阅读说明：本技术 一种颗粒定向排列增强铜基自润滑复合材料及其制备方法 (Particle oriented arrangement reinforced copper-based self-lubricating composite material and preparation method thereof ) 是由 吴集思 杨成刚 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种颗粒定向排列增强铜基自润滑复合材料及其制备方法,属于金属基复合材料制备技术领域。制备方法为：第一步,各颗粒分散均匀的混合浆料制备；第二步,浆料的定向凝固及冰晶的脱除；第三步,生坯的压制成型及氢气氛下的有机物脱除和金属铜颗粒的还原处理；第四步,烧结,得到颗粒定向排列增强铜基自润滑复合材料。本发明方法具有操作简单、工艺少、成本低廉、对设备无特殊要求等优点；且所用增强相颗粒粒径范围较宽。本发明方法适宜制备出颗粒均匀分布且定向排列于基体中的复合材料,材料具有典型的力学性能和摩擦性能各向异性,并沿着平行面的摩擦性能有较大提高。(The invention discloses a copper-based self-lubricating composite material reinforced by directional arrangement of particles and a preparation method thereof, belonging to the technical field of preparation of metal-based composite materials. The preparation method comprises the following steps: firstly, preparing mixed slurry with uniformly dispersed particles; secondly, directional solidification of slurry and removal of ice crystals; thirdly, pressing and forming the green body, removing organic matters and reducing metal copper particles in a hydrogen atmosphere; and fourthly, sintering to obtain the particle oriented arrangement reinforced copper-based self-lubricating composite material. The method has the advantages of simple operation, less process, low cost, no special requirement on equipment and the like; and the grain size range of the used reinforcing phase is wide. The method is suitable for preparing the composite material with uniformly distributed and directionally arranged particles in the matrix, the material has typical mechanical property and anisotropic friction property, and the friction property along a parallel surface is greatly improved.)

1. A preparation method of a copper-based self-lubricating composite material reinforced by particle oriented arrangement is characterized by comprising the following steps:

step one, preparing mixed slurry

a. Weighing reinforcing phase powder, copper or copper alloy powder, a binder, a dispersant and water according to a stoichiometric ratio;

b. dividing deionized water according to the formula amount into two parts, taking one part of the deionized water to dissolve a dispersant, and carrying out mechanical ball milling on a dispersant solution and reinforcing phase powder, copper or copper alloy powder;

c. dissolving the other part of deionized water into the binder, adding the binder into the reaction system obtained in the step b after the binder is completely dissolved, and continuously performing ball milling to obtain mixed slurry;

step two, preparing a green body material

Adding the mixed slurry into a freezing mould, performing bidirectional solidification, and performing vacuum drying at-60 to-5 ℃ after freezing to obtain a green body material;

step three, pressing and molding the green body material prepared in the step two, and carrying out organic matter removal and reduction treatment on metal copper particles in a hydrogen atmosphere;

step four, sintering

Sintering the green body material treated in the third step to obtain the copper-based self-lubricating composite material reinforced by the directional arrangement of the particles.

2. The method for preparing the copper-based self-lubricating composite material reinforced by the oriented arrangement of the particles according to claim 1, wherein the reinforcing phase powder is a material with 2D structural characteristics; the reinforcing phase powder has a particle size ranging from 0.1 to 50.0 μm.

3. The method for preparing the copper-based self-lubricating composite material reinforced by the directional arrangement of the particles according to claim 2, wherein the material with the 2D structural characteristic is graphite, molybdenum disulfide or tungsten disulfide.

4. The method for preparing the copper-based self-lubricating composite material reinforced by the directional arrangement of the particles according to claim 1, wherein the binder is one or more of polyvinyl alcohol, polyacrylic acid, polyurethane, epoxy resin and gelatin; the binder accounts for 0.1-10.0 wt% of the total water in the raw materials.

5. The preparation method of the copper-based self-lubricating composite material reinforced by oriented arrangement of particles according to claim 1, wherein the ball-to-material ratio in ball milling in the first step is 2-5: 1; in the step b, the ball milling speed is 50-150rpm, and the ball milling time is 2-4 h; in the step c, the ball milling speed is 80rpm-200rpm, and the ball milling time is more than or equal to 20 h.

6. The method for preparing copper-based self-lubricating composite material reinforced by oriented arrangement of particles according to claim 1, wherein the sum of the volume of the copper or copper alloy powder and the reinforcing phase powder is 5-40 vol% of the volume of the slurry, and the volume of all the powders accounts for 1-30 vol% of the volume of the whole slurry.

7. The preparation method of the copper-based self-lubricating composite material reinforced by oriented arrangement of particles according to claim 1, wherein the vacuum drying time in the second step is not less than 24 h; the bidirectional solidification temperature field is constructed by an upper freezing end, a lower freezing end and a wedge-shaped die, wherein the upper end temperature is 5-25 ℃, the lower end temperature is-60 to-5 ℃, and the freezing time of the mixed slurry is more than or equal to 4 hours.

8. The method for preparing the copper-based self-lubricating composite material reinforced by the oriented arrangement of the particles according to claim 1, wherein the pressure of the compression molding in the third step is 10-20Mpa and is performed along the direction perpendicular to the arrangement of the particles; the temperature of the reduction treatment is 300-450 ℃, and the time is 2-6 h.

9. The method for preparing the copper-based self-lubricating composite material reinforced by the directional arrangement of the particles according to claim 1, wherein the sintering treatment is carried out in a hot pressing furnace, an isostatic pressing furnace or a discharge plasma furnace; the sintering treatment temperature is 600-900 ℃, and the time is 5-120 min; the sintering pressure is 10-50 MPa.

10. An orientation-arrangement-reinforced copper-based self-lubricating composite material of particles prepared by the preparation method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of metal matrix composite material preparation, in particular to a copper-based self-lubricating composite material reinforced by directional arrangement of particles and a preparation method thereof.

Background

The metal-based self-lubricating composite material has good heat conductivity, excellent mechanical property and wear resistance of a metal material, and excellent lubricating and antifriction properties of a solid lubricating material, and has wide application prospects in the fields of aerospace, automobiles, machinery and the like. The copper-based self-lubricating composite material has the characteristics of low manufacturing cost, good corrosion resistance, easiness in processing and the like, has good mechanical property and frictional wear property, and is commonly used for spot welding electrode workpieces, bearing bushes, lead frames of integrated circuits, contact elements in electronic communication devices and the like. The lubricating phase particles used in the self-lubricating composite material have typical 2D structural characteristics, so that better and excellent tribological characteristics can be obtained when the lubricating phase particles slide along the planes parallel to the particles; therefore, the oriented arrangement of the lubricating phase particles in the composite material can be realized, and the performance of the material can be effectively improved.

The preparation method of the copper-based self-lubricating composite material mainly comprises the following steps: powder metallurgy, hot extrusion of liquid metals, die plate methods, and the like. The powder metallurgy method has the advantages of simple process, convenient operation, high material utilization rate, large designability of material composition and the like, and is a common method for preparing the metal-based self-lubricating material at present; and the lubricating phase particles are present in the matrix in a disordered manner due to the inability of the mechanical ball milling process to cause rearrangement of the particles in the matrix. The hot extrusion method of the liquid metal requires higher preparation temperature and special equipment, and lubricating particles in the obtained composite material are only directionally arranged to a certain extent; such as: zhang et al prepared silver-based-molybdenum disulfide composite material by hot extrusion method, and its microscopic groupWeave Structure shows MoS₂The particles are arranged along the extrusion direction and slide along the extrusion direction, so that better lubricating performance can be obtained; but is limited to a small area in the composite material. The template method is an effective method for directionally assembling particles with different scales (from nano-scale to micron-scale), and a proper template agent can be selected according to requirements so as to obtain a target structural material; with the increasingly prominent modern environmental protection problem, the selection of an environment-friendly template has become the mainstream direction; wherein, when the water is used as the template agent, the particles in the slurry are forced to aggregate and rearrange according to the growth driving force of the solidification process of the water. Such as: shen et al used an ice crystal template method to achieve directional assembly of h-BN particles and compounded the second phase (polydimethylsiloxane) by immersion, and found that the heat conduction rate along the parallel particle arrangement direction is significantly improved, but the structural uniformity of the material is poor and there is a certain defect in the directional arrangement of the particles.

Disclosure of Invention

The invention aims to provide a copper-based self-lubricating composite material reinforced by particle oriented arrangement and a preparation method thereof, which are used for solving the problems in the prior art, so that the material has good structural uniformity, typical mechanical property and friction property anisotropy, and the friction property along a parallel surface is greatly improved.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a preparation method of a copper-based self-lubricating composite material reinforced by oriented arrangement of particles, which comprises the following steps:

step one, preparing mixed slurry

a. Weighing reinforcing phase powder, copper or copper alloy powder, a binder, a dispersant and water according to a stoichiometric ratio;

b. dividing deionized water according to the formula amount into two parts, taking one part of the deionized water to dissolve a dispersant, and carrying out mechanical ball milling on a dispersant solution and reinforcing phase powder, copper or copper alloy powder;

c. dissolving the other part of deionized water into the binder, adding the binder into the reaction system obtained in the step b after the binder is completely dissolved, and continuously performing ball milling to obtain mixed slurry;

step two, preparing a green body material

Adding the mixed slurry into a freezing mould, performing bidirectional solidification, and performing vacuum drying at-60 to-5 ℃ after freezing to obtain a green body material;

step three, pressing and molding the green body material prepared in the step two, and carrying out organic matter removal and reduction treatment on metal copper particles in a hydrogen atmosphere;

step four, sintering

Sintering the green body material treated in the third step to obtain the copper-based self-lubricating composite material reinforced by the directional arrangement of the particles.

Further, the reinforcing phase powder is a material having 2D structural characteristics; the reinforcing phase powder has a particle size ranging from 0.1 to 50.0 μm.

Further, the material with 2D structural characteristics is graphite, molybdenum disulfide, or tungsten disulfide.

Further, the binder is one or more of polyvinyl alcohol, polyacrylic acid, polyurethane, epoxy resin and gelatin; the binder accounts for 0.1-10.0 wt% of the total water in the raw materials.

Further, the ball-material ratio in the ball milling in the first step is 2-5: 1; in the step b, the ball milling speed is 50-150rpm, and the ball milling time is 2-4 h; in the step c, the ball milling speed is 80rpm-200rpm, and the ball milling time is more than or equal to 20 h.

Further, the sum of the volumes of the copper or copper alloy powder and the reinforcing phase powder is 5-40 vol% of the volume of the slurry, and all the powder volumes account for 1-30 vol% of the volume of the whole slurry.

Further, the vacuum drying time in the step two is more than or equal to 24 hours; the bidirectional solidification temperature field is constructed by an upper freezing end, a lower freezing end and a wedge-shaped die, wherein the upper end temperature is 5-25 ℃, the lower end temperature is-60 to-5 ℃, and the freezing time of the mixed slurry is more than or equal to 4 hours.

Further, the pressure of the compression molding in the third step is 10-20Mpa, and the compression molding is carried out along the direction vertical to the arrangement of the particles; the temperature of the reduction treatment is 300-450 ℃, and the time is 2-6 h.

Further, the sintering treatment is performed in a hot pressing furnace, an isostatic pressing furnace, or a discharge plasma furnace.

Further, the temperature of the sintering treatment is 600-900 ℃, and the time is 5-120 min; the sintering pressure is 10-50 MPa.

The invention also provides a copper-based self-lubricating composite material reinforced by the directional arrangement of the particles prepared by the preparation method.

The invention discloses the following technical effects:

the process for preparing the composite material is obviously different from the traditional powder metallurgy preparation process (namely mixing → cold pressing → sintering), and the method adopted by the invention is as follows: preparing a slurry which is stable in performance and contains solid-phase particles by adding a water-based solution into base powder and reinforcing phase powder; then, the driving force generated in the water crystallization process is adopted to lead the particles in the slurry to be gathered in the layered ice crystals and force the particles of the reinforcing phase to be rearranged, and the layered porous green body material is obtained by low-temperature vacuum drying; then, carrying out cold pressing forming on the green material, removing and reducing organic matters and oxidized particles contained in the material by adopting a heat treatment method, and finally carrying out hot pressing treatment at higher temperature to obtain the copper-based self-lubricating material with reinforced particle directional arrangement. The material obtained by the preparation method has the advantages that the reinforced phase particles are uniformly distributed and directionally arranged in the matrix, the friction coefficient of the material with directionally arranged particles under the same volume fraction is reduced by 10.0-20.0 percent compared with that of the material with randomly distributed particles, and the wear rate of the material is reduced by 5.0-15.0 percent; the compressive strength parallel to the direction of alignment of the particles is significantly lower than that obtained perpendicular to the direction of alignment of the particles; and the preparation process of the material is simple and is suitable for small-scale production.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed 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 creative efforts.

FIG. 1 is a schematic view of a freezing mold apparatus according to the present invention;

FIG. 2 is a schematic representation of the grain alignment enhanced Cu-WS prepared in example 1 of the present invention₂Scanning electron micrographs of the cross section of the composite;

wherein FIG. 2(a) is an electron micrograph at 500 times and FIG. 2(b) is an electron micrograph at 5000 times.

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.

The "parts" in the present invention are all parts by mass unless otherwise specified.

The mass percentage of copper element in the copper or copper alloy powder used in the embodiment of the invention is more than or equal to 50.0%.

The freezing mould used in the application is composed of a red copper base with good heat conductivity and an organic square mould (acrylic) with high heat insulation, a wedge-shaped mould is placed above the base, the area of the metal base is matched with the size of the square mould, and the size of the metal base is 10 multiplied by 10mm²-100×100mm²FIG. 1 is a schematic view of a freezing mold;

the wedge-shaped die is made of one of cured epoxy resin, polytetrafluoroethylene and polymethylsiloxane.

Example 1

(1) Preparing the mixed slurry with uniformly dispersed particles

6.2gWS was added to the compounding tank₂Ball milling is carried out on powder (the average particle size is 5.0 mu m), 39.8g of Cu powder (the purity is more than 99.0%, the average particle size is 10.0 mu m), 0.2g of dispersing agent (polyvinylpyrrolidone) and 50.0g of deionized water for 2h (the ball milling rotation speed is 100rpm, and the ball-to-material ratio is 2: 1);

meanwhile, 50.0g of deionized water and 2.5g of gelatin are added into a beaker, the beaker is placed into a drying box at 60 ℃ for dissolution, the mixture is poured into the mixing tank for mixing and ball milling (the ball milling speed is 100rpm, the ball-to-material ratio is 2:1) after the dissolution is completed, and mixed slurry with stable performance is obtained after ball milling for 20 hours.

(2) Preparation of porous Green body Material

Pouring the mixed slurry into a freezing mould containing a wedge-shaped mould (the angle is 15 ℃), putting the freezing mould containing the slurry into a directional temperature field (the temperature of the lower end of the mould is set to be minus 40 ℃ and the temperature of the upper end is 5 ℃) for bidirectional solidification, putting the mould into a low-temperature vacuum drying machine after the slurry is frozen and solidified, and drying for 24 hours at the temperature of minus 30 ℃ to obtain the layered porous green body material.

(3) Press forming of green body, organic matter removal and reduction treatment of metal copper particles

Cutting the dried laminated porous material into 12 × 34 × 24mm³The cuboid is placed into a steel die with a corresponding size for cold pressing forming (the pressure is 10MPa), the cold pressing forming is carried out along the direction vertical to the arrangement of the particles, and then the square green body is placed into a tubular atmosphere furnace for removing organic matters in hydrogen atmosphere and reducing copper particles (the heat treatment temperature is 350 ℃ and the heat preservation time is 4 hours).

(4) Sintering

Placing the sample obtained by the above processes into a graphite mold with a corresponding size, and performing discharge plasma sintering molding (sintering pressure of 40MPa, sintering temperature of 700 ℃, sintering time of 5min), wherein the sintering process is performed in a hot pressing furnace; preparation to obtain WS₂Cu-WS with uniformly distributed and directionally arranged particles in matrix₂A composite material.

FIG. 2 is a schematic representation of the grain alignment enhanced Cu-WS prepared in example 1 of the present invention₂Scanning electron micrographs of the cross section of the composite;

wherein, the attached FIG. 2(a) is an electron microscope image of 500 times, and the attached FIG. 2(b) is an electron microscope image of 5000 times; the Cu/WS thus prepared can be seen from FIG. 1₂The green material having distinct layer structure characteristics and the particles being agglomerated in each layer, WS₂In which the particles are aligned.

Cu-WS prepared in this example₂The composite material has typical laminated structure characteristics, and the obtained material has the compressive strength of 275.6MPa in the direction vertical to the particle arrangement direction and 201.4MPa in the direction parallel to the particle arrangement direction; the coefficient of friction in the direction parallel to the particle alignment was 0.16, and the coefficient of friction in the direction perpendicular to the particle alignment was 0.24.

Example 2

(1) Preparing the mixed slurry with uniformly dispersed particles

Adding 5.1g of MoS into a mixing tank in sequence₂(average particle size 5.0 μm)37.5gCu₃₀Ni alloy powder (nickel content 30.0%, particle size 5-25 μm), 0.2g minuteBall milling is carried out on the powder (polyvinylpyrrolidone) and 50.0g of deionized water for 3h (the ball milling speed is 150rpm, and the mass ratio of the ball materials is 3: 1);

meanwhile, 1.0g of epoxy resin and 50.0g of deionized water are added into a 100ml beaker, the mixture is placed into a drying box at 60 ℃ for dissolution, the mixture is poured into the mixing tank for mixing and ball milling after the mixture is completely dissolved (the ball milling speed is 80rpm, the mass ratio of ball materials is 3: 1), and stable mixed slurry with good rheological property is obtained after ball milling is carried out for 22 hours.

(2) Preparation of porous Green body Material

Pouring the mixed slurry into a freezing mould containing a wedge-shaped mould (the angle is 5 ℃), putting the freezing mould containing the slurry into a directional temperature field (the temperature of the lower end of the mould is set to be minus 60 ℃ and the temperature of the upper end is 25 ℃) for bidirectional solidification, putting the mould into a low-temperature vacuum drying machine after the slurry is frozen and solidified, and drying for 24 hours at the temperature of minus 5 ℃ to obtain the layered porous material.

(3) Press forming of green body, organic matter removal and reduction treatment of metal copper particles

Cutting the dried laminated porous material into 12 × 34 × 24mm³The cuboid is placed into a steel die with a corresponding size for cold pressing forming (the pressure is 15MPa), the cold pressing forming is carried out along the direction vertical to the arrangement of the particles, and then the square green body is placed into a tubular atmosphere furnace for removing organic matters and reducing copper particles under hydrogen atmosphere (the heat treatment temperature is 450 ℃ and the heat preservation time is 2 hours).

(4) Sintering

And (3) placing the sample obtained through the processes into a graphite die with a corresponding size for spark plasma sintering molding (the sintering pressure is 10MPa, the sintering temperature is 600 ℃, the sintering time is 120min), and sintering in an isostatic pressing furnace. This example finally obtained Cu₃₀Ni-20MoS₂Wherein XRD indicates MoS in the composite₂Is oriented in the matrix.

The compressive strength of the obtained material in the direction perpendicular to the alignment direction of the particles was 378.5MPa, while the compressive strength in the direction parallel to the alignment direction of the particles was 269.2 MPa; the coefficient of friction in the direction parallel to the particle alignment was 0.18, and the coefficient of friction in the direction perpendicular to the particle alignment was 0.26.

Example 3

(1) Preparing the mixed slurry with uniformly dispersed particles

Adding 6.2gWS into a mixing tank in sequence₂(average particle size 50.0 μm) 1.3g of MoS₂Powder (average particle size of 0.1 μm)37.5g of Cu powder (average particle size of 10.0 μm), 0.2g of dispersant (polyvinylpyrrolidone) and 50.0g of deionized water were ball milled for 4h (ball milling speed of 50rpm, ball to material ratio of 5: 1);

meanwhile, 10g of a mixture of polyvinyl alcohol and gelatin (the mass ratio of polyvinyl alcohol to gelatin is 1:1) and 50.0g of deionized water are added into a 100ml beaker, the mixture is placed into a drying box at 60 ℃ for dissolution, the mixture is poured into the mixing tank for mixing and ball milling (the ball milling speed is 100rpm, the mass ratio of ball materials is 5:1) after complete dissolution, and mixed slurry with stable performance can be obtained after ball milling for 23 hours.

(2) Preparation of porous Green body Material

Pouring the mixed slurry into a freezing mould containing a wedge-shaped mould (the angle is 40 ℃), putting the freezing mould containing the slurry into a directional temperature field (the temperature of the lower end of the mould is set to be minus 5 ℃ and the temperature of the upper end is 10 ℃) for bidirectional solidification, putting the mould into a low-temperature vacuum drying machine after the slurry is frozen, and drying for 25 hours at the temperature of minus 60 ℃ to obtain the layered porous material.

(3) Press forming of green body, organic matter removal and reduction treatment of metal copper particles

Cutting the dried laminated porous material into 12 × 34 × 24mm³The cuboid is placed into a steel die with a corresponding size for cold pressing forming (the pressure is 20MPa), the cold pressing forming is carried out along the direction vertical to the arrangement of the particles, and then the square green body is placed into a tubular atmosphere furnace for removing organic matters and reducing copper particles under hydrogen atmosphere (the heat treatment temperature is 400 ℃ and the heat preservation time is 6 hours).

(4) Sintering

And (3) putting the sample obtained through the processes into a graphite die with a corresponding size for spark plasma sintering molding (the sintering pressure is 50MPa, the sintering temperature is 900 ℃, the sintering time is 120min), and the sintering is carried out in a spark plasma furnace.

This example finally obtained Cu-15WS₂-5MoS₂Wherein WS₂Particles and MoS₂The particles are uniformly distributed and directionally arranged in the matrix. The compressive strength of the obtained material in the direction perpendicular to the alignment direction of the particles was 234.7MPa, while the compressive strength in the direction parallel to the alignment direction of the particles was 156.8 MPa; the coefficient of friction in the direction parallel to the particle alignment was 0.15, and the coefficient of friction in the direction perpendicular to the particle alignment was 0.23.

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.