Preparation method of high-performance silver alloy-based electric contact material

Abstract

The invention discloses a preparation method of a high-performance silver alloy-based electric contact material, and belongs to the technical field of silver-based composite material preparation. The preparation method comprises the following steps: (1) carrying out ball milling on pure silver powder and alloy element powder to obtain silver alloy powder; (2) the silver alloy powder and the silver oxide powder obtained in the step (1) are subjected to ball milling treatment, and composite powder is obtained; and (3) the composite powder obtained in the step (2) is subjected to hot pressed sintering, and the silver alloy-based electric contact material is obtained. Silver oxide is used as an oxygen source, oxygen elements are introduced, and the oxygen elements are distributed more widely, uniformly and stably, so that reinforcing phase elements are more easily in contact with the oxygen elements to synthesize a metal oxide reinforcing phase in situ, the reinforcing effect of the silver alloy-based electric contact material is more uniform, and the reinforcing effect of the reinforcing phase elements is more fully exerted.

Description

Technical Field

[0001] The invention belongs to the technical field of silver-based composite material preparation, and relates to a method for preparing a high-performance silver alloy-based electrical contact material. Background Art

[0002] Silver alloy-based electrical contact materials are widely used in electrical contact applications such as circuit breakers, contactors, ignition systems, temperature control switches, and wind turbines due to their excellent resistance to welding, corrosion, mechanical wear, low contact resistance, and mechanical properties. However, with the continuous advancement of technology, the performance requirements for silver alloy-based electrical contact materials in related technical fields are also increasing. Therefore, it is necessary to further strengthen silver alloy-based electrical contact materials to achieve even better performance to meet these increasingly demanding performance requirements.

[0003] At present, the performance of silver alloy-based electrical contact materials is mainly enhanced by reinforcing phase composites. The reinforcing phases mainly include graphite, ceramics, metal oxides, etc. By strengthening the reinforcing phase, the silver alloy-based electrical contact materials can have more excellent mechanical properties and meet more stringent usage requirements. Among them, strengthening the silver alloy-based electrical contact materials with metal oxides can not only improve the mechanical properties of the silver alloy-based electrical contact materials, but also enhance the arc erosion resistance of the silver alloy-based electrical contact materials. Therefore, metal oxide-reinforced silver alloy-based electrical contact materials have received widespread attention and have a wide range of applications.

[0004] Existing metal oxide reinforced silver alloy-based electrical contact materials usually first introduce the elemental elements of the metal oxide reinforcement phase into silver, and then oxidize the elemental elements of the reinforcement phase to convert them into metal oxides to become reinforcement phases. When the elemental elements of the reinforcement phase exist in the silver alloy-based electrical contact material, the reinforcement effect cannot be achieved. Therefore, the oxidation effect of the elemental elements directly affects the reinforcement effect of the final silver alloy-based electrical contact material. The more fully the elemental elements in the silver alloy-based electrical contact material are oxidized, the more of the elements originally evenly distributed in the material can be converted into metal oxides, thereby obtaining more metal oxide reinforcement phases, and making the distribution of metal oxides in the material more uniform, thereby making the elemental elements of the reinforcement phase more fully exert their reinforcement effect, and making the metal oxide reinforcement phase more uniform in the reinforcement effect of the silver alloy-based electrical contact material, and finally making the performance of the silver alloy-based electrical contact material more uniform, which is beneficial to its practical use.

[0005] Therefore, it is necessary to provide a preparation method for high-performance silver alloy-based electrical contact materials, so that the reinforcing phase element distributed in the material can be oxidized more fully, thereby promoting the generation of more metal oxides in the silver alloy-based electrical contact materials, giving full play to the strengthening effect of the reinforcing phase elements, and making the performance of the silver alloy-based electrical contact materials more uniform. Summary of the Invention

[0006] In order to overcome the problems in the background technology, the present invention introduces oxygen elements by using silver oxide as an oxygen source, and utilizes the strong brittleness of silver oxide itself to make it easier to be broken and evenly mixed with the silver alloy powder during the ball milling dispersion process. In addition, after the silver oxide and the silver alloy powder are ball milled, the silver oxide can also be anchored on the surface of the silver alloy powder, so that the oxygen element can better maintain uniform dispersion, making the distribution of the oxygen element in the material more extensive and more uniform, thereby increasing the probability that the reinforcing phase element (alloy element) distributed in the material contacts the oxygen element and undergoes in-situ synthesis to generate metal oxides, thereby making the element oxidation more complete.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions: The present invention provides a method for preparing a high-performance silver alloy-based electrical contact material, the preparation method comprising the following steps: (1) ball milling pure silver powder and alloy element powder to obtain silver alloy powder; (2) ball milling the silver alloy powder and silver oxide powder obtained in step (1) to obtain a composite powder; (3) The composite powder obtained in step (2) is subjected to hot pressing and sintering to obtain a silver alloy-based electrical contact material.

[0008] Preferably, in step (1), the alloy element powder includes one or two of copper, nickel, chromium, tin and cadmium.

[0009] Preferably, in step (1), the total mass of the alloying element powder added is 0.2% to 2.0% of the total mass of the pure silver powder and the alloying element powder. When there are multiple alloying element powders, it is preferred that the mass percentage of each alloying element powder added is equal to the mass percentage of the pure silver powder and the alloying element powder.

[0010] Preferably, in step (1), the ball milling speed is 300-800 r / min, the ball milling time is 6-12 h, the ball-to-material ratio is 10:1, and argon gas is used for protection during the ball milling process.

[0011] Preferably, in step (2), the mass percentage of the added mass of silver oxide in the total mass of the silver alloy powder is equal to the mass percentage of the total mass of the alloying element powder in the total mass of the pure silver powder and the alloying element powder.

[0012] Preferably, in step (2), the ball milling speed is 100-300 r / min, the ball milling time is 2-6 h, the ball-to-material ratio is 10:1, and argon gas is used for protection during the ball milling process.

[0013] As a preference, in step (3), the hot pressing sintering vacuum degree is <10 -1Pa, the sintering temperature is 600~850℃, the holding time is 60~180min, and the sintering pressure is 50MPa.

[0014] Preferably, in step (3), the hot pressing sintering heating rate is 10°C / min.

[0015] Beneficial effects of the present invention: 1. The present invention uses silver oxide as an oxygen source to introduce oxygen into the silver alloy powder. Taking advantage of the strong brittleness of silver oxide, it is easily broken and mixed during the ball milling mixing process, making the silver oxide more evenly distributed in the silver alloy powder, and thus making the distribution of oxygen more uniform and extensive, ultimately increasing the probability of oxidation of the alloying elements that are already uniformly dispersed in the pure silver powder, and making the oxidation of the alloying elements more complete.

[0016] 2. The present invention uses silver oxide as an oxygen source. After ball milling with silver alloy powder, the silver oxide can be anchored on the surface of the silver alloy powder, thereby maintaining good uniformity and dispersion of the oxygen element during the hot pressing and sintering process. During the hot pressing and sintering process, the alloying elements have a higher probability of contacting with the oxygen element and undergoing in-situ synthesis to form a metal oxide reinforcement phase, thereby distributing more metal oxides in the material, achieving a more uniform strengthening effect and high quality.

[0017] 3. Since the process of in-situ synthesis of alloying elements and oxygen elements to form a metal oxide reinforcement phase takes place during the hot pressing sintering stage, and hot pressing sintering applies pressure to the composite powder, hot pressing sintering is beneficial to alleviate defects such as bubbles and hollows generated during the in-situ synthesis of alloying elements and oxygen elements, thereby reducing the impact of the aforementioned defects on silver alloy-based electrical contact materials.

[0018] 4. The preparation method of the present invention is relatively simple, has good applicability, relatively low energy consumption, and is suitable for industrial promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the process flow of the preparation method of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0021] Example 1 In this embodiment, a tin oxide particle reinforced silver-based composite material was prepared by the following preparation method: (1) Pure Ag powder with a purity of 99.9% and a particle size of 2 μm and Sn powder with a purity of 99.9% and a particle size of about 50 nm were ball-milled to disperse the nano-Sn powder evenly in the pure Ag powder, thereby obtaining flaky silver alloy powder. During the ball milling process, the ball mill speed was 300 r / min, the ball milling time was 12 h, the ball-to-material ratio was 10:1, and the ball mill was filled with high-purity argon for protection. The amount of Sn powder added was 0.5% of the total mass of the Sn and Ag powders, and was recorded as Ag-0.5Sn powder.

[0022] (2) The Ag-0.5Sn powder and silver oxide obtained in step (1) are added to a ball mill and uniformly mixed to obtain a composite powder; wherein the ball mill speed is 100 r / min and the ball milling time is 6 h; the amount of silver oxide added is 0.5% of the total mass of the Ag-0.5Sn powder and the silver oxide powder.

[0023] (3) The composite powder obtained in step (2) is subjected to hot pressing and sintering to obtain a tin oxide reinforced silver alloy-based electrical contact material. During the hot pressing and sintering process, the sintering temperature is 600°C, the heat preservation time is 180 minutes, the sintering pressure is 50 MPa, and the vacuum degree is <10 -1 Pa, heating rate 10℃ / min.

[0024] Since silver oxide itself has relatively excellent dispersion properties in this embodiment and can be anchored relatively evenly on the flaky Ag-0.5Sn powder, when silver oxide and Sn powder are in situ synthesized into a tin oxide reinforcement phase, the Sn powder is more thoroughly oxidized into a tin oxide reinforcement phase, and after hot pressing and sintering, there are almost no defects such as bubbles and hollows. Combined with the Sn powder that has been ball-milled and relatively evenly dispersed in the material, the silver alloy-based electrical contact material prepared in this embodiment has a good reinforcement effect and a relatively uniform reinforcement effect.

[0025] Example 2 In this embodiment, a cadmium oxide particle-reinforced silver-based composite material was prepared by the following preparation method: (1) Pure Ag powder with a purity of 99.9% and a particle size of 5 μm and Cd powder with a purity of 99.9% and a particle size of about 10 nm were ball-milled to make the nano-Cd powder dispersed evenly in the pure Ag powder to obtain flaky silver-based microalloy powder. During the ball milling process, the ball mill speed was 600 r / min, the ball milling time was 8 h, the ball-to-material ratio was 10:1, and the ball mill was filled with high-purity argon for protection; the amount of Cd powder added was 0.2% of the total mass of Cd powder and Ag powder, recorded as Ag-0.2Cd powder.

[0026] (2) The Ag-0.2Cd powder obtained in step (1) and silver oxide are uniformly mixed to obtain a mixed powder; wherein the ball milling speed is 150 r / min and the ball milling time is 4 h; the amount of silver oxide added is 0.2% of the total mass of the Ag-0.2Cd powder and the silver oxide powder, and the remainder is Ag-0.2Cd.

[0027] (3) The composite powder treated in step (2) is hot pressed and sintered to obtain a cadmium oxide reinforced silver-based composite material. During the hot pressing and sintering process, the sintering temperature is 700°C, the heat preservation time is 90 minutes, the sintering pressure is 50 MPa, and the vacuum degree is <10 -1 Pa, heating rate 10℃ / min.

[0028] The strengthening effect of the silver alloy-based composite material prepared in this embodiment is similar to that of the composite material in Example 1.

[0029] Example 3 In this embodiment, nickel oxide particle reinforced silver-based composite material was prepared by the following preparation method: (1) Pure Ag powder with a purity of 99.9% and a particle size of 5 μm and Ni powder with a purity of 99.9% and a particle size of approximately 2 nm were ball-milled to uniformly disperse the nano-Ni powder in the pure Ag powder, resulting in a flaky silver-based microalloy powder, designated as Ag-0.5Ni powder. During the ball milling process, the mill speed was 800 r / min, the milling time was 6 h, the ball-to-material ratio was 10:1, and the milling jar was filled with high-purity argon for protection. The amount of Ni powder added was 0.5% of the total mass of the Ni and Ag powders, with the remainder being pure Ag matrix.

[0030] (2) The Ag-0.5Ni powder obtained in step (1) and silver oxide are homogenized to obtain a mixed powder; wherein the ball milling speed is 300 r / min and the ball milling time is 2 h; the amount of silver oxide added is 0.5% of the total mass of the Ag-0.5Ni powder and the tin hydroxide powder, and the remainder is Ag-0.5Ni.

[0031] (3) The composite powder treated in step (2) is hot pressed and sintered to obtain a nickel oxide reinforced silver matrix composite material. During the hot pressing and sintering process, the sintering temperature is 750°C, the heat preservation is 120 minutes, the sintering pressure is 50 MPa, and the vacuum degree is <10 -1 Pa, heating rate 10℃ / min.

[0032] The strengthening effect of the silver alloy-based composite material prepared in this embodiment is similar to that of the composite material in Example 1.

[0033] Example 4 In this embodiment, a silver alloy-based composite material is prepared by the following preparation method: (1) Pure Ag powder with a purity of 99.9% and a particle size of 5 μm and Ni powder and Sn powder with a purity of 99.9% and a particle size of about 2 nm were ball-milled to make the nano-Ni powder and nano-Sn powder dispersed evenly in the pure Ag powder to obtain flaky silver-based microalloy powder. During the ball milling process, the ball mill speed was 500 r / min, the ball milling time was 12 h, the ball-to-material ratio was 10:1, and the ball mill was filled with high-purity argon for protection; the addition amount of Ni powder and Sn powder was 0.1% of the total mass of Sn powder, Ni powder and Ag powder, and the remainder was pure Ag matrix, recorded as Ag-0.1Ni-0.1Sn powder.

[0034] (2) The Ag-0.1Ni-0.1Sn powder obtained in step (1) and silver oxide are uniformly mixed to obtain a mixed powder; wherein the ball milling speed is 200 r / min and the ball milling time is 2 h; the amount of silver oxide added is 0.2% of the total mass of the Ag-0.1Ni-0.1Sn powder and the silver oxide powder, and the remainder is Ag-0.1Ni-0.1Sn.

[0035] (3) Hot pressing and sintering the composite powder treated in step (2) to obtain a nickel oxide and tin oxide particle reinforced silver-based composite material; during the hot pressing and sintering process, the sintering temperature is 850°C, the heat preservation time is 60 minutes, the sintering pressure is 50 MPa, and the vacuum degree is <10 -1 Pa, heating rate 10℃ / min.

[0036] The strengthening effect of the silver alloy-based composite material prepared in this embodiment is similar to that of the composite material in Example 1.

[0037] Example 5 In this embodiment, a silver alloy-based composite material is prepared by the following preparation method: (1) Pure Ag powder with a purity of 99.9% and a particle size of 5 μm and Ni powder and Sn powder with a purity of 99.9% and a particle size of about 2 nm were ball-milled to make the nano-Ni powder and nano-Sn powder dispersed evenly in the pure Ag powder to obtain flaky silver-based microalloy powder. During the ball milling process, the ball mill speed was 500 r / min, the ball milling time was 12 h, the ball-to-material ratio was 10:1, and the ball mill was filled with high-purity argon for protection; the amount of Ni powder added was 0.7% of the total mass of Sn powder, Ni powder and Ag powder, the amount of Sn powder added was 1.3% of the total mass of Sn powder, Ni powder and Ag powder, and the remainder was pure Ag matrix, recorded as Ag-0.7Ni-1.3Sn powder.

[0038] (2) The Ag-0.7Ni-1.3Sn powder obtained in step (1) and silver oxide are uniformly mixed to obtain a mixed powder; wherein the ball milling speed is 200 r / min and the ball milling time is 2 h; the amount of silver oxide added is 2% of the total mass of the Ag-1Ni-1Sn powder and the silver oxide powder, and the remainder is Ag-1Ni-1Sn.

[0039] (3) The composite powder treated in step (2) is subjected to hot pressing and sintering to obtain a nickel oxide and tin oxide particle reinforced silver-based composite material; during the hot pressing and sintering process, the sintering temperature is 850°C, the heat preservation time is 90 minutes, the sintering pressure is 50 MPa, and the vacuum degree is <10 -1 Pa, heating rate 10℃ / min.

[0040] The strengthening effect of the silver alloy-based composite material prepared in this embodiment is similar to that of the composite material in Example 1.

[0041] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-performance silver alloy-based electrical contact material, characterized in that: The preparation method comprises the following steps: (1) ball milling pure silver powder and alloy element powder to obtain silver alloy powder; (2) ball milling the silver alloy powder and silver oxide powder obtained in step (1) to obtain a composite powder; (3) The composite powder obtained in step (2) is subjected to hot pressing and sintering to obtain a silver alloy-based electrical contact material.

2. The preparation method according to claim 1, wherein: In the step (1), the alloy element powder includes one or two of copper, nickel, chromium, tin and cadmium.

3. The preparation method according to claim 1 or 2, characterized in that: In the step (1), the total mass of the alloy element powder added is 0.2% to 2.0% of the total mass of the pure silver powder and the alloy element powder.

4. The preparation method according to claim 1, wherein: In the step (1), the ball milling speed is 300-800 r / min, the ball milling time is 6-12 h, the ball-to-material ratio is 10:1, and argon gas is used for protection during the ball milling process.

5. The preparation method according to claim 1 or 3, characterized in that: In the step (2), the mass percentage of the added mass of silver oxide to the total mass of the silver alloy powder is equal to the mass percentage of the total mass of the alloying element powder to the total mass of the pure silver powder and the alloying element powder.

6. The preparation method according to claim 1, wherein: In the step (2), the ball milling speed is 100-300 r / min, the ball milling time is 2-6 h, the ball-to-material ratio is 10:1, and argon gas is used for protection during the ball milling process.

7. The preparation method according to claim 1, wherein: In the step (3), the hot pressing sintering vacuum degree is less than 10 - 1 Pa, the sintering temperature is 600~850℃, the holding time is 60~180min, and the sintering pressure is 50MPa.

8. The preparation method according to claim 1 or 7, characterized in that: In the step (3), the hot pressing sintering heating rate is 10°C / min.

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