Method for measuring ablation rate of tungsten-copper alloy irradiated by high-current pulsed electron beam

Abstract

The invention belongs to the technical field of high-current pulsed electron beam measurement of the ablation rate of an electrode material, and discloses a method for measuring the ablation rate of a tungsten-copper alloy irradiated by a high-current pulsed electron beam. Fixing a shielding object with a certain shape on the surface of W70Cu subjected to surface pretreatment, cutting after high-current pulse electron beam irradiation, measuring the ablation depth by using a metallographic microscope, obtaining the burning loss volume, dividing the burning loss volume by the ablation time to obtain the burning loss rate, and taking the burning loss rate as an evaluation index of electrode material ablation. The working parameters of the high-current pulsed electron beam are as follows: the working distance is 18cm, the vacuum degree is 7.0 * 10 <-3 > Pa, the electron beam acceleration voltage is 27kV, the pulse width is 2.0 microseconds, the energy density is 6J / cm < 2 >, and the irradiation frequency is 1-50. The method is low in cost, short in period, high in efficiency and simple in operation process, and plays a very important role in evaluating the ablation of the electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring the ablation rate of the electrode material of high-current pulsed electron beams, and particularly relates to a method for measuring the ablation rate of tungsten-copper alloy irradiated by high-current pulsed electron beams. Background Art

[0002] With the development of technology, the demand for electricity has been increasing year by year. Ultra-high voltage power transmission technology is an important way to realize the strategies of "transmitting electricity from the west to the east" and "transmitting electricity from the north to the south" in China, and has significant advantages such as large power transmission capacity, long transmission distance, low energy consumption, less land occupation, and good economy. As a device for controlling and protecting switches, high-voltage circuit breakers play an important role in the power system. As the core component of a high-voltage circuit breaker, the performance of the electrode directly affects the safe, stable, and efficient operation of the power system, and it is an indispensable key material in the power system.

[0003] Tungsten-copper alloy is composed of two phases of tungsten and copper. Tungsten and copper neither dissolve in each other nor form intermetallic compounds, and it is a typical pseudo-alloy. Because it has both the high melting point, high strength, and hardness of tungsten and the excellent electrical and thermal conductivity of copper, it is widely used as the electrode material in high-voltage circuit breakers. During the opening process of a high-voltage circuit breaker, the voltage between the electrodes rises rapidly, and the electric field strength increases sharply. When the applied electric field is large enough, a large number of free electrons are excited on the electrode surface, and strong ionization occurs to form an arc. The high temperature of the arc will cause the melting, evaporation, and sputtering of the electrode material, thus causing ablation of the electrode. Ablation not only affects the performance of the electrode but also reduces the service life and reliability of the high-voltage circuit breaker. Therefore, the evaluation of electrode material ablation is particularly important. Currently, the ablation evaluation index of materials is mainly based on the mass loss rate. However, this method can only provide the change in material mass and has low accuracy.

[0004] High-current pulsed electron beam is a newly emerging material surface modification technology in recent years. It uses short-pulse, high-energy-density electron beams to irradiate the surface of materials. The energy carried by the electron beam is instantaneously deposited, causing a sudden change in the temperature of the material surface layer, inducing processes such as melting, vaporization, non-equilibrium solidification, and solid-state phase transformation, resulting in the formation of a special surface microstructure. Therefore, by irradiating tungsten-copper alloy with high-current pulsed electron beams, the ablation of the material can be evaluated more simply, efficiently, and intuitively. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for measuring the ablation rate of tungsten-copper alloy irradiated by high-current pulsed electron beams.

[0006] The technical solution of the present invention is as follows: A method for measuring the ablation rate of tungsten-copper alloy irradiated by high-current pulsed electron beams, fixing an obstacle with a certain shape on the surface of W70Cu after surface pretreatment, cutting it after irradiation with high-current pulsed electron beams, and obtaining the ablation depth of the cross-section by using a metallographic microscope.

[0007] The measurement method of the ablation rate of a high-current pulsed electron beam irradiated tungsten-copper alloy is as follows:

[0008] (1) Surface pretreatment:

[0009] Select a W70Cu plate prepared by the infiltration method, cut it into tungsten-copper alloy samples of a certain shape and size, mechanically grind and polish the surface and then set aside. Ensure that the surface roughness Ra of the sample is ≤ 0.05 μm, and the upper and lower surfaces are parallel; select an occlusion and fix it on the surface of the tungsten-copper alloy sample.

[0010] (2) High-current pulsed electron beam irradiation treatment:

[0011] Fix the tungsten-copper alloy sample on the target, and use the "HOPE-Ⅰ" type high-current pulsed electron beam device to irradiate the tungsten-copper alloy sample.

[0012] (3) Cross-section pretreatment:

[0013] Remove the tungsten-copper alloy sample after electron beam irradiation treatment, cool it, cut it into two samples of a certain shape and size, mechanically grind and polish the surface and then set aside.

[0014] (4) Cross-section depth measurement:

[0015] Use a metallurgical microscope to measure the ablation depth of the sample. Place the irradiated surfaces of the two samples closely opposite to each other, obtain the ablation volume according to the cross-sections of the two samples, divide the ablation volume by the ablation time to obtain the ablation rate, and use the ablation rate as the evaluation index for the ablation of the tungsten-copper alloy electrode material.

[0016] In step (1), the sample cut into a certain shape and size means: cut into a 10×10×5 mm sample using a wire cutting machine; the mechanical grinding and polishing is to polish the surface with metallurgical sandpaper, and the sandpapers used are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence. The polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm until there are no obvious scratches on the tungsten-copper alloy sample; the occlusion is an annular occlusion with an inner diameter of 5 mm, which is fixed on the surface of the tungsten-copper alloy sample.

[0017] In step (2), the technical parameters of the high-current pulsed electron beam irradiation are: the working distance is 18 cm, the vacuum degree is 7.0×10 -3 Pa, the electron beam acceleration voltage is 27 kV, the pulse width is 2.0 μs, the energy density is 6 J / cm 2 , and the irradiation times are 1 to 50 times.

[0018] In step (3), specifically: The tungsten copper alloy sample after electron beam irradiation treatment is taken off and cooled, and is cut into samples of 10×5×5 mm along the diameter of the central circle by a wire cutting machine; for the mechanical grinding and polishing, the surface is polished with metallographic sandpaper, and the sandpapers used are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence. The polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm until there are no obvious scratches on the sample.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] First, the technical solution of the present invention has low cost, short cycle, high efficiency, and simple operation process, and plays a very important role in evaluating the ablation of electrode materials.

[0021] Second, as an emerging surface modification technology of energy-carrying beam, high-current pulsed electron beam irradiation has the advantages of high energy utilization rate and flexible and controllable processing method. Pulsed electron beams deposit a large amount of energy in a very small area on the material surface in an extremely short time, making the material surface reach an extremely high temperature rapidly. This high-energy density deposition will cause the material surface to melt, vaporize, and even evaporate rapidly, thus forming an ablation phenomenon. Through HCPEB irradiation treatment, it is easier to obtain the microscopic and macroscopic parameters of the ablation morphology, realizing the high safety and repeatability of the ablation experiment of electrode materials. Description of the Drawings

[0022] Figure 1 is the OM cross-sectional view of the unirradiated area;

[0023] Figure 2 is the OM cross-sectional view after 50 irradiations. Detailed Embodiments

[0024] (1) Surface pretreatment:

[0025] First step, select W70Cu plates prepared by infiltration method, cut them into samples of 10×10×5 mm by a wire cutting machine, polish the surface mechanically and then set aside, and it is necessary to ensure that the sample surface is smooth and flat, the surface roughness Ra≤0.05 μm, and the upper and lower surfaces are parallel. Among them, the sandpapers used for grinding are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence, and the polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm.

[0026] Second step, select an annular cover with an inner diameter of 5 mm and fix it on the surface of the tungsten copper alloy sample.

[0027] (2) High-current pulsed electron beam irradiation treatment:

[0028] Fix the tungsten-copper alloy sample on the target, and irradiate the tungsten-copper alloy sample with the "HOPE-Ⅰ" high-current pulsed electron beam device. The working distance is 18 cm, the vacuum degree is 7.0×10 -3 Pa, the electron beam acceleration voltage is 27 kV, the pulse width is 2.0 μs, and the energy density is 6 J / cm 2 . The number of irradiation times is 50 times.

[0029] (3) Cross-section pretreatment:

[0030] Take down the sample after electron beam irradiation and cool it. Cut the sample into a 10×5×5 mm sample along the diameter of the central circle using a wire cutting machine. After mechanically grinding and polishing the surface, it is ready for use. The sandpapers used for grinding are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence, and the polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm.

[0031] (4) Cross-section depth measurement:

[0032] Measure the ablation depth of the sample using a metallographic microscope. Place the irradiated surfaces closely opposite to each other, and obtain the ablation volume (471±2.52)×10 -3 mm 3 . Divide the ablation volume by the ablation time to obtain the ablation rate (471±2.52)×10 - 5 mm 3 / μs, and use the ablation rate as an evaluation index for the ablation of the electrode material.

Claims

1. A method for measuring the ablation rate of a tungsten-copper alloy irradiated by a high-current pulsed electron beam, characterized in that, Fix an obstacle of a certain shape on the surface of W70Cu after surface pretreatment. After irradiation with a high-current pulsed electron beam, cut it, and use a metallurgical microscope to obtain the ablation depth of the cross-section.

2. The method for measuring the ablation rate of a tungsten-copper alloy irradiated by a high-current pulsed electron beam according to claim 1, characterized in that The specific steps are as follows: (1) Surface pretreatment: Select W70Cu plates prepared by the infiltration method, cut them into tungsten-copper alloy samples of a certain shape and size, mechanically grind and polish the surface and then set aside. Ensure that the surface roughness Ra of the sample is ≤ 0.05 μm, and the upper and lower surfaces are parallel; select an obstacle and fix it on the surface of the tungsten-copper alloy sample; (2) High-current pulsed electron beam irradiation treatment: Fix the tungsten-copper alloy sample on the target, and use the "HOPE-Ⅰ" type high-current pulsed electron beam device to irradiate the tungsten-copper alloy sample; (3) Cross-section pretreatment: Remove the tungsten-copper alloy sample after electron beam irradiation treatment, cool it, cut it into two samples of a certain shape and size, mechanically grind and polish the surface and then set aside; (4) Cross-section depth measurement: Use a metallurgical microscope to measure the ablation depth of the sample. Place the irradiated surfaces of the two samples closely opposite to each other, obtain the ablation volume according to the cross-sections of the two samples, divide the ablation volume by the ablation time to obtain the ablation rate, and use the ablation rate as the evaluation index for the ablation of the tungsten-copper alloy electrode material.

3. The measurement method of the ablation rate of a high-current pulsed electron beam irradiated tungsten copper alloy according to claim 2, characterized in that, In step (1), the sample cut into a certain shape and size means: cut the sample into a 10×10×5 mm sample using a wire cutting machine; the mechanical grinding and polishing is to polish the surface with metallographic sandpaper, and the sandpapers used are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence. The polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm until there are no obvious scratches on the tungsten-copper alloy sample.

4. The measuring method for ablation rate of tungsten copper alloy irradiated by high-current pulsed electron beam according to claim 3, wherein The obstacle is an annular cover with an inner diameter of 5 mm, which is fixed on the surface of the tungsten-copper alloy sample.

5. The measurement method of the ablation rate of a high-current pulsed electron beam irradiated tungsten-copper alloy according to claim 2, characterized in that, In step (2), the technical parameters of the high-current pulsed electron beam irradiation are as follows: the working distance is 18 cm, the vacuum degree is 7.0×10 - 3 Pa, the electron beam acceleration voltage is 27 kV, the pulse width is 2.0 μs, the energy density is 6 J / cm 2 , and the irradiation times are 1 to 50 times.

6. The measurement method of the ablation rate of a high-current pulsed electron beam irradiated tungsten copper alloy according to claim 2, wherein In step (3), specifically: remove the tungsten-copper alloy sample after electron beam irradiation treatment, cool it, and cut it into a 10×5×5 mm sample along the diameter of the central circle using a wire cutting machine; the mechanical grinding and polishing is to polish the surface with metallographic sandpaper, and the sandpapers used are 80, 150, 400, 800, 1000, 1500, 2000, and 2500 mesh in sequence. The polishing agent used for polishing is diamond polishing paste with a particle size of 0.5 μm until there are no obvious scratches on the sample.

Images