CN114875267A - Preparation method of silver-based electric contact material with adjustable work function - Google Patents

Abstract

The invention discloses a method for preparing a silver-based electrical contact material with adjustable work function. The method uses Th, Ce or Ba as a work function regulator, and adopts an intermediate frequency induction melting method combined with an internal oxidation method to prepare AgSnO with adjustable work function. ₂ Contact material. The method of the invention can improve the surface work function of the traditional AgSnO ₂ contact material, reduce the surface temperature rise effect and the degree of ablation, and improve the arc erosion resistance and the electrical service life cycle.

Description

A kind of preparation method of silver-based electrical contact material with adjustable work function

technical field

The invention relates to the preparation of electrical contact materials, in particular to a preparation method of a silver-based electrical contact material with adjustable work function used in the fields of nanometer electrical contacts, new energy low-voltage switching appliances and the like.

Background technique

As an electrical connection element material, silver-based composite contact materials are widely used in various light and heavy loads aerospace electrical appliances, high and low voltage applications due to their good electrical wear resistance, welding resistance, electrical conductivity, small and stable contact resistance and other properties. Electrical appliances, automotive appliances, household appliances and other fields. However, traditional Ag-based composite contact materials such as AgSnO ₂ are prone to premature failure of the service life of the contact material under the combined action of arc heat and force, and even serious safety accidents. The reason is that the arc formed by the contact material during the breaking process transmits thousands of heat to the contact surface, causing serious surface ablation and aggravating the degradation of the surface microstructure and electrical contact performance of the contact material. It can be found that changing the type of working atmosphere, arc extinguishing method or contact surface shape has little effect on reducing arc ablation. The work function of the contact material is an intrinsic key factor in determining arc ablation. Studies have shown that the work function of the material surface directly affects the emission capability of thermionics on the surface of the contact material, which in turn affects the temperature field distribution on the contact surface, as well as the thermal shock and ablation degree of thermions on the contact surface. Controlling and reducing the work function of the contact surface helps to improve the thermal electron emission capability, reduce the temperature of the contact surface, thereby reducing the temperature rise effect and ablation degree of the contact surface, and prolonging the electrical life of the contact material. Service performance and safety and reliability sex. The existing methods to control the work function of the contact surface mainly rely on crystal orientation, surface defects, adatoms, step density, and material types. The key factor of the surface work function of the system. Relevant literature shows that the third component (such as Bi, Cu, Ni, etc.) introduced into the AgSnO ₂ contact material system contributes to the physical properties and electrical life service performance of the AgSnO ₂ contact material. However, based on the research idea of work function tunable, there are few reports on introducing specific work function regulators into the internal oxidation preparation technology to achieve the purpose of optimizing the comprehensive performance of AgSnO ₂ contact materials.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a preparation method of AgSnO ₂ contact material with adjustable work function. Th, Ce or Ba are used as work function regulators, and intermediate frequency induction melting combined with internal oxidation method is used to prepare work function adjustable Tuned AgSnO ₂ contact material. The product prepared by this method can be used to improve the surface work function of the traditional AgSnO ₂ contact material, reduce the surface temperature rise effect and the degree of ablation, and improve its arc erosion resistance and electrical service life. The invention provides a new idea for preparing a novel oxide-reinforced silver-based composite contact material for the new energy field with a long service life.

In order to solve the above-mentioned technical problems, the solution adopted in the present invention is:

A method for preparing a silver-based electrical contact material with adjustable work function, which specifically includes the following steps:

(1) Adjustable work function modified AgSn alloy

One of Th, Ce, Ba, etc. is used as the work function regulator, and the Ni component is used as the grain refiner, and the modified AgSn alloy ingot with uniform structure is obtained by the medium frequency induction melting method. Weigh a certain amount of raw materials such as Ag ingot, Sn ingot, Th powder, Ce powder, Ba powder, and Ni powder in a vacuum glove box environment (see Table 1 for detailed formula), and introduce the weighed raw materials into a graphite crucible. Then, put the graphite crucible loaded with raw materials into the intermediate frequency induction melting furnace, set the corresponding melting temperature (1000 ~ 1400 ° C), and fully react in a certain melting time (8 ~ 12h), and finally obtain adjustable work function. The Th, Ce or Ba modified AgSn alloy ingots were obtained, and the work function characterization of the obtained modified AgSn alloy ingots was carried out.

Table 1 Component formula and smelting process

(2) Adjustable work function modified AgSnO ₂ contact material

Using the above prepared Th, Ce or Ba modified AgSn alloy ingot as a precursor, an internal oxidation process is used to prepare a work function adjustable modified AgSnO ₂ contact material. According to the calculation of the thermodynamic Gibbs free energy function, it is preferable to design a thermodynamically feasible oxygen partial pressure parameter value (3～7MPa), set the corresponding internal oxidation temperature (600～900℃), and set the internal oxidation time (10～24h) at a certain internal oxidation time. ) is fully oxidized, and finally a modified _AgSnO2 contact material with tunable work function is obtained. Finally, the modified AgSnO ₂ contact materials with adjustable work function prepared by the above process were evaluated for their contact temperature rise, electrical life and service ability.

Innovations and beneficial effects of the present invention

Based on the research idea that the work function of the material surface can be adjusted, the invention proposes a preparation method of _AgSnO2 contact material with adjustable work function by using the respective technical advantages of the intermediate frequency induction melting method and the internal oxidation method, and forms the structure through the intermediate frequency induction melting method. Homogeneous Th, Ce or Ba modified AgSn alloy, and optimized by internal oxidation process to prepare Th, Ce or Ba modified AgSnO ₂ contact materials with adjustable work function, and effectively control the performance of the prepared modified AgSnO ₂ contact materials. The surface work function can reduce the surface temperature rise effect and the degree of ablation, improve its resistance to arc erosion, and increase its electrical service life.

Detailed ways

The implementation of the present invention will be described in detail below through specific embodiments.

Example 1:

(1) Adjustable work function modified AgSn alloy

Using Th, Ce or Ba as work function regulator and Ni component as grain refiner, the modified AgSn alloy ingot with uniform structure was obtained by medium frequency induction melting method. Weigh a certain amount of raw materials such as Ag ingot, Sn ingot, Th powder, Ce powder, Ba powder, Ni powder in a vacuum glove box environment (see Table 2 for detailed formula), and introduce the weighed raw materials into a graphite crucible. Then, put the graphite crucible loaded with raw materials into the intermediate frequency induction melting furnace, set the corresponding melting temperature (1000 ° C), and fully react in a certain melting time (8h), and finally obtain Th and Ce with adjustable work function. Or Ba modified AgSn alloy ingot.

Table 2 Component formula and smelting process

(2) Adjustable work function modified AgSnO ₂ contact material

Using the above prepared Th, Ce or Ba modified AgSn alloy ingot as a precursor, an internal oxidation process is used to prepare a work function adjustable modified AgSnO ₂ contact material. According to the calculation of the thermodynamic Gibbs free energy function, it is preferable to design a thermodynamically feasible oxygen partial pressure parameter value (3MPa), set the corresponding internal oxidation temperature (900°C), and fully oxidize it within a certain internal oxidation time (10h), and finally _A modified AgSnO2 contact material with tunable work function was obtained. Finally, the modified AgSnO ₂ contact materials with adjustable work function prepared by the above process were evaluated for their contact temperature rise, electrical life and service ability.

Example 2:

(1) Adjustable work function modified AgSn alloy

Using Th, Ce or Ba as work function regulator and Ni component as grain refiner, the modified AgSn alloy ingot with uniform structure was obtained by medium frequency induction melting method. Weigh a certain amount of Ag ingot, Sn ingot, Th powder, Ce powder, Ba powder, Ni powder and other raw materials in a vacuum glove box environment (see Table 3 for detailed formula), and introduce the weighed raw materials into a graphite crucible. Then, put the graphite crucible loaded with raw materials into the intermediate frequency induction melting furnace, set the corresponding melting temperature (1400 ° C), and fully react in a certain melting time (12 h), and finally obtain Th and Ce with adjustable work function. Or Ba modified AgSn alloy ingot.

Table 3 Component formula and smelting process

(2) Adjustable work function modified AgSnO ₂ contact material

Using the above prepared Th, Ce or Ba modified AgSn alloy ingot as a precursor, an internal oxidation process is used to prepare a work function adjustable modified AgSnO ₂ contact material. According to the calculation of the thermodynamic Gibbs free energy function, it is preferable to design a thermodynamically feasible oxygen partial pressure parameter value (7MPa), set the corresponding internal oxidation temperature (650°C), and fully oxidize it within a certain internal oxidation time (24h), and finally _A modified AgSnO2 contact material with tunable work function was obtained. Finally, the modified AgSnO ₂ contact materials with adjustable work function prepared by the above process were evaluated for their contact temperature rise, electrical life and service ability.

Example 3:

(1) Adjustable work function modified AgSn alloy

Using Th, Ce or Ba as work function regulator and Ni component as grain refiner, the modified AgSn alloy ingot with uniform structure was obtained by medium frequency induction melting method. Weigh a certain amount of raw materials such as Ag ingot, Sn ingot, Th powder, Ce powder, Ba powder, and Ni powder in a vacuum glove box environment (see Table 4 for detailed formula), and introduce the weighed raw materials into a graphite crucible. Then, put the graphite crucible loaded with raw materials into the intermediate frequency induction melting furnace, set the corresponding melting temperature (1150 ° C), and fully react in a certain melting time (10 h), and finally obtain Th and Ce with adjustable work functions. Or Ba modified AgSn alloy ingot.

Table 4 Component formula and smelting process

(2) Adjustable work function modified AgSnO ₂ contact material

Using the above prepared Th, Ce or Ba modified AgSn alloy ingot as a precursor, an internal oxidation process is used to prepare a work function adjustable modified AgSnO ₂ contact material. According to the calculation of the thermodynamic Gibbs free energy function, it is preferable to design a thermodynamically feasible oxygen partial pressure parameter value (5MPa), set the corresponding internal oxidation temperature (820°C), and fully oxidize it within a certain internal oxidation time (16h), and finally _A modified AgSnO2 contact material with tunable work function was obtained. Finally, the modified AgSnO ₂ contact materials with adjustable work function prepared by the above process were evaluated for their contact temperature rise, electrical life and service ability.

It can be seen from Table 5 that the work function of the modified AgSnO ₂ contact materials obtained in Examples 1-3 is significantly lower than that of the traditional AgSnO ₂ . The contact temperature rise and electrical life service capability have been effectively improved, providing data support for its further long-life service performance and reliability applications in the field of electrical contact materials.

Table ₅ Characterization of contact temperature rise, electrical life and service ability of modified AgSnO2 contact materials with adjustable work function

Claims (4)

1. The silver-based electric contact material with adjustable work function is characterized in that one of Th, Ce and Ba is used as a work function regulator, and the formula of each component is shown in table 1:

TABLE 1 formulation of the components

。

2. The method for preparing the silver-based electric contact material with the adjustable work function according to claim 1, which comprises the following steps:

1) preparation of modified AgSn alloy with adjustable work function

Taking one of Th, Ce or Ba as a work function regulator, taking Ni as a grain refiner, and obtaining a modified AgSn alloy ingot with uniform structure by adopting a medium-frequency induction smelting method;

2) preparation of modified AgSnO with adjustable work function ₂ Contact material

Preparing modified AgSnO with adjustable work function by adopting the modified AgSn alloy ingot prepared in the step 1) as a precursor and adopting an internal oxidation process ₂ A contact material.

3. The method for preparing the silver-based electric contact material with the adjustable work function according to claim 2, wherein the step 1) is specifically as follows:

weighing Ag ingots, Sn ingots, Ni powder and a work function regulator in a vacuum glove box environment, placing the components in a medium-frequency induction furnace, setting the smelting temperature to be 1000-1400 ℃, and smelting for 8-12 hours to finally obtain the modified AgSn alloy ingot with uniform tissue.

4. The method for preparing the silver-based electric contact material with the adjustable work function according to claim 2, wherein in the step 2), the AgSnO with the adjustable work function and the modified function is prepared by adopting an internal oxidation process ₂ The specific conditions of the contact material are as follows: the oxygen partial pressure parameter value is 3-7 MPa, the internal oxidation temperature is 600-900 ℃, and the internal oxidation time is 10-24 h.