Silver tin oxide electric contact material and manufacturing method thereof

Abstract

The invention belongs to the field of electrical material manufacturing, and particularly relates to a silver tin oxide electrical contact material and a manufacturing method thereof. The manufacturing method comprises the following steps: firstly, crushing alloy liquid into fine liquid drops by using a water atomization method, then preparing silver-tin powder by using an ultrasonic atomization method, and then carrying out oxidation, sintering, hot extrusion, drawing and other procedures to obtain the silver tin oxide electric contact material. Water atomization and ultrasonic atomization are combined, silver-tin powder which is more uniform and narrow in particle size distribution compared with silver-tin powder obtained through a traditional water atomization method is obtained, the prepared material has better ductility and toughness, and in other words, the processability of the material is better than that of a traditional atomization process. Furthermore, a flow converter is used for oxidizing the powder, the temperature in the furnace is uniformly distributed due to flowing of bed materials, and the oxidation efficiency is improved. The silver tin oxide material prepared by the method has the advantages that the uniformity of the silver tin oxide material is obviously improved, excellent processing performance and higher stability are shown, and the prepared rivet-type contact shows better electrical life under alternating current and direct current conditions.

Description

Technical Field

[0001] The invention belongs to the field of electrical material manufacturing, and in particular relates to a silver tin oxide electrical contact material and a manufacturing method thereof. Background Art

[0002] Silver tin oxide (AgSnO2) is an important material in electrical contacts. Due to its excellent conductivity and resistance to arc erosion, it is widely used in low-voltage electrical equipment and circuit breakers. Compared to traditional silver cadmium oxide (AgCdO), silver tin oxide (AgSnO2) is non-toxic and environmentally friendly, making it an ideal alternative to silver cadmium oxide (AgCdO).

[0003] Currently, the main methods for preparing AgSnO2 are internal oxidation of alloys and powder metallurgy. The oxidation depth of electrical contact materials produced using the internal oxidation method is limited, making it impossible to produce materials with high SnO2 content. The SnO2 powder of electrical contact materials produced using the powder metallurgy method is unevenly dispersed, resulting in fluctuations in material properties. The electrical contact materials produced by the above processes all have poor composition uniformity, which makes the wire easily break during processing, affects the material yield, and causes failure when the contacts are in service, reducing the material's performance and increasing costs.

[0004] The applicant's prior patent CN201210439786.8 discloses a method for preparing a silver tin oxide material, which includes the following steps: (1) preparing raw materials; the raw materials are base materials or a mixture of base materials and additives; (2) subjecting the raw materials to medium frequency melting and oxidation treatment while water atomizing to obtain alloy powder; (3) drying and screening the alloy powder, and isostatically pressing to form an isostatically pressed ingot; (4) sintering the isostatically pressed ingot in a hydrogen heating furnace, and hot extruding the sintered ingot to extrude a sheet or wire of silver tin oxide material. The traditional water atomization method is a process in which a high-pressure water flow impacts a metal melt, causing it to break up and rapidly solidify into fine metal powder. Finally, the material is formed into an electrical contact material through isostatic pressing, hot extrusion, and drawing. Since the powder particle size distribution obtained by the traditional water atomization process varies greatly, it affects the consistency of the product. Therefore, it is necessary to improve the existing electrical contact material manufacturing process.

[0005] An ultrasonic atomizer typically consists of core components such as an ultrasonic generator and an ultrasonic transducer. The ultrasonic generator generates high-frequency vibrations, which are transmitted to an ultrasonic transducer in contact with the molten metal. The ultrasonic transducer converts electrical energy into mechanical energy, generating ultrasonic waves in the molten metal. When ultrasonic waves propagate through the molten metal, they cause pressure changes within the liquid, forming localized low-pressure areas that cause the liquid to evaporate and form bubbles, a phenomenon known as cavitation. These bubbles rapidly grow and burst during the subsequent vibration process, generating a powerful impact force that breaks the molten metal into tiny droplets, which then form metal particles upon cooling. Ultrasonic atomization produces particles with a relatively regular, mostly spherical shape and a narrow particle size distribution, enabling the production of metal particles with a uniform particle size. Preparing metal powders through ultrasonic atomization can theoretically improve the poor compositional uniformity of silver tin oxide electrical contact materials. However, the relatively low production efficiency of ultrasonic atomization makes it unsuitable for large-scale industrial production, and as a result, ultrasonic atomization is rarely used in industry. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a silver tin oxide electrical contact material and a method for making the same.

[0007] The technical solution adopted by the present invention is as follows: A method for manufacturing a silver tin oxide electrical contact material, which comprises the following steps:

[0008] (1) Preparation of silver-tin powder: silver plate, tin plate and additives are melted into liquid metal, the liquid metal is initially atomized by water atomization, and the liquid metal is broken into droplets by a high-pressure water flow with a water pressure of 10-50 MPa; the droplets formed by the water atomization method are introduced into an ultrasonic atomization device through a N2 gas protection channel at a temperature of 1000-1200°C, and the droplets are broken into nano-sized droplets by high-frequency ultrasonic vibration with a frequency of 20 kHz-2 MHz to obtain silver-tin powder;

[0009] (2) Powder drying and screening: removing moisture from the powder obtained in step (1) by drying to obtain dry powder;

[0010] (3) Fluidized bed furnace powder oxidation: using a fluidized bed oxidation furnace to oxidize the powder obtained in step (2) to obtain silver tin oxide powder;

[0011] (4) Isostatic pressing: using a cold isostatic press to press the silver tin oxide powder obtained in step (3) into an ingot;

[0012] (5) Sintering: Sintering the ingot obtained in step (4) using a sintering device;

[0013] (6) Extrusion: The sintered AgSnO2 ingot is heated and then formed into a sheet or wire using an extruder.

[0014] Furthermore, the mass ratio of silver, tin and additives ranges from 85:10:5 to 85:12:3. The additives can be various additives currently known to be used in silver tin oxide contact materials, and can be one or more of indium, copper, antimony, zinc, bismuth, nickel, lanthanum, yttrium, cerium, tungsten, titanium and oxides of the above metals.

[0015] Furthermore, in step (2), the drying temperature is 100-300°C.

[0016] Furthermore, in step (2), the dried powder is sieved using a 400-mesh sieve.

[0017] Furthermore, in step (3), the fluidized bed oxidation temperature is 300-800°C, the oxidation time is 3-8h, and the gas flow rate is 0.1-0.5m / s;

[0018] Furthermore, in step (4), the pressing pressure is 20-200 MPa.

[0019] Furthermore, in step (5), the sintering temperature is 200-600°C.

[0020] Furthermore, in step (6), the heating temperature is 700-900° C., and the heating time is 3-6 hours.

[0021] The silver tin oxide electrical contact material is prepared by the method for preparing the silver tin oxide electrical contact material as described above.

[0022] The beneficial effects of the present invention are as follows: The present invention uses a combination of water atomization and ultrasonic atomization to prepare silver-tin powder, and the resulting silver-tin powder has a uniform tissue distribution and no significant difference in particle size. Simultaneously, a fluidized bed furnace is used to oxidize the powder, which accelerates the oxidation process and shortens the oxidation time. The electrical contact material prepared using the process of the present invention has a uniform tissue distribution. When observed under a 100x optical microscope, no oxide aggregation is observed within the field of view. The material has good processing performance, and the prepared electrical contact material has a lifespan of more than 100,000 times under certain current conditions, and has good resistance to welding and burning. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be described in further detail below.

[0024] Example 1:

[0025] A method for manufacturing a silver tin oxide electrical contact material comprises the following steps:

[0026] (1) Preparation of silver-tin powder: Silver, tin and indium are mixed in a ratio of 85:10:5. Silver plates, tin plates and indium ingots are melted into liquid metal, and the liquid metal is initially atomized using water atomization. The liquid metal is broken into droplets with larger particle sizes by high-pressure water flow. The droplets formed by the water atomization method are introduced into the ultrasonic atomization device through an N2 gas protection channel at a temperature of 1000-1200°C, and the droplets are broken into nano-sized droplets by high-frequency ultrasonic vibration. The water pressure used in the water atomization method is 30MPa, the temperature of the N2 gas protection channel is 1050°C, and the frequency used in the ultrasonic atomization method is 50kHz;

[0027] (2) Powder drying and screening: Use an oven or other drying equipment to remove moisture from the powder obtained in step (1) to obtain dry powder, and use a 400-mesh sieve to sieve the powder, and treat the sieve-surface material as scrap material. The drying temperature is 150° C. and the drying time is 3 h.

[0028] (3) Fluidized bed furnace powder oxidation: The powder obtained in step (2) is oxidized in a fluidized bed oxidation furnace to obtain silver tin oxide powder. The oxidation temperature is 750°C, the oxidation time is 4 hours, and the gas flow rate is 0.3 m / s;

[0029] (4) Isostatic Pressing: The silver tin oxide powder obtained in step (3) is pressed into an ingot using a cold isostatic press at a pressure of 150 MPa.

[0030] (5) Sintering: Sintering the ingot obtained in step (4) using a sintering device, wherein the sintering temperature is 600° C.;

[0031] (6) Extrusion: The sintered AgSnO2 ingot is heated at 800°C for 4 hours and then formed into a Φ5 mm wire using an extruder;

[0032] (7) Drawing: According to the drawing process, the Φ5 mm wire is drawn into a Φ1.6 mm wire by a medium frequency wire drawing machine.

[0033] Example 2:

[0034] The difference from Example 1 is that the input ratio is different. The input formula ratio is 85:11:4 for silver, tin and indium.

[0035] Example 3:

[0036] The difference from Example 1 and Example 2 is that the input raw material content is different, and the input formula ratio is 85:12:3 of silver, tin and indium.

[0037] Comparative Example 1:

[0038] The same amount of raw materials as in Example 1 was used to prepare an electrical contact material using the method disclosed in CN201210439786.8.

[0039] Using the above method, AgSnO2 / Cu rivet contacts were fabricated and subjected to simulated electrical performance experiments. The experimental conditions were as follows: 220VAC, 15A, closing force 100g, breaking force 70g, and contact frequency 70 times / minute; and 24VDC, 5A, closing force 100g, breaking force 60g, and contact frequency 70 times / minute. The experimental results are shown in Table 1.

[0040] Table 1 Parameter settings and test results of different embodiments and comparative examples

[0041]

[0042] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a silver tin oxide electrical contact material, characterized in that The steps are as follows: (1) Preparation of silver-tin powder: silver plate, tin plate and additives are melted into liquid metal, the liquid metal is initially atomized by water atomization, the liquid metal is broken into droplets by a high-pressure water flow with a water pressure of 10-50 MPa, the droplets formed by the water atomization method are introduced into an ultrasonic atomization device through a N2 gas protection channel at a temperature of 1000-1200°C, and the droplets are broken into nano-sized droplets by high-frequency ultrasonic vibration with a frequency of 20 kHz-2 MHz to obtain silver-tin powder; (2) Powder drying and screening: removing moisture from the powder obtained in step (1) by drying to obtain dry powder; (3) Fluidized bed furnace powder oxidation: using a fluidized bed oxidation furnace to oxidize the powder obtained in step (2) to obtain silver tin oxide powder; (4) Isostatic pressing: using a cold isostatic press to press the silver tin oxide powder obtained in step (3) into an ingot; (5) Sintering: Sintering the ingot obtained in step (4) using a sintering device; (6) Extrusion: The sintered AgSnO2 ingot is heated and then formed into a sheet or wire using an extruder.

2. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: The mass ratio of silver, tin and additives ranges from 85:10:5 to 85:12:

3.

3. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (2), the temperature used for drying is 100-300°C.

4. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (2), the dried powder is sieved using a 400-mesh sieve.

5. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (3), the fluidized bed oxidation temperature is 300-800° C., the oxidation time is 3-8 h, and the gas flow rate is 0.1-0.5 m / s.

6. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (4), the pressing pressure is 20-200 MPa.

7. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (5), the sintering temperature is 200-600°C.

8. The method for manufacturing the silver tin oxide electrical contact material according to claim 1, wherein: In step (6), the heating temperature is 700-900° C., and the heating time is 3-6 hours. 9 . The silver tin oxide electrical contact material prepared by the method for preparing the silver tin oxide electrical contact material according to claim 1 .

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