Tungsten-rhenium thermocouple
Tungsten-rhenium thermocouple is high temperature resistant thermocouple. It has the advantages of good linear relationship between temperature and potential, reliable thermal stability and cheap price. With the display instrument, can directly measure the temperature of liquid, steam and gas media. It can partially replace the platinum rhodium thermocouple as a high-tech metallurgy industry, high temperature electronic thermoelectric system structure engineering and space vehicles, nuclear reactor ultra high temperature measurement tools.
The relationship between the thermoelectric potential of tungsten-rhenium thermocouple and temperature conforms to zbn05003-88 scale, which is equivalent to ASTME696 -- 84 standard. In vacuum, reduction, inert atmosphere, can be used in the range of 0 ~ 2300℃. Tungsten-rhenium couples with special protective tubes can also be used in an oxidizing atmosphere at 1600℃ for a long time, and their price is lower than that of platinum-rhodium thermocouples.
The tungsten-rhenium thermocouple was first developed by Goedecke in 1931, and was developed in the 1960s and 1970s as the most successful refractory metal thermocouple. The characteristics of tungsten-rhenium thermocouple are: high melting point of hot electrode wire (3300℃), low vapor pressure, easy oxidation; Good chemical stability in non-oxidizing atmosphere. Large electromotive force, high sensitivity, the most important or cheap price.
Tungsten-rhenium thermocouples dividing W/(W-26Re)，(W-3Re)/(W-25Re)，(W-5Re)/(W-26Re), and (W-5Re)/(W-20Re), etc. Long-term use temperature is 2000 ~ 2400℃, short-term use up to 3000℃.
The relationship between the thermoelectric potential of tungsten-rhenium thermocouple and temperature conforms to zbn05003-88 scale, which is equivalent to ASTME696 -- 84 standard. In vacuum, reduction, inert atmosphere, can be used in the range of 0 ~ 2300℃. Tungsten-rhenium couples with special protective tubes can also be used in an oxidizing atmosphere at 1600℃ for a long time, and their price is lower than that of platinum-rhodium thermocouples.
The relationship between the thermoelectric potential of tungsten-rhenium thermocouple and temperature conforms to zbn05003-88 scale, which is equivalent to ASTME696 -- 84 standard. In vacuum, reduction, inert atmosphere, can be used in the range of 0 ~ 2300℃. Tungsten-rhenium couples with special protective tubes can also be used in an oxidizing atmosphere at 1600℃ for a long time, and their price is lower than that of platinum-rhodium thermocouples.
Use of tungsten-rhenium thermocouple. Non-contact method is used to measure the temperature above 1600℃, but the error of this method is large, such as the contact law can accurately measure the true temperature. In the high temperature thermocouple, the precious metal thermocouple is expensive and the highest temperature can only be below 1800℃, while the tungsten-rhenium thermocouple not only has a high temperature measurement upper limit, but also has good stability. Therefore, the tungsten-rhenium thermocouple is widely used in metallurgy, building materials, aerospace, aviation and nuclear energy and other industries. Tungsten is abundant in China, and tungsten-rhenium thermocouple is cheap, which can partially replace precious metal thermocouple. It is a promising temperature measuring material in the field of high temperature testing.Service temperature. Its maximum operating temperature can reach 2800℃, however, above 2300℃, data dispersion. Therefore, the best use of temperature at about 2000℃.
Use the ambient atmosphere. Tungsten - rhenium thermocouple is easy to oxidize, suitable for use in inert or dry hydrogen, or with a dense protective tube to make it isolated from oxygen can be used. Should not be used in atmospheres containing carbon (e.g. in atmospheres containing hydrocarbons, temperatures above 1000℃ are corroded). Tungsten or tungsten-rhenium tend to form stable carbides in a carbon-containing atmosphere, thus reducing their sensitivity and causing brittle fracture, and accelerating carbonization in the presence of hydrogen.
