CN113073245B

CN113073245B - Silver-molybdenum alloy film and preparation method and application thereof

Info

Publication number: CN113073245B
Application number: CN202110313669.6A
Authority: CN
Inventors: 周灵平; 高宝龙; 朱家俊; 符立才; 杨武霖; 李德意
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2022-10-14
Anticipated expiration: 2041-03-24
Also published as: CN113073245A

Abstract

The invention provides a silver-molybdenum alloy film and a preparation method and application thereof. Preparing a silver-molybdenum alloy film on any inorganic material substrate by adopting a double-target focusing codeposition method, wherein the film has high hardness due to the existence of molybdenum; because of the existence of the pure silver phase, the material has good conductivity, and simultaneously, the silver can also be used as a soft lubricating phase, so that the tribological performance of the material is improved. By coating a layer of silver-molybdenum alloy film on the surface of a cheap and suitable electric contact material, the cost can be saved, and the electric conduction, wear resistance and electric corrosion resistance of the film can be exerted. It can also be used as the transition layer of electromagnetic gun track coating, the 'sweating' material resisting extreme high temperature (above 2000 ℃), and the silver/molybdenum composite interconnection material.

Description

Silver-molybdenum alloy film and preparation method and application thereof

Technical Field

The invention relates to the technical field of electric contact materials, in particular to a silver-molybdenum alloy film and a preparation method and application thereof.

Background

At present, the electric contact material in the electronic and electric industry is used as a contact of a relay, a contactor, an instrument and a meter, is used for connecting and disconnecting current, and is formed by compounding silver with the best conductivity with other materials. Due to the low hardness and poor electrical wear resistance of pure silver, other hard phases are usually required to be added into the silver matrix to enhance the hardness, abrasion resistance, welding resistance and the like of the composite material, and the reliability and service life of an electric switch and an instrument are directly influenced by the good and bad performance of the formed composite material. Because the phenomena generated by the electric contact in the opening and closing processes are extremely complex and have more influence factors, the ideal electric contact material must have good physical properties, electric contact properties, processing and manufacturing properties and the like, and the silver-based electric contact material is generally divided into three types according to the type of the added hard phase: silver-metal oxides, silver-based pseudoalloys, and silver-based alloys. The general silver-based pseudo alloy composite material comprises silver tungsten, silver nickel, silver iron and the like, which not only have the excellent performance of synthetic materials, but also have the characteristics of each component material, such as excellent arc erosion resistance, frictional wear resistance, welding resistance, low and stable contact resistance and the like, and play an important role in the whole electrical contact material system, and the composite material can also fully play the synergistic effect of the component materials, so that the material design has great freedom.

At present, bulk silver-molybdenum pseudo alloy materials are generally prepared by methods such as powder metallurgy, infiltration, mechanical alloying, mixed powder sintering and the like, the bulk silver-molybdenum pseudo alloy materials are not mutually soluble in a solid state or a molten state, and due to positive mixing enthalpy and large difference of physicochemical properties, the bulk silver-molybdenum pseudo alloy materials do not react after being mixed and respectively keep intrinsic characteristics. Chinese patent (publication No. CN 111048339A, a method for manufacturing a silver-molybdenum electrical contact with a continuous oxidation-resistant layer on the surface and a product thereof) proposes that a powder metallurgy infiltration process is adopted to prepare the silver-molybdenum electrical contact, and a continuous oxidation-resistant molybdenum carbide layer is formed through surface treatment, so that the phenomenon that the resistance is high and even is not conducted due to the fact that molybdenum is easily oxidized in a damp and hot environment is solved. Chinese patent (publication No. CN 110000374A, a preparation process of a silver-molybdenum contact material and a product thereof) proposes that a silver-molybdenum electric contact material is prepared by adopting an infiltration process, a silver layer is mainly wrapped outside molybdenum particles to obtain a monodisperse core-shell molybdenum-silver material, and then the electric contact material is formed by pressing.

The bulk silver-molybdenum composite material obtained by the preparation technology has high cost because silver and molybdenum are rare and noble metals, and cannot meet the requirements of high performance and low cost in the field of electronic and electric appliances.

The silver and the molybdenum are immiscible systems which are not solid-dissolved or combined with each other under the equilibrium condition, so that the pseudo alloy with two elementary substance phases can be formed. However, when a thin film is deposited by a method such as magnetron sputtering, ion beam sputtering, electron beam evaporation and the like under non-equilibrium conditions, a metastable solid solution is often formed by a immiscible system, a pseudo alloy under equilibrium conditions (melting, powder metallurgy and the like) is not formed, and the solid solution has poor conductivity although high in hardness and is not suitable for being used as a coating of an electrical contact material. Therefore, the silver-molybdenum alloy is made into a film similar to a pseudo alloy, and the film can be used as a coating of an electric contact material.

Disclosure of Invention

The invention provides a silver-molybdenum alloy film and a preparation method and application thereof.

In order to achieve the above object, the present invention provides a silver-molybdenum alloy thin film including a pure silver phase and a solid solution phase in which silver is solid-dissolved in molybdenum.

Preferably, in the thin film, the atomic percentage of molybdenum is: 50 to 89at.%.

Preferably, the solid solubility of silver in the solid solution phase is less than 10at.%.

Preferably, the film thickness is: 0.1-30 μm.

The invention also provides a method for preparing the silver-molybdenum alloy film on any inorganic material substrate by adopting a double-target focusing codeposition method, wherein the double targets are respectively a pure molybdenum target and a pure silver target.

Preferably, the focused co-deposition method includes one of magnetron sputtering and ion beam sputtering.

Preferably, the sputtering power ratio of the molybdenum target to the silver target is:

0.7 to 0.9.

The invention also provides the application of the silver-molybdenum alloy film in the coating of the electric contact material.

The invention also provides the application of the silver-molybdenum alloy film in the coating of the track of the electromagnetic gun.

The invention also provides the application of the silver-molybdenum alloy film in the sweating material.

The molybdenum-silver alloy film consists of a solid solution of silver dissolved in molybdenum and a pure silver phase, and has high hardness due to the existence of molybdenum; because of the existence of the pure silver phase, the material has good conductivity, and simultaneously, the silver can also be used as a soft lubricating phase, thereby improving the tribological performance of the material. The alloy film can be used for common electric contact material coatings, electromagnetic gun track coatings, coatings (sweat-resistant materials) resistant to extreme high temperature (above 2000 ℃) and transition layers of silver/molybdenum composite interconnection materials.

The scheme of the invention has the following beneficial effects:

(1) The silver-molybdenum alloy film of the invention can be used as a surface coating of a common electric contact material, saves cost compared with a bulk silver-molybdenum alloy composite material, and improves comprehensive performance;

(2) The silver-molybdenum alloy film comprises a pure silver phase and a solid solution phase of silver dissolved in molybdenum, can show the comprehensive characteristics of high conductivity and high hardness of the two phases, and other immiscible alloy systems prepared by the same method are metastable solid solutions with higher hardness but poorer conductivity;

(3) In the invention, the molybdenum-based solid solution is used as a hard wear-resistant phase, and the silver is used as a soft lubricating phase, so that the molybdenum-based solid solution has low friction coefficient and high wear resistance, thereby greatly reducing the friction loss of an electric contact point and prolonging the service life of an electric appliance element;

(4) The solid solution in the material is formed by partially dissolving silver atoms in molybdenum crystal lattices, so that the notch sensitivity of the alloy can be reduced to a certain extent, and the plasticity of the alloy is improved;

(5) The material is prepared by adopting a vacuum codeposition technology, and a film with uniform components and phases is easily obtained;

(6) The preparation method of the material is simple, and the alloy film with a certain stoichiometric ratio can be obtained only by adjusting the power supply of the molybdenum target and the silver target simultaneously;

(7) The material of the invention can be prepared by molybdenum (4.9 multiplied by 10) ^-6 K ^-1 ) And silver (18.9X 10) ^-6 K ^-1 ) The thermal expansion coefficient is adjusted by the component ratio of (A) to (B) to make the material contact other than the electric contact materialThe thermal expansion coefficients of the materials are matched, so that the cracking and falling caused by large thermal stress generated in subsequent work are prevented;

(8) The material can also be used as a track coating of an electromagnetic gun; by utilizing the principle that simple substance silver is evaporated at high temperature, the material can also be used as a 'sweating' material resistant to extreme high temperature (above 2000 ℃); by utilizing the characteristic of soaking the molybdenum film with silver and molybdenum materials, the molybdenum film can be used as a transition layer of a silver-plated film on the surface of molybdenum to improve the bonding strength of a film substrate.

Drawings

FIG. 1 shows SEM pictures (a) and X-ray diffraction pictures (b) of pure Ag films and SEM pictures (c) and X-ray diffraction pictures (d) of pure Mo films obtained in example 1 of the invention.

FIG. 2 shows SEM photograph (a) and X-ray diffraction chart (b) of the silver-molybdenum alloy thin film obtained in example 2 of the present invention

FIG. 3 is an SEM photograph (a) and an X-ray diffraction chart (b) of a silver-molybdenum alloy thin film obtained in example 3 of the present invention

FIG. 4 is an SEM image (a) and an X-ray diffraction image (b) of the Ag-Mo alloy film obtained in example 4 of this invention.

FIG. 5 is an SEM photograph (a) and an X-ray diffraction photograph (b) of the Ag-Mo alloy thin film obtained in example 5 of this invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

Example 1

First, n-Si is polished on one side<100>Cutting the wafer into 10mm × 10mm substrates, sequentially soaking in acetone and alcohol solution, respectively ultrasonically cleaning for 20min, drying, and mounting on a station circular table with a distance of 20mm from the center of the sample table by magnetron sputtering (MIS 800); then, the rotating speed of the sample stage is adjusted to be 5rpm, the vertical target distance is 55cm, the inclination angle of a target head is not changed when a pure film is sputtered by a single target, and the central extension line positions of two targets are adjusted to be converged at the central position of the sample stage during sputtering codeposition; finally, when the background vacuum is 5X 10 ^-4 When Pa is needed, the sample stage is placed at a Kaufman ion source cleaning station, the screen level and the beam current are adjusted to be 600V and 50mA respectively, low-energy cleaning is carried out for 20min, the sample stage is turned to a sputtering deposition position, and Ar gas is adjustedThe air input is 60sccm, the air pressure is 0.8Pa, and the target power is independently adjusted to prepare the film.

In order to observe the section appearances of the pure molybdenum and the pure silver films, the molybdenum target and the silver target are respectively adjusted to be vertically opposite to the surface of a sample, the power of the molybdenum target is adjusted to be 200W, the power of the silver target is adjusted to be 120W, after the pre-sputtering is carried out for 5min, the baffle plates are respectively opened to respectively deposit for 30min, and the pure silver and the pure molybdenum films are respectively deposited on different sample tables. FIG. 1 shows SEM cross-sectional shapes and corresponding X-ray diffraction patterns of pure silver and pure molybdenum film samples, respectively. The result shows that the pure silver film has a compact structure, and the pure molybdenum film has a columnar structure. The diffraction patterns all matched well with the corresponding cards (Ag: PDF #87-0597, mo. The average resistivity of the pure silver and the pure molybdenum is respectively 1.6 mu omega cm and 7.2 mu omega cm measured by a four-probe tester. The average hardness of the pure silver film and the pure molybdenum film measured by a nano indentation tester is 1.1GPa and 10.6GPa respectively.

Example 2

The same deposition conditions as example 1 are adopted, only the inclination angle of the molybdenum target and the silver target is adjusted to about 30 degrees, the extension lines of the centers of the two target heads in the same plane are converged at the center of the sample platform, the power of the molybdenum target is adjusted to be 220W, the power of the silver target is adjusted to be 24W, and Mo is obtained ₈₆ Ag ₁₄ The sectional morphology and the X-ray diffraction pattern of the film are shown in FIGS. 2 (a) and (b), and the diffraction peaks of pure silver and a solid solution become obvious, and the crystallinity is good. The film had a measured average resistivity of 140.7. Mu. Omega. Cm, and an average hardness and Young's modulus of 14.6GPa and 195.1GPa, respectively, were measured.

Example 3

Mo was co-deposited under the same deposition conditions as in example 2, except that the power of the molybdenum target was adjusted to 140W and the power of the silver target was adjusted to 22W ₇₅ Ag ₂₅ The film has the cross-sectional morphology and X-ray diffraction pattern shown in FIGS. 3 (a) and (b). The film is formed by columnar particles and a small amount of particles through the section appearance, the film is compact, and the half-height width of the peak of the X-ray diffraction pattern is very wide. The average resistivity of the film was measured to be 164.5. Mu. Omega. Cm, and the average hardness and Young's modulus of the film were measured to be 12.7GPa and 186.0GPa, respectively。

Example 4

Using the same deposition conditions as in example 2, the power of the silver target was changed to 30W while the power of the molybdenum target was adjusted to 140W, to obtain Mo ₆₆ Ag ₃₄ The film had the sectional morphology and X-ray diffraction pattern shown in FIGS. 4 (a) and (b). The film consists of columnar crystals and silver particles, and the diffraction peak of pure Ag in the diffraction pattern is more obvious. The results of combining the above two samples show that the solid solutions of the two are saturated and precipitated, and a large amount of silver is precipitated in the form of particles in the gaps and intermediate positions of columnar crystals. The film was measured to have an average resistivity of 131.9. Mu. Omega. Cm, and an average hardness and Young's modulus of 9.9GPa and 158.8GPa, respectively.

Example 5

Mo was obtained by adjusting the power of the molybdenum target to 140W and the power of the silver target to 42W under the same deposition conditions as in example 2 ₅₃ Ag ₄₇ The film, the cross-sectional morphology and the X-ray diffraction pattern of which are shown in FIGS. 5 (a) and (b), shows more distinct diffraction peaks of pure silver. The measured average resistivity was 103.1. Mu. OMEGA.cm, the measured average hardness and Young's modulus were 8.8GPa and 139.4GPa, respectively, and the hardness was only slightly lower than that of pure molybdenum, but the resistivity was greatly reduced.

Example 6

Preparing Mo with the thickness of 0.2 mu m on a GH4169 substrate by adopting an ion beam sputtering method ₇₉ Ag ₂₁ Samples were then subjected to a frictional wear test. Selecting a ball-disk circular motion friction mode in a friction and wear instrument (model: WTM-2E), and selecting Si with the size of 5mm ₃ N ₄ When a friction pair (hardness of 19 GPa) is made, the legal load is 2N, the sliding speed is 47mm/s, the frequency is 3Hz, the friction time is 10min, and finally the wear rate of the obtained film is 1.22 multiplied by 10 ^-4 mm ³ ·N ^-1 ·m ^-1 The average coefficient of friction was 0.52, relative to pure silver (2.6X 10) ^-4 mm ³ ·N ^-1 ·m ^-1 ) And pure molybdenum (8.4X 10) ^-4 mm ³ ·N ^-1 ·m ^-1 ) Has a very low wear rate.

While the foregoing is directed to the preferred embodiment of the present invention, it will be appreciated by those skilled in the art that various changes and modifications may be made therein without departing from the principles of the invention as set forth in the appended claims.

Claims

1. The silver-molybdenum alloy thin film is characterized by comprising a pure silver phase and a solid solution phase of silver dissolved in molybdenum, and the thickness of the thin film is as follows: 0.1 to 30 mu m;

the silver-molybdenum alloy film is prepared on any inorganic material substrate by adopting a double-target focusing codeposition method, wherein the double targets are a pure molybdenum target and a pure silver target respectively;

the focusing codeposition method is magnetron sputtering;

in the film, the atomic percentage of molybdenum is as follows: 50 to 89 at.%;

in the solid solution phase, the solid solubility of silver is less than 10 at%;

the sputtering power ratio of the molybdenum target to the silver target is as follows:

0.7 to 0.9.

2. Use of the silver-molybdenum alloy thin film according to claim 1 in the coating of an electrical contact material.

3. Use of the silver-molybdenum alloy thin film of claim 1 in an electromagnetic gun rail coating.

4. Use of the silver-molybdenum alloy thin film according to claim 1 in "sweating" materials.