• Mikolajick, Thomas
• Fankhänel, Beate
• Lang, Hans Jürgen
• Tomandl, Gerhard
• Rank, Jürgen
• Schreiber, Gerhard

Abstract

<p>Galvanic cells containing an ion conducting solid electrolyte and sulphur sensitive auxiliary electrodes have been developed. The target application of these devices is the continuous measurement of the sulphur content of both the tin melt and the protective gas in the float glass process. Essential improvements to the sulphur concentration chain have been made with the fluoride solid electrolyte (LaF3)0·95(SrF2)0·05 and sulphide auxiliary electrodes based on strontium sulphide. Lanthanum strontium sulphide of the composition La0·876Sr0·124S1·438 from an in-situ sulphidation forms the sulphide auxiliary electrodes on the fluoride ion conductor (LaF3)0·95(SrF2)0·05 containing 5 wt% SrS. Reversible cell voltages were achieved above 400°C with these sulphide auxiliary electrodes in a tin melt, saturated with SnS. A silver/ silver sulphide reference system was used. The response time of this sulphur cell can still be some hours depending on working temperature. In addition the fluoride ion conductor does not have a sufficient mechanical stability for practical application. To measure the sulphur partial pressures in H2S–H2–N2 protective gases solid electrolytes of the composition (LaF3)0·95(SrF2)0·05 containing 3 wt% SrS and 10 wt% LiF in a suspended tube made of corundum have been used. At working temperatures above 400°C galvanic sulphur cells reacted within seconds to changes of the sulphur partial pressure in the H2S–H2–N2 gases. This type of galvanic sulphur cell is suitable for practical application in H2S–H2–N2 protective gases. Depending on the H2S–H2 partial pressure ratio and operating temperature calibration of the cell may be necessary on the basis of a higher electronic conductivity in the sulphide auxiliary electrodes. It is necessary for the industrial application of a galvanic sulphur cell in the protective gas and especially in the tin melt of the float glass process to effectively protect the sulphide auxiliary electrodes by an oxygen absorber.</p>

Topics

• impedance spectroscopy
• silver
• Oxygen
• melt
• glass
• glass
• Strontium
• Lanthanum
• tin
• Sulphur