Molybdenum rod for vacuum electronic device and preparation method thereof

Abstract

The invention discloses a molybdenum rod for a vacuum electronic device and a preparation method of the molybdenum rod. The chemical component of the molybdenum rod is pure molybdenum, and the molybdenum content is not less than 99.95 wt%; the diameter is 20-90 mm; the relative density is greater than or equal to 99.5%; the surface roughness is superior to 0.2 mu m; and the tensile strength is not less than 600MPa, the yield strength is not less than 550MPa, and the ductility is not less than 30%. The preparation method of the molybdenum bar comprises the steps that high-purity molybdenum powder serves as a raw material, and a cold isostatic pressing blank is prepared; hydrogen-vacuum composite sintering is conducted; low-temperature large-deformation cogging is conducted; intermediate annealing and straightening processing are conducted; reducing processing is conducted; alkali washing and coping are conducted; annealing treatment is conducted; machining is conducted; and finally, the large-diameter and high-toughness molybdenum bar with uniform structure components, high density and good toughness is obtained and can be used as a machining raw material of a large-size vacuum electronic molybdenum-based device.

Description

technical field [0001] The invention belongs to the field of refractory metal powder metallurgy and deformation processing, and in particular relates to a large-diameter, high-strength and tough molybdenum rod for vacuum electronic device processing and a preparation method thereof. Background technique [0002] Molybdenum, a refractory metal, has high melting point, low thermal expansion coefficient, high high temperature strength, good thermal stability, good air tightness (extremely low high temperature outgassing rate can be obtained after degassing), and better machinable / deformable processing performance. Excellent (compared to tungsten), excellent welding performance and other characteristics, it has been widely used in vacuum electronic devices, and its product forms include rods, wires, pipes, plates, strips, foils, etc. Among them, molybdenum rods are especially Molybdenum rods with larger diameters can be easily machined into various non-standard parts, special-...

AI Technical Summary

Problems solved by technology

The above commercially available conventional molybdenum bar products, especially For products with larger diameter specifications, broken teeth, broken wires, cracks, air leakage, etc. often cannot be processed or scrapped when processing or using high-strength requirements, special-shaped or thin-walled parts, and vacuum-tight parts. rate below 20%

[0004] The patent ZL 200610165738.9 applied by Western Metal Materials Co., Ltd. has prepared a molybdenum rod with a tensile strength greater than 630MPa and an elongation greater than 20% through precise temperature-controlled heating of the billet and die forging with a single fire and a large processing rate, but its specifications are limited to The diameter is less than 20mm; the patent ZL 201310032476.9 applied by Jinduicheng Molybdenum Industry Co., Ltd. realizes the preparation and optimization of large unit weight (45-50kg) molybdenum rods through the setting and optimization of precision forging, heat treatment and continuous rolling process parameters, but the obtained The diameter of the inscribed circle of the regular hexagonal molybdenum rod is only 7-8mm; the patent ZL201410274941.4 applied by Luoyang Kewei Tungsten Molybdenum Co., Ltd. adopts powder metallurgy billet, die forging and tempering at 1200°C to obtain a diameter of 500-700mm , ultra-large fine-grained molybdenum rods with a length of 2500-3000mm, but it does not involve the density and toughness of the rods; the patent application number 201911178640.0 applied by Luoyang Akemai Tungsten and Molybdenum Technology Co., Ltd. uses air hammer forging to open billets and Molybdenum alloy rods containing 2.0-3.0% of lanthanum hydroxide and 0.3-0.7% of yttrium oxide were prepared by rotary forging, the tensile strength was 1158-1170MPa, and the elongation was 15-17%, but the processing method of air hammer + rotary forging was limited. The diameter of the product is only 5-8mm, and it is not suitable for the application of pure molybdenum materials; the patent application number 201911034992.9 applied by Antai Tianlong Tungsten and Molybdenum Technology Co., Ltd. is obtained by adopting staged heating sintering and rapid forging deformation treatment The fine-grained molybdenum rod, its room temperature tensile strength ≥ 550MPa (embodiment 560 ~ 670MPa), elongation after fracture ≥ 15% (embodiment 15 ~ 25%), but does not involve molybdenum rod yield strength, density data, And its strength and toughness matching, especially the toughness of the bar, still cannot meet the performance requirements of vacuum electronic device processing applications.

[0005] In summary, the existing technology only involves the performance improvement of some aspects such as the size specification, density, grain size, and toughness of molybdenum rods / molybdenum rods. Performance requirements of large-diameter high-strength and tough molybdenum rods for electronic device processing

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