Cooling bed electron beam melting process for niobium ingot

Abstract

The invention discloses a cooling bed electron beam melting process for niobium ingots, which comprises the following steps: preassembling a pure niobium plate on a cooling bed, melting the pure niobium plate by using an electron gun, adding niobium-aluminum raw materials, standing for a set time, introducing into an ingot casting crucible, and pulling the ingots by using a dummy ingot head to form the ingots. According to the process, the niobium-aluminum raw materials can be directly used for electron beam smelting, the whole niobium ingot forming process is short, pollution risks in the material transferring and preparing process are reduced, consumed time is short, cost is reduced, energy consumption is reduced, niobium ingot components are excellent, and the process is suitable for popularization.

Description

Technical Field

[0001] The invention relates to the technical field of smelting, and in particular to a cooling bed electron beam smelting process for niobium ingots. Background Art

[0002] The cooling bed electron beam melting process generally refers to the installation of a cooling bed device in the melting equipment. The material is melted, refined, degassed and other processes are completed on the cooling bed. The molten material flows out from the flow port of the cooling bed and enters the ingot casting crucible. The ingot pulling system is operated to complete the ingot casting process. The equipment is equipped with at least two electron guns, one to control the material melting and refining, and the other to complete the ingot casting.

[0003] When preparing niobium ingots by electron beam melting, the raw materials required are relatively high. Usually, niobium plates need to be melted. The niobium aluminum raw materials need to be melted multiple times in a horizontal furnace to obtain melted niobium plates. The melted niobium plates also need to be bundled with niobium wires as raw materials for the electron beam furnace. The forming process of niobium ingots is long and energy-intensive, and needs to be improved. Summary of the invention

[0004] To solve at least one of the above technical defects, the present invention provides the following technical solutions: This application document discloses a cold bed electron beam melting process for niobium ingots, comprising the following steps: First, loading, loading pure niobium plates on the cooling bed; Second, pre-evacuate the furnace, control the pressure rise rate in the furnace at 0.6-1.5Pa / H, start the electron beam system to preheat the ingot head to a fully molten state, start the electron gun to melt the pure niobium plate on the cooling bed, add niobium and aluminum raw materials to the cooling bed through the feeding mechanism, and the residence time of the materials on the cooling bed is selected according to the required purity requirements of the ingot; Third, the material on the cooling bed is guided to the ingot casting crucible by electron beam, and the ingot is pulled by the ingot head to prepare the ingot; Fourth, cool and remove from the oven.

[0005] Furthermore, the mass ratio of the pure niobium plate to the niobium aluminum raw material on the cooling bed is 60-80:20-40.

[0006] Furthermore, the mass ratio of the pure niobium plate to the niobium aluminum raw material on the cooling bed is 70:30.

[0007] Further, pre-vacuum to 4*10 -2 -6*10 -2 Pa.

[0008] Furthermore, the power of the electron gun for preheating the ingot head is 420-460KW, and the power of the electron gun at the cooling bed is 480-520KW.

[0009] Furthermore, when the niobium aluminum raw material is added to the cooling bed, the amount added each time is 15-20 kg, calculated as niobium.

[0010] Furthermore, the residence time of the material on the cooling bed is more than 25 minutes.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention pre-installs pure niobium plates on a cooling bed, melts the pure niobium plates with an electron gun, then adds niobium aluminum raw materials, and introduces them into an ingot casting crucible after staying for a predetermined time, and uses an ingot guide to pull the ingot into an ingot. Compared with the traditional electron beam melting process that can only use smelting niobium plates as raw materials, this process can directly use niobium aluminum raw materials for electron beam melting, and the entire niobium ingot molding process is short, which reduces the risk of pollution during material transfer and preparation, takes less time, reduces costs, reduces energy consumption, and has excellent niobium ingot composition, which is suitable for promotion. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with specific embodiments.

[0013] Example 1 A cooling bed electron beam melting process for niobium ingots comprises the following steps: First, loading, the mass ratio of pure niobium plate to niobium aluminum raw material is predetermined to be 70:30, the composition ratio of niobium aluminum raw material is 85:15, and the pure niobium plate is loaded on the cooling bed.

[0014] Second, pre-vacuum to 5*10 -2 Pa, control the pressure rise rate in the furnace at 1Pa / H, start the electron beam system, preheat the ingot head at the ingot crucible to a completely molten state, the electron gun power is 450KW, and the time is 1.5h.

[0015] Start the electron gun to melt the pure niobium plate on the cooling bed. The electron gun power is 500KW. The time is 1 hour. Niobium and aluminum raw materials are added to the cooling bed through the feeding mechanism. Each addition is 16kg calculated by niobium. The niobium and aluminum raw materials are in granular form (2-30 mesh). The bulk feeder is used as the feeding mechanism. In this example, the ingot is for semiconductor or superconducting grade application. The residence time of the material on the cooling bed is 30 minutes.

[0016] Third, the material on the cooling bed is guided to the ingot casting crucible (water-cooled type) by electron beam, and the ingot is pulled by the ingot guide to prepare the ingot, and the smelting process is repeated until the niobium and aluminum raw materials are completely smelted.

[0017] Fourth, cool down and take out of the furnace. After smelting, turn off the power of the electron gun, turn off the vacuum unit after 3 hours, and take out the material after cooling for 12 hours.

[0018] Example 2 A cooling bed electron beam melting process for niobium ingots comprises the following steps: First, loading, the mass ratio of pure niobium plate to niobium aluminum raw material is predetermined to be 70:30, the composition ratio of niobium aluminum raw material is 85:15, and the pure niobium plate is loaded on the cooling bed.

[0019] Second, pre-vacuum to 4.5*10 -2 Pa, control the pressure rise rate in the furnace at 0.8Pa / H, start the electron beam system, preheat the ingot head at the ingot casting crucible to a completely molten state, the electron gun power is 430KW, and the time is 2h.

[0020] Start the electron gun to melt the pure niobium plate at the cooling bed. The electron gun power is 490KW and the time is 1.2h. Niobium and aluminum raw materials are added to the cooling bed through the feeding mechanism. Each addition is 18kg in terms of niobium. The large pieces of niobium and aluminum raw materials do not need to be crushed and can be directly pushed into the cooling bed through the whole material feeding box. In this case, the ingot is for semiconductor or superconducting grade application, and the residence time of the material on the cooling bed is 26min.

[0021] Third, the material on the cooling bed is guided to the ingot casting crucible by electron beam, and the ingot is pulled by the ingot guide to prepare the ingot, and the smelting process is repeated until the niobium and aluminum raw materials are completely smelted.

[0022] Fourth, cool down and take out of the furnace. After smelting, turn off the power of the electron gun, turn off the vacuum unit after 3 hours, and take out the material after cooling for 12 hours.

[0023] Example 3 A cooling bed electron beam melting process for niobium ingots comprises the following steps: First, loading, the mass ratio of pure niobium plate to niobium aluminum raw material is predetermined to be 70:30, the composition ratio of niobium aluminum raw material is 85:15, and the pure niobium plate is loaded on the cooling bed.

[0024] Second, pre-vacuum to 5.3*10 -2 Pa, control the pressure rise rate in the furnace at 1.5Pa / H, start the electron beam system, preheat the ingot head at the ingot crucible to a completely molten state, the electron gun power is 460KW, and the time is 1.8h.

[0025] Start the electron gun to melt the pure niobium plate at the cooling bed. The electron gun power is 520KW and the time is 50 minutes. Add niobium and aluminum raw materials to the cooling bed through the feeding mechanism. Each addition is 15kg calculated by niobium. The niobium and aluminum raw materials are in granular form (2-30 meshes) and the bulk feeder is used as the feeding mechanism. In this case, the ingot is for semiconductor or superconducting grade application. The residence time of the material on the cooling bed is 28 minutes.

[0026] Third, the material on the cooling bed is guided to the ingot casting crucible by electron beam, and the ingot is pulled by the ingot guide to prepare the ingot, and the smelting process is repeated until the niobium and aluminum raw materials are completely smelted.

[0027] Fourth, cool down and take out of the furnace. After smelting, turn off the power of the electron gun, turn off the vacuum unit after 3 hours, and take out the material after cooling for 12 hours.

[0028] The niobium ingot prepared as above was tested. The niobium content in the formed ingot was greater than 99.99%, O was less than 10ppm, N was less than 10ppm, W was less than 10ppm, Ta was less than 50ppm, and the elements such as Fe, Al, Si, Ni, and V were reduced to less than 1ppm. The yield of niobium ingot was about 91%, and the yield was improved.

[0029] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A cooling hearth electron beam melting process for niobium ingots, characterized in that: The following steps are involved: First, loading, loading pure niobium plates on the cooling bed; Second, pre-evacuate the furnace, control the pressure rise rate in the furnace at 0.6-1.5Pa / H, start the electron beam system to preheat the ingot head to a fully molten state, start the electron gun to melt the pure niobium plate on the cooling bed, add niobium and aluminum raw materials to the cooling bed through the feeding mechanism, and the residence time of the materials on the cooling bed is selected according to the required purity requirements of the ingot; Third, the material on the cooling bed is guided to the ingot casting crucible by electron beam, and the ingot is pulled by the ingot head to prepare the ingot; Fourth, cool and remove from the oven.

2. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 1, characterized in that: The mass ratio of pure niobium plate to niobium aluminum raw material on the cooling bed is 60-80:20-40.

3. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 2, characterized in that: The mass ratio of pure niobium plate to niobium aluminum raw material on the cooling bed is 70:

30.

4. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 1, characterized in that: Pre-vacuum to 4*10 -2 -6*10 -2 Pa.

5. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 1, characterized in that: The power of the electron gun for preheating the ingot head is 420-460KW, and the power of the electron gun at the cooling bed is 480-520KW.

6. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 1, characterized in that: When adding niobium aluminum raw materials to the cooling bed, 15-20 kg is added each time, calculated as niobium.

7. A cooling hearth electron beam melting process for niobium ingots as claimed in claim 1, characterized in that: The residence time of materials on the cooling bed is more than 25 minutes.