Measurement of high temperatures, more than 1000 C, using ceramic based thermocouples is really a well known process. To carry out this successfully the resistance wires in the thermocouple need to be insulated and protected.
The application of Ceramic materials to safeguard the platinum based wire is a technique which has been used for several years, as a result of exceptional heat resistant properties of these materials. The thermocouple sensors is regarded as the commonly used heat measurement implement and is used for measuring the temperature on the inside of a furnace, typically used for that melting or heat treatment of metal or indeed for manufacturing ceramic products.
The ceramic components in the typical thermocouple device will be the outer protection tube that is exposed to the furnace. Occasionally multiple tubes are used inside the other to deliver the level of insulation and protection required.
Ceramic insulators (Tubes with 2 or even more core holes through them) are also employed to isolate the two or more wires that check out the bi-metallic joint with the head the point through which sens0rs temperature is measured.
The typical materials used for that tube is really a 99.7% alumina material, impervious tube, which is attached typically into a metal thermacouple head, containing a terminal block which is used to connect into a standard wire to the instrumentation. In a less demanding heat atmosphere a mullite tube may be used like a cheaper alternative, which will work sufficiently up to 1600 ‘oc. The mullite tube is additionally an impervious tube and has 60% alumina content.