Effects of Gold Addition for the Properties of Casting Pd-Cu-Ag Alloy

DOI 3 Citations
  • YAMATOYA Fumihiko
    Department of Dental Materials Science, Nippon Dental University, Niigata
  • NAKAMURA Kengo
    Department of Dental Materials Science, Nippon Dental University, Niigata
  • GOTO Shin-ichi
    Department of Dental Materials Science, Nippon Dental University, Niigata

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  • 鋳造用銀パラジウム合金の諸性質に及ぼす金添加の影響

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An alloy containing silver palladium together with less than about 5% gold content (hereinafter referred to as Ag-Pd alloy), is commercially available. Although this type of Ag-Pd alloy has mechanical properties comparable to those of 12% gold Ag-Pd alloy, and it is thought it can be used for clinical use, the effects of gold addition to Ag-Pd alloy remain yet to be known.<br> In view of those circumstances, by fixing the total of gold and palladium at 30 wt% and the total of copper and silver at 65 wt%, with the residual quantity 5 wt% of zinc, twelve kinds of (Au-)Pd-Cu-Ag-Zn alloys were melted and cast. The mechanical properties and resistances to tarnishing of each alloy during quenching and aging heat treatment were examined in order to make clear the possible effects of gold addition.<br>In respect of Cu/Ag and Au/Pd factors, the measuring values obtained were subjected to two-way layout orthogonal analysis of variance, and by seeking an orthogonal polynomial function concerning the significant term, isometric curves were drawn, thereby reaching the following conclusions:<br> 1) The tensile strength at quenching treatment varies with the quantity of Cu/Ag, and the more the quantity of copper, the higher it becomes.<br> 2) At aging treatment, the more the copper and gold content, the higher the tensile strength becomes.<br> 3) Alloys containing 10 wt% of gold (20 wt% of palladium) and 15 wt% of copper (50 wt% of silver) show more than 20% of elongation at quenching treatment.<br> 4) The brightness L* after the tarnishing test becomes highest when the quantity of Cu/Ag is (13〜15)/(52〜50), and the larger the gold content, the higher the L*.<br> 5) That is, when the gold content of (Au-)Pd-Cu-Ag-Zn alloy with Au+Pd=30 wt%, is increased, elongation at quenching treatment increases, the ability of hardening at aging treatment increases, and resistance to tarnishing is improved.<br> 6) Whithin the range of the experiment, it was found that the composition of alloy having the best properties was 10Au-20Pd-15Cu-50Ag-5Zn (wt%), and concerning palladium, copper and silver, the tolerance is ±2 wt%.

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