A silver nickel / silver based metal oxide contact material and method of making same

Abstract

The application provides a silver-nickel / silver-based metal oxide contact material and a preparation method thereof, and the preparation method comprises the following steps: segmentally heating raw material strips which are stacked by silver-nickel strips and silver-based metal oxide strips in a protection atmosphere, then performing rolling compounding to obtain silver-nickel / silver-based metal oxide composite strips; segmentally cooling the silver-nickel / silver-based metal oxide composite strips in a protection atmosphere, then performing winding, annealing and rolling to obtain the silver-nickel / silver-based metal oxide contact material. The preparation method simplifies the production process of the contact material in the prior art, improves the production efficiency, and the prepared silver-nickel / silver-based metal oxide contact material has good interface combination, high material yield, is easy to weld, and has excellent electrical performance.

Description

Technical Field

[0001] This invention belongs to the field of contact materials, specifically relating to a silver-nickel / silver-based metal oxide contact material and its preparation method. Background Technology

[0002] Silver-based metal oxide (AgMeO) contact materials contain dispersed metal oxide particles and additive element particles within a silver matrix. They possess excellent electrical and thermal conductivity, resistance to welding, resistance to arc erosion, wear resistance, and electrical life, making them widely used in low-voltage electrical appliances such as relays, contactors, and circuit breakers. In AgMeO contact material applications, to meet the high reliability requirements of electrical appliances, the AgMeO contact material is typically welded onto the contact element before being assembled into the electrical appliance. To ensure a good weld, one side of the sheet-like AgMeO contact material is usually coated with a layer of pure silver, or sequentially coated with a layer of pure silver and a solder layer, through which it is welded to the contact element.

[0003] For AgMeO contact materials with only a pure silver layer on one side, the lack of a solder layer means that the AgMeO contact material cannot be directly soldered onto the contact bridge. Solder or solder paste must be pre-applied between the AgMeO contact material and the contact bridge before soldering can be performed. This results in a complicated soldering process, low production efficiency, poor soldering quality consistency, and directly affects the quality and performance of electrical appliances. For AgMeO contact materials with a pure silver layer and a solder layer sequentially coated on one side, such as the preparation method of a silver oxide / silver / copper three-layer composite strip disclosed in patent CN 105609333 A, during the solder coating process, due to the characteristics of the solder such as thin thickness, high hardness, poor plasticity, and low melting point, problems such as brittle breakage or melting breakage of the solder are easily caused. Secondly, in order to avoid the solder being oxidized in this process and affecting the bonding strength of the composite interface, a reducing atmosphere is generally used for protection. However, this measure makes the surface layer of the AgMeO contact material easily reduced to a silver metal alloy material at high temperature. The silver metal alloy material has a low melting point, high resistivity, poor resistance to fusion welding, and poor resistance to electrical wear, which will seriously affect the performance of the AgMeO contact material. In addition, as a three-layer composite material, the AgMeO contact material not only has a complex production process, low production efficiency, and low yield, but also has large fluctuations in the thickness of the solder layer. Therefore, developing an AgMeO contact material with high production efficiency and stable quality is of great significance for the standardized production and automated welding of contact products. Summary of the Invention

[0004] To address the issues of low production efficiency and poor quality stability of AgMeO contact materials in existing technologies, this invention provides a silver-nickel / silver-based metal oxide contact material and its preparation method. This preparation method simplifies the production process of contact materials in existing technologies, improves production efficiency, and produces contact materials with good interfacial bonding, high yield, easy welding, and excellent electrical properties.

[0005] The technical solution adopted in this invention is: a method for preparing a silver-nickel / silver-based metal oxide contact material, the method comprising: subjecting a raw material strip composed of stacked silver-nickel strip and silver-based metal oxide strip to segmented atmosphere-protected heating, followed by rolling and composite processing to obtain a silver-nickel / silver-based metal oxide composite strip; subjecting the silver-nickel / silver-based metal oxide composite strip to segmented atmosphere-protected cooling, followed by winding, annealing, and rolling to obtain the silver-nickel / silver-based metal oxide contact material. The segmented atmosphere-protected heating comprises: subjecting the raw material strip to initial heating under the protection of an ignited non-reducing combustible gas, followed by intermediate heating under the protection of a non-reducing non-combustible gas, and finally, post-heating under the protection of an ignited non-reducing combustible gas. The segmented atmosphere-protected cooling comprises: subjecting the silver-nickel / silver-based metal oxide composite strip to initial cooling under the protection of an ignited non-reducing combustible gas, followed by intermediate cooling under the protection of a non-reducing non-combustible gas, and finally, post-cooling under the protection of an ignited non-reducing combustible gas.

[0006] Unlike existing technologies that use high-frequency induction furnaces or conventional resistance furnaces for heating, this invention employs segmented atmosphere-protected heating for raw material strips made of stacked silver-nickel strips and silver-based metal oxide strips. The preferred temperature for this segmented atmosphere-protected heating is 650–940°C, for example, 650°C, 750°C, 800°C, 850°C, 900°C, or 940°C. This segmented atmosphere-protected heating can be performed in a segmented atmosphere-protected resistance furnace. Specifically, the furnace is divided into three sections: a front section, a middle section, and a rear section. The raw material strip is heated sequentially in these sections, with each section filled with a different protective gas. For example, the middle section is filled with a non-reducing, non-flammable gas, while the front and rear sections are filled with non-reducing, flammable gases. Preferably, the non-reducing non-flammable gas is selected from at least one of nitrogen or argon; the non-reducing combustible gas is selected from any one of natural gas, methane, acetylene, propane, and butane. The lengths of the front and rear sections of the resistance furnace can be controlled between 10 and 30 cm respectively. During the segmented atmosphere-protected heating process, the raw material strip first enters the front section of the resistance furnace and is heated under the protection of ignited non-reducing combustible gas, effectively isolating and preventing external oxygen-containing atmospheres from entering the furnace. Subsequently, the raw material strip enters the middle section of the furnace and is heated under the protection of non-reducing non-flammable gas, preventing the surface layer of the silver-based metal oxide from being reduced to a silver alloy at high temperatures. Finally, the raw material strip enters the rear section of the furnace and is heated under the protection of ignited non-reducing combustible gas, effectively isolating and preventing external oxygen-containing atmospheres from entering the furnace, and also effectively consuming and removing residual oxygen in the middle section. This invention employs a segmented atmosphere-protected heating method to heat the raw material strip. On one hand, this effectively prevents the surface of the silver-based metal oxide strip from being reduced to a silver alloy during heating, ensuring the electrical properties of the silver-based metal oxide material. On the other hand, it also effectively prevents the nickel particles on the surface of the silver-nickel strip from being oxidized into nickel oxide particles during heating, ensuring the interfacial bonding strength of the silver-nickel / silver-based metal oxide composite strip after hot rolling, thereby guaranteeing the performance of the contact material. It should be noted that, as the silver-nickel layer is a welding layer, if the nickel particles on its surface oxidize, it will greatly affect the effective bonding of the welding interface between the silver-nickel / silver-based metal oxide contact material and the contact element, reducing the performance of the contact material and, in severe cases, leading to premature failure. This technical solution ensures that the nickel particles on the surface of the welding layer are not oxidized, effectively guaranteeing the welding performance and overall performance of the contact material.

[0007] After being heated in a segmented atmosphere, the raw strip is fed into a rolling mill for compounding to obtain a silver-nickel / silver-based metal oxide composite strip. Hot rolling is generally used for compounding, preferably controlling the rolling deformation between 50% and 80%, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, etc. The resulting silver-nickel / silver-based metal oxide composite strip is then subjected to segmented atmosphere-protected cooling. Unlike the conventional natural cooling method in existing technologies, this invention utilizes a segmented atmosphere-protected cooling method to cool the hot-rolled silver-nickel / silver-based metal oxide composite strip before the winding process. The segmented atmosphere-protected cooling can be carried out in a segmented atmosphere-protected cooling device. Specifically, the segmented atmosphere-protected cooling device is divided into three sections: a front section, a middle section, and a rear section. The silver-nickel / silver-based metal oxide composite strip is cooled sequentially in these three sections. Each section is filled with a different protective gas; for example, the middle section is filled with a non-reducing non-flammable gas, while the front and rear sections are filled with non-reducing combustible gases. Preferably, the non-reducing non-flammable gas is selected from at least one of nitrogen or argon; the non-reducing combustible gas is selected from any one of natural gas, methane, acetylene, propane, and butane. The lengths of the front and rear sections are controlled between 10 and 30 cm. In the segmented atmosphere-protected cooling process, the rolled silver-nickel / silver-based metal oxide composite strip first enters the front section of the cooling device and undergoes front-stage cooling under the protection of ignited non-reducing combustible gas, effectively isolating and preventing external oxygen-containing atmosphere from entering the cooling device. Subsequently, the silver-nickel / silver-based metal oxide composite strip enters the middle section of the cooling device and undergoes middle-stage cooling under the protection of non-reducing non-combustible gas, preventing the silver-based metal oxide surface of the silver-nickel / silver-based metal oxide composite strip from being reduced to silver metal alloy material. Finally, the silver-nickel / silver-based metal oxide composite strip enters the rear section of the cooling device and undergoes rear-stage cooling under the protection of ignited non-reducing combustible gas, which not only effectively isolates and prevents external oxygen-containing atmosphere from entering the cooling device, but also effectively consumes and removes residual oxygen in the middle section of the cooling device. This invention employs a segmented atmosphere-protected cooling method instead of traditional natural cooling, which can effectively prevent the surface of the silver-based metal oxide in the silver-nickel / silver-based metal oxide composite strip from being reduced to silver metal alloy material during the cooling process. At the same time, it avoids the nickel particles on the surface of the silver-nickel layer from being oxidized to nickel oxide particles during the cooling process, thus ensuring the electrical properties of the silver-based metal oxide layer in the contact material and the welding performance of the silver-nickel layer.

[0008] Subsequently, the cooled silver-nickel / silver-based metal oxide composite strip is wound up and then annealed and rolled according to conventional processes. Here, intermediate protective annealing is generally used, meaning the annealing process is carried out under a protective atmosphere, preferably nitrogen or argon. During intermediate protective annealing, the temperature is controlled at 650–750℃, and the time is controlled at 1–1.5 hours. After annealing, the silver-nickel / silver-based metal oxide composite strip is rolled, generally using cold rolling, with the cold rolling deformation controlled between 10–25%. The annealing and rolling processes are then repeated until the silver-nickel / silver-based metal oxide composite strip reaches the required thickness, thus obtaining the silver-nickel / silver-based metal oxide contact material.

[0009] Preferably, the method for preparing the silver-nickel / silver-based metal oxide contact material provided by the present invention may further include: post-processing the silver-nickel / silver-based metal oxide contact material, such as slitting and blanking, to obtain finished silver-nickel / silver-based metal oxide contact materials of the required specifications. Specifically, slitting involves cutting the silver-nickel / silver-based metal oxide contact material to the required width; and blanking involves punching the slitting material into the required outer dimensions of the product to obtain finished silver-nickel / silver-based metal oxide contact materials of different specifications, such as sheet contacts, shaped strips, etc., which are then used as finished products for automated welding of contacts.

[0010] This invention also provides a silver-nickel / silver-based metal oxide contact material prepared by the method described above. Figure 1 The contact material comprises a silver-based metal oxide layer and a silver-nickel layer. The silver-nickel layer serves as a welding layer on one side of the silver-based metal oxide layer. Preferably, the thickness of the silver-nickel layer accounts for 5-40% of the total thickness of the contact material, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc. This invention uses a silver-nickel layer as the welding layer of the contact material, which not only saves on the amount of precious metals used in the welding layer material, reducing material costs, but also simplifies the welding process by eliminating the need for pre-made solder or solder paste, allowing direct welding onto the contact bridge due to the good solderability of silver-nickel. This improves production efficiency and product welding quality, thereby effectively enhancing the quality and performance of the electrical appliance. Furthermore, silver-nickel material has low hardness, good plasticity, and a high melting point, effectively solving problems such as brittle fracture or melting fracture that easily occur during the soldering process by replacing traditional solders such as silver, copper, and phosphorus. Secondly, the silver-nickel / silver-based metal oxide contact material provided by this invention is a two-layer composite material, which greatly simplifies the production process, improves production efficiency and yield, and further reduces the fluctuation of solder layer thickness.

[0011] Preferably, the silver-nickel layer comprises 5-40 wt% nickel. This invention uses silver-nickel materials containing 5-40 wt% nickel as the raw material for the silver-nickel layer, such as AgNi(5), AgNi(10), AgNi(15), AgNi(20), AgNi(30), and AgNi(40). This is because the resistivity of such silver-nickel materials is lower than that of solder or solder paste materials. This results in a lower temperature rise in the silver-nickel / silver-based metal oxide contact material after welding and assembling it into low-voltage electrical appliances, further improving its performance. Furthermore, silver-nickel materials also exhibit excellent electrical properties in electrical appliances below 20A, further improving the reliability of the appliances.

[0012] Preferably, the material of the silver-based metal oxide layer is selected from any one of cadmium silver oxide, tin silver oxide, zinc silver oxide, copper silver oxide, indium tin silver oxide, nickel silver oxide, and iron silver oxide.

[0013] The beneficial effects of this invention are:

[0014] (1) The present invention uses a silver-nickel layer as the welding layer of the contact material, which not only saves the amount of precious metals used in the welding layer material and reduces the material cost, but also simplifies the welding process, improves production efficiency and product welding quality, thereby effectively improving the quality and performance of electrical appliances; in addition, it solves the problem of brittle fracture or melting fracture of solder material during the production process; secondly, the silver-nickel / silver-based metal oxide contact material provided by the present invention is a two-layer composite material, which greatly simplifies the production process, improves production efficiency and yield, and further reduces the fluctuation of solder layer thickness.

[0015] (2) This invention uses a silver-nickel material with 5-40 wt% nickel as the raw material for the silver-nickel layer. This results in a lower temperature rise of the silver-nickel / silver-based metal oxide contact material after welding and assembling it into low-voltage electrical appliances, thus further improving its performance. In addition, silver-nickel material also has excellent electrical properties in electrical appliances below 20A, which can further improve the reliability of the electrical appliances.

[0016] (3) The present invention uses a segmented atmosphere protection heating method to heat the raw material strip. On the one hand, it can effectively prevent the surface of the silver-based metal oxide strip from being reduced to silver alloy during the heating process, thus ensuring the electrical properties of the silver-based metal oxide material. On the other hand, it can also effectively prevent the nickel particles on the surface of the silver-nickel strip from being oxidized to nickel oxide particles during the heating process, thus ensuring the interfacial bonding strength of the silver-nickel / silver-based metal oxide composite strip after hot rolling and thus ensuring the performance of the contact material.

[0017] (4) The present invention adopts a segmented atmosphere protection cooling method instead of the traditional natural cooling, which can effectively prevent the silver-based metal oxide surface of the silver-nickel / silver-based metal oxide composite strip from being reduced to silver metal alloy material during the cooling process. At the same time, it avoids the nickel particles on the surface of the silver-nickel layer from being oxidized to nickel oxide particles during the cooling process, thus ensuring the electrical performance of the silver-based metal oxide layer of the contact material and the welding performance of the silver-nickel layer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the internal layered structure of silver-nickel / silver-based metal oxide contact materials.

[0019] Figure 2 A schematic diagram illustrating the preparation process of silver-nickel / silver-based metal oxide contact materials;

[0020] Figure 3 The image shows the metallographic structure of the profiled strip contact product produced in Embodiment 1 of the present invention. In the image, 10-silver-nickel / silver-based metal oxide contact material, 11-silver-based metal oxide layer, 12-silver-nickel layer, 21-first feeding machine, 22-second feeding machine, 23-segmented atmosphere-protected resistance furnace, 231-middle section of resistance furnace, 232-front section of resistance furnace, 233-rear section of resistance furnace, 24-rolling mill, 25-segmented atmosphere-protected cooling device, 251-middle section of cooling device, 252-front section of cooling device, 253-rear section of cooling device, 26-limiting device, 27-receiving machine.

[0021] Figure 4 Examples 1-7 describe the silver-nickel / silver-based metal oxide contact materials and their preparation methods. Detailed Implementation

[0022] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0023] Figure 2This is a schematic diagram of the preparation process of the silver-nickel / silver-based metal oxide contact material of the present invention, including a first feeding machine 21, a second feeding machine 22, a segmented atmosphere-protected resistance furnace 23, a rolling mill 24, a segmented atmosphere-protected cooling device 25, a limiting device 26, and a take-up machine 27. The first feeding machine 21 and the second feeding machine 22 respectively rivet the silver-based metal oxide strip and the silver-nickel strip at the head and then draw them together into the segmented atmosphere-protected resistance furnace 23 for heating. Afterwards, they are sent to the rolling mill 24 for hot rolling composite to obtain the silver-nickel / silver-based metal oxide composite strip. The high-temperature silver-nickel / silver-based metal oxide composite strip after hot rolling composite is drawn into the segmented atmosphere-protected cooling device 25 for cooling, and then wound up by the limiting device 26 and the take-up machine 27. The segmented atmosphere-protected resistance furnace 23 is divided into three sections: a middle section 231, a front section 232, and a rear section 233. The middle section 231 is protected with a non-reducing, non-flammable gas, while the front and rear sections 232 are protected with and ignited by non-reducing, combustible gases. The segmented atmosphere-protected cooling device 25 is divided into three sections: a middle section 251, a front section 252, and a rear section 253. The middle section 251 is protected with a non-reducing, non-flammable gas, while the front and rear sections 252 are protected with and ignited by non-reducing, combustible gases. The non-reducing, non-flammable gas is either nitrogen or argon. The non-reducing, combustible gas is any one of natural gas, methane, acetylene, propane, or butane.

[0024] Example 1:

[0025] Example 1 provides an AgNi(5) / AgCdO(12) contact material, comprising a silver-based metal oxide layer AgCdO(12) and a silver-nickel layer AgNi(5). The silver-based metal oxide layer AgCdO(12) has a thickness of 0.50 mm, accounting for 83.30% of the total thickness of the AgNi(5) / AgCdO(12) contact material; the silver-nickel layer AgNi(5) has a thickness of 0.10 mm, accounting for 16.70% of the total thickness of the AgNi(5) / AgCdO(12) contact material.

[0026] The preparation method of the AgNi(5) / AgCdO(12) contact material includes the following steps:

[0027] Step 1. Obtain AgCdO(12) strip with specifications of L×30mm×2.00mm and AgNi(5) strip with specifications of L×30mm×0.40mm by extrusion. Anneal the AgCdO(12) strip and AgNi(5) strip respectively.

[0028] Step 2. After surface treatment, AgCdO(12) strip and AgNi(5) strip are stacked and used as raw material strips. They are then drawn into a segmented atmosphere-protected resistance furnace for segmented atmosphere-protected heating. The heating temperature of the resistance furnace is 650℃. The raw material strip is first heated in the front section of the resistance furnace under the protection of ignited non-reducing combustible natural gas, then heated in the middle section of the resistance furnace under the protection of non-reducing non-combustible nitrogen gas, and finally heated in the rear section of the resistance furnace under the protection of ignited non-reducing combustible natural gas.

[0029] Step 3. The raw material strip after segmented atmosphere-protected heat treatment is fed into the rolling mill and rolled with a rolling deformation of 50% to obtain a 1.20 mm thick AgNi(5) / AgCdO(12) composite strip;

[0030] Step 4. The hot-rolled composite high-temperature AgNi(5) / AgCdO(12) composite strip is drawn into a segmented atmosphere-protected cooling device for segmented atmosphere-protected cooling; wherein, the AgNi(5) / AgCdO(12) composite strip is cooled in the front section of the cooling device under the protection of ignited non-reducing combustible natural gas, then cooled in the middle section of the cooling device under the protection of non-reducing non-combustible nitrogen gas, and finally cooled in the rear section of the cooling device under the protection of ignited non-reducing combustible natural gas; the AgNi(5) / AgCdO(12) composite strip after segmented atmosphere-protected cooling is wound up by a winding machine;

[0031] Step 5. The AgNi(5) / AgCdO(12) composite strip obtained by winding is subjected to intermediate protective annealing according to conventional process. The annealing temperature is 650℃, the annealing time is 1h, and the annealing protective atmosphere is nitrogen.

[0032] Step 6. The annealed AgNi(5) / AgCdO(12) composite strip is cold rolled, and the cold rolling deformation is controlled between 15% and 25%.

[0033] Step 7. Repeat steps 5 and 6 until the thickness of the resulting AgNi(5) / AgCdO(12) composite strip reaches 0.55 mm, thus obtaining the AgNi(5) / AgCdO(12) contact material;

[0034] Step 8. According to actual needs, the AgNi(5) / AgCdO(12) contact material is slitting and processed into irregular strips with specifications of L×3mm×0.50mm. The metallographic structure of the produced irregular strip contact products is shown in the figure. Figure 3 As shown.

[0035] Examples 2-7:

[0036] Examples 2-7 provide silver-nickel / silver-based metal oxide contact materials prepared from different raw materials and their preparation methods. Compared to Example 1, the preparation processes of the silver-nickel / silver-based metal oxide contact materials provided in Examples 2-7 are basically the same. For details of the specific raw materials and preparation parameters, please refer to... Figure 4 .

[0037] Comparative Example 1:

[0038] Comparative Example 1 provides a conventional Ag / AgSnO2(12) contact material, comprising a silver-based metal oxide layer AgSnO2(12) and a welding layer Ag. The silver-based metal oxide layer AgSnO2(12) has a thickness of 1.58 mm, accounting for 87.80% of the total thickness of the Ag / AgSnO2(12) contact material; the welding layer Ag has a thickness of 0.22 mm, accounting for 12.20% of the total thickness of the Ag / AgSnO2(12) contact material.

[0039] Unlike Example 2, this Ag / AgSnO2(12) contact material is prepared using a conventional process, specifically including the following steps:

[0040] Step 1. Obtain AgSnO2(12) strip with specifications of L×45mm×4.30mm and pure Ag strip with specifications of L×45mm×0.60mm by extrusion. Anneal the AgSnO2(12) strip and pure Ag strip respectively.

[0041] Step 2. After surface treatment, AgSnO2(12) tape and pure Ag tape are stacked and drawn into an electric resistance furnace for heating as raw material tape. The heating temperature of the electric resistance furnace is 750℃.

[0042] Step 3. The heat-treated raw material strip is fed into the rolling mill and rolled with a rolling deformation of 55% to obtain an Ag / AgSnO2(12) composite strip with a thickness of 2.20 mm;

[0043] Step 4. The obtained Ag / AgSnO2(12) composite strip is subjected to intermediate annealing according to conventional process, with an annealing temperature of 700℃ and an annealing time of 1.5h;

[0044] Step 5. The annealed Ag / AgSnO2(12) composite strip is cold rolled, and the cold rolling deformation is controlled between 10% and 15%.

[0045] Step 6. Repeat steps 4 and 5 until the thickness of the resulting Ag / AgSnO2(12) composite strip reaches 1.80 mm;

[0046] Step 7. According to actual needs, the Ag / AgSnO2(12) composite strip is slitting and blanking to process it into sheet contact material with a specification of Φ8mm×1.80mm.

[0047] Comparative Example 2:

[0048] Comparative Example 2 provides a conventional BAg(30)CuZn / Ag / AgSnO2(12) contact material, comprising a silver-based metal oxide layer AgSnO2(12), a transition layer Ag coated on one side of the silver-based metal oxide layer AgSnO2(12), and a welding layer BAg(30)CuZn coated on the other side of the transition layer Ag. The silver-based metal oxide layer AgSnO2(12) has a thickness of 1.48 mm, accounting for 82.20% of the total thickness of the BAg(30)CuZn / Ag / AgSnO2(12) contact material; the transition layer Ag has a thickness of 0.22 mm, accounting for 12.20% of the total thickness of the BAg(30)CuZn / Ag / AgSnO2(12) contact material; and the welding layer BAg(30)CuZn has a thickness of 0.10 mm, accounting for 5.60% of the total thickness of the contact material.

[0049] Unlike Example 2, this BAg(30)CuZn / Ag / AgSnO2(12) contact material is prepared using a conventional process, specifically including the following steps:

[0050] Step 1. Obtain AgSnO2(12) strip with specifications of L×45mm×4.30mm and pure Ag strip with specifications of L×45mm×0.60mm by extrusion. Anneal the AgSnO2(12) strip and pure Ag strip respectively.

[0051] Step 2. After surface treatment, AgSnO2(12) tape and pure Ag tape are stacked and drawn into an electric resistance furnace for heating as raw material tape. The heating temperature of the electric resistance furnace is 750℃.

[0052] Step 3. The heat-treated raw material strip is fed into the rolling mill and rolled with a rolling deformation of 55% to obtain an Ag / AgSnO2(12) composite strip with a thickness of 2.20 mm;

[0053] Step 4. The obtained Ag / AgSnO2(12) composite strip is subjected to intermediate annealing according to conventional process, with an annealing temperature of 700℃ and an annealing time of 1.5h;

[0054] Step 5. The annealed Ag / AgSnO2(12) composite strip is cold rolled, and the cold rolling deformation is controlled between 10% and 15%.

[0055] Step 6. Repeat steps 4 and 5 until the thickness of the resulting Ag / AgSnO2(12) composite strip reaches 1.75 mm;

[0056] Step 7. Using medium-frequency induction or high-frequency induction heating, BAg(30)CuZn solder with a specification of L×45mm×0.10mm is fused onto the Ag layer of Ag / AgSnO2(12) composite strip to obtain BAg(30)CuZn / Ag / AgSnO2(12) composite strip;

[0057] Step 8. Cold roll the obtained BAg(30)CuZn / Ag / AgSnO2(12) composite strip to a thickness of 1.80 mm;

[0058] Step 9. The cold-rolled BAg(30)CuZn / Ag / AgSnO2(12) composite strip is subjected to protective annealing treatment at a temperature of 400℃ for 2 hours. The annealing protective atmosphere is argon to obtain BAg(30)CuZn / Ag / AgSnO2(12) contact material.

[0059] Step 10. According to actual needs, the BAg(30)CuZn / Ag / AgSnO2(12) composite strip is slited and blanked to process into sheet contact materials with a specification of Φ8mm×1.80mm.

[0060] Comparative Example 3:

[0061] Comparative Example 3 provides an AgNi(10) / AgSnO2(12) contact material, comprising a silver-based metal oxide layer AgSnO2(12) and a welding layer AgNi(10). The silver-based metal oxide layer AgSnO2(12) has a thickness of 1.58 mm, accounting for 87.80% of the total thickness of the AgNi(10) / AgSnO2(12) contact material; the welding layer AgNi(10) has a thickness of 0.22 mm, accounting for 12.20% of the total thickness of the AgNi(10) / AgSnO2(12) contact material. Unlike Example 2, in the preparation process of this AgNi(10) / AgSnO2(12) contact material, the raw material strip is only heated under nitrogen protection, and the high-temperature AgNi(10) / AgSnO2(12) composite strip after hot rolling composite is cooled by air instead of segmented atmosphere protection cooling. The specific preparation method includes the following steps:

[0062] Step 1. Obtain AgSnO2(12) strip with specifications of L×45mm×4.30mm and AgNi(10) strip with specifications of L×45mm×0.60mm by extrusion, and anneal the AgSnO2(12) strip and AgNi(10) strip respectively;

[0063] Step 2. After surface treatment, AgSnO2(12) strip and AgNi(10) strip are stacked and used as raw material strips to be drawn into a resistance furnace under ordinary atmosphere protection and heated under nitrogen protection at a temperature of 750℃.

[0064] Step 3. The raw material strip after atmospheric heat treatment is fed into the rolling mill and rolled with a rolling deformation of 55% to obtain a 2.20 mm thick AgNi(10) / AgSnO2(12) composite strip;

[0065] Step 4. The hot-rolled composite high-temperature AgNi(10) / AgSnO2(12) composite strip is directly wound up by a winding machine, and its cooling process is natural cooling in air;

[0066] Step 5. The AgNi(10) / AgSnO2(12) composite strip obtained by winding is subjected to intermediate protective annealing according to conventional process. The annealing temperature is 700℃, the annealing time is 1.5h, and the annealing protective atmosphere is nitrogen.

[0067] Step 6. The annealed AgNi(10) / AgSnO2(12) composite strip is cold rolled, and the cold rolling deformation is controlled between 10% and 15%.

[0068] Step 7. Repeat steps 5 and 6 until the thickness of the resulting AgNi(10) / AgSnO2(12) composite strip reaches 1.80 mm, thus obtaining the AgNi(10) / AgSnO2(12) contact material;

[0069] Step 8. According to actual needs, the AgNi(10) / AgSnO2(12) contact material is slitting and blanking to process it into sheet-shaped contact material with a specification of Φ8mm×1.80mm.

[0070] [Performance Testing]

[0071] The sheet contact materials prepared in Example 2 and Comparative Examples 1-3 were welded, and the welded contact assemblies were tested (5 parallel samples per group). The welding effect of the sheet contacts was confirmed using ultrasonic non-destructive testing equipment and shear force testing equipment. The test results are shown in Table 2.

[0072] Table 2. Welding effect of silver oxide tin sheet contact material

[0073]

[0074] As shown in Table 2, compared with the Ag / AgSnO2(12) sheet contact material produced by conventional process in Comparative Example 1, the AgNi(10) / AgSnO2(12) sheet contact material prepared in Example 2 is easier to weld, and the welding process does not require the addition of solder or solder paste, which can effectively improve the welding effect of the contact material. The welded contact assembly has a higher brazing rate and shear force, further improving the performance of the electrical appliance.

[0075] Compared to Example 2, the BAg(30)CuZn / Ag / AgSnO2(12) sheet contact material produced by conventional process in Comparative Example 2 has more production steps and lower production efficiency. In addition, there are problems such as brittle fracture, melting and uneven cladding thickness during the cladding process, resulting in low product yield and affecting the welding effect of the contact material. This reduces the brazing rate and shear force of the contact assembly after welding, thereby reducing the performance of the electrical appliance.

[0076] Compared to Example 2, under the same experimental conditions, Comparative Example 3 used only nitrogen protection during the heat treatment of the raw material strip, and the high-temperature AgNi(10) / AgSnO2(12) composite strip after hot rolling composite was cooled with air instead of segmented atmosphere protection cooling. As a result, the welding effect of the AgNi(10) / AgSnO2(12) sheet contact material obtained in this way was worse, and the brazing rate and shear force of the contact assembly after welding decreased sharply. It can be seen that the selection of the gas protection method during the heat treatment and cooling treatment before and after hot rolling composite has a significant impact on the welding effect and performance of AgNi(10) / AgSnO2(12) contact material.

[0077] In summary, this invention, through the ingenious combination of various technical solutions and the good control of numerical range, effectively improves the welding effect of silver-nickel / silver-based metal oxide contact materials, thereby enhancing the performance of electrical appliances.

[0078] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing a silver-nickel / silver-based metal oxide contact material, characterized in that, The method includes: The raw material strip, which is composed of stacked silver-nickel strip and silver-based metal oxide strip, is subjected to segmented atmosphere protection heating and then rolled composite to obtain silver-nickel / silver-based metal oxide composite strip. Silver-nickel / silver-based metal oxide composite strips are subjected to segmented atmosphere-protected cooling, followed by winding, annealing, and rolling to obtain silver-nickel / silver-based metal oxide contact materials. The segmented atmosphere protection heating includes: pre-stage heating of the raw material strip under the protection of ignited non-reducing combustible gas, followed by mid-stage heating under the protection of non-reducing non-combustible gas, and finally post-stage heating under the protection of ignited non-reducing combustible gas. The segmented atmosphere protection cooling includes: front-stage cooling of the silver-nickel / silver-based metal oxide composite strip under the protection of ignited non-reducing combustible gas, followed by mid-stage cooling under the protection of non-reducing non-combustible gas, and finally rear-stage cooling under the protection of ignited non-reducing combustible gas.

2. The method as described in claim 1, characterized in that, The temperature of the segmented atmosphere-protected heating is 650~940℃.

3. The method as described in claim 1, characterized in that, The non-reducing non-flammable gas is selected from at least one of nitrogen or argon; The non-reducing combustible gas is selected from any one of natural gas, methane, acetylene, propane, and butane.

4. The method as described in claim 1 or 2, characterized in that, The method further includes: post-processing the silver-nickel / silver-based metal oxide contact material to obtain the finished silver-nickel / silver-based metal oxide contact material of the required specifications.

5. The silver-nickel / silver-based metal oxide contact material prepared by the method as described in claim 1 or 2, characterized in that, The silver-nickel / silver-based metal oxide contact material includes a silver-based metal oxide layer and a silver-nickel layer.

6. The silver-nickel / silver-based metal oxide contact material as described in claim 5, characterized in that, The thickness of the silver-nickel layer accounts for 5 to 40% of the total thickness of the contact material.

7. The silver-nickel / silver-based metal oxide contact material as described in claim 5, characterized in that, The silver-nickel layer comprises 5 to 40 wt% nickel.

8. The silver-nickel / silver-based metal oxide contact material as described in claim 5, characterized in that, The material of the silver-based metal oxide layer is selected from any one of cadmium silver oxide, tin silver oxide, zinc silver oxide, copper silver oxide, indium tin silver oxide, nickel silver oxide, and iron silver oxide.

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