Yasuhiro Tanaka
    Abstract:

    This study investigated the joint properties of a cast Fe-Pt magnetic alloy (Fe-36 at % Pt) laser welded to three Gold Alloys. The Gold Alloys used were ADA Type II and Type IV Gold Alloys, and an Ag-based (Ag-Au) Gold alloy. Cast plates (0.5 × 3.0 × 10 mm) were prepared for each alloy. After the cast Fe-Pt plates were heat treated, they were butted against each of the three Alloys and then laser welded with Nd:YAG laser at 200 V. Homogeneously welded specimens were also prepared for each alloy. Tensile testing was conducted at a crosshead speed of 1 mm/min. Failure load (N) and elongation (%) were recorded. After tensile testing, the fractured surfaces were examined with the use of SEM. The failure-load values of the group of Alloys welded homogeneously were ranked in the order of: Ag-Au alloy > Type IV alloy > Type II alloy > Fe-Pt alloy. The Type IV alloy welded to Fe-Pt alloy had the highest failure-load value among the three Alloys tested. The elongation results tended to follow a similar pattern. The results of this study indicated that Type IV Gold alloy is a suitable alloy for metal frameworks to which cast Fe-Pt magnetic alloy is laser welded. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006

  • Effect of two metal primers on adhesive bonding with type IV Gold Alloys
    Journal of Prosthetic Dentistry, 1995
    Co-Authors: Ikuya Watanabe, Hideo Matsumura, Mitsuru Atsuta
    Abstract:

    Bond strengths of an adhesive resin bonded to two types of Gold Alloys wereinvestigated in vitro with two different metal primers. Disk specimens were cast in a type IV Gold alloy designed for resin-bonded restorations and in a low-temperature age-hardenable Gold alloy. The specimens were primed with either a vinylthiol primer or a thiophosphate primer, then bonded with an adhesive resin initiated with tri- n -butyl borane derivative. Both primers effectively enhanced bond between Gold Alloys and the adhesive. The use of metal primers in conjunction with type IV Gold Alloys is useful for resin-bonded fixed partial dentures

  • Effect of two metal primers on adhesive bonding Gold Alloys
    1995
    Co-Authors: Ikuya Watanabe, Mitsuru Atsuta
    Abstract:

    Bond strengths of an adhesive resin bonded to two types of Gold Alloys were investigated in vitro with two different metal primers. Disk specimens were cast in a type IV Gold alloy designed for resin-bonded restorations and in a low-temperature age-hardenable Gold alloy. The specimens were primed with either a vinylthiol primer or a thiophosphate primer, then bonded with an adhesive resin initiated with tri-n-butyl borane derivative. Both primers effectively enhanced bond between Gold Alloys and the adhesive. The use of metal primers in conjunction with type IV Gold Alloys is useful for resin-bonded fixed partial dentures. (J PROSTHET DENT 1995;73:299-303.)

R. Roberti - One of the best experts on this subject based on the ideXlab platform.

  • On the strengthening mechanisms of 18 carat yellow Gold and its mechanical behaviour
    Materials Science and Engineering A, 2008
    Co-Authors: R. Roberti, Giorgio Cornacchia, Michela Faccoli, Marcello Gelfi
    Abstract:

    In order to contribute to a better understanding of the mechanical properties of Gold Alloys this paper investigates the mechanical behaviour of an 18 carat yellow alloy; the strain hardening behaviour during a tensile test was measured in the annealed as well as in different cold-work conditions. In addition, the contribution of different strengthening mechanisms is discussed on the basis of current results and of data reported in literature. In particular, the contributions of grain size refinement and copper solid solution alloying in improving the mechanical strength of Gold Alloys were quantified. © 2007.

A Czerwinski - One of the best experts on this subject based on the ideXlab platform.

  • electrochemical behavior of palladium Gold Alloys
    Electrochimica Acta, 2003
    Co-Authors: M łukaszewski, A Czerwinski
    Abstract:

    Abstract The behavior of Pd–Au Alloys, prepared by electrochemical codeposition, has been studied in acidic solutions (1 M H 2 SO 4 ) using mainly the cyclic voltammetry technique. Morphology of the alloy surface and bulk compositions were examined by SEM/EDAX method. Various types of voltametric behavior during potential cycling in the oxygen region are presented. The influence of hydrogen absorption on electrochemical properties of surface oxides is demonstrated. The problem of the nature of oxygen electrochemisorbed on Pd–Au Alloys is discussed.

  • electrosorption of hydrogen into palladium Gold Alloys
    Journal of Solid State Electrochemistry, 2003
    Co-Authors: M łukaszewski, K Kuśmierczyk, J Kotowski, H Siwek, A Czerwinski
    Abstract:

    Hydrogen electrosorption into Pd-Au Alloys has been studied in acidic solutions (1 M H2SO4) using cyclic voltammetry. Pd-Au electrodes with limited volume were prepared by electrochemical co-deposition. It was found that the maximum H/(Pd+Au) ratios decrease monotonically with increasing Gold content and reach zero at ca. 70 at% Au. Similarly to the case of Pd limited volume electrodes, two peaks in the hydrogen region, corresponding to two types of sorbed hydrogen, are observed on voltammograms for Pd-rich Alloys. The hydrogen capacity, H/(Pd+Au), measured electrochemically, depends on the sweep rate in the cyclic voltammetry experiments, which suggests that two different mechanisms for hydrogen desorption from the Pd-Au alloy are possible. After a strong decrease of Pd concentration at the electrode surface, caused by long cyclic polarization to sufficiently anodic potentials, the amount of absorbed hydrogen is still significant for Alloys initially rich in Pd. The results obtained from CO adsorption experiments suggest that only Pd atoms are active in the hydrogen absorption/desorption process.