An Improved Accelerated Test Chamber for Electrolytic Metal Migration and Corrosion

Abstract

Many accelerated electrolytic metal migration and corrosion investigations have been performed in accelerated test chambers with unknown gas concentration and flow characteristics. This paper outlines the development of a well‐characterized accelerated test chamber. The length (mean flow path) to hydraulic diameter ratio of the closed‐circuit rectangular flow channel is 20. Velocity and concentration measurements showed minimal horizontal or vertical gradients in the test section. The range of standard deviations (m/s) for the velocity profiles in the test section was 0.0037–0.16 at mean velocities of 0.11–2.9 m/s, respectively. Similarly, the range of standard deviations [ppm(vol.) for the concentration profiles was 1.0–1.2 for a standard gas mixture of in the air. The effect of gas velocity upon the rate of metal migration was demonstrated in the described test chamber using a new accelerated test in an environment. This test, the PEG‐400 drop test, is a moderate accelerated test with metal migration rates that are less than the water‐drop test but greater than a temperature humidity bias test with or without pollutants. The gas velocity was found to have a significant effect upon the rate of copper migration. The effects of gas velocity, humidity, and pollutant concentrations upon the metal migration and corrosion rates can be investigated in this accelerated test chamber.