Tungsten baht thermocouple is the most successful refractory metal thermocouple and the best industrial thermocouple that can be measured above 1800℃. With the development of high and new technology, the application of tungsten fetter thermocouple will be more and more extensive. High melting point (3300℃), high strength. The thermoelectric EMF is large, high sensitivity, and the co-thermoelectric EMF rate is twice that of type S thermocouple and three times that of type B thermocouple. Highly oxidizing. The price is cheap, only 1/3 of the model S thermocouple.
Tungsten hot thermocouple features: high melting point of hot electrode wire (3300℃), low vapor pressure, easy oxidation; good chemical stability in a non-oxidizing atmosphere. Electromotive force is big, sensitivity is high, the most important still is price is cheap. At present, the non-contact method is mostly used to measure the temperature above 1600℃. However, the error of this method is relatively large. For example, the real temperature can be accurately measured by the contact law. In the high temperature thermocouple, precious metal thermocouple is expensive and the highest temperature can only be below 1800℃, and tungsten hot thermocouple not only temperature measurement upper limit is high, and good stability, therefore, tungsten favors thermocouple in metallurgy, building materials, aerospace, aviation and nuclear energy and other industries are widely used. China's tungsten resources, tungsten hot thermocouple cheap, can partially replace the precious metal thermocouple (platinum man thermocouple), it is a high temperature testing in the field of very promising thermometry materials. Its maximum operating temperature can be up to 2800℃, however, at higher than 2300℃, the data are scattered. Therefore, the best use temperature around 2000℃.
Tungsten baht thermocouples are easily oxidized and are suitable for use in inert or dry hydrogen gas, or when isolated from oxygen by dense protective tubes. Should not be used in carbonaceous atmospheres (if used in atmospheres containing hydrocarbons, corrosion will occur if the temperature exceeds 1000℃). Tungsten or tungsten in a carbon-containing atmosphere tends to produce stable carbides that reduce their sensitivity and cause brittle fracture, accelerating carbonization in the presence of hydrogen.
