Oriented oxidation process for silver metal oxide electrical contact material

Abstract

The invention provides a directional oxidation process for a silver metal oxide electrical contact material. The process comprises the following steps: preparing raw materials, smelting and casting to form a silver alloy cast ingot, turning, extruding, carrying out hot rolling and silver compounding, carrying out cold rolling, punching, carrying out surface treatment, coating an anti-oxidation coating on a silver surface of a contact, carrying out internal oxidation, carrying out surface treatment, and carrying out spot inspection and packaging. The invention provides an antioxidant composed of silicon oxide, aluminum oxide, magnesium oxide, sodium oxide and boron oxide, the antioxidant is uniformly mixed with water and then coated on a contact silver layer surface, a compact oxide protective film is formed at high temperature, the viscosity of the protective film is reduced by adding alkali metal, the self-healing of the protective layer is improved, and the service life of the protective layer is prolonged. The coating is prevented from being cracked in the contact oxidation expansion process; the silver metal oxide obtained through the technology is of a directional oxidation structure and is uniform in structure, new equipment is not introduced, the technology is simple, the operation difficulty is low, and the technology is suitable for all internal oxidation technology sheet products.

Description

Technical Field

[0001] The invention relates to the field of electric contact materials, in particular to a directional oxidation process for silver metal oxide electric contact materials. Background Art

[0002] In the field of electrical alloy materials, silver metal oxide (AgMeO) materials are widely used in low-voltage electrical appliances due to their good arc erosion resistance, welding resistance and electrical conductivity. They mainly include silver cadmium oxide, silver tin oxide, silver zinc oxide and silver copper oxide. The preparation processes of silver metal oxide (AgMeO) materials are mainly internal oxidation method, pre-oxidation method, powder mixing method and chemical method, among which the internal oxidation method is the main preparation process.

[0003] During the oxidation process of the silver alloy sheet contact, oxygen diffuses from the surrounding to the middle, and oxidation occurs. At the same time, the reinforcing phase metal in the silver alloy sheet contact diffuses to the outside accordingly, and forms an "oxide-poor zone" in the middle after the oxidation is completed. The "oxide-poor zone" has very little oxide content. When the product burns to this area, it is very likely to form a weld, causing product failure.

[0004] Relevant research institutions at home and abroad have proposed different solutions to solve the problem of "oxide-poor areas". For example: 1) Chinese invention patent: Directed internal oxidation silver tin oxide indium oxide electrical contact material and its preparation method, publication number: CN110391095B, ​​the welding layer is replaced by a silver layer with an AgSn layer or an AgZn layer, and a layer of SnO2 or ZnO film is formed during the oxidation process of the AgSn or AgZn layer to prevent oxygen from entering from the welding layer, thereby achieving the purpose of directional oxidation. However, this preparation method uses an AgSn layer or an AgZn layer to replace the Ag layer. When the AgZn layer is used to replace the Ag layer or other materials are produced by this process, other elements are introduced. The scraps generated during the production process cannot be directly used for feeding, but can only be recycled and reused, and the material utilization rate is low. Secondly, this process polishes the welding surface of the internally oxidized strip or plate to obtain a fresh AgSn or AgZn surface. The operation is relatively complicated, and it is difficult to ensure the consistency of the strip thickness after grinding and polishing. In addition, the oxidized strip has poor machinability and is prone to cracking and other problems during the punching process. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a directional oxidation process for silver metal oxide electrical contact materials. The technical solution adopted by the present invention is as follows:

[0006] A directional oxidation process for silver metal oxide electrical contact material, comprising the following steps:

[0007] S1. Prepare silver ingots, reinforcing metals and other additives according to a certain ratio, melt and cast the silver ingots and reinforcing metals into silver alloy ingots, and saw off the ingot riser;

[0008] S2. removing the surface oxide layer of the silver alloy ingot to obtain a smooth surface ingot, and then heating the silver alloy ingot to extruding it into a silver alloy sheet;

[0009] S3. removing the surface oxide scale of the silver alloy sheet and welding it with the silver plate, obtaining a silver alloy composite silver semi-finished strip by hot rolling, and cold rolling the silver alloy composite silver strip to the desired thickness in multiple passes;

[0010] S4. stamping the cold-rolled strip into silver alloy-clad silver sheet contacts of uniform size;

[0011] S5. Pickling and polishing the silver alloy composite silver sheet contact to remove the oil stain on the surface, applying an anti-oxidation coating on the silver surface of the silver alloy composite silver sheet contact and drying to obtain an anti-oxidation coating, wherein the anti-oxidation coating composition includes:

[0012]

[0013] S6. The silver alloy composite silver sheet contact having an anti-oxidation coating is internally oxidized to obtain a silver metal oxide sheet contact semi-finished product having a clean surface;

[0014] S7. The semi-finished silver metal oxide sheet contact is subjected to surface treatment to obtain a finished silver metal oxide sheet contact with a clean surface. After the contacts are selected for appearance defects, they are packaged as required.

[0015] It is further provided that the reinforcement phase metal includes at least one metal element selected from tin, cadmium, copper, zinc, iron and indium.

[0016] It is further provided that the silver surface of the silver alloy-clad silver sheet contact is coated with an anti-oxidation coating and dried to obtain an anti-oxidation coating, and the coating method is brushing, spraying or rolling.

[0017] It is further provided that the silver layer surface of the silver alloy composite silver sheet contact is coated with an anti-oxidation coating and dried to obtain an anti-oxidation coating, and the anti-oxidation coating is coated on the surface of the silver layer with a thickness of 0.5 to 2.0 mm.

[0018] It is further provided that the silver layer of the silver alloy-clad silver sheet contact is coated with an anti-oxidation coating and dried to obtain an anti-oxidation coating, the drying temperature is 50° C. to 100° C., and the time is 1 to 3 hours.

[0019] It is further configured that the silver layer of the silver alloy composite silver sheet contact is coated with an anti-oxidation coating and dried to obtain an anti-oxidation coating, the material of the anti-oxidation coating is ground to less than 100 meshes, mixed evenly to obtain an antioxidant, and mixed with a polar solvent and stirred evenly to obtain an anti-oxidation coating, the mass ratio of the antioxidant to the polar solvent is 1:8 to 1:1, and the polar solvent is one or more of water, ethanol, and acetone.

[0020] It is further provided that the semi-finished silver metal oxide sheet contact is subjected to surface treatment to obtain a finished silver metal oxide sheet contact with a clean surface, wherein the surface treatment is that the contact after internal oxidation is first soaked in hot water, and then polished to remove the surface anti-oxidation coating, and the product is then polished, and the hot water temperature is 50°C to 100°C, and the soaking time is 0.3 to 1h.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The antioxidant provided by the present invention is composed of several oxides such as silicon oxide, aluminum oxide, magnesium oxide, sodium oxide and boron oxide. After adding water and mixing evenly, it is coated on the contact silver layer, and forms a dense oxide protective film under high temperature conditions, which prevents oxygen from entering from the welding layer and can only oxidize from the product surface to the welding layer, thereby achieving the purpose of directional oxidation, while the conventional oxidation process is to oxidize from the outside to the inside of the product surface; the addition of alkali metals reduces the viscosity of the protective film, increases the self-healing of the protective layer, and prevents the coating from being cracked during the oxidation expansion of the contact;

[0023] 2. The method provided by the present invention does not modify the original structure of the product, the welding surface is still a silver layer, and has no effect on subsequent welding;

[0024] 3. No other elements are introduced into the contact material during the production process of the method provided by the present invention, and the scraps generated during the production process can be processed normally;

[0025] 4. The method provided by the present invention is simple to operate and can achieve batch production under existing equipment conditions without the need to introduce additional equipment;

[0026] 5. When the product is punched by the method provided by the present invention, the material strip is not oxidized and has good processability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0028] Figure 1 is a process flow chart of the present invention;

[0029] Figure 2 This is the cross section of the silver tin oxide (12) electrical contact material prepared in Example 1 of the present invention observed under a metallographic microscope;

[0030] Figure 3This is the cross section of the silver tin oxide (12) electrical contact material prepared by the traditional internal oxidation process in comparative example 1 observed under a metallographic microscope. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Embodiment 1:

[0033] (1) Prepare raw materials: 25 kg of ingredients per furnace, weigh 21.5 kg of silver, 2.75 kg of tin, and the balance of indium according to the ingredients of silver tin oxide (12);

[0034] (2) Smelting: Smelt raw materials such as silver and tin, cast them into silver-tin alloy ingots, and saw off the risers;

[0035] (3) Turning: Use a lathe to turn the surface of the silver-tin alloy ingot to obtain a silver-tin alloy ingot with a smooth surface;

[0036] (4) Extrusion: The silver-tin alloy ingot is heated and extruded into a sheet;

[0037] (5) Hot-rolling silver-clad: The surface oxide scale of the silver-tin alloy sheet is removed and then welded with the silver sheet to obtain a silver-tin alloy silver-clad semi-finished strip by hot-rolling;

[0038] (6) Cold rolling: The silver-tin alloy composite silver strip is cold rolled and thinned in succession;

[0039] (7) Punching: Punching the cold-rolled strip into silver-tin alloy composite silver sheet contacts;

[0040] (8) Surface treatment: The punched product is surface treated to remove oil stains on the surface of the product;

[0041] (9) Applying anti-oxidation coating: Prepare the coating according to the following mass ratio, and its components are:

[0042]

[0043] The above materials were ground into 100 mesh, mixed evenly to obtain an antioxidant, mixed with water and stirred evenly to obtain an antioxidant coating, the mass ratio of the antioxidant to water was 1:7, and applied on the silver surface of the product, the coating thickness was 2.0 mm, and dried at 100° C. for 1 hour;

[0044] (10) Internal oxidation: the product is placed in an oxidation furnace for oxidation;

[0045] (11) Surface treatment: The internally oxidized product was first soaked in 100°C hot water for 0.7 h, then ground for 10 minutes to remove the anti-oxidation coating, and then polished;

[0046] (12)Inspect the packaging.

[0047] Embodiment 2:

[0048] (1) Prepare raw materials: 25 kg of ingredients per furnace, weigh 20.8 kg of silver, 3.4 kg of cadmium, and the balance of tin according to the ingredients of silver cadmium oxide (15);

[0049] (2) Smelting: Smelting raw materials such as silver and cadmium, casting them into silver-cadmium alloy ingots, and sawing off the risers;

[0050] (3) Turning: Using a lathe to turn the surface of the silver-cadmium alloy ingot to obtain a silver-cadmium alloy ingot with a smooth surface;

[0051] (4) Extrusion: The silver-cadmium alloy ingot is heated and extruded into a sheet;

[0052] (5) Hot-rolled silver-clad: After the surface oxide scale of the silver-cadmium plate is removed, it is welded with the silver plate, and the silver-cadmium alloy silver-clad semi-finished material strip is obtained by hot-rolling and laminating;

[0053] (6) Cold rolling: The silver-cadmium alloy composite silver strip is cold rolled and thinned in succession;

[0054] (7) Punching: Punching the cold-rolled strip into silver-cadmium alloy-clad silver sheet contacts;

[0055] (8) Surface treatment: The punched product is surface treated to remove oil stains on the surface of the product;

[0056] (9) Applying anti-oxidation coating: Prepare the coating according to the following mass ratio, and its components are:

[0057]

[0058] The above materials were ground into 120 mesh, mixed evenly to obtain an antioxidant, mixed with ethanol and stirred evenly to obtain an antioxidant coating, the mass ratio of the antioxidant to ethanol was 1:3, and applied on the silver surface of the product, the coating thickness was 1.2 mm, and dried at 80° C. for 1.5 h;

[0059] (10) Internal oxidation: the product is placed in an oxidation furnace for oxidation;

[0060] (11) Surface treatment: The internally oxidized product is first soaked in 80°C hot water for 0.8 h, then ground for 10 minutes to remove the anti-oxidation coating, and then polished;

[0061] (12)Inspect the packaging.

[0062] Embodiment three:

[0063] (1) Prepare raw materials: 25 kg of ingredients per furnace, weigh 22.1 kg of silver, 2.3 kg of copper, and the balance of tin according to the ingredients of silver copper oxide (10);

[0064] (2) Smelting: Smelt raw materials such as silver and copper, cast them into silver-copper alloy ingots, and saw off the risers;

[0065] (3) Turning: Using a lathe to turn the surface of the silver-copper alloy ingot to obtain a silver-copper alloy ingot with a smooth surface;

[0066] (4) Extrusion: The silver-copper alloy ingot is heated and extruded into a sheet;

[0067] (5) Hot-rolled silver-clad: After the surface oxide scale of the silver-copper alloy plate is removed, it is welded with the silver plate and hot-rolled to obtain a silver-copper alloy silver-clad semi-finished strip;

[0068] (6) Cold rolling: The silver-copper alloy silver-clad strip is cold-rolled and thinned in succession;

[0069] (7) Punching: Punching the cold-rolled strip into silver-copper alloy silver-clad sheet contacts;

[0070] (8) Surface treatment: The punched product is surface treated to remove oil stains on the surface of the product;

[0071] (9) Applying anti-oxidation coating: Prepare the coating according to the following mass ratio, and its components are:

[0072]

[0073] The above materials were ground into 100 mesh, mixed evenly to obtain an antioxidant, mixed with acetone and stirred evenly to obtain an antioxidant coating, the mass ratio of the antioxidant to acetone was 1:4, and applied on the silver surface of the product, the coating thickness was 1mm, and dried at 70°C for 2h;

[0074] (10) Internal oxidation: the product is placed in an oxidation furnace for oxidation;

[0075] (11) Surface treatment: The internally oxidized product is first soaked in 90°C hot water for 0.5 h, then ground for 10 minutes to remove the anti-oxidation coating, and then polished;

[0076] (12)Inspect the packaging.

[0077] Embodiment 4:

[0078] (1) Prepare raw materials: 25 kg of ingredients per furnace, weigh 22.4 kg of silver, 1.9 kg of zinc, and the balance of tin according to the ingredients of silver zinc oxide (8);

[0079] (2) Smelting: Smelt raw materials such as silver and zinc, cast them into silver-zinc alloy ingots, and saw off the risers;

[0080] (3) Turning: Use a lathe to turn the surface of the silver-zinc alloy ingot to obtain a silver-zinc alloy ingot with a smooth surface;

[0081] (4) Extrusion: The silver-zinc alloy ingot is heated and extruded into a sheet;

[0082] (5) Hot-rolled silvering: After the surface oxide scale of the silver-zinc alloy sheet is removed, it is welded with the silver sheet and hot-rolled to obtain a silver-zinc alloy silvering semi-finished strip;

[0083] (6) Cold rolling: The silver-zinc alloy silver-clad strip is cold-rolled and thinned in succession;

[0084] (7) Punching: Punching the cold-rolled strip into silver-zinc alloy-clad silver sheet contacts;

[0085] (8) Surface treatment: The punched product is surface treated to remove oil stains on the surface of the product;

[0086] (9) Applying anti-oxidation coating: Prepare the coating according to the following mass ratio, and its components are:

[0087]

[0088] The above materials are ground into 100 meshes, mixed evenly to obtain an antioxidant, ethanol and water are mixed to obtain a mixed solution, the antioxidant and the mixed solution are mixed and stirred evenly to obtain an antioxidant coating, the mass ratio of ethanol to water is 2:1, the mass ratio of the antioxidant to the mixed solution is 1:1, and the coating is applied on the silver surface of the product, the coating thickness is 0.7 mm, and it is dried at 55° C. for 3 hours;

[0089] (10) Internal oxidation: the product is placed in an oxidation furnace for oxidation;

[0090] (11) Surface treatment: The internally oxidized product is first soaked in 50°C hot water for 1 h, then ground for 10 minutes to remove the anti-oxidation coating, and then polished;

[0091] (12)Inspect the packaging.

[0092] Comparative Example 1:

[0093] (1) Prepare the raw materials: 25 kg of ingredients per furnace, weigh 21.5 kg of silver according to the ingredients of silver tin oxide (12)

[0094] kg, tin 2.75 kg, the balance is indium;

[0095] (2) Smelting: Smelt raw materials such as silver and tin, cast them into silver-tin alloy ingots, and saw off the risers;

[0096] (3) Turning: Use a lathe to turn the surface of the silver-tin alloy ingot to obtain a silver-tin alloy ingot with a smooth surface;

[0097] (4) Extrusion: The silver-tin alloy ingot is heated and extruded into a sheet;

[0098] (5) Hot-rolled silver-clad: After the surface oxide scale of the silver-tin alloy sheet is removed, it is welded with the silver sheet and hot-rolled to obtain a silver-tin alloy silver-clad semi-finished strip;

[0099] (6) Cold rolling: The silver-tin alloy composite silver strip is cold rolled and thinned in succession;

[0100] (7) Punching: Punching the cold-rolled strip into silver-tin alloy composite silver sheet contacts;

[0101] (8) Surface treatment: The punched product is surface treated to remove oil stains on the surface of the product;

[0102] (9) Internal oxidation: the product is placed in an oxidation furnace for oxidation;

[0103] (10) Surface treatment: The product is polished;

[0104] (11)Inspect the packaging.

[0105] Figure 2 This is the cross section of the silver tin oxide (12) electrical contact material prepared in Example 1 of the present invention observed under a metallographic microscope. Figure 3 This is the cross section of the silver tin oxide (12) electrical contact material prepared by the conventional internal oxidation process in Comparative Example 1 observed under a metallographic microscope. Figure 2 , Figure 3 By comparison, it can be seen that the silver tin oxide (12) electrical contact material prepared by the present invention has uniform tissue distribution and no oxygen-deficient zone defect in the middle.

[0106] The above disclosure is only the preferred embodiment of the present invention, which 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 directional oxidation process for silver metal oxide electrical contact materials, characterized in that: The following steps are involved: S1. melting and casting the silver ingot and the reinforcing phase metal into a silver alloy ingot; S2. removing the surface oxide layer of the silver alloy ingot to obtain a smooth surface ingot, and extruding it into a silver alloy sheet; S3. removing the surface oxide scale of the silver alloy sheet and welding it with the silver plate, obtaining a silver alloy composite silver semi-finished strip by hot rolling, and cold rolling the silver alloy composite silver strip to the desired thickness; S4. stamping the cold-rolled strip into a silver alloy composite silver sheet contact; S5. Pickling and polishing the silver alloy composite silver sheet contact, applying an antioxidant coating on the silver surface of the silver alloy composite silver sheet contact and drying to obtain an antioxidant coating, wherein the antioxidant coating composition comprises: SnO2 20~45wt% Al2O3 15~30wt% MgO 10~25wt% Na2O 5~10wt% B2O3 10~20wt%; S6. The silver alloy composite silver sheet contact having an oxidation-resistant coating is internally oxidized to obtain a semi-finished silver metal oxide sheet contact; S7. The semi-finished silver metal oxide sheet contact is subjected to surface treatment to obtain a finished silver metal oxide sheet contact with a clean surface.

2. The directional oxidation process of silver metal oxide electrical contact material according to claim 1, characterized in that: In step S5, the materials in the antioxidant coating are ground to less than 100 meshes, mixed evenly to obtain an antioxidant, and the antioxidant is mixed with a polar solvent and stirred evenly to obtain an antioxidant coating, the mass ratio of the antioxidant to the polar solvent is 1:8 to 1:1, and the polar solvent is one or more of water, ethanol, and acetone.

3. The directional oxidation process of silver metal oxide electrical contact material according to claim 1, characterized in that: In step S5, the coating thickness of the anti-oxidation coating is 0.5 to 2.0 mm.

4. The directional oxidation process of silver metal oxide electrical contact material according to claim 1, characterized in that: In step S5, the silver layer of the silver alloy-clad silver sheet contact is coated with an anti-oxidation coating and dried to obtain an anti-oxidation coating. The anti-oxidation coating is coated by brushing, spraying or rolling.

5. The directional oxidation process of silver metal oxide electrical contact material according to claim 1, characterized in that: In step S5, the anti-oxidation coating is dried at a temperature of 50° C. to 100° C. for a period of 1 to 3 hours.

6. A directional oxidation process for silver metal oxide electrical contact materials according to claim 1, characterized in that: In step S1, the reinforcing phase metal includes at least one of tin, cadmium, copper, zinc, iron, and indium.

7. A directional oxidation process for silver metal oxide electrical contact materials according to claim 1, characterized in that: In step S7, the surface treatment is as follows: the silver metal oxide sheet contact semi-finished product is first soaked in hot water, then polished to remove the surface antioxidant coating, and the product is then polished, the hot water temperature is 50°C to 100°C, and the soaking time is 0.3 to 1h.

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