Ni-me co-doped modified silver tungsten electric contact material and preparation method thereof

Abstract

This invention discloses a Ni-Me co-doped modified silver-tungsten electrical contact material and its preparation method. The preparation method of the silver-tungsten electrical contact material includes the following steps: (1) Weigh each component according to the following formula for later use; Ni 1.0-1.8 wt.%, Me 0.1-0.5 wt.%, silver powder 35-45 wt.%, and the balance is tungsten powder; wherein, Me represents the doping element Co, Sr or Ti; the doping element is weighed in the form of its nitrate; (2) Perform a mechanical alloying-assisted molten salt decomposition reaction on the weighed components to obtain Ni-Me co-doped AgW powder; (3) The obtained powder is molded to obtain a Ni-Me co-doped AgW skeleton, and the obtained skeleton and Ag sheet are placed in a protective atmosphere for melting and infiltration to obtain the final product. The Ag / W electrical contact material prepared by this method has a low wetting angle at the interface between the W phase and the Ag phase, exhibiting excellent salt spray corrosion resistance and electrical lifetime.

Description

Technical Field

[0001] This invention relates to the field of electrical contact materials technology, specifically to a Ni-Me co-doped modified silver-tungsten electrical contact material and its preparation method. Background Technology

[0002] With the rapid development of new energy industries such as photovoltaics and wind power, the demand for highly reliable power equipment in the new energy field is increasing, which has driven the significant development of high-performance silver-based electrical contact materials for control electrical appliances in power equipment. Large-scale photovoltaic and wind power plants in China are often built in coastal or high-altitude areas in the central and western regions with large temperature differences between day and night. They face harsh natural environments such as cold and heat, strong radiation, strong pipe bursts, humidity, condensation, icing, and strong salt corrosion, posing significant challenges to the comprehensive performance of silver-based electrical contact materials for control electrical appliances in new energy systems, including their resistance to damp heat during switching and their service life.

[0003] In the silver-based electrical contact material system, silver-tungsten electrical contact material (Ag / W electrical contact material) is one of the key materials in new energy control electrical appliances. Ag / W electrical contact materials exhibit poor salt spray corrosion resistance and short service life during the service of new energy control electrical appliances. A major reason for this is the poor wettability of the W phase and Ag phase interface and the uneven silver infiltration structure of the W skeleton in Ag / W electrical contact materials. In response, relevant scholars have introduced trace additives such as Ni, Cu, and Ce or adjusted factors such as the partial pressure of melting and infiltration hydrogen and melting and infiltration temperature to reduce the wetting angle of the W phase and Ag phase interface (Zhang Xiufang, Fang Yaoxing, Song Ke, et al. Development of AgWNi contact material for miniature circuit breakers [J]. Electrical Engineering Materials, 2010(4):20-22.). Meanwhile, some scholars have improved the electrical life of Ag / W electrical contact materials by adjusting powder metallurgy process parameters, infiltration process, W phase structure and particle size. Studies have found that Ag / W electrical contact materials composed of fine tungsten particles have better anti-welding properties. However, because fine tungsten is more easily oxidized, it performs poorly in terms of contact resistance, which leads to a decrease in the salt spray corrosion resistance of Ag / W electrical contact materials and a shortened service life (Chi H. Leung, Christine Bourda, Yusheng Cui, Lifu Hu. Weibull and Gamma analysis of contact fusion welding of AgW contacts with different tungsten particle sizes [C] / / . Proceedings of the 5th International Conference on Reliability and Electrical Contact of Electrical Products. 2014:46-51.).

[0004] The present invention aims to obtain a multi-component composite co-doped AgW framework with low Ag and W two-phase wetting angle by controlling the introduction method and content of trace doping elements and the molding process, and to further prepare Ag / W electrical contact materials with the obtained framework, so as to effectively improve the performance of the obtained electrical contact materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the prior art, such as poor wettability of the W phase and Ag phase interface and uneven silver infiltration structure of W skeleton. The invention provides a Ni-Me co-doped modified silver-tungsten electrical contact material and its preparation method. The Ag / W electrical contact material prepared by the method has a low wetting angle at the W phase and Ag phase interface, and exhibits excellent salt spray corrosion resistance and electrical lifetime.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing a Ni-Me co-doped modified silver-tungsten electrical contact material includes the following steps:

[0008] (1) Using tungsten powder as raw material and Ni and Me as doping elements, weigh out each component according to the following formula for later use;

[0009] Ni 1.0–1.8 wt.%, Me 0.1–0.5 wt.%, silver powder 35–45 wt.%, balance tungsten powder;

[0010] Where Me represents Co, Sr or Ti; when weighing, the dopant element is weighed in the form of its nitrate.

[0011] (2) The weighed tungsten powder, silver powder and the corresponding nitrates of the doped elements are mechanically alloyed, and the resulting material is placed in a reducing atmosphere to carry out molten salt decomposition reaction to obtain Ni-Me co-doped AgW powder.

[0012] (3) The obtained Ni-Me co-doped AgW powder is molded to obtain a Ni-Me co-doped AgW skeleton. The obtained skeleton and Ag sheet are placed in a protective atmosphere for melting and infiltration to obtain the Ni-Me co-doped modified silver tungsten electrical contact material.

[0013] In step (1) of the above preparation method, tungsten powder with an average particle size of 0.8 to 0.9 μm is usually selected as raw material.

[0014] In step (1) of the above preparation method, when Me represents Co, it is weighed in the form of Co(NO3)3 for later use; when Me represents Sr, it is weighed in the form of Sr(NO3)2 for later use; when Me represents Ti, it is weighed in the form of Ti(NO3)4 for later use; and Ni is weighed in the form of Ni(NO3)2 for later use.

[0015] In step (2) of the above preparation method, the mechanical alloying process is the same as in the prior art. Preferably, the weighed components are placed in a ball mill jar and ball-milled at 300–500 rpm for 10–30 h under an inert atmosphere (such as nitrogen, argon, or nitrogen atmosphere). In this step, the molten salt decomposition reaction is preferably carried out at 200–500 °C for a reaction time of 2–5 h; the reducing atmosphere usually refers to a hydrogen atmosphere.

[0016] In step (3) of the above preparation method, compression molding is preferably performed at a pressing pressure of 7.0–9.0 T / cm. 2 The experiment was conducted under controlled conditions, with the density of the resulting skeleton controlled at 11.0–11.8 g / cm³. 3 In this step, the melting temperature is typically 1050–1150°C, and the melting time is typically 30–60 minutes; the protective atmosphere typically refers to a hydrogen or ammonia decomposition gas atmosphere.

[0017] The present invention also includes Ni-Me co-doped modified silver-tungsten electrical contact materials prepared by the above method.

[0018] Compared with existing technologies, this invention introduces a trace amount of the modifying component Me into the W skeleton, which helps to regulate the chemical potential difference between the Ag matrix and the W component. Ni-Me co-doped AgW powder is prepared using a mechanical alloying-assisted molten salt decomposition method. A high-porosity modified AgW skeleton is obtained through a molding process, effectively reducing the wetting angle between the modified skeleton and the silver matrix. This promotes the smooth spread of molten silver during the melting and infiltration of the W skeleton, forming a uniform and dense silver-infiltrated structure without problems of incomplete or excessive infiltration. This achieves higher density in the modified Ag / W electrical contact material and improves its salt spray corrosion resistance. Furthermore, the prepared modified Ag / W electrical contact material exhibits lower resistivity (during arc erosion, the contact resistance (R) of the modified Ag / W electrical contact material is lower, and the corresponding Joule heating effect decreases (Q = I)). 2 Rt) reduces the thermal shock of high-temperature electric arc on modified Ag / W electrical contact materials, improves the stability of electrical contact performance of modified Ag / W electrical contact materials during electric arc action, and thus improves the cycle life of modified Ag / W electrical contact materials. Attached Figure Description

[0019] Figure 1 These are photographs of the Ni-Co co-doped AgW framework prepared in Example 1 of this invention and the final Ni-Co co-doped modified AgW(50) electrical contact material, wherein (a) is the Ni-Co co-doped AgW framework and (b) is the final Ni-Co co-doped modified AgW(50) electrical contact material.

[0020] Figure 2This is a micrograph (200×) of the Ni-Co co-doped modified AgW(50) electrical contact material finally prepared in Example 1 of the present invention. Detailed Implementation

[0021] To better explain the technical solution of the present invention, the present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0022] Example 1: Preparation of Ni-Co co-doped modified AgW(50) electrical contact material

[0023] (1) Weigh out each component according to the following formula and set aside:

[0024] Ni 1.0 wt.%, Co 0.5 wt.%, silver powder (average particle size 70-74 μm) 40 wt.%, balance tungsten powder (average particle size 0.8-0.9 μm);

[0025] When weighing, Ni and Co elements are weighed in the forms of Ni(NO3)2 and Co(NO3)3, respectively;

[0026] (2) Weigh out tungsten powder, silver powder, Ni(NO3)2 and Co(NO3)3 and place them in a ball mill jar. Under nitrogen atmosphere protection, the mixture is ball milled at 300 rpm for 30 h. The resulting material is placed in a reduction furnace that is pre-protected by hydrogen atmosphere and kept at 500℃ for 2 h to obtain Ni-Co co-doped AgW powder.

[0027] (3) The obtained Ni-Co co-doped AgW powder was processed by compression molding to obtain the corresponding co-doped AgW framework. The specific molding process was as follows: the pressing pressure was 7.5T / cm. 2 The density of the resulting skeleton was controlled to be 11.2 g / cm³. 3 A Ni-Co co-doped AgW skeleton with a porosity of 17% was obtained. Then, Ag sheets were weighed according to a Ni-Co co-doped AgW skeleton to Ag sheets weight ratio of 4.5:1. The skeleton and Ag sheets were stacked together and placed in a graphite boat and placed in a high-temperature furnace for melting and infiltration. The melting and infiltration was carried out in a hydrogen atmosphere at a temperature of 1050℃ for 60 minutes to obtain Ni-Co co-doped modified AgW(50) electrical contact material.

[0028] The Ni-Co co-doped AgW framework prepared in this embodiment and the physical photos of the finally obtained Ni-Co co-doped modified AgW(50) electrical contact material are shown below. Figure 1 As shown, the microstructure of the Ni-Co co-doped modified AgW(50) electrical contact material finally prepared in this embodiment is as follows. Figure 2 As shown.

[0029] Comparative Example 1

[0030] Repeat Example 1, except that Co is omitted from the formulation in step (1), and the amount of tungsten powder is increased by 0.5 wt.%.

[0031] Comparative Example 2

[0032] Repeat Example 1, except that Ni and Co elements are omitted in the formulation of step (1), and the amount of tungsten powder is increased by 1.5 wt.%.

[0033] Comparative Example 3

[0034] (1) Weigh out each component according to the following formula and set aside:

[0035] Ni powder (average particle size 5-8 μm) 1.0 wt.%, Co powder (average particle size 6-12 μm) 0.5 wt.%, silver powder (average particle size 70-74 μm) 40 wt.%, balance tungsten powder (average particle size 0.8-0.9 μm);

[0036] (2) Weigh out tungsten powder, silver powder, Ni powder and Co powder and place them in a ball mill jar. Under nitrogen atmosphere protection, the mixture is ball milled at 300 rpm for 30 h. The resulting material is placed in a reduction furnace that is pre-protected by hydrogen atmosphere and kept at 500℃ for 2 h to obtain Ni-Co co-doped AgW powder.

[0037] (3) Same as Example 1.

[0038] Example 2: Preparation of Ni-Sr co-doped modified AgW(50) electrical contact material

[0039] (1) Weigh out each component according to the following formula and set aside:

[0040] Ni 1.8 wt.%, Sr 0.2 wt.%, silver powder (average particle size 70-74 μm) 42 wt.%, balance tungsten powder (average particle size 0.8-0.9 μm);

[0041] When weighing, Ni and Sr elements are weighed in the form of Ni(NO3)2 and Sr(NO3)2, respectively.

[0042] (2) Weigh out tungsten powder, silver powder, Ni(NO3)2 and Sr(NO3)2 and place them in a ball mill jar. Under nitrogen atmosphere protection, ball mill at 400 rpm for 20 h. The resulting material is placed in a reduction furnace that is pre-protected by hydrogen atmosphere and kept at 200℃ for 5 h to obtain Ni-Sr co-doped AgW powder.

[0043] (3) The obtained Ni-Sr co-doped AgW powder was processed by compression molding to obtain the corresponding co-doped AgW framework. The specific molding process was as follows: the pressing pressure was 8.0 T / cm.2 The density of the resulting skeleton was controlled to be 11.5 g / cm³. 3 A Ni-Sr co-doped AgW skeleton with a porosity of 14% was obtained. Then, Ag sheets were weighed according to a Ni-Sr co-doped AgW skeleton to Ag sheets weight ratio of 5.6:1. The skeleton and Ag sheets were stacked together and placed in a graphite boat and placed in a high-temperature furnace for melting and infiltration. The melting and infiltration was carried out in a hydrogen atmosphere at a temperature of 1080℃ for 30 minutes to obtain Ni-Sr co-doped modified AgW(50) electrical contact material.

[0044] Example 3: Preparation of Ni-Ti co-doped modified AgW(55) electrical contact material

[0045] (1) Weigh out each component according to the following formula and set aside:

[0046] Ni 1.5 wt.%, Ti 0.3 wt.%, silver powder (average particle size 70-74 μm) 35 wt.%, balance tungsten powder (average particle size 0.8-0.9 μm);

[0047] When weighing, Ni and Ti elements are weighed in the forms of Ni(NO3)2 and Ti(NO3)4, respectively.

[0048] (2) Weigh out tungsten powder, silver powder, Ni(NO3)2 and Ti(NO3)4 and place them in a ball mill jar. Under nitrogen atmosphere protection, ball mill at 300 rpm for 30 h. The resulting material is placed in a reduction furnace pre-protected by hydrogen atmosphere and kept at 400℃ for 3.5 h to obtain Ni-Ti co-doped AgW powder.

[0049] (3) The obtained Ni-Co co-doped AgW powder was processed by compression molding to obtain the corresponding co-doped AgW framework. The specific molding process was as follows: the pressing pressure was 9.0 T / cm. 2 The density of the resulting skeleton was controlled to be 11.8 g / cm³. 3 A Ni-Ti co-doped AgW skeleton with a porosity of 16% was obtained. Then, Ag sheets were weighed according to the weight ratio of Ni-Ti co-doped AgW skeleton to Ag sheets of 4.85:1. The skeleton and Ag sheets were stacked together and placed in a graphite boat and placed in a high-temperature furnace for melting and infiltration. The melting and infiltration was carried out in a hydrogen atmosphere at a temperature of 1150℃ for 30 minutes to obtain Ni-Ti co-doped modified AgW (55) electrical contact material.

[0050] The AgW skeletons prepared in the above examples and the final Ag / W electrical contact materials were used as research objects. The porosity, wettability at the Ag droplet interface, and resistivity of the AgW skeletons were characterized and analyzed using a porosimeter, a video contact angle meter, and a resistivity meter. The salt spray corrosion resistance and cycle life of the final Ag / W electrical contact materials were tested according to industry testing standards for salt spray resistance and electrical life service performance. The results are shown in Table 1 below.

[0051] Table 1:

[0052]

[0053] As shown in Table 1, the method described in this invention (Examples 1-3) can yield Ni-Me co-doped modified Ag / W electrical contact materials with excellent salt spray resistance (>100h) and mutual wetting between the AgW skeleton and the Ag interface. Compared with Comparative Examples 1-3, the prepared Ni-Me co-doped Ag / W electrical contact materials exhibit superior performance in terms of interface wettability, salt spray resistance, resistivity, and cycle life. Among them, the Ni-Co co-doped modified Ag / W electrical contact material shows the best service performance in terms of salt spray resistance and electrical life, and is expected to realize the engineering application of Ni-Me co-doped modified Ag / W electrical contact materials in the field of new energy.

Claims

1. A method for preparing a Ni-Me co-doped modified silver-tungsten electrical contact material, comprising the following steps: (1) Using tungsten powder as raw material and Ni and Me as doping elements, weigh out each component according to the following formula for later use; Ni 1.0–1.8 wt.%, Me 0.1–0.5 wt.%, silver powder 35–45 wt.%, balance tungsten powder; Where Me represents Co, Sr or Ti; when weighing, the dopant element is weighed in the form of its nitrate. (2) The weighed tungsten powder, silver powder and the corresponding nitrates of the doped elements are mechanically alloyed, and the resulting material is placed in a reducing atmosphere to carry out molten salt decomposition reaction to obtain Ni-Me co-doped AgW powder. (3) The obtained Ni-Me co-doped AgW powder is molded to obtain a Ni-Me co-doped AgW skeleton. The obtained skeleton and Ag sheet are placed in a protective atmosphere for melting and infiltration to obtain the Ni-Me co-doped modified silver tungsten electrical contact material.

2. The preparation method according to claim 1, characterized in that, In step (1), when Me represents the Co element, it is weighed in the form of Co(NO3)3; when Me represents the Sr element, it is weighed in the form of Sr(NO3)2; when Me represents the Ti element, it is weighed in the form of Ti(NO3)4; and the Ni element is weighed in the form of Ni(NO3)2.

3. The preparation method according to claim 1, characterized in that, In step (1), the average particle size of the tungsten powder is 0.8 to 0.9 μm.

4. The preparation method according to claim 1, characterized in that, In step (2), the mechanical alloying process is as follows: ball milling at a speed of 300-500 rpm for 10-30 hours in an inert atmosphere.

5. The preparation method according to claim 1, characterized in that, In step (2), the molten salt decomposition reaction is carried out at 200–500 °C.

6. The preparation method according to claim 1, characterized in that, In step (3), compression molding is performed at a pressing pressure of 7.0–9.0 T / cm. 2 The experiment was conducted under controlled conditions, with the density of the resulting skeleton controlled at 11.0–11.8 g / cm³. 3 .

7. The preparation method according to claim 1, characterized in that, In step (3), the melting temperature is 1050-1150℃ and the time is 30-60min.

8. The Ni-Me co-doped modified silver-tungsten electrical contact material prepared by the method according to any one of claims 1 to 7.

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