Preparation method of surface coating of fuse contact

Abstract

The invention provides a preparation method of a surface coating of a fuse contact. The preparation method comprises the following steps: S1, deoiling and polishing the surface of the fuse contact; s2, performing first cold metal spraying on the surface of the deoiled and polished fuse contact; and S3, performing second cold spraying of metal powder on the surface of the fuse contact after the first cold spraying of metal to obtain a surface coating of the fuse contact. According to the method, a metal electroplating process is changed into a cold spraying surface coating preparation process, the preparation mode is simple, meanwhile, the safety of the process is improved, and the clean production requirement is met.

Description

Technical Field

[0001] The invention belongs to the technical field of cold spraying technology, and in particular relates to a method for preparing a surface coating of a fuse contact. Background Art

[0002] A fuse is an electrical appliance that protects a circuit. When the circuit current is too large due to various reasons such as overload or short circuit, the current thermal effect of the large current is used to heat up and melt the fuse material, thereby achieving the purpose of breaking the circuit and protecting the circuit. Most fuses are equipped with a contact structure. Taking the drop-out fuse as an example, the upper moving contact and the lower moving contact at both ends of the fuse tube of the drop-out fuse rely on the fusing system. After the upper moving contact is pushed into the protruding part of the duckbill, the upper static contact made of phosphor copper sheet and the like presses against the upper moving contact, so that the tube is firmly stuck in the duckbill. The contact is a key component of the drop-out fuse. The contacts should be in close contact, the contact pressure on both sides should be uniform, and the contact surface should be flat and clean. Traditional processes all use direct silver / copper / tin plating processes to give the contacts good performance. The main processes are pre-plating treatment, silver plating and post-plating treatment. The existing silver plating process requires cyanide copper plating and pre-silver plating before silver plating. The process is complicated, and the cyanide copper plating solution contains a large amount of toxic cyanide, which does not meet the requirements of clean production. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a method for preparing the surface coating of a fuse contact, which changes the metal electroplating process into cold spraying to prepare the surface coating. The preparation method is simple and the safety of the process is improved, which meets the requirements of clean production.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a surface coating of a fuse contact, comprising the following steps: S1. Degrease and polish the surface of the fuse contact; S2, performing a first cold spraying of metal on the surface of the degreased and polished fuse contact; S3, performing a second cold spraying of metal powder on the surface of the fuse contact after the first cold spraying of metal, to obtain a surface coating of the fuse contact.

[0005] It should be noted that the present application does not limit the specific methods of degreasing and polishing. For example, degreasing can be performed by using an organic solvent, and polishing can be performed by electrolysis.

[0006] Preferably, in step S2, the first cold-sprayed metal may be copper, copper alloy, stainless steel alloy, silver alloy or aluminum alloy.

[0007] Preferably, in step S2, the thickness of the metal layer obtained by the first cold spraying of the metal is 0.1-500 μm.

[0008] Preferably, in step S3, the metal powder is silver, copper or tin.

[0009] Preferably, in step S3, the particle size of the metal powder in the second cold spraying is 15-70 μm.

[0010] Preferably, the working gas of the first cold spraying and the second cold spraying is at least one of air, nitrogen or helium; and / or, The spraying pressure of the first cold spraying and the second cold spraying is 2.5-7Mpa; and / or, The spraying temperature of the first cold spraying and the second cold spraying is 150-1000° C.; and / or, The gas velocity of the first cold spraying and the second cold spraying is 100-1100 m / s; and / or, The spraying distances of the first cold spraying and the second cold spraying are 20-110 mm.

[0011] Preferably, in step S3, after the surface coating of the fuse contact is obtained, the surface coating is ultrasonically forged by an ultrasonic micro-forging device.

[0012] Preferably, the conditions for ultrasonic forging are: ultrasonic frequency of 20-30KHz and pressure of 600-800N.

[0013] Preferably, in steps S2 and S3, the first cold spraying and the second cold spraying are both performed using cold spraying equipment; the cold spraying equipment is provided with an ultrasonic device, and during the spraying process of the cold spraying equipment, the ultrasonic device starts ultrasound to improve the spraying effect.

[0014] The cold spraying equipment is provided with an ultrasonic device. During the spraying process of the cold spraying equipment, the ultrasonic device activates ultrasound to improve the spraying effect.

[0015] Preferably, the ultrasonic power is 200-500W; and / or, The ultrasonic frequency is 5-10KHz.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention changes the electroplating metal process into a cold spraying process for preparing the surface coating, which simplifies the preparation method and improves the safety of the process, thereby meeting the requirements of clean production.

[0017] (2) In the cold spraying process of the present invention, ultrasonic treatment is used as an aid. Due to the cavitation effect and mechanical action of the ultrasonic wave, the metal powder is evenly distributed on the contact, thereby reducing the roughness of the metal powder on the contact, improving the coating density of the contact and the conductive stability.

[0018] (3) After cold spraying, the surface coating is further ultrasonically forged to further improve the density and conductive stability of the coating. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0020] Example 1 A method for preparing a surface coating of a fuse contact is provided, comprising the following steps: first, the surface of the fuse contact is cleaned with hydrochloric acid to remove oil, and then polished by electrolysis. After polishing, a copper coating is sprayed with a cold spraying device, the coating thickness is 20 μm, and the spraying conditions are as follows: the working gas of the first cold spraying is air, the spraying pressure is 5 MPa; the spraying temperature is 200°C; the gas velocity of the first cold spraying is 500 m / s; and the spraying distance is 50 mm. After spraying, a cold spraying device is used to cold spray a silver coating, the coating thickness is 20 μm, and the spraying conditions are as follows: the working gas of the second cold spraying is air, the spraying pressure is 5 MPa; the spraying temperature is 200°C; the gas velocity of the second cold spraying is 500 m / s; and the spraying distance is 50 mm. The cold spraying device is provided with an ultrasonic device, and during the first cold spraying and the second cold spraying of the cold spraying device, the ultrasonic device starts ultrasound, the ultrasonic power is 200 W, and the ultrasonic frequency is 5 KHz. After the surface coating of the fuse contact is obtained, an ultrasonic micro-forging device is used to perform ultrasonic forging on the surface coating. The ultrasonic forging conditions are: an ultrasonic frequency of 20 KHz and a pressure of 600N.

[0021] Example 2 A method for preparing a surface coating of a fuse contact is provided. The preparation method is the same as that in Example 1, except that the ultrasonic power of the ultrasonic equipment is 300 W, the ultrasonic frequency is 8 KHz, and the ultrasonic forging conditions are as follows: the ultrasonic frequency is 25 KHz, and the pressure is 700 N.

[0022] Example 3 A method for preparing a surface coating of a fuse contact is provided. The preparation method is the same as that in Example 1, except that the ultrasonic power of the ultrasonic equipment is 500 W, the ultrasonic frequency is 10 KHz, and the ultrasonic forging conditions are: the ultrasonic frequency is 30 KHz, and the pressure is 800 N.

[0023] Comparative Example 1 A method for preparing a surface coating of a fuse contact is provided. The preparation method is the same as that in Example 1, except that no ultrasonic equipment is provided, and no ultrasonic step is performed during the first cold spraying and the second cold spraying.

[0024] Comparative Example 2 A method for preparing a surface coating of a fuse contact is provided. The preparation method is the same as that of Example 1, except that no ultrasonic forging equipment is provided, and after the surface coating is obtained, no ultrasonic forging step is performed.

[0025] Comparative Example 3 A method for preparing a surface coating of a fuse contact is provided. The preparation method is the same as that in Example 1, except that after a copper metal layer is formed on the contact by electroplating, metallic silver is plated on the surface of the copper layer using a conventional silver plating process to obtain a surface coating.

[0026] Performance testing and results The average void size and porosity of the surface coatings obtained in Examples 1-3 and Comparative Examples 1-3 were detected in a conventional manner, and the conductive properties of the surface coatings obtained in Examples 1-3 and Comparative Examples 1-3 were tested using a MODEL-800 surface resistance tester. The results are shown in Table 1.

[0027] Table 1

[0028] This application replaces the electroplating metal process by spraying, which has a simple preparation method and improves the safety of the process, meeting the requirements of clean production. Combined with the data in Table 1, it can be seen that during the cold spraying process, ultrasonic treatment is used as an aid. Due to the cavitation effect and mechanical action of the ultrasonic wave, the metal powder is evenly distributed on the contact, thereby reducing the roughness of the metal powder on the contact, and improving the coating density and conductive stability of the contact. After cold spraying, the present invention further ultrasonically forges the surface coating to further improve the coating density and conductive stability.

[0029] Other raw materials or structures not specifically described in the present invention already exist in the prior art and can be directly purchased from the market.

[0030] The above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a surface coating of a fuse contact, characterized in that: The following steps are involved: S1. Degrease and polish the surface of the fuse contact; S2, performing a first cold spraying of metal on the surface of the degreased and polished fuse contact; S3, performing a second cold spraying of metal powder on the surface of the fuse contact after the first cold spraying of metal, to obtain a surface coating of the fuse contact.

2. The method according to claim 1, characterized in that In step S2 , the first cold-sprayed metal may be copper, copper alloy, stainless steel alloy, silver alloy or aluminum alloy.

3. The method according to claim 1, characterized in that In step S2, the first cold sprayed metal obtains a metal layer with a thickness of 0.1-500 μm.

4. The method according to claim 1, characterized in that: In step S3, the metal powder is silver, copper or tin.

5. The method according to claim 1, characterized in that: In step S3, the particle size of the metal powder in the second cold spraying is 15-70 μm.

6. The method according to claim 1, characterized in that The working gas of the first cold spraying and the second cold spraying is at least one of air, nitrogen or helium; and / or, The spraying pressure of the first cold spraying and the second cold spraying is 2.5-7Mpa; and / or, The spraying temperature of the first cold spraying and the second cold spraying is 150-1000° C.; and / or, The gas velocity of the first cold spraying and the second cold spraying is 100-1100 m / s; and / or, The spraying distances of the first cold spraying and the second cold spraying are 20-110 mm.

7. The method according to claim 1, characterized in that In step S3, after the surface coating of the fuse contact is obtained, ultrasonic forging is performed on the surface coating.

8. The method according to claim 7, characterized in that The conditions for ultrasonic forging are: ultrasonic frequency of 20-30KHz and pressure of 600-800N.

9. The method according to claim 8, characterized in that In steps S2 and S3, the first cold spraying and the second cold spraying are both performed using a cold spraying device; the cold spraying device is provided with an ultrasonic device, and during the spraying process of the cold spraying device, the ultrasonic device activates ultrasound to improve the spraying effect.

10. The method according to claim 9, characterized in that The ultrasonic power is 200-500W; and / or, The ultrasonic frequency is 5-10KHz.

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