Electrochemical Studies on Platinum Dissolution from Ag-Au-Pt Alloy in Dilute Nitric Acid

摘要

The electrochemical studies on pure Pt and Ag-Au-Pt alloy were investigated. The corrosion behavior of Pt in Ag-Au-Pt (10:3:1) wt% ternary alloy was studied. Corrosion studies were conducted using potentiodynamic polarization technique with a three-electrode arrangement. The Ag-Au-Pt ternary alloy was used as working electrode. The experiments were conducted in 50 wt% HNO{sub}3 at 65°C. Samples were analyzed before and after the corrosion studies using SEM and EDAX. Corrosion rate of 0.26 and 4.69×10{sup}6 micrometers per year were observed for pure Pt and ternary alloy, respectively. The surface of the corroded alloy was composed of individual grains. Different concentrations of platinum were observed on the grain surface, grain edge, and bottom of the grain. Concentration of Pt on top of the grain and at the edge of the grain is 10.09 and 15.55 wt%, respectively. Platinum content of 4.68±1 wt% observed in the EDAX analysis of corrosion product confirmed the corrosion of Pt from Ag-Au-Pt alloy in 50 wt% HNO{sub}3. It can be concluded that dissolution of Pt from the sample is due to bulk as well as grain boundary diffusion.