A method for preparing a silver-nickel-iron oxide electrical contact material

Abstract

The present application belongs to the field of electrical metal-based composite contact material, and particularly relates to a preparation method of silver-nickel-iron oxide electrical contact material. The present application uses fiber nickel and granular iron oxide to enhance the wear resistance and welding performance of the material, and silver is used to ensure that the contact material has good electrical conductivity. The third phase of iron oxide is added by a chemical deposition method to improve the large current welding performance and wear resistance of the material. The traditional powder mixing process is used to add the reinforcing phase of iron oxide particles, which are coarse and agglomerated. The coarse particles have low hardness and are easy to burn, which can cause large local contact resistance. The material of the present application has good ductility and electrical conductivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrical metal-based composite contact materials, and particularly relates to a preparation method of a silver-nickel-iron oxide electrical contact material. BACKGROUND

[0002] New energy technology is undergoing rapid changes, and energy consumption patterns with intelligent features, such as smart homes, white goods and new energy, are being recognized. The original household power relays not only bear the service conditions under resistive load conditions, but also better bear inductive loads and capacitive loads with large surges, such as the popular use of LED light cold light sources, so that the contacts exist continuous arc corrosion during service or a transient current of hundreds of amperes during service. Moreover, with the integration of control circuits, the current carried by some electrical appliances has also increased significantly, from the original 5A, 10A to 16A, 25A or even higher. The conventional silver-nickel material can fully meet the service life requirements under the service conditions of 5A and 10A resistive load conditions, but as the load type and current level increase, the original AgNi10, AgNi15, AgNi20 and AgNi30 are prone to bonding or fast burning under a large surge current, resulting in a non-conduction phenomenon.

[0003] AgMeO (silver metal oxide) has good resistance to welding, but it can appear to be a working surface bulge under plastic encapsulation conditions, and the contacts can appear mechanical bonding during closing and opening, continuous arc during the gap process, leading to bonding failure, and even the risk of burning other structures. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide a preparation method of a silver-nickel-iron oxide electrical contact material.

[0005] The technical scheme adopted by the present application is as follows: a preparation method of a silver-nickel-iron oxide electrical contact material, the mass component composition of the silver-nickel-iron oxide electrical contact material comprising:

[0006] Ag 80-88 mass parts;

[0007] Ni 6-18 mass parts;

[0008] Fe2O3 1-5 mass parts;

[0009] the balance being additives;

[0010] The method comprises the following steps:

[0011] (1) preparing a nitrate mixed solution, the nitrate mixed solution containing silver nitrate and iron nitrate;

[0012] (2) Put the nitrate mixture obtained in step (1) into the sodium carbonate solution reactor, and react while stirring. After the reaction is completed, stand still to obtain a precipitate, and wash the precipitate until the solution is neutral;

[0013] (3) Put the deposit in step (2) into a container, dry it first, and then calcine it at 700-800°C to obtain AgFe2O3 powder;

[0014] (4) Mix the AgFe2O3 powder obtained in step (3) with the remaining Ag powder, Ni powder, and additives uniformly by a high-speed powder mixer to obtain a uniform composite powder;

[0015] (5) After the uniform composite powder obtained in step (4) is completed by rapid plasma electric spark, a dense silver-nickel-iron oxide ingot is obtained;

[0016] (6) The silver-nickel-iron oxide ingot obtained in step (5) is extruded into a wire or sheet to obtain a silver-nickel-iron oxide contact material.

[0017] Preferably, in step (1), Ag and Fe are dissolved in 0.1-0.3 mol / L nitric acid to obtain silver nitrate and iron nitrate solutions, which are mixed together to obtain a nitrate mixture. In step (2), the sodium carbonate solution is 0.3-0.5 mol / L.

[0018] Preferably, in step (3), the AgFe2O3 powder obtained has a mass content of Ag of 50%-60%, and the remaining amount is Fe2O3 powder. The amount of Ag and Fe in step (1) is calculated based on the content of the intermediate product AgFe2O3 powder.

[0019] Preferably, in step (2), the nitrate mixture is transferred into the sodium carbonate solution within 2 minutes. After the mixed nitrate is completely transferred into the reactor, stirring is performed for 5-10 minutes at a stirring speed of 200-350 rpm.

[0020] Preferably, in step (4), the Ag powder has a particle size in the range of 100-350 mesh, the nickel particles range from 2 μm to 8 μm, and the additive particles range from 2 μm to 8 μm.

[0021] Preferably, in step (4), the additive composition can be one or both of the following:

[0022] Fe: 0-1 parts by mass; In2O3: 0-0.5 parts by mass.

[0023] Preferably, in step (5), the uniformly mixed powder is transferred into a discharge plasma device for pressing and sintering. The ingot has a diameter of 80-120 cm, a pressure of 500-2000 kN, and a time of 10-15 minutes.

[0024] Preferably, in step (6), the silver-nickel-iron oxide ingot obtained in step (5) is extruded into a wire with a diameter of 5mm-8mm in a temperature 750-830C holding furnace, and processed into a contact with a desired shape and specification.

[0025] The beneficial effects of the present application are as follows: the present application uses fiber nickel and particle iron oxide to enhance the wear resistance and welding performance of the material, and silver is used to ensure that the contact material has good electrical conductivity. The third phase is a fine particle iron oxide enhanced phase obtained by chemical deposition method, which has a melting point temperature of 1539C, a high melting point temperature, and improves the problem that nickel is easy to soften at low temperature, improves the large current welding performance and wear resistance of the material, and the two-phase enhanced phase composition is stable, which can better play the synergistic effect of the material performance. Using the traditional powder mixing process, the enhanced phase iron oxide particles can be coarse and agglomerated. In addition, the material obtained by the present application has good processing plasticity and processing performance. At the same time, the present application also adds trace Fe and / or indium oxide additives, which mainly improve the wetting performance of the material, and the trace Fe additive can consume trace oxygen to reduce the consumption characteristics and bulging phenomenon of nickel. Through the present application, the large current impact resistance under large current service conditions can be improved, the material strength is increased, and the easy consumption performance of silver-nickel material is improved. The material of the present application has good ductility and electrical conductivity.

[0026] Compared with the prior art, the material of the present application has high hardness, high welding resistance, and low wear and consumption, which meets the service life and safety under capacitive or inductive load service conditions. The material of the present application can be widely used in smart home. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings obtained according to these drawings without creative labor are still within the scope of the present application.

[0028] Figure 1 Process flow chart of the preparation method described in the present application;

[0029] Figure 2 Metallographic phase diagram prepared by the process in Example One Longitudinal 200X;

[0030] Figure 3 Metallographic structure of commonly used AgNi15 Longitudinal 200X. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings. Embodiment

[0032] 99.99% silver, 99.5% Fe, 99.5% In2O3, 99.5% Zn, 99.9% Ni powder, the mass ratio is shown in Table 1, first prepare silver-iron oxide composite powder with a mass ratio of 50% of iron oxide to silver, first dissolve the required in 0.2 mol / L nitric acid, after complete dissolution, remove the excess nitric acid by heating, then mix the iron nitrate and silver nitrate uniformly, filter. The prepared 0.3 mol / L sodium carbonate solution is added to the reaction kettle, the stirrer is started, the speed is set to 300 rpm, the nitrate mixture is injected into the reaction kettle within 1 min, after stirring for 10 min, stand for half an hour, measure the PH value, the PH value is in the range of 7-8, vacuum extract the upper clear liquid, add deionized water and stir repeatedly, stir and wash for more than 5 min, measure the PH value after standing for 15 min, the PH value = 7 is washed, the prepared powder is baked at a temperature of 140℃-160 for 10 h, crushed and calcined at 650℃-700℃ for 1-3 h, crushed to 80 mesh, the undersize material enters the next process, the prepared silver-iron oxide composite powder is configured with the required silver powder, nickel powder and additives according to the composition requirements of Table 1, mixed in a powder mixer for 1-3 h, the powder is added to the plasma pressure ingot sintering equipment for pressure ingot sintering, 10-20 min ingot, the ingot is heated in the holding furnace of the extrusion equipment at 750℃-890℃, and is extruded into a rod, the ingot is extruded into a rod with a diameter of Ø5mm-Ø8mm after sintering.

[0033]

[0034]

[0035] From the material physical properties in Table 2, the bulk resistance of the material is good, slightly higher than that of silver-nickel material with the same volume ratio, and lower than that of silver-oxide material with the same proportion of volume. The hardness and tensile strength of the material are obviously improved. As shown in Figs. 1 and 2, after adding the third phase of silver-nickel-oxide, the metallographic structure of the material not only presents the characteristics of particle reinforcement, but also presents short fiber or particle reinforcement. This not only improves the wear resistance of the material, but also improves the phenomenon of large nickel presenting on the surface during arc corrosion, which leads to poor silver wettability, spatter and surface nickel enrichment. Thus affecting the contact and pressure resistance of the contact. Figure 2 and Figure 3 As shown in Figs. 1 and 2, after adding the third phase of silver-nickel-oxide, the metallographic structure of the material not only presents the characteristics of particle reinforcement, but also presents short fiber or particle reinforcement. This not only improves the wear resistance of the material, but also improves the phenomenon of large nickel presenting on the surface during arc corrosion, which leads to poor silver wettability, spatter and surface nickel enrichment. Thus affecting the contact and pressure resistance of the contact.

[0036] The above merely provides the preferred embodiment of the application, and cannot allude the protection scope of the application, therefore any equivalent changes made according to the claims of the application shall be within the scope of the application.

Claims

1. A method for preparing a silver-nickel-iron oxide electrical contact material, characterized in that: The mass composition of the silver-nickel-iron oxide electrical contact material includes: Ag 80-88 parts by weight; Ni 6-18 parts by weight; Fe2O3 1-5 parts by mass; The balance is for additives, which consist of one or both of Fe and In2O3, with Fe: 0-1 parts by mass and In2O3: 0-0.5 parts by mass. The method includes the following steps: (1) Prepare a nitrate mixture containing silver nitrate and ferric nitrate; (2) Transfer the nitrate mixture obtained in step (1) into the sodium carbonate solution reaction vessel and react while stirring. After the reaction is complete, let it stand to obtain a precipitate. Wash the precipitate until the solution is neutral. (3) The sediment from step (2) is placed in a container, dried, and then calcined at 700℃-800℃ to obtain AgFe2O3 powder; (4) The AgFe2O3 powder obtained in step (3) is mixed with the remaining Ag powder, Ni powder and additives by a high-speed mixer to obtain a uniform composite powder. (5) The uniform composite powder obtained in step (4) is transferred into a discharge plasma device for pressing and sintering to obtain a dense silver-nickel iron oxide ingot. (6) The silver-nickel iron oxide ingots obtained in step (5) are extruded into wires or sheets to obtain silver-nickel iron oxide contact materials.

2. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 1, characterized in that: In step (1), Ag and Fe are dissolved in 0.1-0.3 mol / L nitric acid to obtain silver nitrate and iron nitrate solutions. The two are easily mixed together to obtain a nitrate mixture. In step (2), sodium carbonate solution is 0.3-0.5 mol / L.

3. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 2, characterized in that: In the AgFe2O3 powder obtained in step (3), the mass content of Ag is 50%-60%, and the remainder is Fe2O3 powder. The amount of Ag and Fe in step (1) is calculated based on the content of the intermediate product AgFe2O3 powder.

4. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 2, characterized in that: In step (2), the nitrate mixture is transferred into the sodium carbonate solution within 2 minutes. After the nitrate mixture is completely transferred into the reaction vessel, it is stirred for 5-10 minutes at a stirring speed of 200-350 rpm.

5. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 1, characterized in that: In step (4), the Ag powder is a particle with a particle size in the range of 100-350 mesh, the nickel particles are in the range of 2μm-8μm, and the additive particles are in the range of 2μm-8μm.

6. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 1, characterized in that: In step (5), the spindle diameter is 80cm-120cm, the pressure is 500kN-2000kN, and the time is 10min-15min.

7. The method for preparing a silver-nickel-iron oxide electrical contact material according to claim 1, characterized in that: In step (6), the silver-nickel iron oxide ingots obtained in step (5) are kept at a temperature of 750℃-830℃ and then extruded into wires with a diameter of Ø5mm-Ø8mm to form the required shape and specifications of contacts.

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