Measurement of high temperatures, higher than 1000 C, using ceramic based thermocouples is a well established process. To carry out this successfully the resistance wires in the thermocouple have to be insulated and guarded.
The use of Ceramic materials to protect the platinum based wire is a technique which has been used for many years, due to the exceptional heat resistant properties of such materials. The thermocouple sensor is regarded as the widely used heat measurement implement which is used for measuring the temperature inside of a furnace, typically used for your melting or heat management of metal or indeed for manufacturing ceramic products.
The ceramic components in the typical thermocouple device are definitely the outer protection tube that may be subjected to the furnace. Sometimes multiple tubes are being used inside one another to offer the amount of insulation and protection required.
Ceramic insulators (Tubes with 2 or even more core holes through them) can also be accustomed to isolate the two or more wires that go to the bi-metallic joint in the head the point from which sens0rs temperature is measured.
The standard materials used to the tube is really a 99.7% alumina material, impervious tube, that is attached typically to your metal thermacouple head, containing a terminal block which is used in order to connect to your standard wire to the instrumentation. In a less demanding heat atmosphere a mullite tube can be utilized as being a cheaper alternative, that can work sufficiently around 1600 ‘oc. The mullite tube is also an impervious tube and it has 60% alumina content.