A method of hot rolling a molybdenum-ruthenium alloy foil sheet

Abstract

A hot rolling method of molybdenum-ruthenium alloy foil sheet, comprising the following steps: 1) preparing a molybdenum-ruthenium alloy blank plate with a density greater than 92%, a thickness of 10-30 mm, and a ruthenium content of 15-45 wt%; 2) hot rolling the molybdenum-ruthenium alloy blank plate, heating the molybdenum-ruthenium alloy blank plate in a heating furnace before each pass, and annealing once every 2 passes until a molybdenum-ruthenium alloy plate with a thickness of 2-5 mm is obtained; 3) fixing the molybdenum-ruthenium alloy plate in a transfer heat preservation tool, and then placing them together in a heating furnace for heating; 4) after heating, transferring the molybdenum-ruthenium alloy plate with the transfer heat preservation tool to a two-roll rolling mill, and hot rolling the molybdenum-ruthenium alloy plate, heating the molybdenum-ruthenium alloy plate with the transfer heat preservation tool in a heating furnace before each pass, and then transferring the molybdenum-ruthenium alloy plate with the transfer heat preservation tool to the two-roll rolling mill, annealing once every 2 passes until a molybdenum-ruthenium alloy foil sheet with a thickness of 0.1-0.2 mm is obtained.

Description

Technical Field

[0001] This invention relates to the field of molybdenum-ruthenium alloy foils and sheets, and more specifically to a hot rolling method for molybdenum-ruthenium alloy foils and sheets. Background Technology

[0002] Conventional molybdenum alloys can usually be processed into foils using cold rolling processes; however, molybdenum-ruthenium alloys are characterized by high hardness, poor toughness, and difficulty in processing. When deforming foils at room temperature, defects such as brittle fracture, cracking, and corner chipping are very likely to occur. Therefore, it is impossible to obtain foils by processing thin slabs of cold-rolled molybdenum-ruthenium alloys.

[0003] Molybdenum-ruthenium alloys possess a certain degree of toughness in high-temperature environments above 1100℃, allowing for multi-pass hot rolling with small deformation. However, during hot rolling, as the thickness of the molybdenum-ruthenium alloy billet gradually increases to 2mm-5mm, the heat dissipation area of ​​the billet increases significantly. During the transfer of the billet from the heating furnace to the rolling mill, it rapidly cools to below 700℃ within seconds under ambient air cooling. Once the temperature drops to 700℃ or below, it becomes difficult to hot roll molybdenum-ruthenium alloy foil sheets with a thickness of 0.1-0.2mm.

[0004] In the prior art, the invention patent CN113199168A, entitled "Molybdenum-Ruthenium Alloy Foil for High-Temperature Welding and Its Preparation Method," provides a method for preparing molybdenum-ruthenium alloy foil. Specifically, the method involves first rolling pure molybdenum foil, then spraying ruthenium slurry onto both sides of the molybdenum foil, followed by drying, sintering, and annealing. Finally, the molybdenum foil with the ruthenium slurry coating is cold-rolled to obtain the molybdenum-ruthenium alloy foil. However, the molybdenum-ruthenium alloy foil prepared by this method suffers from insufficient compositional uniformity and high difficulty in composition control due to the ruthenium slurry being sprayed onto the molybdenum foil. Therefore, the resulting material is not a true molybdenum-ruthenium alloy foil. How to produce a truly meaningful molybdenum-ruthenium alloy foil has long remained an unsolved problem. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a hot rolling method for molybdenum-ruthenium alloy foil sheets. This method uses a transfer and insulation fixture to transfer the molybdenum-ruthenium alloy sheet from the heating furnace to the two-roll mill, ensuring that the temperature of the molybdenum-ruthenium alloy sheet is greater than 1100℃ during rolling, thereby achieving hot rolling to produce molybdenum-ruthenium alloy foil sheets with a thickness of 0.1–0.2 mm.

[0006] The technical solution of this invention is: a hot rolling method for molybdenum-ruthenium alloy foil sheets, comprising the following steps:

[0007] 1) A molybdenum-ruthenium alloy blank plate with a density greater than 92%, a thickness of 10-30 mm, and a ruthenium content of 15-45 wt% was prepared using conventional powder metallurgy processes.

[0008] 2) The molybdenum-ruthenium alloy blank is hot rolled using a two-roll mill. The rolling temperature for each pass is 1350℃~1600℃, the roll temperature is controlled at 200℃~300℃, and the deformation amount per pass is 5%~10%. Before each pass, the molybdenum-ruthenium alloy blank is heated in a heating furnace at a billet temperature of 1550℃~1650℃. Annealing is performed once every two passes until a molybdenum-ruthenium alloy blank with a thickness of 2~5mm is obtained.

[0009] 3) Fix a 2-5mm thick molybdenum-ruthenium alloy sheet between the upper and lower plates of a transfer and insulation fixture, and then place the transfer and insulation fixture together with the molybdenum-ruthenium alloy sheet into a heating furnace for heating. The billet temperature is 1350℃-1450℃.

[0010] 4) After heating, the molybdenum-ruthenium alloy sheet is transferred from the heating furnace to the two-roll mill along with the transfer and insulation fixture. The upper plate of the transfer and insulation fixture is removed, exposing the molybdenum-ruthenium alloy sheet above the lower plate of the transfer and insulation fixture. The sheet moves together with the lower plate and is subjected to multiple hot rolling passes. Before each pass, the molybdenum-ruthenium alloy sheet is heated in the heating furnace along with the transfer and insulation fixture at a billet temperature of 1350℃~1450℃. Then, it is transferred from the heating furnace to the two-roll mill along with the transfer and insulation fixture. The rolling temperature for each pass is 1250℃~1400℃, the roll temperature is controlled at 200℃~300℃, the deformation amount per pass is 5%~8%, and annealing is performed once every two passes until a molybdenum-ruthenium alloy foil sheet with a thickness of 0.1~0.2mm is obtained.

[0011] Preferably, the transfer and insulation fixture consists of an upper plate and a lower plate. The lower plate is provided with a fixed slot along the running direction of the roll. The gap between the upper plate and the lower plate is adjusted by a screw. One side of a 2-5mm thick molybdenum-ruthenium alloy sheet is bent to form a bent section. After the bent section of the molybdenum-ruthenium alloy sheet is inserted into the fixed slot, the screw is adjusted to make the upper plate and the lower plate press the molybdenum-ruthenium alloy sheet together.

[0012] Preferably, the length of the bent portion is 2mm to 5mm, and the bending angle is 90°.

[0013] Preferably, in step 1), the prepared molybdenum-ruthenium alloy blank is polished to a roughness of less than Ra0.8.

[0014] Preferably, in step 2), the annealing temperature is 1300℃~1400℃.

[0015] Preferably, the transfer and insulation fixture is made of a material with a hardness greater than that of molybdenum-ruthenium alloy and a melting point higher than that of molybdenum-ruthenium alloy.

[0016] Preferably, the transfer and insulation fixture is made of tungsten-rhenium alloy.

[0017] Preferably, in step 4), the annealing temperature is 1250–1300°C.

[0018] Preferably, the method further includes the following steps:

[0019] 5) Polish and grind the surface of the molybdenum-ruthenium alloy foil sheet;

[0020] 6) Anneal the molybdenum-ruthenium alloy foil sheet at a temperature of 1100-1200℃ in a vacuum or protective atmosphere for 30 minutes.

[0021] The advantages of this invention are as follows: The invention uses a high-temperature resistant, high-strength material to create a heat-insulating transfer fixture, preventing the rapid cooling of the molybdenum-ruthenium alloy sheet during transfer from the heating furnace to the rolling mill, which would otherwise hinder its hot rolling into 0.1-0.2mm foil. The heat-insulating transfer fixture also prevents the molybdenum-ruthenium alloy sheet from extensive contact with air during transfer, while providing a high-temperature environment. This effectively increases the heat carrying capacity of the molybdenum-ruthenium alloy sheet, ensuring that its temperature upon entering the rolls exceeds 1100℃, thus guaranteeing its hot rolling capability. Furthermore, this invention has a wide range of applications and can be used for processing other foil materials that are brittle at room temperature but tough at high temperatures. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of the transfer and insulation tooling of the present invention for transferring molybdenum-ruthenium alloy plates;

[0023] Figure 2 This is a cross-sectional schematic diagram of the molybdenum-ruthenium alloy plate and the lower plate of the transfer insulation fixture of the present invention;

[0024] Figure 3 The finished molybdenum-ruthenium alloy foil sheet prepared according to an embodiment of the present invention. Detailed Implementation

[0025] A hot rolling method for molybdenum-ruthenium alloy foil sheet includes the following steps:

[0026] 1) A molybdenum-ruthenium alloy blank plate with a density greater than 92%, a thickness of 10-30 mm, and a ruthenium content of 15-45 wt% is prepared using conventional powder metallurgy processes. The powder metallurgy process includes batching, powder mixing, pressing, and sintering. The prepared molybdenum-ruthenium alloy blank plate is polished to a roughness of less than Ra0.8 to avoid the surface oxide scale (such as the molybdenum oxide layer MoO3 and the ruthenium oxide layer RuO2) being pressed into the surface of the plate by the rolls during high-temperature hot rolling, forming subcutaneous inclusions, pits, and indentations, which would lead to increased surface roughness and even local peeling.

[0027] 2) The molybdenum-ruthenium alloy blank is hot rolled using a two-roll mill. The rolling temperature for each pass is 1350℃~1600℃, the roll temperature is controlled at 200℃~300℃, and the deformation amount per pass is 5%~10%. Before each pass, the molybdenum-ruthenium alloy blank is heated in a heating furnace at a billet temperature of 1550℃~1650℃. Annealing is performed once every two passes at a temperature of 1300℃~1400℃ until a molybdenum-ruthenium alloy blank with a thickness of 2~5mm is obtained.

[0028] 3) See Figure 1 A 2-5mm thick molybdenum-ruthenium alloy sheet is fixed between the upper and lower plates of a transfer and insulation fixture. The transfer and insulation fixture, along with the molybdenum-ruthenium alloy sheet, is then placed in a heating furnace for heating at a billet temperature of 1350℃-1450℃. The transfer and insulation fixture consists of an upper plate 1 and a lower plate 2. The lower plate 2 has a fixing groove 21 along the rolling direction. The gap between the upper plate 1 and the lower plate 2 is adjusted by a screw. One side of the 2-5mm thick molybdenum-ruthenium alloy sheet 3 is bent to form a bent section 31. The length of the bent section is 2mm-5mm, and the bending angle is 90°, ensuring that the molybdenum-ruthenium alloy sheet 3 can be firmly fixed in the fixing groove 21 to prevent it from shifting during hot rolling. After the bent portion 31 of the molybdenum-ruthenium alloy sheet 3 is inserted into the fixing groove 21, the adjusting screw presses the upper plate 1 and lower plate 2 together to compress the molybdenum-ruthenium alloy sheet 3. This prevents large-area contact with room temperature air and subsequent cooling during the transfer of the heated molybdenum-ruthenium alloy sheet from the heating furnace to the two-roll mill. The transfer insulation fixture is made of a material with a hardness greater than that of the molybdenum-ruthenium alloy and a melting point higher than that of the molybdenum-ruthenium alloy. This ensures that the lower plate of the transfer insulation fixture moves along with the molybdenum-ruthenium alloy sheet on the two-roll mill without being deformed by the rolls. At the same time, it ensures that the molybdenum-ruthenium alloy will not melt when heated to the required hot rolling temperature in the heating furnace. Preferably, the transfer insulation fixture is made of tungsten-rhenium alloy, especially tungsten-rhenium-20 alloy.

[0029] 4) After heating, the molybdenum-ruthenium alloy sheet is transferred from the heating furnace to the two-roll mill using a transfer and insulation fixture. See [link to relevant documentation]. Figure 2 The upper plate of the transfer and insulation fixture is removed, exposing the molybdenum-ruthenium alloy sheet above the lower plate of the fixture. The sheet moves with the lower plate, undergoing multi-pass hot rolling. Before each pass, the sheet is heated in a furnace with the transfer and insulation fixture at a starting temperature of 1350℃~1450℃. It is then transferred from the furnace to a two-roll mill with the fixture. Each pass is rolled at a temperature of 1250℃~1400℃, with the roll temperature controlled at 200℃~300℃. The deformation per pass is 5%~8%. Annealing is performed every two passes at a temperature of 1250~1300℃. This process continues until a molybdenum-ruthenium alloy foil sheet with a thickness of 0.1~0.2mm is obtained.

[0030] 5) Polish and grind the surface of the molybdenum-ruthenium alloy foil sheet;

[0031] 6) Anneal the molybdenum-ruthenium alloy foil sheet at a temperature of 1100-1200℃ in a vacuum or protective atmosphere for 30 minutes to obtain a finished molybdenum-ruthenium alloy foil sheet with a thickness of 0.1-0.2 mm. Example

[0032] A molybdenum-ruthenium alloy foil with a thickness of 0.2 mm and a ruthenium content of 43 wt% was prepared.

[0033] 1) Using conventional powder metallurgy processes, molybdenum powder and ruthenium powder are used as raw materials. The ruthenium content is 43wt%, and the materials are mixed in a ball mill jar after purging with argon gas for 12 hours. The mixture is then pressed into 30mm thick slabs using a mold. After high-temperature sintering, the slabs are 25mm thick with a density of 95%. The surface is then polished using a grinding machine.

[0034] 2) The molybdenum-ruthenium alloy billet is hot-rolled using a two-roll mill, with the roll temperature controlled at 200℃~300℃. The molybdenum-ruthenium alloy billet is placed in a heating furnace and heated. The initial rolling temperature is 1600℃, and the rolling temperature for each pass is 1450℃~1550℃. The deformation amount per pass is 8%. Before each pass, the molybdenum-ruthenium alloy billet is heated in the heating furnace. Annealing is performed once every two passes at a temperature of 1400℃ until a 3mm thick molybdenum-ruthenium alloy sheet is obtained.

[0035] 3) Grind the oxide on the surface of the 3mm thick molybdenum-ruthenium alloy plate, bend it at 4mm at one end with an angle of 90°, and fix it between the upper and lower plates of a transfer and insulation fixture made of tungsten-rhenium alloy. Then, put the transfer and insulation fixture into the heating furnace along with the molybdenum-ruthenium alloy plate and heat it at a billet temperature of 1400℃.

[0036] 4) After heating, the molybdenum-ruthenium alloy sheet is transferred from the heating furnace to the two-roll mill using a transfer and insulation fixture. The upper plate of the transfer and insulation fixture is removed, exposing the molybdenum-ruthenium alloy sheet above the lower plate of the fixture. The sheet moves with the lower plate and undergoes multiple hot rolling passes. Before each pass, the molybdenum-ruthenium alloy sheet is heated in the heating furnace with the transfer and insulation fixture at a draft temperature of 1450℃. It is then transferred from the heating furnace to the two-roll mill with the transfer and insulation fixture. Each pass is rolled at a temperature of 1300℃~1400℃, with the roll temperature controlled at 200℃~300℃. The deformation per pass is 5%. Annealing is performed every two passes at a temperature of 1300℃. This process continues until a molybdenum-ruthenium alloy foil sheet with a thickness of 0.2mm is obtained.

[0037] 5) Polish and grind the surface of the molybdenum-ruthenium alloy foil sheet;

[0038] 6) Anneal the molybdenum-ruthenium alloy foil sheet at a temperature of 1200℃ under vacuum for 30 minutes to obtain a finished molybdenum-ruthenium alloy foil sheet with a thickness of 0.2 mm. Figure 3 .

Claims

1. A hot rolling method of a molybdenum-ruthenium alloy foil sheet, characterized by, The method comprises the following steps: 1) preparing a molybdenum-ruthenium alloy blank plate with a density greater than 92%, a thickness of 10-30 mm, and a ruthenium content of 15-45 wt% by using a general powder metallurgy process, wherein the powder metallurgy process comprises batching, powder mixing, pressing, and sintering; 2) hot rolling the molybdenum-ruthenium alloy blank plate by using a two-roller rolling mill, wherein the rolling temperature of each pass is 1350-1600°C, the roller temperature is controlled to be 200-300°C, the deformation processing amount of each pass is 5-10%, the molybdenum-ruthenium alloy blank plate is heated in a heating furnace before each pass, the breakdown temperature is 1550-1650°C, annealing is performed once every 2 passes, and a molybdenum-ruthenium alloy plate with a thickness of 2-5 mm is obtained by hot rolling; 3) fixing the molybdenum-ruthenium alloy plate with a thickness of 2-5 mm between the upper plate and the lower plate of a transfer heat preservation tooling, and then placing the transfer heat preservation tooling and the molybdenum-ruthenium alloy plate in a heating furnace for heating, wherein the breakdown temperature is 1350-1450°C; 4) after heating, transferring the molybdenum-ruthenium alloy plate and the transfer heat preservation tooling from the heating furnace to the two-roller rolling mill, removing the upper plate of the transfer heat preservation tooling, exposing the molybdenum-ruthenium alloy plate above the lower plate of the transfer heat preservation tooling, and moving the molybdenum-ruthenium alloy plate together with the lower plate to perform multi-pass hot rolling, wherein the molybdenum-ruthenium alloy plate is heated together with the transfer heat preservation tooling in the heating furnace before each pass, the breakdown temperature is 1350-1450°C, the molybdenum-ruthenium alloy plate is transferred from the heating furnace to the two-roller rolling mill together with the transfer heat preservation tooling, the rolling temperature of each pass is 1250-1400°C, the roller temperature is controlled to be 200-300°C, the deformation processing amount of each pass is 5-8%, annealing is performed once every 2 passes, and a molybdenum-ruthenium alloy foil with a thickness of 0.1-0.2 mm is obtained. The transfer heat preservation tooling is composed of an upper plate (1) and a lower plate (2), the lower plate (2) is provided with a fixed clamping groove (21) along the running direction of rolling, the gap between the upper plate (1) and the lower plate (2) is adjusted by a screw rod, one side of the molybdenum-ruthenium alloy plate (3) with a thickness of 2-5 mm is bent to form a bent part (31), and the bent part (31) of the molybdenum-ruthenium alloy plate (3) is clamped into the fixed clamping groove (21), and the screw rod is adjusted to press the molybdenum-ruthenium alloy plate (3) tightly by the upper plate (1) and the lower plate (2).

2. A method of hot rolling a molybdenum-ruthenium alloy foil sheet according to claim 1, characterized in that: The length of the bent part is 2-5 mm, and the bending angle is 90°.

3. A method of hot rolling a molybdenum-ruthenium alloy foil sheet according to claim 2, characterized in that: In step 1), the prepared molybdenum-ruthenium alloy blank plate is polished to a roughness less than Ra0.

8.

4. The method of claim 1, wherein the molybdenum-ruthenium alloy foil sheet is heated to a temperature of 300°C to 600°C. In step 2), the annealing temperature is 1300-1400°C.

5. The hot rolling method for a molybdenum-ruthenium alloy foil sheet according to claim 1, characterized in that: The transfer heat preservation tooling is made of a material with a hardness greater than that of the molybdenum-ruthenium alloy and a melting point higher than that of the molybdenum-ruthenium alloy.

6. The method of claim 1, wherein the molybdenum-ruthenium alloy foil sheet is heated to a temperature of 300°C to 600°C. The transfer heat preservation tooling is made of a tungsten-rhenium alloy.

7. A method of hot rolling a molybdenum-ruthenium alloy foil sheet according to claim 6, characterized in that: In step 4), the annealing temperature is 1250-1300°C.

8. The hot rolling method for a molybdenum-ruthenium alloy foil sheet according to claim 1, characterized in that: The method further comprises the following steps:

9. The hot rolling method for a molybdenum-ruthenium alloy foil sheet according to claim 1, characterized in that: 5) polishing and grinding the surface of the molybdenum-ruthenium alloy foil; 6) annealing the molybdenum-ruthenium alloy foil, wherein the annealing temperature is 1100-1200°C, the atmosphere is vacuum or a protective atmosphere, and the annealing time is 30 min. ​

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