Molybdenum thermocouple
The production of molybdenum rods into thermocouples is a complex process that involves multiple steps covering the processing of the material, precise control and strict quality management. Molybdenum rod, as one of the key materials of molybdenum thermocouple, has become an important material for high temperature measurement because of its high melting point (2620°C), corrosion resistance and good electrical conductivity. The following is the basic process of producing molybdenum thermocouples:
1. Molybdenum rod raw material preparation
First, the production of molybdenum thermocouples starts with high purity molybdenum rods. High purity molybdenum ore is purified and powder metallurgy process, molybdenum powder is formed, and then molybdenum billet is formed by pressing and sintering. After many forging and rolling, the billet is processed into high purity, uniform density molybdenum rod. In the production process, the chemical composition of molybdenum rod is strictly controlled to avoid impurities affecting its conductive and thermoelectric properties.
2. Molybdenum rod processing
Molybdenum rods need to be further processed into thin wires for use in thermocouples. Molybdenum rod is usually made into molybdenum wire by drawing process. This process requires the use of specific wire drawing equipment, through a number of gradual stretching, to thin the molybdenum rod. When the molybdenum rod is drawn into a molybdenum wire with a precise diameter, its tensile strength and high temperature resistance will be further improved.
3. Combination of thermocouple materials
Molybdenum thermocouples are usually composed of two different materials, such as pure molybdenum and molybdenum-rhenium alloys. Molybdenum wire acts as the positive electrode, while molybdenum-rhenium alloy wire (such as molybdenum-5% rhenium or molybdenum-41% rhenium) acts as the negative electrode. The combination of these materials produces a thermoelectric effect, which creates an electromotive force when there is a temperature difference between the contact points, enabling temperature measurement. Precision control of the purity and alloy composition of each material ensures the thermocouple has accurate measurement performance in high temperature environments.
4. Assembly of thermocouples
After the molybdenum wire is processed, the next step is to assemble the thermocouple. First, the molybdenum wire and the molybdenum-rhenium wire are welded together to form a temperature measuring end. The welding process is very demanding to ensure that the joint part does not break or oxidize at high temperatures. The quality of the joint directly affects the service life and accuracy of the thermocouple. In addition, in order to protect the molybdenum thermocouple from oxidation at high temperatures, the thermocouple is usually coated with a protective tube (such as aluminum oxide, molybdenum tube or quartz tube).
5. Calibration and testing
After assembly, molybdenum thermocouples need to undergo rigorous calibration and testing. It is usually tested at high temperature by a standard temperature furnace to ensure that it can provide a stable and accurate thermoelectric signal at high temperatures. During calibration, the thermoelectric motive force of the thermocouple is measured to verify that it conforms to the predefined thermoelectric potential curve standard.
Mosten Alloy can produce molybdenum sheet, molybdenum block, molybdenum foil, molybdenum rod, molybdenum wire, molybdenum processing workpiece according to customer demand.
