Single-face decarburized silver graphite strip and manufacturing method thereof

Abstract

The invention relates to the technical field of electric contact material preparation, in particular to a single-face decarburized silver graphite strip and a manufacturing method thereof.The manufacturing method includes the steps that silver powder and graphite powder are evenly mixed and pressed into a silver graphite spindle through isostatic pressing, and the silver graphite strip is formed through hot extrusion; and then the two silver graphite strips are compounded through hot rolling to form a silver graphite double-layer composite strip, the silver graphite double-layer composite strip is subjected to decarburization treatment, and then the silver graphite double-layer composite strip is separated into two single-face decarburized silver graphite strips after being subjected to cold rolling treatment. The silver graphite strip with the single face coated with the silver layer is produced through the manufacturing method, the process is simple and feasible, the material utilization rate is high, and the manufacturing method is suitable for batch production.

Description

Technical Field

[0001] The present invention relates to the technical field of electric contact material preparation, in particular to a single-side decarburized silver graphite strip and a manufacturing method thereof. Background Art

[0002] AgC contact materials are widely used as static contacts in low-voltage molded case circuit breakers due to their excellent resistance to welding, long electrical life, and environmental performance. Due to the excellent resistance to welding of silver graphite, conventional silver graphite welding surfaces require a silver coating to achieve contact welding. Common methods for preparing the silver layer in AgC contact materials include extrusion lamination, double-sided decarburization, and single-sided decarburization with a protective agent, as described in the following patents:

[0003] CN201010187520.X A preparation method of a silver graphite-silver composite electrical contact material and a special antioxidant coating thereof. The main principle is to spray an antioxidant on one side of the material surface to achieve single-sided decarburization.

[0004] CN200910153565.2 A method for preparing a silver-graphite electrical contact strip, which mainly involves wrapping a silver sleeve on the surface of a silver-graphite ingot and then extruding it to produce a silver-clad strip.

[0005] CN202111619954.7 A method for preparing silver-graphite electrical contact material mainly involves decarburizing an ingot, wrapping it with a silver sleeve, and then extruding it into a silver-graphite-clad silver strip. This process is basically similar to CN200910153565.2.

[0006] CN202310263214.7 A method for preparing a silver-graphite strip electrical contact material mainly adopts processes such as ingot pressing, extrusion, single-sided decarburization, and laser sintering of the decarburized layer to close the decarburized voids.

[0007] Summarizing the above methods, they can be roughly divided into three categories of silver-graphite coated silver layer schemes, one of which is the extrusion composite process, the second is the single-sided decarburization process, and the third is double-sided decarburization and single-sided milling. Among them, the extrusion composite process has the problem of low bonding strength between the extruded silver layer and the graphite layer, and the single-sided decarburization process has the problem of using a single-sided antioxidant protective agent and requiring subsequent cleaning, which has the problem of wastewater discharge; the double-sided decarburization and single-sided milling scheme is to decarburize the silver graphite strip as a whole and then remove the decarburized silver layer on one side by surface milling to form a silver graphite strip with a single-sided decarburization layer. This scheme has problems with milling yield and consumption rate, resulting in high processing cost. With the diversification of electrical application environments, conventional single methods cannot be used, and new methods need to be developed for use. The above schemes are not suitable for large-scale industrial production and promotion. It is necessary to develop a silver-graphite strip with a single-sided silver layer that has a simple and feasible process and high material utilization. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a single-sided decarburized silver graphite strip and a method for producing the same.

[0009] The technical solution adopted by the present invention is as follows: a method for producing a single-sided decarburized silver graphite strip, comprising the following steps:

[0010] (1) silver powder and graphite powder are fully mixed and then isostatically pressed into silver-graphite ingots;

[0011] (2) sintering the silver-graphite ingot pressed and formed in step (1) under the protection of a reducing atmosphere;

[0012] (3) forming a silver-graphite strip by hot extrusion of the silver-graphite ingot sintered in step (2);

[0013] (4) hot-rolling the two silver-graphite strips prepared in step (3) to form a silver-graphite double-layer composite strip;

[0014] (5) decarburizing the silver-graphite double-layer composite strip prepared in step (4);

[0015] (6) cold rolling the silver-graphite double-layer composite strip after the decarburization treatment in step (5);

[0016] (7) Separating the silver-graphite double-layer composite strip after the cold rolling treatment in step (6) to obtain a silver-graphite strip with single-side decarburization.

[0017] Preferably, in step (1), the mass ratio of silver powder to graphite powder is 90-99.9:10-0.1.

[0018] Preferably, in step (1), the isostatic pressure is 50MPa-300MPa, and the isostatic diameter is

[0019] Preferably, in step (2), the sintering temperature is 350° C.-920° C., and the sintering time is 3 min-300 min. This step can be sintered by resistance heating, induction heating, direct current heating, or the like.

[0020] Preferably, in step (3), the extrusion temperature is 300°C-950°C, the thickness of the extruded strip is 2-4mm, and the width of the extruded strip is 2-20mm. This step can be performed by hot extrusion using forward extrusion, reverse extrusion or continuous extrusion.

[0021] Preferably, in step (4), the hot rolling composite temperature is 400° C.-800° C., and the deformation amount is 5-80%. This step can be carried out using equipment such as a two-roll hot rolling mill and a groove rolling mill.

[0022] Preferably, in step (5), the decarburization treatment temperature is 400°C-850°C, the time is 5min-400min, and the oxygen partial pressure is 0.01MPa-1.0MPa. This step can be carried out by continuous decarburization or single furnace decarburization.

[0023] Preferably, in step (6), the deformation amount of the cold rolling treatment is 0.1 mm to 0.5 mm, and the rolling equipment used in this step can be groove rolling or open multi-roll rolling.

[0024] Preferably, in step (7), the silver-graphite double-layer composite strip is separated by an up-and-down winding method.

[0025] The single-side decarburized silver-graphite strip is prepared by the method for preparing the single-side decarburized silver-graphite strip as described above.

[0026] The technical principle of the present invention is as follows: a thin, slightly decarburized silver layer is naturally formed on the surface of the strip formed by hot extrusion in step (3). The slightly decarburized silver layer enables the two-layer strip to be composited by hot rolling in step (4), thereby achieving single-sided decarburization directly by decarburization without the use of a single-sided antioxidant. At the same time, since the slightly decarburized silver layer is relatively thin, the composite strength of the two-layer strip is not high, and the decarburized voids are then bridged by cold rolling. Such a composite strip is easy to separate during the strip separation process.

[0027] The silver graphite strip material coated with a silver layer on one side is produced by the manufacturing method of the present invention, which has a simple and feasible process, a high material utilization rate and is suitable for batch production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0029] Figure 1 It is a process flow chart of the present invention;

[0030] Figure 2 This is a metallographic photograph of the cross section of the composite strip after decarburization in Example 1. DETAILED DESCRIPTION

[0031] 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 with reference to the accompanying drawings.

[0032] Example 1:

[0033] The preparation of a single-sided decarburized AgC4 / Ag strip comprises the following steps:

[0034] 1. Prepare 9.6kg of silver powder and 0.4kg of graphite powder and mix them in a pear shovel mixer for 4 hours to prepare AgC4 mixed powder. Press the AgC4 mixed powder under 120MPa isostatic pressure to form AgC4 ingots were sintered at 850±20℃ for 4h under hydrogen protection;

[0035] 2. The sintered AgC4 ingot is re-pressed under an isostatic pressure of 170 MPa;

[0036] 3. The AgC4 ingot after re-pressing is heated in hydrogen at 850±20℃ for 3h and then hot-extruded into an AgC4 strip with a 3mm×10mm interface;

[0037] 4. The two AgC4 strips are rolled and laminated under high-frequency heating to form an AgC4 composite strip with a cross section of 2 mm × 10 mm;

[0038] 5. Decarburize the AgC4 composite strip in a pit-type decarburization furnace at 600°C and 0.3MPa oxygen pressure for 4 hours to achieve surface decarburization of 0.1-0.15mm on the AgC4 composite strip;

[0039] 6. The AgC4 composite strip with surface decarburization is rolled to 1.6 mm × 10 mm;

[0040] 7. The surface-decarburized AgC4 composite tape was torn off from the composite surface to prepare an AgC4 / Ag tape with a single-side decarburized layer, with a specification of 0.8 mm × 10 mm.

[0041] The physical properties of the AgC4 / Ag single-sided decarburized strip prepared in this example are as follows: density 8.95g / cm 3 , resistivity 2.21μΩ.cm, hardness (HV0.3)50.

[0042] Example 2:

[0043] The preparation of a single-sided decarburized AgC3 / Ag strip comprises the following steps:

[0044] 1. Prepare 9.7kg of silver powder and 0.3kg of graphite powder and mix them in a three-motion powder mixer for 3 hours to prepare AgC3 mixed powder. Press the AgC3 mixed powder under 100MPa isostatic pressure to form The AgC3 ingot was sintered at 850±20℃ under hydrogen protection for 4h;

[0045] 2. The sintered AgC3 ingot is re-pressed under an isostatic pressure of 150 MPa;

[0046] 3. The AgC3 ingot after re-pressing is heated in hydrogen at 800±20℃ for 3h and then hot-extruded into an AgC3 strip with an interface of 2.5mm×10mm;

[0047] 4. The two AgC3 strips are rolled and laminated under high-frequency heating to form an AgC3 composite strip with a cross-section of 1.8 mm × 10 mm;

[0048] 5. Decarburize the AgC3 composite strip in a pit-type decarburization furnace at 550°C and 0.2MPa oxygen pressure for 3 hours to achieve surface decarburization of 0.1-0.15mm on the AgC3 composite strip;

[0049] 6. The AgC3 composite strip with surface decarburization is rolled to 1.5 mm × 10 mm;

[0050] 7. The surface decarburized AgC3 composite tape is torn off from the composite surface to prepare an AgC3 / Ag strip with a single-sided decarburized layer, with a specification of 0.7 mm × 10 mm;

[0051] The physical properties of the AgC3 / Ag single-sided decarburized strip prepared in this example are as follows: density 9.15g / cm 3 , resistivity 2.15μΩ.cm, hardness (HV0.3)55.

[0052] Example 3:

[0053] The preparation of single-sided decarburized AgC7 / Ag strip comprises the following steps:

[0054] 1. Prepare 9.3kg of silver powder and 0.7kg of graphite powder and mix them in a ball mill for 8 hours to prepare AgC7 mixed powder. Press the AgC7 mixed powder under 100MPa isostatic pressure to form AgC7 ingots were sintered at 850±20℃ for 4h under hydrogen protection;

[0055] 2. The sintered AgC7 ingot is re-pressed under an isostatic pressure of 200 MPa;

[0056] 3. The AgC7 ingot after re-pressing is heated in hydrogen at 850±20℃ for 3h and then hot-extruded into an AgC7 strip with a 3mm×10mm interface;

[0057] 4. The two AgC7 strips are rolled and laminated under high-frequency heating to form an AgC7 composite strip with a cross-section of 2.2 mm × 10 mm;

[0058] 5. Decarburize the AgC7 composite strip in a pit-type decarburization furnace at 650°C and 0.35MPa oxygen pressure for 6 hours to achieve surface decarburization of 0.1-0.15mm on the AgC7 composite strip;

[0059] 6. The AgC7 composite strip with surface decarburization is rolled to 2.0 mm × 10 mm;

[0060] 7. The surface decarburized AgC7 composite tape is torn off from the composite surface to prepare an AgC7 / Ag strip with a single-sided decarburized layer, with a specification of 1.0 mm × 10 mm;

[0061] The physical properties of the AgC7 / Ag single-sided decarburized strip prepared in this example are as follows: density 8.25g / cm 3 , resistivity 2.62μΩ.cm, hardness (HV0.3) 45 (annealed state).

[0062] 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 producing a single-sided decarburized silver-graphite strip, characterized in that The following steps are involved: (1) silver powder and graphite powder are fully mixed and then isostatically pressed into silver-graphite ingots; (2) sintering the silver-graphite ingot pressed and formed in step (1) under the protection of a reducing atmosphere; (3) forming a silver-graphite strip by hot extrusion of the silver-graphite ingot sintered in step (2); (4) hot-rolling the two silver-graphite strips prepared in step (3) to form a silver-graphite double-layer composite strip; (5) decarburizing the silver-graphite double-layer composite strip prepared in step (4); (6) cold rolling the silver-graphite double-layer composite strip after the decarburization treatment in step (5); (7) Separating the silver-graphite double-layer composite strip after the cold rolling treatment in step (6) to obtain a silver-graphite strip with single-side decarburization.

2. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (1), the mass ratio of silver powder to graphite powder is 90-99.9:10-0.

1.

3. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (1), the isostatic pressure is 50MPa-300MPa, and the isostatic diameter is 4. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (2), the sintering temperature is 350° C.-920° C., and the sintering time is 3 min-300 min.

5. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (3), the extrusion temperature is 300° C.-950° C., the thickness of the extruded strip is 2-4 mm, and the width of the extruded strip is 2-20 mm.

6. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (4), the hot rolling composite temperature is 400° C.-800° C., and the deformation amount is 5-80%.

7. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (5), the decarburization treatment temperature is 400°C-850°C, the time is 5min-400min, and the oxygen partial pressure is 0.01MPa-1.0MPa.

8. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (6), the deformation amount of the cold rolling treatment is 0.1mm-0.5mm.

9. The method for producing a single-sided decarburized silver-graphite strip according to claim 1, wherein: In step (7), the silver-graphite double-layer composite strip is separated by an up-and-down winding method.

10. The single-side decarburized silver-graphite strip prepared by the method for preparing the single-side decarburized silver-graphite strip according to any one of claims 1 to 9.

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