Abstract
Twelve kinds of Ag-Pd-Cu ternary alloys, containing 25, 30, 35, 40wt% Pd and 15, 25, 30wt% Cu were melted and cast using dental precision casting. After solution treatment at 800℃, water quenching (softening heat treatment) , and subsequently, 450→250℃ oven cooling (hardening heat treatment) were applied to the alloys and their mechanical properties and tarnishing resistance were measured.After softening hear treatment, the tensile strength of the experimental alloys, ranged from 39〜57kgf/mm2 and the elongation ranget from 14〜28%, while after herdening heat treatment, they ranged from 66〜107kgf/mm2, 1〜7%, respectively.After hardening heat treatment, the estimated composition showing the maximum tensile strength was about 34〜35Pd-20Cu-45〜46Ag and the estimated strength was 104±3kgf/mm2. After softening heat treatment, the Vickers hardness number(VHN)was 141〜200, and after herdening heat treatment VHN was 241〜431. VHN increased with increasing Pd and Cu contents. The brightness(L*)of the specimens immersed in 0.1% sodium sulfide solution at 37℃ for 3 days, was 60〜67 and their tarnishing resistance was improved with increasing Pd content and decreasing Cu content.
