Corrosion of MgO-PSZ in a HF solution and its effect on synthesis of an auxiliary electrode for high-temperature sulfur sensors

Abstract

An auxiliary electrode for high-temperature sulfur sensors was synthesized with H2S at the surface of zirconia partially stabilized by magnesia (MgO-PSZ). MgO-PSZ was first corroded in a 40% HF solution under ultrasonic conditions at room temperature for different times. A sulfur sensor, Mo|Mo, Mo2S3|ZrS2 + MgS|ZrO2(MgO)|ZrS2 + MgS|[S]Fe|Mo, was developed and tested in carbon-saturated liquid iron. The results show that a phase transformation from tetragonal to monoclinic takes place on the surface of ZrO2 after MgO-PSZ is exposed to a HF solution. HF treatment of MgO-PSZ can promote formation of the auxiliary electrode. The variations of electromotive force versus [wt% S] can be obtained as follows: E = −53.247 ln [wt%S] + 142.86 (r = 0.97).