High-temperature-ablation-resistant gas spark switch W-Cu-CrNb electrode and preparation method thereof

Abstract

The invention discloses a gas spark switch W-Cu-CrNb electrode resistant to high-temperature ablation and a preparation method of the gas spark switch W-Cu-CrNb electrode, and belongs to the technical field of high-power pulses. According to the gas spark switch W-Cu-CrNb alloy electrode and the preparation method thereof, Cr and Nb with the specific atomic percent are added into a W-Cu matrix, an intermetallic compound Cr2Nb reinforced phase is generated at a W-Cu interface in the sintering process through the powder metallurgy technology, and finally the gas spark switch W-Cu-CrNb alloy electrode with the optimized structural performance is obtained. Compared with a traditional gas spark switch W-Cu electrode, the gas spark switch W-Cu-CrNb alloy electrode has the advantages that under the same ablation condition, the volume loss and the surface roughness are obviously reduced, and the surface appearance is more complete. The invention provides a new material solution for high-performance and long-life manufacturing of key parts of the pulse power device, and has important significance for improving the intelligent level and operation reliability of the pulse power device.

Description

Technical Field

[0001] This invention relates to the field of high-power pulse technology, specifically to a high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode and its preparation method. Background Technology

[0002] In recent years, pulsed power technology has developed rapidly and is widely used in an increasing number of fields, such as high-energy physics, military, nuclear energy, materials processing, and medical treatment. The switch is the core component of a pulsed power device, and its operating characteristics directly determine the performance of the entire device. Gas spark switches are widely used in various pulsed power devices due to their advantages such as robust structure, high operating voltage, large switching current, low on-resistance, high reliability, and long lifespan. However, their operation is often accompanied by spark and arc discharges, forming a high-temperature, high-current-density plasma channel that erodes the electrode surface. After repeated discharges, electrode evaporation and sputtering cause electrode damage, contamination of the switch's internal environment, and deterioration of the insulating medium, leading to abnormal discharges and ultimately affecting the service life, operational reliability, and stability of the pulsed equipment.

[0003] Therefore, developing electrode materials with excellent high-temperature ablation resistance is not only fundamental to improving the working efficiency of gas spark switches, but also an essential way to ensure their long-term operational reliability and stability. Currently, widely used electrode materials mainly include two categories: non-metallic electrodes (graphite electrodes) and metallic electrodes. However, although graphite electrodes possess high melting points, excellent heat resistance, and good electrical and thermal conductivity, their low intrinsic strength and weak interparticle bonding make them prone to spalling under external forces or arc impacts, leading to a significant increase in mass loss and volumetric ablation rate after discharge ablation. This phenomenon further exacerbates switch jitter, ultimately severely restricting the long-term stability and service life of the switch. In contrast, metallic electrodes (such as W-Cu alloys, stainless steel, brass, Mo, etc.) are widely used due to their high melting points, good plasticity, and excellent electrical and thermal conductivity. Among these, W-Cu alloys exhibit outstanding ablation resistance among various electrode materials. However, due to the significant differences in physical properties and crystal structure between W and Cu, they are neither miscible nor react with each other, and can only form pseudo-alloys. The structure of pseudo-alloys is unstable, and interface failure will occur under the action of high-temperature ablation, thereby affecting the overall high-temperature stability of the alloy and aggravating the ablation of the electrode material.

[0004] Therefore, how to effectively improve the high-temperature ablation resistance of W-Cu alloys is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, existing gas spark switch W-Cu-CrNb electrodes suffer from weak interfacial bonding, poor microstructural stability, and susceptibility to ablation and spalling under high-temperature arc environments. This invention provides a gas spark switch W-Cu-CrNb electrode with improved high-temperature ablation resistance and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode is disclosed, wherein Cr and Nb are introduced into a W-Cu matrix, and the W-Cu-CrNb alloy electrode is prepared by powder metallurgy. During sintering, Cr and Nb form an intermetallic compound Cr2Nb phase in the matrix. The electrode is composed of the following atomic percentages of elements: W: 43%-55%, Cu: 8%-15%, Cr: 24.6%-40.4%, Nb: 5.4%-8.6%.

[0008] Preferably, the electrode is composed of the following elements in atomic percentage: W: 48.8%, Cu: 9.5%, Cr: 35.9%, Nb: 5.8%.

[0009] The beneficial effects of adopting the above-mentioned further scheme are that the Cr2Nb phase at the interface can serve as an effective pinning point, significantly enhancing the interfacial bonding strength and improving the microstructure stability and ablation resistance of the electrode under high-temperature arc impact.

[0010] This invention also provides a method for preparing the above-mentioned high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode, comprising the following steps: (1) Take the raw material powder corresponding to each element according to the above atomic percentage; (2) Weigh out the raw material powder containing W, Cu, Cr and Nb elements, mix them together, and then press the mixed powder into a green body; (3) Hot pressing and sintering are performed on the green blank so that Cr and Nb elements react during the sintering process to form the Cr2Nb intermetallic compound. Cr2Nb is distributed at the W-Cu matrix interface. After cooling, a gas spark switch W-Cu-CrNb electrode is obtained.

[0011] Furthermore, the mixing in step (2) is ball milling; the ball-to-material ratio of the ball milling mixture is 3:1 to 5:1, the rotation speed is 180-250 r / min, the ball milling time is 6-10 h, and argon gas is introduced during ball milling to protect against oxidation.

[0012] Furthermore, in step (2), the pressure for pressing the embryo is 450-600 MPa, and the holding time is 3-6 min.

[0013] Furthermore, the hot pressing sintering in step (3) is performed at a temperature of 1200-1280 ℃ and a pressure of 30-50 MPa for 1.5-2.5 h.

[0014] Furthermore, the dimensions of the W-Cu-CrNb electrode of the gas spark switch are 15-25 mm × 15-25 mm × 3 mm.

[0015] Furthermore, the dimensions of the W-Cu-CrNb electrode of the gas spark switch are preferably 25 mm × 25 mm × 3 mm and 15 mm × 15 mm × 3 mm.

[0016] Furthermore, the temperature and atmosphere of the sintering process must meet the requirements for Cr and Nb to react and form the Cr2Nb phase.

[0017] The beneficial effect of adopting the above-mentioned further scheme is that by controlling the sintering process, Cr and Nb can be ensured to react to form a stable Cr2Nb reinforcing phase and be preferentially distributed in the interface region, thereby achieving the best strengthening effect.

[0018] The W-Cu-CrNb alloy electrode for gas spark switches prepared using the above-mentioned scheme of the present invention is suitable for use in gas spark switches. It can maintain structural integrity and functional reliability under conditions of high temperature, high voltage, high current and frequent arc discharge, and significantly extend the service life of the switch.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By adding Cr and Nb elements and generating Cr2Nb intermetallic compounds, the interfacial bonding force of W-Cu pseudo-alloys is effectively enhanced, and the spalling and structural instability of the material under high-temperature electric arc are suppressed. 2. As a high-temperature stable reinforcing phase, the Cr2Nb phase has a significant grain-refining strengthening effect on the matrix, further improving the high-temperature mechanical properties and ablation resistance of the alloy. 3. The electrode of this invention exhibits lower volume loss and more complete surface morphology in the breakdown and ablation test, making it suitable for high-voltage and high-current devices such as gas spark switches with stringent requirements for lifespan and reliability. Attached Figure Description

[0020] Figure 1 The images show the XRD patterns of the W-Cu alloy and the W-Cu-CrNb alloy of this invention.

[0021] Figure 2 The figures show the volume loss curves of the W-Cu alloy electrode and the W-Cu-CrNb electrode of this invention.

[0022] Figure 3The images show surface SEM images of the W-Cu alloy electrode and the W-Cu-CrNb electrode of this invention.

[0023] Figure 4 The surface roughness curves are for the W-Cu alloy electrode and the W-Cu-CrNb electrode of this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In all embodiments of the present invention, W, Cu, Cr, and Nb elemental powders with a purity of 99.9% or higher are used.

[0026] Example 1: A high-temperature erosion-resistant W-Cu-CrNb electrode for gas spark switches (1) Weigh W: 48.8%, Cu: 9.5%, Cr: 35.9%, Nb: 5.8% precisely according to atomic percentage, and achieve uniform mixing by ball milling. The ball-to-material ratio is 4:1, the rotation speed is 200 r / min, the ball milling time is 8 h, and argon gas is introduced during ball milling to prevent oxidation. (2) Press the mixed powder into shape (hold pressure at 550 MPa for 5 min) to obtain a pre-sintered green body; (3) The billet was sintered under pressure in a protective atmosphere (1250 ℃, 40 MPa pressure for 2 h). After sintering, it was cooled, processed and surface treated to obtain gas spark switch W-Cu-CrNb alloy electrodes with dimensions of 25 mm×25 mm×3 mm and 15 mm×15 mm×3 mm respectively. (4) The obtained electrodes were ultrasonically cleaned sequentially with ultrapure water, acetone and alcohol, each cleaning step lasting 15 minutes, and then dried.

[0027] (5) The treated electrodes were used as the cathode and anode of the gas spark switch for ablation experiments.

[0028] Specifically: Adjust the gas cylinder pressure to 0.3 MPa, open the air inlet valve to fill the switch chamber with dry air; turn on the high-voltage power supply and charge the positive and negative capacitors to about 17 kV for performance testing.

[0029] Example 2 (1) Weigh W: 43%, Cu: 8%, Cr: 40.4%, Nb: 8.6% precisely according to atomic percentage, and achieve uniform mixing by ball milling. The ball-to-material ratio is 5:1, the rotation speed is 180 r / min, the ball milling time is 10h, and argon gas is introduced during ball milling to prevent oxidation. (2) Press the mixed powder into shape (hold pressure at 450 MPa for 6 min) to obtain a pre-sintered green body; (3) The billet was sintered under pressure in a protective atmosphere (1200 ℃, 50 MPa pressure for 2.5 h). After sintering, it was cooled, processed and surface treated to obtain gas spark switch W-Cu-CrNb alloy electrodes with dimensions of 25 mm×25 mm×3 mm and 15 mm×15 mm×3 mm respectively. (4) The obtained electrodes were ultrasonically cleaned sequentially with ultrapure water, acetone and alcohol, each cleaning step lasting 15 minutes, and then dried.

[0030] Example 3 (1) Weigh W: 55%, Cu: 8%, Cr: 28.4%, Nb: 8.6% precisely according to atomic percentage, and achieve uniform mixing by ball milling. The ball-to-material ratio is 3:1, the rotation speed is 250 r / min, the ball milling time is 6 h, and argon gas is introduced during ball milling to prevent oxidation. (2) Press the mixed powder into shape (hold pressure at 600MPa for 3 min) to obtain a pre-sintered green body; (3) The billet was sintered under pressure in a protective atmosphere (1280℃, 30 MPa pressure for 1.5h). After sintering, it was cooled, processed and surface treated to obtain gas spark switch W-Cu-CrNb alloy electrodes with dimensions of 25 mm×25 mm×3 mm and 15 mm×15 mm×3 mm respectively. (4) The obtained electrodes were ultrasonically cleaned sequentially with ultrapure water, acetone and alcohol, each cleaning step lasting 15 minutes, and then dried.

[0031] Example 4 (1) Weigh W: 55%, Cu: 15%, Cr: 24.6%, Nb: 5.4% precisely according to atomic percentage, and achieve uniform mixing by ball milling. The ball-to-material ratio is 4:1, the rotation speed is 220 r / min, the ball milling time is 9 h, and argon gas is introduced during ball milling to prevent oxidation. (2) Press the mixed powder into shape (hold pressure at 500 MPa for 4 min) to obtain a pre-sintered green body; (3) The billet was sintered under pressure in a protective atmosphere (1200℃, 50MPa pressure for 2.5h). After sintering, it was cooled, processed and surface treated to obtain gas spark switch W-Cu-CrNb alloy electrodes with dimensions of 25 mm×25 mm×3 mm and 15 mm×15 mm×3 mm respectively. (4) The obtained electrodes were ultrasonically cleaned sequentially with ultrapure water, acetone and alcohol, each cleaning step lasting 15 minutes, and then dried.

[0032] Comparative Example 1 The gas spark switch W-Cu electrode differs from that in Example 1 in that it uses a commercially available gas spark switch W-Cu electrode. Specifically, the atomic ratio of W to Cu in the electrode material is W: 44.35% and Cu: 55.65%, respectively, and no Cr or Nb is added.

[0033] Performance testing 1. Alloy microstructure and property testing XRD analysis confirmed the successful synthesis of Cr2Nb intermetallic compounds in W-Cu-CrNb alloys. Figure 1 As shown, compared with W-Cu alloys containing only BCC structure W phase and FCC structure Cu phase, W-Cu-CrNb alloy exhibits clear Laves phase structure Cr2Nb diffraction peaks in its spectrum.

[0034] 2. Physical performance testing Electrical conductivity, thermal conductivity, and hardness are three key parameters that determine a material's resistance to high-temperature ablation. High electrical conductivity reduces Joule heat accumulation and arc erosion; excellent thermal conductivity rapidly dissipates heat and inhibits localized melting; and high hardness resists plasma erosion and maintains surface integrity.

[0035] Table 1 shows that the hardness of the W-Cu-CrNb alloy electrode of the gas spark switch in Example 1 is approximately twice that of the W-Cu alloy electrode of Comparative Example 1, indicating that the W-Cu-CrNb alloy electrode exhibits stronger resistance to mechanical exfoliation and greater structural stability during ablation. However, the W-Cu-CrNb alloy electrode sacrifices some electrical and thermal conductivity due to the addition of Cr and Nb to the W-Cu-CrNb alloy, resulting in inferior electrical and thermal conductivity compared to the standard W-Cu-CrNb electrode.

[0036] Table 1 Performance of different electrode materials

[0037] 3. Ablation performance test Depend on Figure 2It can be seen that, under the same ablation cycles, applied voltage, and 0.3 MPa dry air conditions, the volume loss of the W-Cu-CrNb alloy electrode of the gas spark switch in Example 1 is smaller than that in Comparative Example 1. After 5000 ablation cycles, the volume loss of the W-Cu-CrNb alloy electrode of the gas spark switch in Example 1 is only 1.01 × 10⁻⁶. -3 cm 3 In contrast, the volume loss of the W-Cu-CrNb electrode in the gas spark switch of Comparative Example 1 reached 1.47 × 10⁻⁶. -3 cm 3 This demonstrates that the W-Cu-CrNb alloy electrode of the gas spark switch described in this invention has excellent high-temperature ablation resistance and exhibits lower ablation loss.

[0038] Figure 3 The images show SEM images of the surfaces of Example 1 and Comparative Example 1 before ablation and after 1000, 2000, 3000, 4000, and 5000 ablation cycles. With increasing ablation cycles, the number of pores on the surface of the W-Cu-CrNb alloy electrode of the gas spark switch in Example 1 increased, but its overall skeletal structure remained relatively intact. In contrast, the ablated surface of the W-Cu-CrNb electrode of the gas spark switch in Comparative Example 1 showed a larger area of ​​loose and collapsed regions, with more severe material damage within the micro-regions. It can be observed that the ablation of the W-Cu-CrNb electrode of the gas spark switch in Comparative Example 1 was more severe, resulting in larger pits after ablation; the W-Cu-CrNb alloy electrode of the gas spark switch in Example 1 did not have large pits.

[0039] Depend on Figure 4 It can be seen that, under the same ablation cycles, applied voltage, and 0.3 MPa dry air conditions, the surface roughness of the W-Cu-CrNb alloy electrode for the gas spark switch in Example 1 is smaller than that in Comparative Example 1. After 5000 ablation cycles, the surface roughness of the W-Cu-CrNb alloy electrode for the gas spark switch in Example 1 is 1.443 μm, while the surface roughness of the W-Cu-CrNb electrode for the gas spark switch in Comparative Example 1 reaches 3.116 μm. This further verifies that the W-Cu-CrNb alloy electrode for the gas spark switch in Example 1 has excellent high-temperature ablation resistance, indicating that the method of introducing Cr and Nb to form the intermetallic compound Cr2Nb phase in the matrix can improve the high-temperature ablation resistance of the W-Cu-CrNb electrode for the gas spark switch. The W-Cu-CrNb alloy electrode for the gas spark switch designed in this invention can effectively extend the service life of the gas spark switch electrode.

[0040] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A W-Cu-CrNb electrode for a gas spark switch resistant to high-temperature ablation, characterized in that, The electrode is composed of the following elements in atomic percentage: W: 43%-55%, Cu: 8%-15%, Cr: 24.6%-40.4%, Nb: 5.4%-8.6%.

2. The W-Cu-CrNb electrode for a gas spark switch resistant to high-temperature ablation as described in claim 1, characterized in that, The electrode is composed of the following atomic percentages of elements. Composition: W: 48.8%, Cu: 9.5%, Cr: 35.9%, Nb: 5.8%.

3. A method for preparing a high-temperature erosion-resistant W-Cu-CrNb electrode for gas spark switches, characterized in that, Includes the following steps: (1) Take the raw material powder corresponding to each element according to the atomic percentage described in claim 1 or 2; (2) Weigh out the raw material powder containing W, Cu, Cr and Nb elements, mix them together, and then press the mixed powder into a green body; (3) Hot pressing and sintering are performed on the green blank so that Cr and Nb elements react during the sintering process to form the Cr2Nb intermetallic compound. Cr2Nb is distributed at the W-Cu matrix interface. After cooling, a gas spark switch W-Cu-CrNb electrode is obtained.

4. The method for preparing a high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode according to claim 3, characterized in that, The mixing described in step (2) is ball milling mixing; The ball milling mixture has a ball-to-material ratio of 3:1 to 5:1, a rotation speed of 180-250 r / min, and a milling time of 6-10 h. Argon gas is introduced during milling to protect against oxidation.

5. The method for preparing a high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode according to claim 3, characterized in that, In step (2), the pressure for pressing the embryo is 450-600 MPa, and the holding time is 3-6 min.

6. The method for preparing a high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode according to claim 3, characterized in that, The hot pressing sintering in step (3) is performed at a temperature of 1200-1280 ℃ and a pressure of 30-50 MPa for 1.5-2.5 h.

7. The method for preparing a high-temperature erosion-resistant gas spark switch W-Cu-CrNb electrode according to claim 3, characterized in that, The dimensions of the W-Cu-CrNb electrode of the gas spark switch are 15-25 mm × 15-25 mm × 3 mm.

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