Method for oxidising a thermocouple sheath
A method for forming an oxygen resistant aluminum oxide layer on an outer surface of a thermocouple sheath composed of a nickel alloy containing between 1% to 7% aluminum comprises removing a pre-formed oxide layer from the outer surface so as to create a prepared sheath; performing a controlled oxidation by subjecting the prepared sheath to atmospheric conditions at a temperature between 1000° C. and 1250° C. so as to form the oxygen resistant layer on the thermocouple sheath and to thus form an oxidized sheath; and cooling the oxidized sheath so as to prepare the oxidized sheath for service.
1. A method for forming an oxygen resistant aluminum oxide layer on an outer surface of a thermocouple sheath composed of a nickel alloy containing between 1% to 7% aluminum, the method consisting of:
removing a pre-formed oxide layer from the outer surface so as to create a prepared sheath;
performing a controlled oxidation by subjecting the prepared sheath to atmospheric conditions at a temperature between 1000° C. and 1250° C. so as to form the oxygen resistant layer on the thermocouple sheath and to thus form an oxidized sheath; and
cooling the oxidized sheath so as to prepare the oxidized sheath for service.
2. The method as recited in claim 1 , wherein the nickel alloy contains between 4% to 5% aluminum.
3. The method as recited in claim 1 , wherein the temperature for the controlled oxidation is between 1100° C. and 1150° C.
4. The method as recited in claim 1 , wherein the removing of the pre-formed oxide layer includes grinding.