Abstract
The oxidation behavior of gold alloys containing small amounts of Sn and/or In was investigated in order to analyze adherence mechanisms in the porcelain-fused-to-metal (PFM) system. Experimental gold alloys (99.5wt%Au-0.5wt%Sn, 99.5wt%Au-0.5wt%In and 99.0wt%Au-0.5wt%Sn-0.5wt%In) were oxidized over an oxygen partial pressure (Po2) range from 0.016 to 0.8atm and a temperature range from 700 to 900°C, and a commercial PFM alloy (Ceramic Gold) was done at Po2≤0.2atm.
Both the concentrated amounts of In in Au-In alloy and of Sn and In in Au-Sn-In alloy on each alloy surface after oxidation increased at Po2<0.2atm by the transition from internal to external oxidation, and nodules consisting of alloy matrix were observed on the oxidized surface. The oxidation behavior of the commercial PFM alloy was similar to that of Au-Sn-In alloy. Indium in the alloy determined the oxidation behavior and surface characteristics.
