Silver-tungsten electric contact material

Abstract

The invention discloses a silver-tungsten electric contact material, and belongs to the technical field of silver-tungsten electric contact materials. A W layer with a high melting point and a high specific gravity is used as a base, an Ag layer with high thermal conductivity, high electric conductivity and relatively low specific gravity is used as a deposition layer, Ni, Cr, B, Fe and W are used as reinforcing elements, the Ag / W composite material is prepared by adopting a combined chip electron beam evaporation technology, and the layered composite material with good diffusion interface bonding is finally obtained through a proper heat treatment process. The short-process preparation of the silver-tungsten electric contact material is realized, and a new method is provided for the preparation of the silver-tungsten electric contact material. The prepared silver-tungsten electric contact material has the characteristics of high density, uniform microstructure, high interface bonding strength, good electric conductivity and thermal conductivity, high hardness, wear resistance, no toxicity and the like, and can be applied to the fields of electric appliances such as lighting switches, circuit breakers, contactors and the like.

Description

Technical Field

[0001] The present invention relates to a silver-tungsten electrical contact material, belonging to the technical field of silver-tungsten electrical contact materials. Background Art

[0002] Silver-tungsten electrical contact materials have both the good electrical conductivity and thermal conductivity of silver and the characteristics of tungsten such as high melting point, high hardness, high breaking capacity, arc erosion resistance, wear resistance, anti-welding, and less material transfer, and are widely used in fields such as lighting switches, universal circuit breakers, molded case circuit breakers, and leakage circuit breakers. At present, the main preparation methods of silver-tungsten electrical contact materials are as follows: (1) Solid-phase sintering and repressing densification method. The process is: first, tungsten powder and silver powder are mixed evenly in proportion, then the mixture is pressed into shape in a mold, solid-phase sintering is carried out in a hydrogen atmosphere, and then the blank is placed in the mold for repressing densification. The relative density of the material can reach more than 96%. This method is only used for materials with a tungsten content less than 60%. (2) Liquid-phase sintering and repressing densification method. In order to improve the density of the material, when mixing tungsten powder and silver powder, an activated sintering element nickel or cobalt is added, then the mixture is pressed into shape in a mold, liquid-phase sintering is carried out in a hydrogen atmosphere, and then the blank is placed in the mold for repressing densification. The relative density of the material reaches more than 98%. The materials prepared by this method have uneven structures, and their mechanical properties, electrical conductivity, and thermal conductivity are relatively low. (3) Tungsten skeleton infiltration method. Using the infiltration principle of powder metallurgy, first, tungsten powder, activator powder, and silver powder are mixed in proportion, then the mixture is pressed into shape in a mold, high-temperature tungsten skeleton sintering is carried out in a hydrogen atmosphere, and then the tungsten skeleton is infiltrated with silver at high temperature and in a hydrogen atmosphere. The relative density of the material can reach 98%. The materials prepared by this method have greatly improved electrical conductivity, thermal conductivity, hardness, strength, and density, and are suitable for preparing high-performance silver-tungsten materials. In practical applications, silver-tungsten composite materials with a high tungsten content have higher application values. However, due to the poor diffusion ability of silver to tungsten, it is very difficult to obtain an electrical contact material with a low resistivity by the tungsten skeleton infiltration method under the condition of a low silver content (below 40%). Summary of the Invention

[0003] In order to overcome the problems in the background art, the purpose of the present invention is to provide a silver-tungsten electrical contact material, using a silver alloy as the evaporation material and tungsten as the deposition material, adding elements W, Ni, Cr, B, and Fe to silver to form a solid solution alloy, which plays a role in solid solution strengthening and dispersion strengthening, and at the same time improves the diffusion effect between Ag and W, and improves the physical, mechanical, and electrical contact properties of the silver-tungsten electrical contact material. Furthermore, by using electron beam evaporation technology and diffusion heat treatment technology, the comprehensive properties such as hardness and electrical conductivity of Ag-based electrical contact materials with high W content and low W content are improved.

[0004] In order to achieve the above purpose, the present invention is realized through the following technical solutions:

[0005] A silver-tungsten electrical contact material, comprising the following elements: Ni, Cr, B, Fe, W and Ag;

[0006] The preparation method of the silver-tungsten electrical contact material comprises the following steps: irradiating a silver alloy material with an electron beam in a vacuum environment to change the silver alloy material from a solid state to a gaseous state, then condensing the gaseous substance into a film on the surface of a tungsten substrate, and finally performing heat treatment to obtain the silver-tungsten electrical contact material.

[0007] The silver alloy material contains the following elements by weight percentage: 0.1%-1% Ni, 0.1%-1% Cr, 0.1%-1% B, 0.1%-1% Fe, and the balance is Ag.

[0008] The present invention first uses the combined chip technology to condense a material film on the surface of a tungsten substrate. Through subsequent heat treatment and diffusion treatment, a solid solution strengthening and dispersion strengthening alloy layer of multiple elements is formed. Compared with other single coating technologies, the multi-element alloy layer has a better composite strengthening effect. The combined chip technology is a technology that uses the principle of electron beam evaporation in a vacuum chamber, directly irradiates the silver alloy material placed in a crucible with an electron gun to change the film material from a solid state to a gaseous state, and then condenses it into a film on the surface of the tungsten substrate.

[0009] The electron beam evaporation source consists of three parts: a hot cathode that emits electrons, an electron accelerator, and a coating material as the anode. After the electron gun filament is heated, a large number of thermoelectrons are emitted. These thermoelectrons are accelerated by the acceleration anode, thereby obtaining a large amount of kinetic energy. Then, after being deflected by a magnetic field, they finally bombard the material to be evaporated, converting the kinetic energy into heat energy, causing the material to be evaporated to vaporize, and finally depositing on the substrate to achieve evaporation coating. The energy of the electron beam evaporation source can be highly concentrated, causing the local area of the coating material to reach a high temperature and evaporate, without affecting the material in the area not bombarded by the electron beam. During the experiment of the present invention, the evaporation rate of the coating material is precisely controlled by adjusting the power of the electron beam, and at the same time, the growth rate and thickness of the thin film are monitored by a crystal oscillator film thickness gauge; the controllable process parameters of the electron beam evaporation method mainly include voltage, current, time, heat treatment temperature, time, etc. By changing the process parameters, the composition, structure, density, etc. of the prepared thin film material can be regulated.

[0010] Then, by combining the combined chip technology and the heat treatment technology, the density of the material is effectively increased, and the obtained microstructure is uniform. At the same time, an interdiffusion layer of multiple additive elements is formed by the combined chip technology and the heat treatment technology. On the one hand, the interfacial bonding strength and microstructure uniformity of the Ag / W material are improved, and on the other hand, the density, hardness, strength, and arc ablation performance of the electrical contact material are improved.

[0011] More preferably, the silver alloy material comprises Ni, Cr, B, Fe and Ag.

[0012] More preferably, the voltage of the electron beam is 1 - 50 V, and the current is 1 - 10 A.

[0013] More preferably, the thickness of the film condensed on the surface of the tungsten substrate is (0.1 - 0.3) mm.

[0014] More preferably, the temperature of the heat treatment is 500 - 800 °C, and the time is 10 - 60 min.

[0015] Advantages of the present invention: The present invention uses a W layer with a high melting point (3410 °C) and a high specific gravity (19.26 g / cm 3 ) as the base, and an Ag layer with high thermal conductivity, high electrical conductivity, and a relatively low specific gravity (10.5 g / cm 3 ) as the deposition layer. The Ag / W composite material is prepared by using the combined chip electron beam evaporation technology, and through an appropriate heat treatment process, a laminated composite material with a well-bonded diffusion interface is finally obtained, realizing the short-process preparation of the silver tungsten electrical contact material, and providing a new method for the preparation of the silver tungsten electrical contact material. The prepared silver tungsten electrical contact material has the characteristics of high density, uniform microstructure, high interfacial bonding strength, good electrical and thermal conductivity, high hardness, wear resistance, non-toxicity, etc., and can be applied to electrical fields such as lighting switches, circuit breakers, and contactors. Specific Embodiments

[0016] The following further elaborates the present invention with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0017] In the examples and comparative examples of the present invention, chemical reagents not specified were all used for experiments with commercially available analytical pure reagents.

[0018] Example 1

[0019] A method for preparing a silver tungsten electrical contact material, the preparation steps are as follows:

[0020] (1) In the vacuum chamber of the combined chip electron beam evaporation equipment, the silver alloy material placed in the crucible (specific composition: Ni 0.1 wt%, Cr 0.1 wt%, B 0.1 wt%, Fe 0.1 wt%, the balance is Ag) is directly irradiated by an electron gun. The voltage of the electron beam emitted by the electron gun is 10 V and the current is 1 A. The silver alloy material changes from solid state to gaseous state, and then the gaseous substance condenses into a 0.1 mm thick Ag / W film on the surface of a 1 mm thick tungsten sheet. The produced Ag / W film mainly consists of Ag10W, with a size of 15 × 20 mm, and the content of W is 90%.

[0021] (2) Then, the tungsten sheet with the condensed Ag / W film is heat-treated at 500 °C for 10 min to obtain a silver tungsten electrical contact material thin film.

[0022] Hardness HV of the silver tungsten electrical contact quinary material thin film0.2 is 100, and the conductivity is 90% IACS.

[0023] Example 2

[0024] A preparation method of a silver-tungsten electrical contact material, the preparation steps are as follows:

[0025] (1) In the vacuum chamber of a combined chip electron beam evaporation device, use an electron gun to directly irradiate the silver alloy material placed in the crucible (specific composition: Ni 0.2 wt%, Cr 0.2 wt%, B 0.2 wt%, Fe 0.2 wt%, the balance is Ag). The electron beam voltage emitted by the electron gun is 20 V and the current is 2 A. The silver alloy material changes from solid state to gaseous state, and then the gaseous substance condenses into an Ag / W film (thickness 0.15 mm) on the surface of a 1 mm thick tungsten sheet. The produced Ag / W film mainly consists of Ag15W and has a size of 15×20 mm.

[0026] (2) Then heat-treat the tungsten sheet with the condensed Ag / W film at 550 °C for 15 min to obtain a silver-tungsten electrical contact material thin film.

[0027] The hardness HV of the silver-tungsten electrical contact five-element material thin film 0.2 is 115, and the conductivity is 85% IACS.

[0028] Example 3

[0029] A preparation method of a silver-tungsten electrical contact material, the preparation steps are as follows:

[0030] (1) In the vacuum chamber of a combined chip electron beam evaporation device, use an electron gun to directly irradiate the silver alloy material placed in the crucible (specific composition: Ni 0.3 wt%, Cr 0.3 wt%, B 0.3 wt%, Fe 0.3 wt%, the balance is Ag). The electron beam voltage emitted by the electron gun is 25 V and the current is 3 A. The silver alloy material changes from solid state to gaseous state, and then the gaseous substance condenses into an Ag / W film (thickness 0.2 mm) on the surface of the tungsten sheet. The Ag / W film mainly consists of Ag20W, has a size of 15×20 mm, and the content of W is 80%.

[0031] (2) Then heat-treat the tungsten sheet with the condensed Ag / W film at 600 °C for 20 min to obtain a silver-tungsten electrical contact material thin film.

[0032] The hardness HV of the silver-tungsten electrical contact five-element material thin film 0.2 is 120, and the conductivity is 80% IACS.

[0033] Example 4

[0034] A preparation method of a silver-tungsten electrical contact material, the preparation steps are as follows:

[0035] (1) In the vacuum chamber of the combined chip electron beam evaporation equipment, the electron gun is used to directly irradiate the silver alloy material (specific composition: Ni 0.4 wt%, Cr 0.4 wt%, B 0.4 wt%, Fe 0.4 wt%, the balance is Ag) placed in the crucible. The electron beam voltage emitted by the electron gun is 30 V and the current is 3 A. The silver alloy material changes from solid state to gaseous state, and then the gaseous substance condenses into an Ag / W film (thickness 0.25 mm) on the surface of the tungsten sheet. The composition of the Ag / W film is Ag25W, the size is 15×20 mm, and the content of W is 75%.

[0036] (2) Then, the tungsten sheet with the Ag / W film condensed on it is heat-treated at 650 °C for 20 min to obtain a silver-tungsten electrical contact material thin film.

[0037] The hardness HV of the silver-tungsten electrical contact five-element material thin film 0.2 is 130, and the conductivity is 75% IACS.

[0038] Example 5

[0039] A preparation method of a silver-tungsten electrical contact material, the preparation steps are as follows:

[0040] (1) In the vacuum chamber of the combined chip electron beam evaporation equipment, the electron gun is used to directly irradiate the silver alloy material (specific composition: Ni 1 wt%, Cr 1 wt%, B 1 wt%, Fe 1 wt%, the balance is Ag) placed in the crucible. The electron beam voltage emitted by the electron gun is 35 V and the current is 5 A. The silver alloy material changes from solid state to gaseous state, and then the gaseous substance condenses into an Ag / W film (thickness 0.3 mm) on the surface of the 1 mm thick tungsten sheet. The main composition of the Ag / W film is Ag30W, the size is 15×20 mm, and the content of W is 70%.

[0041] (2) Then, the tungsten sheet with the Ag / W film condensed on it is heat-treated at 700 °C for 20 min to obtain a silver-tungsten electrical contact material thin film.

[0042] The hardness HV of the silver-tungsten electrical contact five-element material thin film 0.2 is 155, and the conductivity is 60% IACS.

[0043] The present invention also explores the influence of the composition of the silver alloy material on the performance of the silver-tungsten electrical contact material thin film, and finds that when a certain element is missing in the silver alloy material, the hardness HV of the silver-tungsten electrical contact material thin film 0.2 significantly decreases, and the change in conductivity is not obvious.

[0044] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. 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 silver-tungsten electrical contact material, characterized in that: Includes the following elements Ni, Cr, B, Fe, W and Ag; The preparation method of the silver-tungsten electrical contact material comprises the following steps: irradiating a silver alloy material with an electron beam in a vacuum environment to change the silver alloy material from a solid state to a gaseous state, then condensing the gaseous substance on the surface of a tungsten substrate to form a film, and finally performing heat treatment to obtain the silver-tungsten electrical contact material; The silver alloy material contains the following elements in percentage by weight: 0.1%-1% Ni, 0.1%-1% Cr, 0.1%-1% B, 0.1%-1% Fe, and the balance is Ag.

2. The silver-tungsten electrical contact material according to claim 1, characterized in that: The voltage of the electron beam is 1-50V, and the current is 1-10A.

3. The silver-tungsten electrical contact material according to claim 1, characterized in that: The heat treatment temperature is 500-800°C and the time is 10-60 minutes.