DEVELOPMENT OF AN OXYGEN SENSOR FOR CONTINUOUS MEASUREMENT IN MOLTEN STEEL

THIS EFFORT IS DIRECTED TOWARD THE DEVELOPMENT OF A CONTINUOUS READING OXYGEN SENSOR FOR LIQUID STEEL SERVICE. ALTHOUGH WELL KNOWN AS A CRITICAL PARAMETER IN THE ENERGY-EFFICIENT PRODUCTION OF QUALITY STEEL, OXYGEN CONTENT IS CURRENTLY MEASURED USING A DISPOSABLE ZIRCONIA SENSOR CAPABLE OF ONLY INTERMITTENT OPERATION. DESPITE THE FACT THAT FUNDAMENTALLY NOTHING HAS PRECLUDED THE USE OF SUCH A ZIRCONIA-BASED SENSOR FOR CONTINUOUS DETERMINATION OF OXYGEN CONTENT, TWO MAJOR OBSTACLES HAVE PREVENTED THIS IMPORTANT TECHNICAL ADVANCE. FIRST, THE SIMULTANEOUS AND CONTINUOUS TEMPERATURE MEASUREMENT REQUIRED BY THE ZIRCONIA CELL WAS NEVER AVAILABLE; SECOND, ZIRCONIA IS VERY SENSITIVE TO THERMAL SHOCK. OVERCOMING THESE OBSTACLES REQUIRES THE USE OF SPIN-OFF TECHNOLOGY FROM EARLIER EFFORTS THAT LED TO A SHOCK-RESISTANT CONTINUOUS TEMPERATURE MEASUREMENT DEVICE SUITABLE FOR STEEL MILL SERVICE. IN PHASE I, A ROBUST ZIRCONIA CELL WITH AN ABLATIVE CAP IS BEING DESIGNED, FABRICATED, AND ITERATIVELY TESTED UNTIL A CONFIGURATION CAPABLE OF DIRECT IMMERSION IS ACHIEVED. THE RECENTLY DEVELOPED CONTINUOUS TEMPERATURE MEASUREMENT TECHNOLOGY WILL THEN BE ADAPTED FOR CLOSE PROXIMITY MEASUREMENT TO THE ZIRCONIA CELL. THE STEEL OXYGEN CONTENT IS DETERMINED WHEN ELECTROMAGNETIC FORCE AND TEMPERATURE ARE MEASURED SIMULTANEOUSLY AND A KNOWN OXYGEN CONTENT REFERENCE MATERIAL (TYPICALLY CHROME/CHROME OXIDE) IS PLACED IN CONTACT WITH THE ZIRCONIA CELL.