是最成功的难熔金属热电偶、也是可测到1800°以上的工业热电偶中最好的热电偶。 Tungsten-rhenium thermocouple is the most successful refractory metal thermocouple and the best thermocouple among industrial thermocouples that can be measured above 1800 °. Now widely used in metallurgy, building materials, aerospace, aviation and nuclear energy industries. Its advantages are: (1) The upper limit of temperature measurement is high. The maximum operating temperature can reach 2800 °, but the data is scattered when it is higher than 2300 °, so the operating temperature is preferably below 2000 °. (2) In a non-oxidizing atmosphere, especially in a reducing atmosphere, the chemical stability is good, the sensitivity is high, and the thermoelectric potential is large. Its thermoelectric temperature change rate is about twice that of the S-type thermocouple. (3) Cheap. Its price is only 1/6 of the S-type thermocouple, and 1/8 of the B-type thermocouple. (4) is easily oxidized. The melting point of the hot electrode wire is as high as 3300 °, the vapor pressure is low, and it is easy to be oxidized. It is suitable for use in inert or dry hydrogen, or use a dense protective tube to isolate it from oxygen. The oxidation resistance of tungsten-rhenium thermocouple has attracted more and more attention from scholars at home and abroad. The purpose layer method can make tungsten-rhenium thermocouples work for nearly 50 hours in an oxidizing atmosphere above 1600 °, but it is still not ideal. The method of filling the oxide powder to form a solid body is often adopted at the scene, which is simple and easy to implement and has obvious effects. The specific method is to fill alumina (or magnesia) powder between the insulation tube and the protection tube, and the inner protection tube and the outer protection tube, and fill it as tightly as possible, and then use phosphoric acid to kiss or the high temperature adhesive to protect the tube. Mouth sealed.
There are two types of tungsten-rhenium thermocouples listed in national standards in China: tungsten-rhenium 5-tungsten-rhenium 26, and the index number is WRe5-WRe26.
的特点是：热电极丝熔点高(3300℃)，蒸气压低，极易氧化；在非氧化性气氛中化学稳定性好。 The characteristics of tungsten rhenium thermocouples produced by Jinhu Dongxiang are: high melting point of the hot electrode wire (3300 ℃), low vapor pressure, and easy oxidation; good chemical stability in non-oxidizing atmosphere. Large electromotive force and high sensitivity, the main thing is cheap. At present, when measuring temperatures above 1600 ° C, the non-contact method is often used. However, the error of this method is relatively large. If the contact method is used, the real temperature can be accurately measured. Among high-temperature thermocouples, high-temperature noble metal thermocouples (platinum-rhodium thermocouples) are expensive and the highest temperature can only be below 1800 ° C. Tungsten-rhenium thermocouples not only have a high temperature measurement limit, but also have good stability. Therefore, tungsten-rhenium thermocouples Even widely used in various industries. China has abundant tungsten resources. Tungsten-rhenium thermocouples are cheap and can partially replace high-temperature precious metal thermocouples (platinum-rhodium thermocouples).
The maximum operating temperature of tungsten-rhenium thermocouples can reach 2800 ° C. However, when the temperature is higher than 2300 ° C, the data is scattered. Therefore, the best use temperature is around 2000 ° C. Tungsten-rhenium thermocouples are extremely susceptible to oxidation and are suitable for use in inert or dry hydrogen, or they can be isolated from oxygen with a dense protective tube. Can not be used in carbon-containing atmosphere (such as in a hydrocarbon-containing atmosphere, the temperature exceeds 1000 ℃ will be corroded). Tungsten or tungsten thorium is easy to form stable carbides in a carbon-containing atmosphere, which reduces its sensitivity and causes brittle fracture. In the presence of hydrogen, it will accelerate carbonization.
抗氧化问题一直是国内外学者所关注的课题，并致力于研究解决。 The anti-oxidation problem of tungsten-rhenium thermocouples has always been a topic of concern to scholars at home and abroad, and is committed to research and solution. Our company has adopted the international advanced manufacturing process and successfully developed the assembled high temperature and high pressure tungsten rhenium thermocouple. The temperature range of this product is 0 ～ 1800 ℃, which is widely used in metallurgy, coking, chemical furnaces, heat treatment, glass, etc. Industry, it has the advantages of high accuracy, low price, stable performance, and is not restricted by the working environment atmosphere. It is an ideal product to replace platinum and rhodium thermocouples. The tungsten-rhenium thermocouple produced by our company has been widely used in many units, and its performance has reached the level of similar products at home and abroad. Its main technical indicators are as follows:
1. Indexing number: W-Re3 / 25, W-Re5 / 26
2. Temperature measurement range: 0 ～ 1800 ℃
3. Temperature measurement accuracy: <± 1% t; <± 0.5% t
4. Time constant: ≥180 s
5. Insulation resistance:> 5MΩ
6. Specifications: 300, 500, 750, 1000, 1100 (mm)