Our consultant will save your time!
+7 (905) 270-13-45
Domestic tungsten-rhenium alloys are produced in two types: BP5 (95% W, 5% Re) and BP20 (80% W, 20% Re). Rolled wire is presented. Wire for stabilization when working in a high-temperature environment is doped with silica-alkali additives: 0.1% — 0.5% SiO2; Al2O3: KCl. The alloy is designated as VAR. VR-wire for thermocouples graduated and annealed with the nominal properties of thermal conversion VR (A) -1 meets the specifications of YaO.021.142 for the production of thermocouples VR-20 / VR-5 (VAR-5).
The basis of tungsten-rhenium alloy BP5 is tungsten, which has extreme refractoriness, its melting point is 3410 ° C. The heat resistance of rhenium combined with the highest resistance to corrosion allows it to form a worthy pair of tungsten, a melting point of 3170 ° C. Tungsten-rhenium alloys in terms of refractoriness and hardness are superior to other materials. When alloying tungsten 5% Re, the plasticity of the alloy increases. BP5 is used in a thermocouple in the form of a positive electrode.
To achieve the maximum thermo-emf of a tungsten-rhenium alloy and use as a negative electrode in it should be up to 35% Re. Domestic metallurgy produces alloys containing up to 20% Re. This makes it possible to measure t ° of the order of 2500 ° C while maintaining the stability to the medium Ar2, He2, N2 and H2. When alloying with siliceous additives, the stability of the alloy increases significantly at up to t ° 2000 ° C.
Category of alloys
Due to the fluctuations in the thermo-emf values of tungsten-rhenium thermoelectrode pairs, BP alloys are divided into categories. Category A-1 is used at t ° 2200 ° C; A-2 and 3 — up to t ° 1800 ° C. Do not combine wire from different lots, because Each of the lots has its own indicators of thermo-emf.
Tungsten-rhenium thermocouples are indispensable for measuring very high temperatures in metallurgical furnaces. The error to 2500 ° C is ± 0.01 ° C. The cost of VR thermocouples depends on the price of tungsten and rhenium. Because they are quite expensive, and their production is associated with a number of difficulties. The cost of thermocouples based on the alloys of BP5, BP20 is not small. Nevertheless, it is much lower than the cost of alternative instruments for high-temperature thermometry.
|Temperature ° С||1400||1500||1600|
|Nominal value of thermo-emf, mV||21.97||23.31||24.59|
|Deviation of the thermo-emf from the nominal, μV||± 96||± 99||± 102|
It is not allowed to complete the thermocouple from different series of thermoelectrode wire, even with the same nominal static characteristic of thermoelectrodes.
Buy at the best price
The wide range of thermocouples is offered on the site of «_" Ltd. High quality of products and absence of intermediaries determine the most profitable offers for the acquisition. Delivery in the shortest time in any region of the country and abroad, the compliance of regulatory products has long won the trust of loyal customers.