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。 Tungsten-rhenium thermocouples are characterized by a high melting point of the hot electrode wire (3300 ° C), low vapor pressure, and easy oxidation, and good chemical stability in a non-oxidizing atmosphere. Large electromotive force and high sensitivity, the main thing is cheap.
At present, when measuring temperatures above 1600 ° C, non-contact methods are 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, precious metal thermocouples are expensive and the highest temperature can only be below 1800 ° C. Tungsten-rhenium thermocouples not only have high temperature measurement limits, but also good stability. Therefore, tungsten-rhenium thermocouples are used in metallurgy, building materials, and aerospace , Aviation and nuclear energy industries are widely used. China has abundant tungsten resources. Tungsten-rhenium thermocouples are cheap and can partially replace precious metal thermocouples (platinum-rhodium thermocouples). It is a promising temperature measurement material in the field of high temperature testing.
Its maximum operating temperature can reach 2800 ° C. However, when it 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.
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 foreign products. Its 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)
Tungsten-rhenium molten steel rapid temperature measurement thermocouple is specially designed for measuring the temperature of molten steel, molten iron and other metal melts. It has the advantages of small size, fast thermal response, high accuracy, and low price. Its technical indicators are as follows:
1. Maximum temperature measurement temperature: 1800 ℃
2.Temperature measurement accuracy: ≤ 0.5%
3.Insulation resistance: ≥30 MΩ
4.Measurement rate: ≥98%
5. Response time: <5 s
分三类： At present, the tungsten-rhenium thermocouples produced by our company are divided into three categories:
The first type is a fine ceramic protection tube. The specifications of the ceramic tube are: diameter of Ф8, Ф10, Ф12, Ф14, Ф16, and length of 300 ~ 1100mm. This type of thermocouple can be long-term in any atmosphere without being restricted by the working environment atmosphere. Use, the temperature range is 0 ~ 1800 ℃
The other type is pure molybdenum protection tube. Molybdenum tube and tungsten tube specifications are: diameter Ф6, Ф8, Ф10mm, length 500 ~ 700mm, this type of thermocouple can only work for a long time in the environment protected by vacuum, reduction or inert gas, Molybdenum tubes are best used for a long time at a temperature below 1800 ° C, and the short-term use temperature can reach 2000 ° C;
Another type is tungsten protection tube. As for tungsten tube, it can work at 2100 ℃ for a long time, but it is difficult to process and it is very expensive.
Please choose the thermocouple suitable for you according to our parameters.
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 temperature limit 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) Extremely susceptible to oxidation. 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. 在1600°以上的氧化性气氛下工作近50h，但仍不够理想。 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.