In-situ Synthesis of an Auxiliary Electrode of Solid Electrochemical Sulfur Sensor by CaAl₄O₇ Coating

摘要

A novel auxiliary electrode CaAl4O7+Al2O3+CaS used for solid electrochemical sulfur sensor, wassynthesized by the in-situ reaction of CaAl4O7 coating on the surface of the ZrO2(MgO) electrolytetube by: l4O7 [ ] 2 l2O3 [O . The CaAl4O7 coating was synthesized using aluminumnitrate solution and calcium hydroxide solution as raw materials and then was fabricated on the surfaceof the ZrO2(MgO) electrolyte tube using solid sintering technology at 1500 °C. The microstructure ofthe coating was dense and well combined with the ZrO2(MgO) electrolyte. The solid electrochemicalsulfur sensor F [ F l4O7 Z O2 M O 2O3 Mo was assembled and tested in the carbonsaturated molten iron at 1500 °C. The results showed that the sensor had a good stability and accuracy,and the CaAl4O7 coating was converted to CaAl4O7+Al2O3+CaS when the sulfur sensor was insertedinto the molten iron. The phase composition and microstructure of the synthetized auxiliary electrodewere investigated after the sulfur sensor was tested, indicating that the auxiliary electrode coating witha thickness of 40-50 μm w s synth tiz d. The empirical formula of the sulfur sensor was obtained asfollows:E(mV) ? 45.891n[wt%S] ? 24.39.