Process for manufacturing platinum temperature-measuring resistance element

A process for manufacturing a platinum temperature-measuring resistance element having a thermosensitive part composed of platinum resistance wire or platinum resistance film comprising the steps of:

• raising a temperature of the thermosensitive part inside a furnace;
• purging the furnace with inert gas containing oxygen to a temperature region in which the platinum is in reduced form at a partial pressure of oxygen in an applicable purge gas as determined from platinum oxide formation free energy;
• substituting the purge gas in the furnace with inert gas in which oxygen is 1 kPa or less;
• and
• in the presence of the inert gas, decreasing the temperature inside the furnace to the temperature region in which PtO2 is in oxidized form at a partial pressure of oxygen in the purge gas of 1 kPa or less, gas containing oxygen is taken as the purge gas in the furnace and the surface of the platinum resistance wire or platinum resistance film of said thermosensitive part is sufficiently oxidized with PtO2.

A process for manufacturing a platinum temperature-measuring resistance element comprises the step of preparing a thermosensitive part having a portion to be sealed coated with a glaze;

• the step of placing a pre-sealing element on a tray and inserting the same in a chamber;
• the step of enclosing a purge gas containing an inert gas and oxygen in the chamber;
• the step of raising the internal temperature of the chamber to a region in which the platinum is in reduced form at a partial pressure of oxygen in the purge gas as determined from platinum oxide formation free energy;
• the step of replacing the purge gas with an inert gas wherein oxygen is 1 kPa or below;
• and the step of rapidly heating the interior of the chamber to a frit melting temperature by means of a lamp heating unit to thereby seal the portion to be sealed of the thermosensitive part.