Effect of addition of palladium on properties of Ag2Hg3 (γ1) phase

The effect of palladium addition on the microstructure, compressive strength, creep rate and mercury release rate of Ag2Hg3 (γ1) phase was evaluated. Experimental results indicated that fairly pure γ1 phase could be fabricated using the present trituration method. The heat treatment of γ1 at 90 °C increased porosity level, increased dimensional shrinkage, increased mercury vapour release and enhanced the formation of β1 phase. Addition of palladium in γ1 slowed down the amalgamation reaction, largely suppressed the phase transition to β1 and caused a slight shift in open circuit potential toward the anodic direction. Although the overall anodic polarization profiles did not show a significant effect of palladium, scanning electron microscopy revealed morphological differences between pure and palladium-containing γ1. Addition of palladium in γ1 also increased compressive strength, increased creep resistance, and largely reduced both mercury vapour and ion release rates. Considering overall performance, the optimal palladium content in γ1 seems to be in the range between 0.50 and 0.75 wt%.