Development of electrochemical silicon sensors for iron and steel melts

Abstract

Based on the commonly used oxygen sensors with O2‐ ion‐conducting ZrO2 electrolytes and solid metal‐metal oxide references, new sensors have been developed for direct measurements of Si content in iron and steel melts. The sensors are designed in such a way that local chemical equilibrium of the reaction ZrO2 + [Si] + 2[O] = ZrSiO4 is established at the surface of the ZrO2 electrolyte tube or inside a cavity adjacent to the ZrO2 electrolyte sensor tip using a saturating ZrO2‐ZrSiO4 mixture. Concepts and dimensions of the sensors were optimized in view of a fast EMF response upon immersion and the maintenance of a stable EMF recording over extended periods. Reliable measurements were performed in Fe‐Si melts at 0.05 to 5 wt.‐% Si.

Steel and related materials

“…Considerable work has been performed with silicon probes. Typically based on Zr02-ZrSi04 equilibria, the response time of certain designs has been dropped to less than 15 s and reliable determinations have been made over the range 0.05-5 % silicon (135)(136)(137)(138)(139)(140). An electrochemical probe containing Na2S has been used to monitor the sulfur content of molten iron (141).…”

Novel concept of disposable emf sensors for in situ measurements of solute contents of liquid metals in metal‐refining processes*

“…[%Al]2 [a O ] 3 derived from the CELOX emf readings will be higher than the true equilibrium value. For example, with pure Al 2 O 3 as the deoxidation product, the true equilibrium value at 1600aeC is [%Al] 2 [a O ] 3 Ω [%Al] 2 [ppm O ¡ f O ] 3 Ω0.024, whilst the CELOX measurements give [%Al] 2 [a O ] 3 Ω0.119, which is used in the interpretation of plant data on steel deoxidation.…”

Sensors based on new oxide electrolyte and oxygen reference materials for on-line measurements in steel melts

“…Besides, the length of the solid oxide electrolyte plug was increased up to 10-12 mm. Furthennore, a new combined tube plug-type sensor (figure 2b) which was already proposed for Si detection in Fe-0-Si melts[22] was used. The sensor consists of a conventional partially stabilized Zr0 2 tube (6 mm outer diameter, 4 mm inner diameter, 35 mm length) containing a porous Zr0 2 (Y 2 03) plug and the reference material on top of it.…”