A copper-chromium contact material for vacuum circuit breakers and a method for producing the same

Abstract

The application discloses a copper-chromium contact material surface alloy film for a vacuum circuit breaker and a preparation method thereof, and belongs to the technical field of contact material surface modification. The preparation method of the copper-chromium contact material surface alloy film for the vacuum circuit breaker is as follows: Cu target, Cr target and Nb target are used as target materials, a CuCrNb alloy film is deposited on a CuCr alloy substrate by adopting a magnetron sputtering method, and a CuCr alloy substrate with the CuCrNb alloy film is obtained; the CuCr alloy substrate with the CuCrNb alloy film is subjected to annealing treatment under inert atmosphere protection, Cu phases on the surface of the CuCrNb alloy film are uniformly distributed during the annealing process, and Cr2Nb phases are generated, and a copper-chromium contact material surface alloy film is obtained. The CuCrNb alloy film prepared by the application improves arc dispersion capacity of a contact surface, stability and voltage resistance strength of a discharge process, and thus improves arc ablation resistance of the contact.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of contact material surface modification, and more particularly to a CuCr contact material surface alloy film for vacuum circuit breaker and a preparation method thereof. BACKGROUND

[0002] As a key component for controlling the on-off of the circuit, the vacuum circuit breaker plays an important role in power distribution network, power generation facilities, substation and many industrial fields. With the development trend of power system towards larger capacity, higher voltage and smaller size, the performance requirements of the contact material are also improved. The core component of the vacuum circuit breaker is the contact, which realizes the on-off of the circuit by controlling its opening and closing. The vacuum arc is generated during the breaking process of the contact, and the transient high temperature of the arc causes serious ablation on the surface of the contact. The ablation damage mode and the ablation morphology of the contact affect its electrical performance and reliability. If the ablation is concentrated in a small area, it will accelerate the failure of the contact material. Therefore, in addition to having high electrical conductivity and thermal conductivity, the contact material should also have good arc dispersion ability to make the arc disperse rapidly on the surface and not cause concentrated ablation.

[0003] The CuCr alloy mainly used in the vacuum circuit breaker has excellent electrical conductivity and thermal conductivity as well as good arc ablation resistance, but with the development of large capacity and high voltage of the power system, the vacuum circuit breaker industry has higher performance requirements for CuCr contact. To further improve the arc ablation resistance of CuCr contact, more precise composition and structure control of the contact is needed, but due to the constraints of the preparation method of the overall CuCr alloy contact material, such as powder mixing sintering, vacuum melting, vacuum infiltration and arc melting, it is difficult to accurately control the composition, phase composition and microstructure distribution of the alloy, only micron-scale structure can be obtained and the distribution is uneven, which cannot obtain good arc dispersion ability and cannot meet the higher requirements for contact reliability and service life. SUMMARY

[0004] In view of the above problems, the present application provides a CuCr contact material surface alloy film for vacuum circuit breaker and a preparation method thereof. The CuCrNb alloy film is plated on the surface of the CuCr alloy substrate, and after annealing treatment, uniform Cu phase and intermetallic compound phase Cr2Nb phase are generated. The CuCrNb alloy film improves the arc dispersion ability of the contact surface, the stability of the discharge process and the voltage resistance, thereby improving the arc ablation resistance of the contact, and solving the problem of poor arc ablation resistance of the existing CuCr contact material due to the coarse and uneven structure.

[0005] The first object of the present application is to provide a preparation method of a CuCr contact material surface alloy film for vacuum circuit breaker, comprising the following steps:

[0006] Cu target, Cr target and Nb target as target material, using magnetron sputtering method on CuCr alloy substrate deposition CuCrNb alloy film, get growth of CuCrNb alloy film of CuCr alloy substrate.

[0007] The CuCrNb alloy film of the CuCr alloy substrate is annealed at 400-850 DEG C under inert atmosphere protection, and the Cu phase of the CuCrNb alloy film surface is uniformly distributed during annealing, and Cr2Nb phase is generated, to obtain a copper chromium contact material surface alloy film.

[0008] For example, the annealing temperature is 400 DEG C, 450 DEG C, 500 DEG C, 550 DEG C, 600 DEG C, 650 DEG C, 700 DEG C, 750 DEG C, 800 DEG C, 850 DEG C, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0009] In a preferred embodiment of the application, the annealing time is 1-8h, for example, the annealing time is 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, but not limited to the listed values, other values not listed in the above value range are also applicable.

[0010] In a preferred embodiment of the application, the annealing temperature is 850 DEG C.

[0011] In a preferred embodiment of the application, the annealing time is 1h.

[0012] In a preferred embodiment of the application, in the magnetron sputtering method, the sputtering current of the Cu target is 3.5-6.5A, for example, the sputtering current of the Cu target is 3.5A, 4A, 4.5A, 5A, 5.5A, 6A, 6.5A, etc.

[0013] The sputtering current of the Cr target is 1.3-7A, for example, the sputtering current of the Cr target is 1.3A, 1.5A, 2A, 2.5A, 3A, 3.5A, 4A, 4.5A, 5A, 5.5A, 6A, 6.5A, 7A, etc.

[0014] The sputtering current of the Nb target material is 6-7A, for example, the sputtering current of the Nb target material is 6A, 6.2A, 6.4A, 6.6A, 6.8A, 7A, etc., but not limited to the listed values, other values not listed in the above value range are also applicable.

[0015] In a preferred embodiment of the present application, the sputtering deposition time is 100 min to 230 min, for example, the sputtering deposition time is 100 min, 130 min, 150 min, 170 min, 190 min, 210 min, 230 min, etc., but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0016] In a preferred embodiment of the present application, the purity of the Cu target, the Cr target and the Nb target is all ≥ 99.9%.

[0017] In a preferred embodiment of the present application, the sputtering gas pressure is 0.2 Pa to 0.3 Pa, for example, the sputtering gas pressure is 0.2 Pa, 0.22 Pa, 0.24 Pa, 0.26 Pa, 0.28 Pa, 0.3 Pa, etc., but is not limited to the listed values, and other values not listed in the above value range are also applicable.

[0018] A second object of the present application is to provide a copper-chromium contact material surface alloy film for a vacuum circuit breaker prepared by the above preparation method.

[0019] In a preferred embodiment of the present application, in the copper-chromium contact material surface alloy film, the atomic percentage of metal elements is: Cu 50% to 55%, Nb 10% to 39%, and the rest is Cr, totaling 100%.

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

[0021] The present application realizes the regulation of Cu and Cr phase solid solution and precipitation state by adjusting the temperature and time of annealing treatment, so that the surface Cu phase is uniformly and dispersedly distributed, and the dispersion performance of the film to the vacuum arc is improved. The present application is to prepare a CuCrNb alloy film on the surface of a CuCr contact substrate by a magnetron sputtering method, and after annealing at 400℃ to 850℃, fine and uniformly distributed Cu particles can be precipitated in the supersaturated solid solution phase. The Cu particles are beneficial to reducing the duration of the arc on the surface and more dispersing, and avoiding the occurrence of concentrated ablation holes. Under the premise of ensuring good conductivity of the contact material, the dispersion ability of the vacuum arc is greatly improved, the occurrence of concentrated ablation is reduced, the vacuum breakdown stability of the contact is improved, and the service life of the contact is prolonged.

[0022] The Cu particles precipitated from the grain to the surface of the copper-chromium contact material surface alloy film prepared by the application are in nanometer scale. Because in the breaking process of the contact, the cathode spot is first formed when the arc is generated, the current path is formed by the electrons emitted from the cathode spot, and then the arc is formed, the size of the cathode spot is about micrometer, which is smaller than the grain size and phase size of the traditional micrometer-scale material, so after the arc is formed, the arc can only burn the phase in the region where the arc is located, and it is easy to cause concentrated ablation and form an erosion pit. The smaller nanometer scale is smaller than the size of the cathode spot, so the Cu phase in the position where the arc is generated cannot maintain the burning of the arc, and the arc can only move to continue burning. Therefore, the advantage of the nanometer-scale film over the traditional bulk alloy is that the arc can move and diffuse on the surface better, and concentrated ablation is not caused.

[0023] The CuCrNb alloy film formed by adding an appropriate amount of Nb to the CuCr binary alloy can form a Cr2Nb phase between Cr and Nb elements after annealing, and the phase has the advantages of high melting point and low work function, which can provide more arc initiation sites for the film, and the generation of the high melting point phase can further improve the voltage resistance strength of the film. The voltage resistance strength of the anti-vacuum arc ablation CuCrNb alloy film prepared by the application is more than 1 times that of the CuCr substrate, the average ablation depth after 10 times of vacuum breakdown is less than 1 / 2 of that of the CuCr substrate, the arc ablation area is 3 times that of the CuCr substrate, and the arc dispersion performance is obviously improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The XRD pattern of the copper-chromium contact material surface alloy film for a vacuum circuit breaker in Example 1.

[0025] Figure 2 The micro-morphology pattern of the copper-chromium contact material surface alloy film for a vacuum circuit breaker in Example 1.

[0026] Figure 3 The EDS energy spectrum composition distribution pattern of the copper-chromium contact material surface alloy film for a vacuum circuit breaker in Example 1, wherein a is the Cu element, b is the Cr element, and c is the Nb element.

[0027] Figure 4 The current value change pattern of the copper-chromium contact material surface alloy film for a vacuum circuit breaker in Example 1 and the CuCr contact substrate in the process of 10 times of vacuum breakdown.

[0028] Figure 5 The voltage resistance strength change pattern of the copper-chromium contact material surface alloy film for a vacuum circuit breaker in Example 1 and the CuCr contact substrate in the process of 10 times of vacuum breakdown.

[0029] Figure 6 is a plot of the current interruption value change of the copper-chromium contact material surface alloy film for vacuum circuit breakers of examples 1-4 during 10 vacuum breakdowns.

[0030] Figure 7 is a plot of the voltage withstand change of the copper-chromium contact material surface alloy film for vacuum circuit breakers of examples 1-4 during 10 vacuum breakdowns.

[0031] Figure 8 is a plot of the results of the copper-chromium contact material surface alloy film for vacuum circuit breakers of example 1 after 10 vacuum breakdowns, wherein a is a morphology plot of the ablation area, and b is a 3D profile plot of the corresponding area in a.

[0032] Figure 9 is a plot of the results of the CuCr50 alloy contact body in the control group after 10 vacuum breakdowns, wherein a is a morphology plot of the ablation area, and b is a 3D profile plot of the corresponding area in a.

[0033] Figure 10 is a plot of the morphology of the ablation area and the 3D profile plot of the corresponding area of the copper-chromium contact material surface alloy film for vacuum circuit breakers of examples 2-4 after 10 vacuum breakdowns, wherein a is a morphology plot of the ablation area in example 2, b is a 3D profile plot of the corresponding area in a, c is a morphology plot of the ablation area in example 3, d is a 3D profile plot of the corresponding area in c, e is a morphology plot of the ablation area in example 4, and f is a 3D profile plot of the corresponding area in e.

[0034] Figure 11 is a micro-morphology plot of the copper-chromium contact material surface alloy film for vacuum circuit breakers of comparative example 1.

[0035] Figure 12 is an EDS energy spectrum composition distribution plot of the copper-chromium contact material surface alloy film for vacuum circuit breakers of comparative example 1, wherein a is the Cu element, b is the Cr element, and c is the Nb element.

[0036] Figure 13 is a plot of the results of the copper-chromium contact material surface alloy film for vacuum circuit breakers of comparative example 1 and the CuCr contact body after 10 vacuum breakdowns, wherein a is a morphology plot of the ablation area, and b is a 3D profile plot of the corresponding area in a.

[0037] Figure 14 is a micro-morphology plot of the copper-chromium contact material surface alloy film for vacuum circuit breakers of comparative example 2.

[0038] Figure 15 is an EDS energy spectrum composition distribution plot of the copper-chromium contact material surface alloy film for vacuum circuit breakers of comparative example 2, wherein a is the Cu element, and b is the Cr element.

[0039] Figure 16 is the result graph of the CuCr contact material surface alloy film for vacuum circuit breaker of Comparative Example 2 after 10 times of vacuum breakdown, wherein a is an ablation area morphology diagram, and b is a 3D profile diagram of the corresponding area in the a diagram. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] The present application adopts the magnetron sputtering technology to realize the regulation of the CuCr film grain, phase composition and structure by adjusting the process parameters. The CuCr film deposited by magnetron sputtering can form a supersaturated solid solution phase, and the precipitation of each phase and the proportion of the solid solution phase in the film can be controlled by combining the annealing treatment, thereby changing the performance of the film. The addition of high-melting-point alloy elements in the CuCr alloy film can improve the high-temperature resistance of the film. If the alloy element has a lower work function, it is easier to emit electrons and improve the dispersibility of arc energy on the surface. The addition of Nb element in the CuCr alloy can inhibit the precipitation and growth of Cu phase, so that a small amount of Cu particles precipitated are uniformly distributed on the contact surface. Annealing in a specific temperature range can form high-melting-point intermetallic compound Cr2Nb, which can further improve the voltage resistance of the contact material and the arc ablation resistance of the film.

[0042] The diffusion of elements depends on the temperature and time of the annealing treatment. At high temperature, metal atoms diffuse fast and easily form large particles by diffusion and precipitation. The time controls the amount of metal precipitation and the growth rate. Therefore, in the annealing process, the time is reduced at high temperature to control the amount of metal precipitation and the degree of growth. Reducing the annealing temperature can slow down the diffusion and reduce the amount of precipitation. Increasing the annealing time at this time can precipitate as much as possible, and the degree of precipitation can be more easily controlled.

[0043] Example 1

[0044] The present embodiment provides a surface alloy film preparation method for a copper-chromium contact material of a vacuum circuit breaker, comprising the following steps:

[0045] 1) Taking CuCr50 alloy as the substrate, polishing, polishing, cleaning and drying the substrate, and then fixing it on the workpiece rack in the vacuum chamber of the coating equipment, and installing each metal target on the target position of the vacuum coating equipment;

[0046] 2) The vacuum chamber of the magnetron sputtering device is evacuated to an air pressure of ≤5x10 -3 Afterwards, argon is introduced into the vacuum chamber to an air pressure of 0.2 Pa, and a -500 V bias is applied to the substrate to clean the substrate surface by glow discharge sputtering for 30 min.

[0047] 3) Argon is introduced into the vacuum chamber of the magnetron sputtering device to an air pressure of 0.2 Pa, and Cu, Cr and Nb targets are sputtered at target currents of 6.5 A, 7.0 A and 7.0 A respectively, and a -60 V bias is applied to the substrate to deposit a CuCrNb alloy film with a thickness of 3.5 μm for 100 min.

[0048] The atomic percentage of the three metals in the prepared film is: Cu 53%, Cr 36%, and Nb 11%.

[0049] 4) The CuCrNb alloy film is annealed at 850 ℃ in a quartz tube under argon protection, and cooled to room temperature after holding for 1 h, to obtain a copper-chromium contact material surface alloy film for vacuum circuit breakers, denoted as CuCrNb-Th-850.

[0050] Example 2

[0051] The embodiment provides a preparation method of a copper-chromium contact material surface alloy film for a vacuum circuit breaker, which comprises the following steps:

[0052] 1) A CuCr50 alloy is used as a substrate, and the substrate is polished, polished, cleaned, dried and fixed on a workpiece holder in a vacuum chamber of a coating device, and metal targets are installed on target positions of the vacuum coating device;

[0053] 2) The vacuum chamber of the magnetron sputtering device is evacuated to an air pressure of ≤5x10 -3 Afterwards, argon is introduced into the vacuum chamber to an air pressure of 0.2 Pa, and a -500 V bias is applied to the substrate to clean the substrate surface by glow discharge sputtering for 30 min.

[0054] 3) Argon is introduced into the vacuum chamber of the magnetron sputtering device to an air pressure of 0.2 Pa, and Cu, Cr and Nb targets are sputtered at target currents of 4.7 A, 3.5 A and 7.0 A respectively, and a -60 V bias is applied to the substrate to deposit a CuCrNb alloy film with a thickness of 2.9 μm for 130 min.

[0055] The atomic percentage of the three metals in the prepared film is: Cu 52%, Cr 26%, and Nb 22%.

[0056] 4) The film is annealed at 650 ℃ in a quartz tube under argon protection, and cooled to room temperature after holding for 8 h, to obtain a copper-chromium contact material surface alloy film for a vacuum circuit breaker.

[0057] Example 3

[0058] The embodiment provides a surface alloy film preparation method of a copper-chromium contact material for a vacuum circuit breaker.

[0059] 1) taking CuCr50 alloy as a substrate, polishing, polishing, cleaning and drying the substrate, and then fixing the substrate on a workpiece rack in a vacuum chamber of a film plating device, and installing each metal target on a target position of the vacuum film plating device;

[0060] 2) after the vacuum chamber of the magnetron sputtering device is vacuumized to an air pressure of less than or equal to 5*10 -3 Pa, argon gas is introduced into the vacuum chamber to make the air pressure 0.2 Pa, a-500V bias is applied to the substrate, and the surface of the substrate is cleaned by glow discharge for 30 min.

[0061] 3) argon gas is introduced into the vacuum chamber of the magnetron sputtering device to make the air pressure 0.2 Pa, Cu, Cr and Nb targets are sputtered at a target current of 4.0 A, 2.0 A and 7.0 A respectively, a-60V bias is applied to the substrate, and a CuCrNb alloy film with a thickness of 2.5 μm is obtained after deposition for 200 min;

[0062] The atomic percentage of the three metals in the prepared film is: Cu 51%, Cr 18%, and Nb 31%.

[0063] 4) the above film is annealed at 700 DEG C in an argon-protected quartz tube, and after heat preservation for 4 hours, the film is cooled to room temperature with the furnace, and a surface alloy film of a copper-chromium contact material for a vacuum circuit breaker is obtained.

[0064] Example 4

[0065] The embodiment provides a surface alloy film preparation method of a copper-chromium contact material for a vacuum circuit breaker.

[0066] 1) taking CuCr50 alloy as a substrate, polishing, polishing, cleaning and drying the substrate, and then fixing the substrate on a workpiece rack in a vacuum chamber of a film plating device, and installing each metal target on a target position of the vacuum film plating device;

[0067] 2) after the vacuum chamber of the magnetron sputtering device is vacuumized to an air pressure of less than or equal to 5*10 -3 Pa, argon gas is introduced into the vacuum chamber to make the air pressure 0.2 Pa, a-500V bias is applied to the substrate, and the surface of the substrate is cleaned by glow discharge for 30 min.

[0068] 3) The argon gas is introduced into the vacuum chamber of the magnetron sputtering device to make the gas pressure 0.2 Pa, the Cu, Cr and Nb targets are sputtered with the target current of 3.5 A, 1.3 A and 7.0 A respectively, and the -60 V bias is applied to the substrate, and the deposition time is 230 min to obtain the CuCrNb alloy film with the thickness of 2.7 μm;

[0069] The atomic percentage of the three metals in the prepared film is: Cu 50%, Cr 11%, and Nb 39%.

[0070] 4) The film is annealed at 700 ℃ in the argon-protected quartz tube, and the vacuum circuit breaker copper-chromium contact material surface alloy film is obtained after the heat preservation for 1 hour and the furnace cooling to room temperature.

[0071] Example 5

[0072] The copper-chromium contact material surface alloy film preparation method for the vacuum circuit breaker provided in the embodiment comprises the following steps:

[0073] 1) The CuCr50 alloy is used as the substrate, the substrate is polished, polished, cleaned, dried and fixed on the workpiece holder in the vacuum chamber of the film plating device, and the metal targets are installed on the target position of the vacuum film plating device;

[0074] 2) After the vacuum chamber of the magnetron sputtering device is vacuumized to the gas pressure ≤5×10 -3 Pa, the argon gas is introduced into the vacuum chamber to make the gas pressure 0.2 Pa, and the -500 V bias is applied to the substrate, and the substrate surface is cleaned by glow discharge for 30 min.

[0075] 3) The argon gas is introduced into the vacuum chamber of the magnetron sputtering device to make the gas pressure 0.3 Pa, the Cu, Cr and Nb targets are sputtered with the target current of 3.5 A, 1.3 A and 6 A respectively, and the -60 V bias is applied to the substrate, and the deposition time is 230 min to obtain the CuCrNb alloy film;

[0076] 4) The film is annealed at 400 ℃ in the argon-protected quartz tube, and the vacuum circuit breaker copper-chromium contact material surface alloy film is obtained after the heat preservation for 6 hours and the furnace cooling to room temperature.

[0077] Example 6

[0078] The copper-chromium contact material surface alloy film preparation method for the vacuum circuit breaker provided in the embodiment comprises the following steps:

[0079] 1) The CuCr50 alloy is used as the substrate, the substrate is polished, polished, cleaned, dried and fixed on the workpiece holder in the vacuum chamber of the film plating device, and the metal targets are installed on the target position of the vacuum film plating device;

[0080] 2) The vacuum chamber of the magnetron sputtering equipment is vacuumized to an air pressure of ≤5x10 -3 Afterwards, argon is introduced into the vacuum chamber to make the air pressure 0.2 Pa, and a -500 V bias is applied to the substrate to clean the substrate surface by glow sputtering for 30 min.

[0081] 3) Argon is introduced into the vacuum chamber of the magnetron sputtering equipment to make the air pressure 0.25 Pa, and Cu, Cr and Nb targets are sputtered at target currents of 5 A, 3 A and 6.5 A respectively, and a -60 V bias is applied to the substrate to deposit CuCrNb alloy thin film for 230 min;

[0082] 4) The above thin film is annealed at 500 ℃ in a quartz tube under argon protection, and after heat preservation for 5 hours, the furnace is cooled to room temperature to obtain a CuCr contact material surface alloy thin film for vacuum circuit breaker.

[0083] Comparative Example 1

[0084] 1) The CuCr50 alloy is used as the substrate, and the substrate is polished, polished, cleaned, dried and fixed on the workpiece holder in the vacuum chamber of the coating equipment, and the metal targets are installed on the target position of the vacuum coating equipment;

[0085] 2) The vacuum chamber of the magnetron sputtering equipment is vacuumized to an air pressure of ≤5x10 -3 Afterwards, argon is introduced into the vacuum chamber to make the air pressure 0.2 Pa, and a -500 V bias is applied to the substrate to clean the substrate surface by glow sputtering for 30 min.

[0086] 3) Argon is introduced into the vacuum chamber of the magnetron sputtering equipment to make the air pressure 0.2 Pa, and Cu, Cr and Nb targets are sputtered at target currents of 6.5 A, 7.0 A and 7.0 A respectively, and a -60 V bias is applied to the substrate to deposit CuCrNb alloy thin film with a thickness of 3.5 μm for 100 min;

[0087] The atomic percentage of the three metals in the prepared thin film is: Cu 53%, Cr 36%, and Nb 11%.

[0088] 4) The above CuCrNb alloy thin film is annealed at 900 ℃ in a quartz tube under argon protection, and after heat preservation for 1 hour, the furnace is cooled to room temperature to obtain a CuCr contact material surface alloy thin film for vacuum circuit breaker, which is recorded as CuCrNb-Th-900.

[0089] Comparative Example 2

[0090] 1) The CuCr50 alloy is used as the substrate, and the substrate is polished, polished, cleaned, dried and fixed on the workpiece holder in the vacuum chamber of the coating equipment, and the metal targets are installed on the target position of the vacuum coating equipment;

[0091] 2) The vacuum chamber of the magnetron sputtering device was evacuated to an air pressure of ≤5x10 -3 Afterwards, argon was introduced into the vacuum chamber to an air pressure of 0.2 Pa, and a -500 V bias was applied to the substrate, and the substrate surface was cleaned by glow sputtering for 30 min.

[0092] 3) Argon was introduced into the vacuum chamber of the magnetron sputtering device to an air pressure of 0.2 Pa, and the Cu target and the Cr target were sputtered at a target current of 5.7 A and 7.0 A respectively, and a -60 V bias was applied to the substrate, and the deposition time was 70 min to obtain a CuCr alloy thin film with a thickness of 2.5 μm;

[0093] The atomic percentage of the three metals in the prepared thin film was: Cu 51%, Cr 49%.

[0094] 4) The CuCr alloy thin film was annealed at 850 ℃ in an argon-protected quartz tube, and after 1 hour of heat preservation, the furnace was cooled to room temperature, and a copper-chromium contact material surface alloy thin film for a vacuum circuit breaker was obtained, which was recorded as CuCr-Th-850.

[0095] Figure 1 The XRD of the CuCrNb-Th-850 alloy thin film after annealing treatment of Example 1 can be seen that after annealing treatment, the CuCrNb-Th-850 alloy thin film is mainly composed of Cu and Cr phases, and because of the presence of Nb element, Cr2Nb phase appears after annealing.

[0096] Figure 2 The micro-morphology of the CuCrNb-Th-850 alloy thin film prepared in Example 1 can be seen that after annealing treatment, the CuCrNb alloy thin film has fine and dispersed Cu particles precipitated on the surface. The surface composition distribution of the CuCrNb-Th-850 alloy thin film obtained by EDS energy spectrum test is shown in Figure 3 The element distribution in the CuCrNb-Th-850 alloy thin film is uniform, and there is no obvious element segregation area.

[0097] The electrical breakdown experiment was carried out according to the following operation steps:

[0098] 1) The sample prepared in the example was fixed on the breakdown sample stage in the vacuum electrical breakdown device, and the distance between the tungsten needle and the sample stage was adjusted to the appropriate position;

[0099] 2) The vacuum chamber of the vacuum electrical breakdown device was evacuated to an air pressure of ≤6x10 -4 Pa, and then the voltage was adjusted to 10 kV, and the distance between the sample stage and the tungsten needle was shortened until breakdown occurred;

[0100] 3) After the above operation was repeated for 10 times, the sample was taken out, and the surface morphology and area profile of the ablation position were observed,

[0101] CuCr50 alloy was polished, polished, cleaned, dried and then subjected to electrical breakdown test, as a control group, denoted as CK group.

[0102] CuCr50 alloy plated with CuCrNb-Th-850 alloy thin film of Example 1 was subjected to 10 times of vacuum electrical breakdown test, and the current interruption value change in vacuum electrical breakdown is shown in Figure 4 The current interruption value of CuCrNb alloy thin film is stable at 1~2A, while the current interruption value of CuCr substrate gradually increases from 6A to 8A in 10 times of breakdown, so compared with CuCr material without CuCrNb-Th-850 alloy thin film in CK group, CuCrNb-Th-850 alloy thin film can significantly reduce the breakdown current interruption value and enhance the stability of arc discharge process.

[0103] Figure 5 The voltage strength change of CuCr alloy in CK group and CuCrNb-Th-850 alloy thin film containing CuCr alloy in 10 times of vacuum electrical breakdown is shown in Table 2. 7 V·m -1 , and is stable at 10×10 7 V·m -1 , while the voltage strength of CuCr alloy in CK group is the highest at 6.5×10 7 V·m -1 , and gradually decreases to 4.8×10 7 V·m -1 during 10 times of breakdown, it can be seen that CuCrNb-Th-850 alloy thin film has higher voltage strength.

[0104] Figure 8 and Figure 9 are the ablation area morphology and 3D profile of the corresponding area of CuCr50 alloy contact containing CuCrNb-Th-850 alloy thin film prepared in Example 1 and CuCr50 alloy contact in CK group after 10 times of vacuum electrical breakdown. After 10 times of breakdown, the breakdown depth of CuCrNb-Th-850 alloy thin film is about 36μm, which is obviously shallower than that of CuCr alloy in CK group, and the ablation area of CuCrNb-Th-850 alloy thin film is larger, about 3 times of that of CuCr substrate, which shows that CuCrNb-Th-850 alloy thin film is beneficial to the dispersion of arc on the surface of contact substrate.

[0105] The copper-chromium contact material surface alloy thin film of vacuum circuit breaker in Examples 1~4 was subjected to 10 times of vacuum electrical breakdown test, and the current interruption value change in vacuum breakdown is shown in Figure 6The current interruption value in 10 breakdowns is below 3 A, and the current interruption value of CuCrNb film in Example 1 and Example 2 is the most stable, which indicates that the CuCrNb film in the example is stable in the discharge process in the breakdown, and the current interruption value gradually increases with the increase of the Nb addition amount.

[0106] Figure 7 The voltage resistance strength of the copper-chromium contact material surface alloy film for vacuum circuit breaker in Examples 1 to 4 changes in 10 vacuum electric breakdowns. The voltage resistance strength is maintained above 7 A in 10 breakdowns, and does not obviously decrease with the increase of the breakdown times, which indicates that the copper-chromium contact material surface alloy film for vacuum circuit breaker is not failed in multiple breakdowns. The voltage resistance strength of the CuCrNb-Th-850 alloy film in Example 1 is stably maintained at 11 x 10 7 V·m -1 , and the voltage resistance strength slightly decreases with the addition of Nb. This is because the Cu particles precipitated on the surface are uniform and fine. On the one hand, the arc can quickly spread on the surface of the contact base after the arc appears, which can quickly disperse and consume the energy of the arc, evenly dispersing the energy to multiple positions on the surface, so that concentrated ablation does not occur at a certain point. This can be seen from the surface ablation area expansion and shallow ablation depth of Figure 8 , on the other hand, the arc extinction time can be prolonged, which can be seen from the low current interruption value in the current interruption value curve of Figure 6 , which indicates that the discharge is stable in the arc extinguishing process.

[0107] Figure 10 The ablation area morphology and the 3D profile of the corresponding area of the copper-chromium contact material surface alloy film for vacuum circuit breaker in Examples 2 to 4 after 10 vacuum electric breakdowns are shown in the drawings. In the breakdown process, the arc is diffused on the surface, and there is no phenomenon of concentrated ablation. By comparing the range of the ablation area, the ablation area of the CuCrNb-Th-850 alloy film in Example 1 is the largest, and the average ablation depth is about 36 μm, which has the best arc diffusion performance in Examples 1 to 4.

[0108] Figure 11 The micro-morphology of the CuCrNb-Th-900 alloy film prepared in Comparative Example 1 is shown in the drawings. It can be seen that after the CuCrNb alloy film is annealed at this temperature, large Cu particles are precipitated on the surface, and the Cu particles have grown significantly, and their distribution and size are uncontrollable. The surface composition distribution of the CuCrNb-Th-900 alloy film obtained by EDS energy spectrum test is shown in Figure 12 , and the Cu element distribution in the CuCrNb-Th-900 alloy film is obviously segregated, and Cu is distributed on a large area of the surface, which is consistent with the morphology.

[0109] Figure 13is the ablation area morphology and the corresponding 3D profile of CuCr50 alloy contact after 10 times of vacuum electrical breakdown of CuCr-Th-850 alloy film prepared by Comparative Example 1. After 10 times of breakdown, the breakdown depth of CuCr-Th-850 alloy film is about 55 μm, which is significantly deeper than that of CuCrNb-Th-850 alloy film in Example 1, and the obvious visible concentrated ablation area has appeared, which shows that the CuCrNb-Th-850 alloy film with Nb element can better control the uniform and fine distribution of Cu particles on the surface at high temperature, which is conducive to the dispersion of arc on the contact substrate surface, while the growth and uneven distribution of Cu particles in CuCr film without Nb element can lead to the concentration of arc ablation, which cannot achieve good arc dispersion effect.

[0110] Figure 14 The micro-morphology of CuCr-Th-850 alloy film prepared for Comparative Example 2 can be seen that after annealing treatment at the working temperature, the CuCr alloy film without adding Nb element has large Cu particles precipitated and grown on the surface, and the distribution is extremely uneven, which is uncontrollable at this temperature, so the CuCr alloy film without adding Nb element cannot withstand the welding treatment of the contact. The surface composition distribution of CuCr-Th-850 alloy film obtained by EDS energy spectrum test is shown in Figure 15 , and the Cu element distribution in CuCr-Th-850 alloy film appears obvious segregation, and Cu is distributed on a large area of the surface, which is consistent with the morphology.

[0111] Figure 16 is the ablation area morphology and the corresponding 3D profile of CuCr50 alloy contact after 10 times of vacuum electrical breakdown of CuCr-Th-850 alloy film prepared by Comparative Example 1. After 10 times of breakdown, the breakdown depth of CuCr-Th-850 alloy film is about 55 μm, which is significantly deeper than that of CuCrNb-Th-850 alloy film in Example 1, and the obvious visible concentrated ablation area has appeared, which shows that the CuCrNb-Th-850 alloy film with Nb element can better control the uniform and fine distribution of Cu particles on the surface at high temperature, which is conducive to the dispersion of arc on the contact substrate surface, while the growth and uneven distribution of Cu particles in CuCr film without Nb element can lead to the concentration of arc ablation, which cannot achieve good arc dispersion effect.

[0112] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to cover all changes and modifications falling within the scope of the present application.

[0113] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for preparing a copper-chromium contact material surface alloy film for a vacuum circuit breaker, characterized in that: The following steps are involved: Cu, Cr, and Nb targets were used as target materials and a CuCrNb alloy thin film was deposited on a CuCr alloy substrate by magnetron sputtering to obtain a CuCr alloy substrate with a CuCrNb alloy thin film grown thereon. In the magnetron sputtering method, the sputtering current of the Cu target was 3.5A-6.5A, the sputtering current of the Cr target was 1.3A-7A, and the sputtering current of the Nb target was 6A-7A. The sputtering deposition time was 100min-230min and the sputtering gas pressure was 0.2Pa-0.3Pa. The CuCr alloy substrate on which the CuCrNb alloy film is grown is annealed at 400°C to 850°C for 1 to 8 hours under inert atmosphere. During the annealing process, the Cu phase on the surface of the CuCrNb alloy film is uniformly distributed, and a Cr2Nb phase is generated, thereby obtaining a copper-chromium contact material surface alloy film. In the alloy film on the surface of the copper-chromium contact material, the atomic percentage of metal elements is: Cu 50%~55%, Nb 10%~35%, and the rest is Cr, which is 100% in total.

2. The method for preparing a copper-chromium contact material surface alloy film for a vacuum circuit breaker according to claim 1, characterized in that: The annealing temperature is 850°C.

3. The method for preparing a copper-chromium contact material surface alloy film for a vacuum circuit breaker according to claim 2, characterized in that: The annealing time is 1 h.

4. The method for preparing a copper-chromium contact material surface alloy film for a vacuum circuit breaker according to claim 1, characterized in that: The purity of Cu target, Cr target and Nb target are all ≥99.9%.

5. A copper-chromium contact material surface alloy film for vacuum circuit breaker prepared by the preparation method according to any one of claims 1 to 4.

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