Copper-tungsten disulfide self-lubricating composite material with layered structure, preparation method and application
阅读说明：本技术 一种层状结构的铜-二硫化钨自润滑复合材料、制备方法及应用 (Copper-tungsten disulfide self-lubricating composite material with layered structure, preparation method and application ) 是由 吴集思 杨成刚 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种层状结构的铜-二硫化钨(Cu-WS-(2))自润滑复合材料、制备方法及应用,属于金属基自润滑复合材料技术领域,Cu-WS-(2)复合材料中二硫化钨层与铜层呈现出相互交叉叠加的形貌特征,所述复合材料中密实铜层厚度为10～100μm,二硫化钨层厚度为5～15μm。通过双向冷冻技术获得一个具有长程有序且层状结构的多孔二硫化钨支架,并采用真空浸渍将有机铜及其合金浆料渗入二硫化钨支架中,所得浸渗坯体通过SPS烧结制备出Cu-WS-(2)复合材料。通过控制二硫化钨支架制备过程中的固相含量和有机铜浆的固相含量,可获得具有不同铜层和二硫化钨层厚度的铜基复合材料。本发明适宜于制备具有层状结构特性的复合材料。(The invention discloses a copper-tungsten disulfide (Cu-WS) with a layered structure 2 ) A self-lubricating composite material, a preparation method and application, belongs to the technical field of metal-based self-lubricating composite materials, and discloses Cu-WS 2 The tungsten disulfide layer and the copper layer in the composite material present the appearance characteristic of intercrossing stack, the thickness of closely knit copper layer is 10 ~ 100 mu m in the composite material, and the thickness of tungsten disulfide layer is 5 ~ 15 mu m. By means of a two-way freezing technique to obtain a food withThe method comprises the steps of preparing a long-range ordered porous tungsten disulfide support with a layered structure, infiltrating organic copper and alloy slurry thereof into the tungsten disulfide support by adopting vacuum impregnation, and preparing a Cu-WS by using an infiltrated blank through SPS sintering 2 A composite material. By controlling the solid content of the tungsten disulfide support and the solid content of the organic copper slurry in the preparation process, the copper-based composite material with different thicknesses of the copper layer and the tungsten disulfide layer can be obtained. The invention is suitable for preparing composite materials with the characteristics of a laminated structure.)
1. The copper-tungsten disulfide self-lubricating composite material with the layered structure is characterized by comprising a compact copper layer and disulfide which are distributed in a layered mannerTungsten carbide lamellae consisting of directionally arranged WS2The compact copper layers and the tungsten disulfide sheet layers are arranged alternately.
2. The copper-tungsten disulfide self-lubricating composite material with a layered structure as claimed in claim 1, wherein the thickness of the dense copper layer is 5-300 μm, and the thickness of the tungsten disulfide flake layer is 2-40 μm.
3. The copper-tungsten disulfide self-lubricating composite material with a layered structure according to claim 1, wherein the compactness of the dense copper layer is higher than 99.0%, and the compactness of the copper-tungsten disulfide self-lubricating composite material with a layered structure is higher than 95.0%.
4. The layered copper-tungsten disulfide self-lubricating composite material of claim 1, wherein WS2The particles are arranged in each tungsten disulphide layer along its (001) crystal plane, said WS2The particles are hexagonal plate-shaped particles, the WS2The average particle diameter was 5 μm.
5. A preparation method of the copper-tungsten disulfide self-lubricating composite material with the layered structure as claimed in any one of claims 1 to 4, is characterized by comprising the following steps:
the method comprises the following steps: let WS be2Uniformly mixing the particles, deionized water and an organic binder to obtain water-based slurry; the content of the organic binder in the water-based slurry is 1-10% of the mass of the deionized water, and WS2The mass of the particles is 1-30% of that of the deionized water;
step two: pouring the water-based slurry obtained in the step one into a freezing mould containing a wedge-shaped mould, placing the freezing mould in an oriented temperature field, and after the slurry is completely frozen, carrying out vacuum drying for 20-72 h to obtain a vacuum-dried blank; the temperature of the bottom end in the directional temperature field is lower than that of the top end, the temperature of the bottom end is between minus 5 ℃ and minus 120 ℃, the temperature of the top end is less than or equal to 25 ℃, and the temperature difference between the top end and the bottom end is more than 20 ℃;
step three: and taking the blank after vacuum drying out of the mould to obtain the tungsten disulfide support material with long-range order and directional arrangement of particles, cutting the tungsten disulfide support material into cuboids, immersing the cuboids into organic copper slurry, carrying out vacuum pressure impregnation to obtain the blank material with copper particles infiltrated between the layers of the tungsten disulfide sheets, carrying out press forming on the blank material, roasting and heat preservation in a hydrogen furnace, and then carrying out plasma discharge sintering to finally obtain the copper-tungsten disulfide self-lubricating composite material with a laminated structure.
6. The method for preparing the copper-tungsten disulfide self-lubricating composite material with the layered structure as claimed in claim 5, wherein the included angle of the wedge-shaped mold is 5 ° to 30 °.
7. The preparation method of the copper-tungsten disulfide self-lubricating composite material with the layered structure according to claim 5, wherein the organic copper slurry is composed of copper powder and an organic carrier, the mass ratio of the copper powder to the organic carrier is (30:70) - (70:30), the organic carrier comprises terpineol, a binder and a dispersant, and the total mass of the binder and the dispersant is 1% -10% of the mass of the terpineol.
8. The method for preparing the copper-tungsten disulfide self-lubricating composite material with the layered structure according to claim 5, wherein the organic binder in step one is at least one selected from gelatin, polyvinyl alcohol, chitosan and polyacrylic acid.
9. The method for preparing the copper-tungsten disulfide self-lubricating composite material with the laminated structure according to claim 7, wherein the binder is selected from one or more of ethyl cellulose, methyl cellulose, carboxymethyl cellulose and hydroxypropyl cellulose.
10. Use of the copper-tungsten disulfide self-lubricating composite material with a layered structure as defined in any one of claims 1 to 4 in electrical contacts, brush elements of automobile engines, and crystallized devices of continuous casting machines.
Technical Field
The invention relates to the technical field of preparation of metal-based self-lubricating composite materials, in particular to a copper-tungsten disulfide self-lubricating composite material with a layered structure, a preparation method and application.
Background
The metal-based self-lubricating composite material has the characteristics of excellent mechanical property and wear resistance of a metal matrix material, good lubricating and antifriction properties of a solid lubricant, large material designability and the like, and has wide application prospects in industries such as automobiles, electronics, aviation, instruments and the like. The copper-based solid lubricating material is one of the common metal-based self-lubricating materials, has good thermal conductivity, electrical conductivity and corrosion resistance, excellent technological properties and moderate price, and is often used as materials for electric contacts, automobile engine brushes, spot welding electrode working ends, continuous casting machine crystallizers and the like. The lubricant in the metal-based self-lubricating composite material has typical two-dimensional characteristics, more excellent lubricating performance can be obtained when the lubricant slides along the (001) crystal face of the lubricant, and a stable transfer layer can be formed at the friction interface of the material by a continuous lubricating phase, so that the wear resistance of the material is improved; achieving long-range directional alignment of the lubricating phase in the composite has become a difficult issue in modern research.
The preparation method of the copper-based solid lubricating material mainly comprises the following steps: powder metallurgy, liquid metal stirring, liquid metal squeeze casting, vacuum pressure impregnation, and the like. The powder metallurgy method has the advantages of simple operation, high controllability of material composition and the like, and is widely applied to the preparation of metal matrix composite materials, but cannot carry out oriented arrangement on anisotropic components. The liquid metal stirring method is not suitable for preparing easily decomposed composite materials because of the high heat treatment temperature required. Although the liquid metal squeeze casting method can realize the arrangement of particles to a certain extent, the composition and the appearance of the lubricant are damaged by the small size and the high heat treatment temperature and the mechanical action, so that the lubricating performance of the composite material is influenced. The preparation methods can not realize the long-range directional arrangement of the lubricant particles, and the vacuum pressure impregnation method is expected to solve the problems; the structural characteristics and properties of the porous preforms used have a significant impact on the overall performance of the composite material. The methods for preparing porous preforms are numerous today, such as: technical methods such as solution metal foaming, powder metallurgy, 3D printing and the like; in addition to the above preparation methods, a large number of researchers have tried to obtain scaffold materials with a layered structure and oriented arrangement of particles by using a crystal template method. For example, the ice crystal template method adopted by Bouille and the like realizes the oriented assembly of flaky BN particles with the diameter of 8 and the thickness of 1; then, performing vacuum impregnation on Polydimethylsiloxane (PDMS) by slow building and the like to obtain the hBN/PDMS composite material with a layered structure and directionally arranged particles; however, the directionally assembled porous BN scaffold and the composite material laminated structure area obtained in the method have small area and low directional arrangement. The disorder and discontinuity of the solid lubricant in the metal-based self-lubricating composite material are an important reason for the loss of the lubricating property of the composite material, and the realization of long-range ordered directional assembly of lubricant particles in the composite material is always a technical problem.
Disclosure of Invention
The invention provides a copper-tungsten disulfide self-lubricating composite material with a layered structure and a preparation method thereof, aiming at realizing long-range ordered directional assembly of lubricant particles in the composite material.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a copper-tungsten disulfide (Cu-WS) with a layered structure2) The copper-tungsten disulfide self-lubricating composite material with the layered structure comprises a dense copper layer and tungsten disulfide sheet layers which are distributed in a layered mode, wherein the tungsten disulfide sheet layers are formed by WS arranged in an oriented mode2The compact copper layers and the tungsten disulfide sheet layers are alternately arranged to form a block composite material.
Further, the thickness of the compact copper layer is 5-300 mu 0, preferably 10-100 mu m, and the thickness of the tungsten disulfide sheet layer is 2-40 mu m, preferably 5-15 mu m.
Further, the density of the compact copper layer is higher than 99.0%, and the density of the copper-tungsten disulfide self-lubricating composite material with the layered structure is higher than 95.0%.
Further, the WS2The particles are arranged in each tungsten disulphide layer along its (001) crystal plane。
Further, the WS2The particles are hexagonal plate-shaped particles, the WS2The average particle diameter was 5 μm.
Further, the compact copper layer is pure copper and its alloy, and the copper content in the copper alloy is higher than 50.0 wt%.
Further, the area of a single tungsten disulfide sheet layer in the copper-tungsten disulfide self-lubricating composite material with the layered structure is up to 6 multiplied by 6cm2Preferably 3X 3cm2。
Further, the compact copper layer is pure copper and copper alloy, and the copper content in the copper alloy is higher than 50.0 wt%. The copper alloy is preferably at least one of Cu-Pb, Cu-Ni and Cu-Sn alloy.
The Cu-WS with a laminated structure prepared by the invention2The self-lubricating composite material can be applied to the fields of electric contacts, automobile engine brush elements, continuous casting machine crystallization devices and the like.
The invention also provides a preparation method of the copper-tungsten disulfide self-lubricating composite material with the layered structure, which comprises the following steps:
the method comprises the following steps: let WS be2Uniformly mixing the particles, deionized water and an organic binder to obtain water-based slurry; the content of the organic binder in the water-based slurry is 1-10% of the mass of the deionized water, and WS2The mass of the particles is 1-30% of that of the deionized water;
step two: pouring the slurry obtained in the step one into a freezing mould containing a wedge-shaped mould, placing the freezing mould in an oriented temperature field, and after the slurry is completely frozen, carrying out vacuum drying for 20-72 h; the temperature of the bottom end in the directional temperature field is lower than that of the top end and ranges from minus 5 ℃ to minus 120 ℃, the temperature of the top end is less than or equal to 25 ℃, preferably less than or equal to 15 ℃, more preferably less than or equal to more, and the temperature difference between the top end and the bottom end is more than 20 ℃;
step three: and taking the blank after vacuum drying out of the mould to obtain the tungsten disulfide support material with long-range order and oriented arrangement of particles, cutting the tungsten disulfide support material into cuboids, immersing the cuboids into organic copper slurry, carrying out vacuum pressure impregnation to obtain the blank material with copper particles infiltrated between the layers of the tungsten disulfide sheets, carrying out press forming on the blank material, roasting and preserving heat in a hydrogen furnace, then carrying out plasma discharge sintering (SPS), and finally obtaining the copper-tungsten disulfide self-lubricating composite material with a laminated structure. Heating to 350-450 ℃ in a hydrogen furnace at the speed of 5-10 ℃/min, preferably heating to 380-420 ℃, and preserving heat for 2-4 hours to remove organic matters and reduce copper powder. The plasma discharge sintering temperature is 600-800 ℃, preferably 650-750 ℃, more preferably 680-720 ℃, and the temperature is kept for 3-10 min.
The principle of long-range ordered oriented assembly of lubricant particles in the composite material of the invention is as follows: during the directional solidification process of the water-based slurry containing the solid particles, ice crystals grow along the direction of a directional temperature gradient field, the growth of the ice crystals forces the particles in the feed liquid to aggregate and rearrange, and particularly, the powder particles with larger particle sizes are more easily rearranged; and obtaining an ice blank when the slurry is completely frozen. After the ice blank material is subjected to vacuum low-temperature drying, the sublimation of the ice pieces is removed, solid-phase particles are still gathered in the layer wall of the porous material and maintain the directionally arranged porous structure, and the obtained structure and the ice crystal structure have opposite structural characteristics; then densifying the porous green body material to obtain the porous material with good mechanical property.
Further, the included angle of the wedge-shaped die is 5-30 degrees. The wedge-shaped die is one of polytetrafluoroethylene, polydimethylsiloxane and polyvinyl chloride.
Further, the organic copper slurry is composed of copper powder and an organic carrier, the mass ratio of the copper powder to the organic carrier is (30:70) - (70:30), the organic carrier comprises terpineol, a binder and a dispersing agent, the total mass of the binder and the dispersing agent is 1% -10% of the mass of the terpineol, and the mass ratio of the binder to the dispersing agent is 4: 1.
Further, in the step one, the organic binder is at least one selected from gelatin, polyvinyl alcohol, chitosan and polyacrylic acid.
Further, the dispersing agent is one or more of polyvinylpyrrolidone, polypropylene and polystyrene.
Further, the binder is selected from one or more of ethyl cellulose, methyl cellulose, carboxymethyl cellulose and hydroxypropyl cellulose.
The invention discloses the following technical effects:
1. regulation WS of the invention2The types and the contents of various additives in the slurry and the freezing condition are assisted, and the vacuum pressure impregnation and sintering molding technology is assisted to obtain the Cu-WS with the characteristic of a laminated structure2A composite material.
2. The invention improves the condition of preparing the porous material by the ice crystal template method, and the obtained lamellar porous WS with long-range order and directionally arranged particles2The material provides good premise for preparing the copper-based composite material with the characteristic of a laminated structure; simultaneously, the content of a second phase in the porous prefabricated body is adjusted by changing the initial copper content in the organic copper slurry, and finally the Cu-WS with different layer thicknesses is obtained2A composite material.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is an electron microscope image of a copper-tungsten disulfide self-lubricating composite material of a layered structure prepared in example 1, wherein (a) is an electron microscope image of 500 times and (b) is an electron microscope image of 5000 times;
FIG. 2 shows the Cu-WS obtained in example 12The friction coefficient curves of the composite material and the dual disk under different angles;
FIG. 3 is a structural diagram of the composite material obtained in comparative example 1.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
Example 1
Adding 24.4g WS to the mixing tank2Ball milling and mixing powder (average particle size is 5.0 μm), 100g deionized water and 2.0g gelatin for 20h (ball milling rotation speed: 100rpm, ball material mass ratio is 2:1) to obtain WS with stable performance2A water-based slurry; pouring the water-based slurry into a freezing mould containing a wedge-shaped mould, immediately putting the water-based slurry into an oriented temperature field (the bottom temperature is set to be minus 30 ℃ and the top temperature is 5 ℃) for oriented solidification, and putting the obtained sample into a vacuum freeze dryerThe deicing treatment is carried out. Cutting the dried green material into 12 × 35 × 24mm3The organic copper slurry with the mass fraction of 60 percent is infiltrated into the cuboid by adopting a vacuum air pressure method, and the porous WS infiltrated with the copper slurry2Putting the green body material into a hydrogen furnace for organic matter removal and copper powder reduction, heating to 400 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 2 hours; sintering the heat-treated green body material in discharge plasma sintering at a rate of 100 deg.C/min to 750 deg.C and holding at 40MPa for 5min to obtain a dense copper layer with a thickness of 50 μm and WS2Cu-WS with layer structure characteristics with layer thickness of 10 μm2A self-lubricating composite material. An electron microscope image of the copper-tungsten disulfide self-lubricating composite material with a layered structure prepared in example 1 is shown in fig. 1, wherein (a) is an electron microscope image multiplied by 500, and (b) is an electron microscope image multiplied by 5000; the cross-sectional topography is shown in FIG. 2, and the prepared Cu-WS can be seen from FIG. 22The composite material has typical layered structure characteristics, the dense copper layer and the orientation-arranged particles of WS2The layers being arranged alternately to form a bulk composite material, and WS2In which the particles are aligned.
Example 2
15.5g WS was added to the compounding tank2Ball milling and mixing powder (average particle size is 5.0 μm), 100g deionized water and 2.0g chitosan for 20h (ball milling rotation speed: 100rpm, ball material mass ratio is 2:1) to obtain WS with stable performance2A water-based slurry; pouring the slurry into a freezing mould containing a wedge-shaped mould, immediately putting the freezing mould into a directional temperature field (the bottom temperature is set to be minus 40 ℃ and the top temperature is 5 ℃) for directional solidification, and putting the obtained sample into a vacuum freeze dryer for deicing. Cutting the dried green material into 12 × 35 × 24mm3The organic copper-tin alloy slurry with the mass fraction of 50 percent (the tin content is 10.0 percent) is infiltrated into the cuboid by adopting a vacuum air pressure method, and the porous WS infiltrated with the copper-tin particles is2Putting the green body material into a hydrogen furnace, removing organic matters and reducing copper powder, heating to 350 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 2 hours; and sintering the heat-treated green body material in discharge plasma sintering at a speed of 100 ℃/min to 700 ℃ and keeping the temperature for 5min at a sintering pressure of 40 MPa. To obtain the thickness of the compact copper layerIs 40 μm and WS2Cu-WS with layer structure characteristics with a layer thickness of 5 μm2A self-lubricating composite material.
Example 3
Adding 24.4g WS to the mixing tank2Ball milling and mixing powder (average particle size is 5.0 μm), 100g deionized water and 2.0g polyvinyl alcohol for 20h (ball milling rotation speed: 100rpm, ball material mass ratio is 2:1) to obtain WS with stable performance2A water-based slurry; pouring the slurry into a freezing mould containing a wedge-shaped mould, immediately putting the freezing mould into a directional temperature field (the bottom temperature is set to be-30 ℃ and the top temperature is 5 ℃) for directional solidification, and putting the obtained sample into a vacuum freeze dryer for deicing. Cutting the dried green material into 12 × 35 × 24mm3The organic copper-nickel alloy slurry with the mass fraction of 70.0 percent (the nickel content is 15.0 percent) is infiltrated into the cuboid by adopting a vacuum air pressure method, and the porous WS infiltrated with the copper-nickel particles is2Putting the green body material into a hydrogen furnace, removing organic matters and reducing copper powder, heating to 450 ℃ at the heating rate of 5 ℃/min, and preserving heat for 2 hours; and sintering the heat-treated green body material in discharge plasma sintering at a speed of 100 ℃/min to 800 ℃ and keeping the temperature for 5min at a sintering pressure of 40 MPa. Obtaining a dense copper layer with a thickness of 80 μm and WS2Cu-WS with layer structure characteristics with a layer thickness of 15 μm2A self-lubricating composite material.
Example 4
Adding 24.4g WS to the mixing tank2Ball milling and mixing powder (average particle size is 5.0 μm), 100g deionized water and 2.0g polyacrylic acid for 20h (ball milling rotation speed: 100rpm, ball material mass ratio is 2:1) to obtain WS with stable performance2A water-based slurry; pouring the water-based slurry into a freezing mould containing a wedge-shaped mould, immediately putting the water-based slurry into a directional temperature field (the bottom temperature is set to be-100 ℃, and the top temperature is 5 ℃) for directional solidification, and putting the obtained sample into a vacuum freeze dryer for deicing. Cutting the dried green material into 12 × 35 × 24mm3The organic copper slurry with the mass fraction of 60 percent is infiltrated into the cuboid by adopting a vacuum air pressure method, and the porous WS infiltrated with the copper slurry2The green body material is put into a hydrogen furnace for organic matter removal and copper powder reduction, and is heated at the heating rate of 5 ℃/minKeeping the temperature at 400 ℃ for 2 h; sintering the heat-treated green body material in discharge plasma sintering at a rate of 100 deg.C/min to 750 deg.C and holding at 40MPa for 5min to obtain a dense copper layer with a thickness of 50 μm and WS2Cu-WS with layer structure characteristics with layer thickness of 10 μm2A self-lubricating composite material.
Comparative example 1
15.5g WS was added to the compounding tank2Ball milling and mixing powder (average particle size is 5.0 μm), 100g deionized water and 2.0g chitosan for 20h (ball milling rotation speed: 100rpm, ball material mass ratio is 2:1) to obtain WS with stable performance2A water-based slurry; pouring the slurry into a freezing mould, immediately putting the freezing mould into a directional temperature field (the bottom temperature is set to be-30 ℃ and the top temperature is 5 ℃) for directional solidification, and putting the obtained sample into a vacuum freeze dryer for deicing. Cutting the dried green material into 12 × 35 × 24mm3The organic copper-tin alloy slurry with the mass fraction of 50 percent (the tin content is 10.0 percent) is infiltrated into the cuboid by adopting a vacuum air pressure method, and the porous WS infiltrated with the copper-tin particles is2Putting the green body material into a hydrogen furnace, removing organic matters and reducing copper powder, heating to 350 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 2 hours; and sintering the heat-treated green body material in discharge plasma sintering at a speed of 100 ℃/min to 700 ℃ and keeping the temperature for 5min at a sintering pressure of 40 MPa. The resulting Cu-WS2The structure of the self-lubricating composite material is shown in FIG. 3. As can be seen from FIG. 3, Cu-WS2The self-lubricating composite material has an incomplete layered structure.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.