1991 Volume 31 Issue 2 Pages 184-188
A ceramic sensor for monitoring the hydrogen permeated through steels at high temperatures using an electrochemical method has been developed. A new proton conductive solid electrolyte (5 mol%Yb2O3-SrCeO3) was used as an electrolyte in this sensor. It was found possible to measure the diffusivity and the content of hydrogen permeated through a plain carbon steel at 773 K and 0.101 MPa hydrogen gas by joining the sensor to the steel with a platinum past. However, the detectability of hydrogen was poor, because joining of ceramics/steel exerted a large influence on it. Joining of the ceramics to the platinum-plated steel with amorphous copper filler metal led to the great improvement of the detectability of hydrogen. This sensor will be useful for predicting hydrogen attack of steels in operating chemical plants.