Electrochemical Characterization of Precious Metal Braze Alloys Using Potentiodynamic Polarization

Author(s) Information

Maxwell Glen Martin, California Polytechnic State University - San Luis ObispoFollow
Mason Gregory Morgan, California Polytechnic State University - San Luis ObispoFollow
Matthew David Vance, California Polytechnic State University - San Luis ObispoFollow

Department - Author 1

Materials Engineering Department

Degree Name - Author 1

BS in Materials Engineering

Date

6-2014

Primary Advisor

Blair London

Abstract/Summary

This study aimed to characterize the electrochemical behavior of six precious metal braze alloys by performing potentiodynamic polarization tests (ParStat 2273) based on ASTM Specifications G5 and G59. To determine the extent to which the alloys will contribute to galvanic corrosion in a marine environment (3.5 wt% NaCl), corrosion analysis software was used to produce fitted Tafel lines to determine the open circuit potential, V_oc, for each alloy. The V_oc values for the alloys were found to be -66.58 mV for Gold ABA, 13.01 mV for Nicoro^®, -39.00 mV for Nioro^®, 23.4 mV for Palniro-1^®, -47.91 mV for Palniro-7^®, and -205.16 mV for Silver ABA. These values were compared to industry-standard base materials typically used in brazing processes to determine their compatibility as galvanic couples. Differences in V_oc greater than 250 mV within the couple are considered unsuitable for joining without additional galvanic protection. To provide coupling recommendations, 95% confidence intervals were made to estimate each alloy’s V_oc.

URL: https://digitalcommons.calpoly.edu/matesp/99