Processing and application of molybdenum rhenium alloys in rocket engine and gas turbine components
Molybdenum-rhenium (Mo-Re) alloy, with its high melting point (>2600℃), excellent high-temperature strength, creep resistance and oxidation resistance, has become an ideal material for high-temperature components of rocket engines and gas turbines. However, its high hardness and brittleness (especially at low temperatures) make processing rather difficult and require special techniques. In terms of material preparation and forming, molybdenum-rhenium alloys are usually prepared by powder metallurgy. Molybdenum powder and rhenium powder are mixed in proportion (such as Mo-5Re, Mo-41Re, Mo-50Re, etc.), and then formed by isostatic pressing. After that, they are sintered at high temperatures (1800-2200 ℃) in a hydrogen or vacuum environment to form dense blanks. For high-purity requirements, vacuum arc melting or electron beam melting can be adopted to reduce impurities and enhance high-temperature performance. In terms of mechanical processing, molybdenum-rhenium alloys have high hardness, so hard alloys (such as WC-Co) or diamond tools should be used, combined with low-speed and high-feed rate cutting, and coolant (such as oil-based lubricants) should be applied to prevent work hardening. Electrical discharge machining (EDM) is suitable for complex shapes (such as gas film cooling holes in turbine blades), and it is precisely processed based on the principle of electrical erosion. However, the influence of the surface recast layer should be noted. Laser/water jet cutting is used for thin plate or fine structure forming, reducing the heat-affected zone and residual stress.
In terms of welding and connection, molybdenum-rhenium alloys are typically welded by electron beam welding or laser welding, which is carried out under vacuum or inert gas protection to prevent oxidation and cracking. This method is suitable for key components such as nozzles and combustion chambers. Diffusion welding is used for solid-state connections of high-temperature alloy components, reducing interface defects and enhancing high-temperature load-bearing capacity. In terms of surface treatment and protection, molybdenum-rhenium alloys are prone to form volatile oxides (such as MoO3) in high-temperature oxidation environments. Therefore, silicides (such as MoSi2) or iridium (Ir) coatings should be applied to enhance their resistance to high-temperature oxidation. In addition, when combined with a yttria-stabilized zirconia coating as a thermal barrier coating, the substrate temperature can be reduced and the service life of the component can be prolonged. Typical applications of molybdenum-rhenium alloys include rocket engine nozzles and combustion chambers. For instance, molybdenum-rhenium alloys (such as Mo-41Re) are used for the throat linings of liquid rocket engine nozzles and can withstand high-temperature gas erosion above 3000℃. In gas turbines, molybdenum-rhenium alloys can replace nickel-based superalloys for blades and guides, reducing weight and increasing the operating temperature (>1200℃).
In summary, the processing of molybdenum-rhenium alloys relies on powder metallurgy, special cutting, precision welding and coating technologies. Its outstanding high-temperature performance makes it a key material for rocket engines and gas turbines. In the future, with the development of additive manufacturing (3D printing) technology, the manufacturing efficiency of complex-structured molybdenum-rhenium alloy components will be further enhanced, which is expected to drive the technological progress of high-performance components in the aerospace field.
Mosten Alloy can produce molybdenum sheet, molybdenum block, molybdenum foil, molybdenum rod, molybdenum wire, molybdenum processing workpiece according to customer demand.
