Objectives: The purpose of the present investigation was to report a Pd-free high gold alloy for porcelain bonding based on the ternary system of Au-Pt-Zn with a nominal composition of 86Au-11Pt-1.5Zn-0.5In-0.7Rh-0.2Fe-0.1Ir (wt.%). Emphasis was put on the effect of a pre-firing heat treatment on the mechanical properties of the alloy.
Methods: The strengthening effect of the pre-firing heat treatment was investigated by means of hardness measurement, tensile testing, X-ray diffraction, optical microscopy and scanning electron microscopy.
Results: Experimental results showed that both the hardness and tensile strength of the alloy can be significantly improved after heat treatment at the temperature of 980 degrees C for 15 min. The strengthening could be attributed to homogenization of microstructure and alloying elements and precipitation of new fine particles.
Significance: The cast framework of the present new Pd-free alloy could be heat treated before actual firing, and this would improve the processing properties of the alloy during firing.