High temperature thermocouple containing conductors compositionally dissimilar

Abstract

Abstract A TANTALUM SHEATHED THERMOCOUPLE WITH TUNGSTENRHENIUM WIRES AND BERYLLIUM OXIDE INSULATION IS EMPLOYED FOR TEMPERATURE MEASUREMENT IN ABLATIVE MATERIALS. THE ELEMENTS OF THE THERMOCOUPLE ARE MADE RELATIVELY SMALL IN A NARROW RANGE TO ACHIEVE AN EROSION RATE OF THE SHEATH AND INSULATION SUBSTANTIALLY THE SAME AS THE ABLATIVE EROSION RATE AND LESS THAN THE EROSION RATE OF THE WIRES. A CHEMICAL ETCHING STEP IS EMPLOYED FOR REDUCING SHEATH DIAMETER DURING MANUFACTURE OF THE THERMOCOUPLE TO OBTAIN THE SMALL SIZE. UNEXPECTEDLY IT IS FOUND THAT THE THERMOCOUPLE WIRES REWELD AT THE TEMPERATURE OF THE LOWEST MELTING LEG AS THE HOT JUNCTION IS ERODED AWAY DURING EXPOSURE OF THE ABLATIVE TO A HIGH TEMPERATURE ENVIRONMENT. THE REWELDING AT A WELL KNOWN TEMPERATURE PROVIDES A MEANS FOR CALIBRATING THE THERMOCOUPLE DURING USE AND ALSO AFFORDS THE OPPORTUNITY TO MEASURE COOLING TEMPERATURES AFTER THE THERMOCOUPLE HAS BEEN EXPOSED TO TEMPERATURES EXCEEDING ITS MELTING POINT.

Inventors

• 👤 Walter K Moen

Bibliographic Details