Critical variables in gaseous corrosion testing

In recent work at Vanderbilt University, a failure mode was characterized that is accelerated by the presence of hostile gases in the environment. The effect of the velocity of the hostile gas stream was tested. Three different gas velocities were evaluated by measurement of the time of development of a shorting failure over a range of electrical field strengths. It was found that the time to failure decreased in proportion to the square root of the gas velocity as velocity increased in the range of 4 mm/s to 400 mm/s. The electrolyte base was provided by a coating of polyethylene glycol, average molecular weight 400, PEG400, between the Cu electrodes. These results make it possible to relate the time to failure to application variables such as gas concentration and gas-flow velocity, thus making possible at estimate of product lifetime from test results.<>