Tungsten-rhenium thermocouples are easily oxidized, suitable for use in dry inert or hydrogen, or with dense protection tube separate it with oxygen. Cannot be used for carbon atmosphere ( As used in the atmosphere containing hydrocarbons, a temperature over 1000 ℃ or corrosion) 。 Tungsten or tungsten rhenium easy to generate stable carbides in carbon atmosphere, so that to reduce its sensitivity and cause the brittle fracture, the presence of hydrogen, will accelerate carbonization. Our company produces the tungsten-rhenium thermocouples has been widely used in many units, the performance reached the level of similar products abroad. The technical indicators are as follows: 1, dividing W - Re3/25, W - Re5/262, temperature measuring range: 0 ~ 1800 ℃, the temperature measurement accuracy: 4, time constant: p 180 s5, insulation resistance: > 5 m Ω 6, size: 300500750100, 0110 ( mm) At present our company produces the tungsten-rhenium thermocouples fine ceramic protection tube is divided into three categories. Of the specifications of the ceramic tube are: Ф diameter 8, 10, Ф Ф 12, 14, Ф Ф 16, 300 ~ 1100 mm in length, this kind of thermocouple can not be restricted by working environment atmosphere in any atmosphere medium and long-term use, temperature range is 0 ~ 1800 ℃. Another kind is pure molybdenum protection tube. Molybdenum and tungsten tube specifications are: Ф diameter 6, 8, Ф Ф 10 mm, 500 ~ 700 mm in length, the thermocouple in a vacuum, reduction or inert gas protection of the environment medium and long term work, molybdenum tube well is under 1800 ℃ temperature use for a long time, short-term use temperature to 2000 ℃. Category is the protection of tungsten tube. As for the tungsten tube can long-term work under 2100 ℃, but it is hard to processing and its price is very expensive. The characteristics of tungsten-rhenium thermocouples hot wire electrode high melting point ( 3300℃) Extremely easily, low steam and oxidation; In the oxidizing atmosphere chemistry stability is good. Electromotive force is big, high sensitivity, the most main or cheap. At present, a lot of measuring temperature above 1600 ℃, the non-contact method is adopted, however, the method of error is bigger, such as contact law can accurately measure the true temperature. In high temperature thermocouple, thermocouple is expensive and precious metals can only high temperature under 1800 ℃, and tungsten rhenium thermocouple temperature measurement not only high ceiling, and good stability, therefore, tungsten-rhenium thermocouples in metallurgy, building materials, aerospace, aviation, and nuclear power and other industries are widely used. Tungsten resources in our country, the tungsten-rhenium thermocouples cheap, can partially replace precious metal thermocouple ( Platinum rhodium thermocouple) It is promising in the area of high temperature test temperature materials. Its high temperature can reach 2800 ℃, but, when higher than 2300 ℃, scattered data. Therefore, the use of around 2000 ℃ temperature well.