A rugged oxygen gas sensor with solid reference for high temperature applications

An oxygen sensor based on yttria-stabilised zirconia with Ni-NiO mixture as a solid reference electrode for high temperature applications was fabricated and tested. During high temperature use Ni reacts with inner Pt electrode and Pt lead wire, and affects the output signal of the sensor leading to a limited lifetime. This is the first time an Al2O3 isolation layer has been introduced in the design of an oxygen sensor. Use of this isolation layer prevents high temperature alloy formation between Ni and Pt, leading to a significant enhancement in the performance and the stability of the sensor. The sensor shows fast response with good recovery characteristics in the temperature range of 600-1400 C. However, after repeated tests over a longer period, the sensor performance degrades possibly due to grain growth and sintering of the inner electrode at high temperature. 8 refs.