A method for strengthening tantalum metal surface microcrystals

Abstract

The present invention relates to a method for strengthening the surface microcrystals of tantalum metal, comprising the following steps: S1: pre-processing the tantalum metal into a desired shape, then polishing each surface in turn, and then cleaning the surface; S2: using a continuous CO2 laser to perform laser scanning treatment on the tantalum metal pre-processed in step S1; S3: after the treatment in step S2 is completed, cooling the tantalum metal to complete the surface microcrystal strengthening. Compared with the prior art, the present invention can significantly improve the overall corrosion resistance of the tantalum material through the microcrystalization treatment of the surface, thereby effectively combining the advantages of the metal and the advantages of the surface microcrystal layer to meet the use requirements.

Description

Technical Field

[0001] The invention relates to a tantalum metal surface strengthening technology, in particular to a tantalum metal surface microcrystal strengthening method. Background Art

[0002] Tantalum metal is one of the metals with the highest melting point in nature. From the perspective of high temperature resistance, it can be used as a material for stirring paddles, crucibles and other parts. However, since many high-temperature chemical reactions are carried out in high-temperature molten salt systems, direct use of tantalum materials in high-temperature molten salts will be severely corroded and its service life will be greatly shortened. Especially with the continuous progress of domestic nuclear technology application and research, in a large number of nuclear-related high-temperature physical and chemical processes, tantalum metal components and equipment are susceptible to corrosion and damage, resulting in greatly increased operating costs. In addition, a large amount of radioactive waste will be generated when disposing of abandoned equipment, requiring additional post-processing work, further increasing production costs, and potentially causing pollution and damage to the environment.

[0003] Therefore, it is necessary to develop a tantalum surface treatment technology that can make the tantalum metal surface resistant to high-temperature molten salt corrosion and can be recycled multiple times, so as to improve the corrosion resistance of tantalum equipment and thus increase its service life. Summary of the invention

[0004] The purpose of the present invention is to provide a method for microcrystal strengthening of the surface of tantalum metal in order to solve at least one of the above problems. The microcrystal treatment of the surface of tantalum material can significantly improve its overall corrosion resistance, thereby effectively combining the advantages of metal and the advantages of the surface microcrystal layer to meet the use requirements.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for strengthening tantalum metal surface microcrystals, comprising the following steps:

[0007] S1: Pre-process the tantalum metal into the required shape, then grind each surface in turn, and then clean the surface;

[0008] S2: The tantalum metal pre-treated in step S1 is subjected to laser scanning treatment using a continuous CO2 laser;

[0009] S3: After the processing in step S2 is completed, the tantalum metal is cooled to complete surface microcrystalline strengthening.

[0010] Preferably, in step S1, the polishing is performed using water-abrasive sandpaper.

[0011] Preferably, in step S1, the grinding is performed in the order of 200# sandpaper, 400# sandpaper, 800# sandpaper, 1000# sandpaper, 1500# sandpaper and 3000# sandpaper.

[0012] Preferably, in step S1, the surface cleaning includes wiping the surface and ultrasonic cleaning.

[0013] Preferably, the wiping surface is wiped with acetone; and the ultrasonic cleaning is ultrasonic cleaning with alcohol for 5-10 minutes.

[0014] Preferably, in step S1, after the surface of the tantalum metal is cleaned, a graphite blackening coating is coated on the surface of the tantalum metal and dried naturally at room temperature.

[0015] Preferably, the graphite blackening coating has a coating thickness of 50 μm. By coating a layer of graphite blackening coating on the surface of tantalum metal, the absorption rate of the workpiece to laser energy can be increased, thereby enhancing the processing effect.

[0016] Preferably, in step S2, the continuous CO2 laser is a 5000W cross-flow tube-plate continuous CO2 laser.

[0017] Preferably, in step S2, the light spot in the laser scanning process is elliptical, with a major axis of 5 mm and a minor axis of 4 mm, and the major axis is perpendicular to the laser scanning direction, and the equivalent spot diameter is 4.5 mm; the laser output power in the laser scanning process is 1000-3500 W, and the scanning speed is 4 mm / s; the working area is purged with argon gas at 2 L / min in the laser scanning process.

[0018] Preferably, in step S3, the cooling is: reducing the temperature of the tantalum metal to below 200° C., continuously purging with argon gas during the cooling process, and after the tantalum metal is cooled to 100° C., naturally cooling to room temperature.

[0019] The present invention uses a high-energy-density laser beam to partially melt the tantalum surface to form a molten pool, which is rapidly cooled to achieve rapid solidification, so that a microcrystalline structure is formed on the surface of the material, which effectively resists the corrosion of the molten salt on the tantalum material. The microcrystallization treatment of the tantalum surface can significantly improve its overall corrosion resistance, combining the corrosion resistance of the tantalum microcrystallized surface layer with the high-temperature resistance of the tantalum material, effectively improving the service life of tantalum components.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The surface microcrystalline tantalum material prepared by this process can form a 300-600μm thick spherical microcrystalline fused layer on the surface of the original tantalum material. The thickness of the microcrystalline fused layer is evenly distributed, which significantly improves the corrosion resistance and oxidation resistance of the tantalum material.

[0022] 2. The microcrystallization treatment of the tantalum surface can significantly improve its overall corrosion resistance, thereby effectively combining the corrosion resistance of the tantalum microcrystallized surface layer with the high temperature resistance of the tantalum material, effectively improving the service life of tantalum components to meet the use requirements. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to specific embodiments, but this is by no means a limitation of the present invention.

[0024] A metal surface microcrystal strengthening method, the specific working process is as follows:

[0025] According to specific needs, the tantalum material is pre-processed into the required shape (such as 30mm×30mm×2-6mm and other specifications), and then each surface is polished with water abrasive paper in the order of 200#→400#→800#→1000#→1500#→3000#. After that, the surface is wiped with acetone and cleaned with alcohol in an ultrasonic cleaner for 5-10 minutes. A layer of graphite blackening paint with a thickness of about 50μm is coated on the surface of the tantalum workpiece and dried naturally at room temperature to improve the workpiece's absorption rate of laser energy and enhance the treatment effect.

[0026] Turn on and debug a 5000W cross-flow tube-plate continuous CO2 laser (with an adjustable power range of 0.6-3kW and an adjustable scanning speed range of 0.3-1.5m / min), set the beam mode to multi-mode, place the workpiece horizontally on the CNC workbench, adjust the focus, measure the spot diameter, and scan the workpiece relative to the laser.

[0027] The spot shape is set to be elliptical, with the major and minor axis lengths of 5mm and 4mm respectively, the major axis is perpendicular to the laser scanning direction, and the equivalent spot diameter D is 4.5mm; the laser output power is set to 1000W-3500W, and the scanning speed is 4mm / s; during the processing process, the working area is purged with argon gas at 2L / min.

[0028] After the laser microcrystal melting treatment, the workpiece temperature quickly drops to below 200°C. During the cooling process, argon gas is continuously purged. When the temperature drops to 100°C, it is naturally cooled to room temperature.

[0029] Example 1

[0030] After cleaning the pretreated tantalum impeller blade workpiece (20mm×52mm×2mm), place it on the CNC workbench, turn on and debug the 5000W cross-flow tube-plate continuous CO2 laser, set the beam mode to multi-mode, adjust the focus, measure the spot diameter, and scan the workpiece relative to the laser. Set the spot shape to an ellipse, with the major and minor axis lengths of 5mm and 4mm respectively, the major axis perpendicular to the laser scanning direction, and the equivalent spot diameter D to 4.5mm; set the laser output power to 2500W, the scanning speed to 4mm / s; during the processing, purge the working area with argon gas at 2L / min.

[0031] After the laser microcrystal melting of the blade surface is completed, the temperature is rapidly cooled to below 100°C and then naturally cooled to room temperature.

[0032] The surface of the microcrystallized tantalum stirring blade prepared by the process in this case forms a 300-400μm thick spherical microcrystalline molten layer with uniform thickness, which significantly improves the corrosion resistance and oxidation resistance of the tantalum material.

[0033] Example 2

[0034] After cleaning the pre-treated tantalum crucible, place it on the CNC workbench, turn on and debug the 5000W cross-flow tube-plate continuous CO2 laser, set the beam mode to multi-mode, adjust the focus, measure the spot diameter, and scan the workpiece relative to the laser. Set the spot shape to an ellipse, with the major and minor axis lengths of 5mm and 4mm respectively, the major axis perpendicular to the laser scanning direction, and the equivalent spot diameter D to 4.5mm; set the laser output power to 3000W, the scanning speed to 4mm / s; during the processing, purge the working area with argon gas at 2L / min.

[0035] After the laser microcrystal melting of the blade surface is completed, the temperature is rapidly cooled to below 100°C and then naturally cooled to room temperature.

[0036] The surface of the microcrystallized tantalum stirring blade prepared by the process in this case forms a 500-600μm thick spherical microcrystalline molten layer with uniform thickness, which significantly improves the corrosion resistance and oxidation resistance of the tantalum material.

[0037] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for strengthening the surface microcrystals of tantalum metal, characterized in that: The steps include: S1: Pre-process the tantalum metal into the required shape, then grind each surface in turn, and then clean the surface; S2: The tantalum metal pre-treated in step S1 is subjected to laser scanning treatment using a continuous CO2 laser; S3: After the processing in step S2 is completed, the temperature of the tantalum metal is lowered to complete surface microcrystalline strengthening; In step S1, after the surface of the tantalum metal is cleaned, a graphite blackening coating is applied to the surface of the tantalum metal and dried naturally at room temperature; In step S2, the laser scanning process has an elliptical spot with a major axis of 5 mm and a minor axis of 4 mm, and the major axis is perpendicular to the laser scanning direction, and the equivalent spot diameter is 4.5 mm; the laser output power is 1000-3500 W, and the scanning speed is 4 mm / s; the working part is purged with argon gas at 2 L / min during the laser scanning process; In step S3, the temperature reduction is as follows: lowering the temperature of the tantalum metal to below 200° C., continuously purging with argon gas during the temperature reduction process, and naturally cooling the tantalum metal to room temperature after the temperature is reduced to 100° C.; The tantalum metal surface microcrystal strengthening method uses a high-energy-density laser beam to partially melt the tantalum surface to form a molten pool, and the molten pool is rapidly cooled to achieve rapid solidification, so that a microcrystalline structure is formed on the material surface to resist the corrosion of the molten salt to the tantalum material.

2. A method for strengthening the surface of tantalum metal microcrystals according to claim 1, characterized in that: In step S1, the grinding is performed using water-abrasive sandpaper.

3. A method for strengthening the surface of tantalum metal microcrystals according to claim 2, characterized in that: In step S1, the grinding is performed in the order of 200# sandpaper, 400# sandpaper, 800# sandpaper, 1000# sandpaper, 1500# sandpaper and 3000# sandpaper.

4. A method for strengthening the surface of tantalum metal microcrystals according to claim 1, characterized in that: In step S1, the surface cleaning includes wiping the surface and ultrasonic cleaning.

5. A method for strengthening the surface of tantalum metal microcrystals according to claim 4, characterized in that: The wiping surface is wiped with acetone; the ultrasonic cleaning is ultrasonic cleaning with alcohol for 5-10 minutes.

6. A method for strengthening the surface of tantalum metal microcrystals according to claim 1, characterized in that: The graphite blackening paint has a coating thickness of 50 μm.

7. A method for strengthening the surface of tantalum metal microcrystals according to claim 1, characterized in that: In step S2, the continuous CO2 laser is a 5000W cross-flow tube-plate continuous CO2 laser.