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JP-2026514492-A - Tungsten alloy wire, its manufacturing method and use, tungsten carbide alloy filament

JP2026514492AJP 2026514492 AJP2026514492 AJP 2026514492AJP-2026514492-A

Abstract

This invention relates to tungsten alloy wire, its manufacturing method and use, and tungsten carbide alloy filament. The tungsten alloy contains 0.0005 to 0.3 wt% carbon, 0.25 to 2.6 wt% M, 0.05 to 0.5 wt% oxygen, the remainder being tungsten and unavoidable impurities, and does not contain thorium. The tungsten alloy wire has an initial recrystallization temperature of 48% Fc to 56% Fc and/or an average grain size of 1 to 15 μm at 80% Fc. This tungsten alloy wire is thorium-free, has no radioactive contamination issues, has an initial recrystallization temperature of 48% Fc to 56% Fc, and exhibits significantly improved processing performance compared to thorium-containing tungsten materials. Compared to thorium-containing tungsten wire, this tungsten alloy wire has fewer crack detection points. Furthermore, when used as the matrix for tungsten carbide alloy filaments, the crystal grains of the tungsten matrix after carbonization are finer, making the filaments less prone to breakage during the production and use of magnetron coils, thus improving production yield and quality. [Selection Diagram] Figure 1

Inventors

  • イージン ファン
  • ドンホン グォ
  • シャンツァオ ジャン
  • ミンフェン タン
  • ゾンシン ウェイ
  • シャオジュン ジャン
  • グオチン ジャン
  • リャンム リウ
  • フイ ジャオ

Assignees

  • 厦門虹鷺▲きん▼▲ぼく▼工業有限公司

Dates

Publication Date
20260511
Application Date
20240813
Priority Date
20231025

Claims (10)

  1. A method for manufacturing tungsten alloy wire, The tungsten alloy comprises 0.0005 to 0.3 wt% carbon, 0.25 to 2.6 wt% M, 0.05 to 0.5 wt% oxygen, the remainder being tungsten and unavoidable impurities, and its composition does not include thorium. The aforementioned M element is one or more elements selected from La, Y, Sc, Nd, Sm, Lu, Ce, Gd, Tb, Dy, Ho, Pr, Er, Tm, Yb, Eu, Hf, and Zr. The manufacturing process for the tungsten alloy wire includes the steps of doping and powdering, powder pressing, sintering, and pressurization in this order. In the aforementioned pressurized treatment step, the sintered tungsten alloy strip is processed to reduce its diameter to an intermediate standard wire of 1.5 to 3.5 mm, and then the intermediate standard wire is oxidized at (1200 to 1500) °C and an annealing rate of (3 to 10) m/min. After oxidized annealing, the intermediate standard wire is further processed to the desired wire diameter standard to obtain a tungsten alloy wire. A method for manufacturing a tungsten alloy wire, characterized in that the tungsten alloy wire has an initial recrystallization temperature of 48%Fc to 56%Fc, and/or an average grain size of (1 to 15) μm at 80%Fc recrystallization.
  2. In the aforementioned sintering step, a tungsten alloy sintered strip is obtained by a high-temperature sintering method. The heating curve for the aforementioned high-temperature sintering is as follows: The temperature is raised from room temperature to A1 at a predetermined rate, and then maintained at A1 for a predetermined time. The temperature was increased from A1 to A2, the heating time being H3, and then maintained at H4 in A2. A1 was (950-1250)°C, H3 was (1.5-2.5)h, A2 was (1300-1500)°C, and H4 was (2.5-4.5). The temperature is raised from A2 to A3 at a predetermined rate, A3 is (1700-1900)°C, and the temperature is maintained at A3 for a predetermined time. The temperature is raised from A3 to A4 at a predetermined rate, A4 is (2050-2250)°C, and the temperature is maintained at A4 for a predetermined time. A method for producing tungsten alloy wire according to claim 1, characterized in that it is obtained by natural cooling from A4.
  3. The heating curve for the aforementioned high-temperature sintering is as follows: The temperature was raised from room temperature to A1, the heating time H1 was (5-8) hours, and A1 was (950-1250)°C. In A1, the temperature is maintained for the duration of H2, and H2 is (1-3). The temperature was increased from A1 to A2, the heating time was H3, H3 was (1.5 to 2.5) hours, and A2 was (1300 to 1500) °C. The temperature was kept warm in A2 for H4 time, and H4 was (2.5 to 4.5). The temperature was increased from A2 to A3, the heating time was H5, H5 was (1-3) hours, and A3 was (1700-1900)°C. In A3, the temperature is maintained for H6 time, and H6 is (1-3). The temperature was increased from A3 to A4, the heating time was H7, H7 was (1-3) hours, and A4 was (2050-2250)°C. In A4, keep warm for H8 time, and H8 is (5-10). A method for producing tungsten alloy wire according to claim 2, characterized by obtaining it by natural cooling from A4.
  4. A method for producing a tungsten alloy wire according to any one of claims 2 to 3, characterized in that the M element exists in the form of an oxide, and the average size of the oxide particles in the tungsten alloy wire is (100 to 500) nm.
  5. A tungsten alloy wire comprising 0.0005 to 0.3 wt% carbon, 0.25 to 2.6 wt% M, 0.05 to 0.5 wt% oxygen, the remainder being tungsten and unavoidable impurities, and free from thorium. The aforementioned M element is one or more elements selected from La, Y, Sc, Nd, Sm, Lu, Ce, Gd, Tb, Dy, Ho, Pr, Er, Tm, Yb, Eu, Hf, and Zr. The tungsten alloy wire is characterized in that its initial recrystallization temperature is 48%Fc to 56%Fc, and/or its average grain size at 80%Fc recrystallization is (1 to 15) μm.
  6. The tungsten alloy wire according to claim 5, characterized in that the aforementioned element M exists in the form of an oxide, and the average size of the oxide particles in the tungsten alloy wire is (100 to 500) nm.
  7. The aforementioned element M exists in the form of an oxide, and the aforementioned carbon element exists in the form of a carbide or elemental carbon. The oxide M is one or a combination of several selected from lanthanum oxide, yttrium oxide, scandium oxide, neodymium oxide, samarium oxide, lutetium oxide, cerium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, praseodymium oxide, erbium oxide, hafnium oxide, and zirconium oxide. The tungsten alloy wire according to any one of claims 5 to 6, characterized in that the carbide is one or more selected from lanthanum carbide, zirconium carbide, yttrium carbide, hafnium carbide, and tungsten carbide.
  8. The wire diameter is 800 μm or less, and the number of cracks detected is less than 5 per 100 m. and/or, the component further comprises element T, wherein element T is a metallic element, T is at least one selected from K, Re, Mo, Fe, and Co, and the mass content of Re is less than 1000 ppm, characterized in that, the tungsten alloy wire according to claim 5.
  9. The use of tungsten alloy wire, wherein the tungsten alloy filament is carbonized and then used as a cathode alloy wire for microwave heating devices. The use of tungsten alloy wire, characterized in that the tungsten alloy wire is manufactured using a tungsten alloy filament as described in any one of claims 5 to 8, or by a manufacturing method as described in any one of claims 1 to 4.
  10. A tungsten carbide alloy filament, obtained by carbonizing a tungsten alloy wire. The tungsten alloy wire is characterized by being manufactured using a tungsten alloy filament according to any one of claims 5 to 8, or by a manufacturing method according to any one of claims 1 to 4, wherein the tungsten alloy wire is a tungsten alloy filament.

Description

This invention relates to the technical field of filament cathode materials, and more particularly to tungsten alloy wires, methods for manufacturing the same, and their use, as well as tungsten carbide alloy filaments. Filament cathodes, or electron emitters, are widely used in the field of microwave oven magnetrons. The performance of the filament cathode significantly impacts the operating characteristics and lifespan of the magnetron, and it is considered the heart of the magnetron. Existing filament materials are primarily manufactured from tungsten-thorium oxide or tungsten-rare earth oxides. For example, Patent Document 1 (Chinese invention patent, published April 3, 2013) discloses a method for doping powder for magnetron coils. The process of this invention includes steps such as doping, stirring, and steam drying. Its characteristic feature is that an ammonia aqueous solution ( NH₃ · H₂O ), which is a neutralizing additive, is added to a thorium nitrate solution, and the prepared mixed solution is uniformly sprayed onto the surface of blue tungsten oxide WO₂₇ placed in a doping pot and stirred. The doping pot is vacuum-suctioned and heated with water, and stirred while heating. The powder is dried by a steam heating method under vacuum, and finally, a uniformly doped tungsten-thorium oxide doped powder with a low impurity content is obtained. The invention patent (Patent Document 1) describes a magnetron coil material made by adding thorium oxide to pure tungsten, which can achieve continuous operation for over 1,000 hours. However, cathode products manufactured from such composite materials have a high brittle-ductile transition temperature, making them difficult to process and mold. Therefore, the magnetron cathode is prone to fracture during production and transportation. Furthermore, due to its relatively low recrystallization temperature, the recrystallization growth of the magnetron coil progresses abnormally during the carbonization process, leading to frequent fractures during use and transportation, and ultimately, magnetron failure. Additionally, because thorium is a radioactive element, using thorium as the main additive raw material could not only pollute the environment during the smelting, production, transportation, and use processes, but also potentially have adverse health effects on people who come into contact with the final manufactured product. As described above, conventional tungsten-thorium filaments are radioactive and not only contaminate the environment, but also pose potential health risks to people who come into contact with the final manufactured product. Furthermore, existing tungsten-thorium filaments have a relatively low recrystallization temperature, resulting in a high number of crack points per 100 meters of wire. This leads to abnormal recrystallization growth during the carbonization process of magnetron coils, resulting in frequent breakage during production, use, and transportation, leading to reduced product yield and poor quality. Solving these problems is a challenge that those skilled in the art are striving to overcome. Chinese Patent Application Publication No. 102009179 (Chinese Patent Application No. 2010102991399.2) This is a schematic diagram of the partial structure of the tungsten alloy filament after carbonization according to the present invention.This is a schematic diagram of the cross-sectional structure of the tungsten alloy filament after carbonization according to the present invention.This is a schematic diagram of the longitudinal cross-sectional structure of the tungsten alloy filament after carbonization according to the present invention.This is an enlarged view of section A in Figure 2.This is a schematic diagram of the partial cross-sectional structure of a tungsten alloy filament after carbonization according to the present invention.This is a microstructure image of Comparative Example 1 according to the present invention at 44% FC.This is a microstructure image of Comparative Example 1 according to the present invention at 46% FC.This is a microstructure image of Comparative Example 1 according to the present invention at 48% FC.This is a microstructure image of Comparative Example 1 according to the present invention at 50% FC.This is a microstructure image of the metallographic structure of Example 1 of the present invention at 48% FC.This is a microstructure image of the metallographic structure of Example 1 of the present invention at 50% FC.This is a microstructure image of the metallographic structure of Example 1 of the present invention at 52% FC.This is a schematic diagram of the crystal structure of Comparative Example 1 according to the present invention.This is a schematic diagram of the crystal structure of Example 1 according to the present invention.This figure shows the channel distribution in a cross-section of Example 1 according to the present invention.This figure shows the channel distribution in a longitud