PTFE-filled tin bronze powder and method for producing the same

Abstract

The application relates to the technical field of metal powder materials, and provides a tin bronze powder for PTFE filling and a preparation method thereof, which comprises the following steps: preparing uniform mixed powder material composed of copper powder, tin powder and zinc powder; metallurgically transforming the mixed powder material into a Cu-Sn-Zn alloy in a reducing atmosphere; and preparing the tin bronze powder for PTFE filling through crushing and sieving. The prepared tin bronze powder has uniform component distribution and developed dendritic morphology, and can significantly improve the interface bonding strength of PTFE composite materials and the excellent comprehensive mechanical properties of the PTFE composite materials, such as tensile strength, compressive strength, hardness and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of metal powder materials technology, and in particular to a tin bronze powder for PTFE filling and its preparation method. Background Technology

[0002] Polytetrafluoroethylene (PTFE) is a high-performance engineering plastic with a perfluorinated linear molecular structure, widely used in seals, bearing liners, chemical corrosion protection linings, and high-frequency electronic components. However, the monomeric molecular structure of PTFE results in relatively weak intermolecular forces, leading to a series of inherent mechanical and thermal defects that limit its application in more demanding conditions, such as low mechanical strength, poor wear resistance, and poor thermal conductivity.

[0003] To address the aforementioned shortcomings of PTFE, filler modification is the mainstream technical approach in the industry. Existing filler modification methods mainly fall into the following two categories:

[0004] The first type involves adding organic materials such as polyphenylene ester and polyimide. While this method can slightly improve creep resistance, it can hardly improve the material's hardness, thermal conductivity, and inherent wear resistance, and may introduce shortcomings in chemical resistance or temperature resistance.

[0005] The second category involves adding inorganic fillers such as glass fiber, carbon fiber, molybdenum disulfide (MoS2), and copper powder. While these fillers can improve a single performance indicator, they may lead to a decline in other key properties or introduce new problems. For example, MoS2 can improve lubricity and creep resistance, but it can significantly reduce the tensile and impact strength of the material; carbon fiber can enhance and improve thermal conductivity, but its sharp ends can easily cause wear on mating parts and are not conducive to high-frequency insulation applications; metal powders (such as copper powder) can improve thermal and electrical conductivity, but their interfacial bonding with the PTFE matrix is ​​weak, making them prone to peeling at the interface and causing overall failure of the composite material.

[0006] Therefore, how to provide a high-efficiency filler that can form a strong bond with the PTFE matrix and synergistically and evenly improve mechanical strength, wear resistance and other multi-dimensional properties has become an urgent technical problem to be solved. Summary of the Invention

[0007] In view of this, in order to overcome the shortcomings of the prior art, the present invention aims to provide a tin bronze powder for PTFE filling and a method for preparing the same.

[0008] According to a first aspect of the present invention, a method for preparing tin bronze powder for PTFE filling is provided, the method comprising: preparing a uniformly mixed powder composed of copper powder, tin powder and zinc powder; metallurgically transforming the mixed powder into a Cu-Sn-Zn alloy in a reducing atmosphere; and obtaining tin bronze powder for PTFE filling by crushing and sieving.

[0009] Optionally, in the method for preparing tin bronze powder for PTFE filling of the present invention, the mixed powder includes 7-12% tin powder, 1-5% zinc powder, and the balance being copper powder by mass percentage.

[0010] Optionally, in the method for preparing tin bronze powder for PTFE filling of the present invention, the particle size of tin powder is -500 mesh, the particle size of zinc powder is -300 mesh, and the particle size of copper powder is -300 mesh.

[0011] Optionally, in the method for preparing tin bronze powder for PTFE filling of the present invention, the purity of tin powder is not less than 99.9%, the purity of zinc powder is not less than 99%, and the purity of copper powder is not less than 99.8%.

[0012] Optionally, in the method for preparing tin bronze powder for PTFE filling of the present invention, the reducing atmosphere is composed of a nitrogen-hydrogen mixture, and the flow ratio of hydrogen to nitrogen is 0.6:2.

[0013] Optionally, the method for preparing PTFE-filled tin bronze powder of the present invention involves metallurgically transforming the mixed powder into a Cu-Sn-Zn alloy in the following manner: placing the mixed powder in a reducing atmosphere, heating it to 350-500°C, and holding it at that temperature for 60-180 minutes.

[0014] Optionally, in the method for preparing PTFE-filled tin bronze powder of the present invention, the temperature is increased to the holding temperature at a rate of 30°C / min.

[0015] Optionally, in the method for preparing PTFE-filled tin bronze powder of the present invention, after heat preservation, the atmosphere is switched to nitrogen protective gas and cooled to 25°C to obtain Cu-Sn-Zn alloy.

[0016] Optionally, the method for preparing tin bronze powder for PTFE filling of the present invention involves crushing Cu-Sn-Zn alloy by roller crushing and sieving tin bronze powder with a particle size distribution of -45μm from the crushed material.

[0017] According to a second aspect of the present invention, a tin bronze powder for PTFE filling is provided, which is prepared according to the method described above.

[0018] The present invention relates to tin bronze powder for PTFE filling and its preparation method, which has the following beneficial technical effects:

[0019] 1) Through controllable alloying treatment, Cu-Sn-Zn alloy powder with uniform composition distribution is obtained, avoiding segregation of metal powders due to differences in specific gravity, ensuring compositional consistency and stability, with a short preparation process and high production efficiency, which is conducive to industrial-scale production.

[0020] 2) The obtained tin bronze powder particles have a well-developed dendritic morphology, forming a strong mechanical interlock and chemical bond with the PTFE matrix, significantly improving the interfacial bonding strength between the filler and the matrix. At the same time, the uniform composition distribution and appropriate alloying degree significantly improve the tensile strength and compressive strength of the filled PTFE composite material, and the increased hardness further enhances the creep resistance and wear resistance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 These are 1000x SEM micrographs of the copper powder used in Examples 1-6 of this invention.

[0023] Figure 2 These are 2000x SEM micrographs of the tin powder used in Examples 1-6 of this invention.

[0024] Figure 3 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 1 of the present invention.

[0025] Figure 4 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 2 of the present invention.

[0026] Figure 5 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 4 of the present invention.

[0027] Figure 6 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 5 of the present invention.

[0028] Figure 7 The energy spectrum distribution of copper, tin, and zinc elements and the total elemental distribution spectrum of the tin bronze powder prepared according to Example 2 of the present invention are shown. Detailed Implementation

[0029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0031] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0032] Example 1

[0033] In this embodiment, tin bronze powder for PTFE filling is prepared in the following manner:

[0034] Step 1: Prepare the mixed powder

[0035] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0036] The ingredients, including 7% tin powder, 2% zinc powder, and the remainder copper powder by weight, are added to a three-dimensional mixer and mixed at 20 r / min for 30 minutes to prepare a mixed powder.

[0037] Step 2: Preparation of Cu-Sn-Zn alloy

[0038] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 450°C at a rate of 30°C / min and held for 120 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0039] Step 3: Preparation of Tin Bronze Powder

[0040] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0041] Example 2

[0042] Step 1: Prepare the mixed powder

[0043] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0044] The ingredients, including 10% tin powder, 2% zinc powder, and the remainder copper powder by weight, are added to a three-dimensional mixer and mixed at 20 r / min for 30 minutes to prepare a mixed powder.

[0045] Step 2: Preparation of Cu-Sn-Zn alloy

[0046] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 400°C at a rate of 30°C / min and held for 120 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0047] Step 3: Preparation of Tin Bronze Powder

[0048] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0049] Example 3

[0050] Step 1: Prepare the mixed powder

[0051] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0052] The mixture is prepared by adding 12% tin powder, 2% zinc powder, and the remainder copper powder by weight into a three-dimensional mixer and mixing at 20 r / min for 30 min to prepare a mixed powder.

[0053] Step 2: Preparation of Cu-Sn-Zn alloy

[0054] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 350°C at a rate of 30°C / min and held for 120 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0055] Step 3: Preparation of Tin Bronze Powder

[0056] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0057] Example 4

[0058] Step 1: Prepare the mixed powder

[0059] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0060] The ingredients, including 10% tin powder, 1% zinc powder, and the remainder copper powder by weight, are added to a three-dimensional mixer and mixed at 20 r / min for 30 minutes to prepare a mixed powder.

[0061] Step 2: Preparation of Cu-Sn-Zn alloy

[0062] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 500°C at a rate of 30°C / min and held for 120 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0063] Step 3: Preparation of Tin Bronze Powder

[0064] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0065] Example 5

[0066] Step 1: Prepare the mixed powder

[0067] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0068] The ingredients, including 10% tin powder, 5% zinc powder, and the remainder copper powder by weight, are added to a three-dimensional mixer and mixed at 20 r / min for 30 minutes to prepare a mixed powder.

[0069] Step 2: Preparation of Cu-Sn-Zn alloy

[0070] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 400°C at a rate of 30°C / min and held for 60 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0071] Step 3: Preparation of Tin Bronze Powder

[0072] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0073] Example 6

[0074] Step 1: Prepare the mixed powder

[0075] Prepare the following materials: tin powder with a particle size of -500 mesh and a purity of not less than 99.9%, zinc powder with a particle size of -300 mesh and a purity of not less than 99%, and copper powder with a particle size of -300 mesh and a purity of not less than 99.8%.

[0076] The mixture is prepared by adding 12% tin powder, 1% zinc powder, and the remainder copper powder by weight into a three-dimensional mixer and mixing at 20 r / min for 30 min to prepare a mixed powder.

[0077] Step 2: Preparation of Cu-Sn-Zn alloy

[0078] The mixture was placed in a heat treatment furnace with a thickness of 5 cm. Hydrogen and nitrogen were introduced at a flow ratio of 0.6:2 to form a reducing atmosphere composed of nitrogen-hydrogen mixed gas. The temperature was raised to 400°C at a rate of 30°C / min and held for 180 min. The atmosphere in the furnace was then switched to a nitrogen protective atmosphere and cooled to 25°C with the furnace to obtain Cu-Sn-Zn alloy.

[0079] Step 3: Preparation of Tin Bronze Powder

[0080] The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

[0081] Example 7

[0082] The tin bronze powder prepared in Examples 1 to 6 was mixed with PTFE at a mass ratio of 2:3 and then cold-pressed. The cold pressing pressure was 35 MPa. The temperature was increased to 375°C at a rate of 50°C / h and held for 150 min. The temperature was then decreased to 315°C at a rate of 15°C / h and then allowed to cool naturally to room temperature in the furnace before being removed from the furnace to obtain a composite board of tin bronze powder and PTFE.

[0083] Example 8

[0084] The morphology of the copper and tin powders used in Examples 1-6 was observed and analyzed using a Hitachi SU8000 scanning electron microscope. Figure 1 These are 1000x SEM micrographs of the copper powder used in Examples 1-6 of this invention. Figure 2 These are 2000x SEM micrographs of the tin powder used in Examples 1-6 of this invention.

[0085] like Figure 1 As shown, the copper powder particles used in this embodiment of the invention have a dendritic morphology, a rough surface, and a large specific surface area. This morphological feature endows the powder with good pressing performance and formability. During sintering, the particles are in close contact and easily diffuse and fuse. At the same time, its wide particle size distribution (-300 mesh) helps to achieve effective gradation and filling between powder particles, and it has good compatibility with powder metallurgy forming processes.

[0086] like Figure 2 As shown, the tin powder particles used in this embodiment of the invention have an approximately spherical or droplet-like morphology. The ultra-fine particle size (-500 mesh) gives it a low melting point and good wettability, enabling it to rapidly melt and fill the gaps between the skeleton particles during sintering, achieving a uniform liquid phase distribution and significantly promoting the alloying process. At the same time, its fine and uniform particle size is beneficial for achieving homogeneous dispersion during mixing, and it has high compatibility with mixing and metallurgical transformation processes.

[0087] The microstructure and EDS surface distribution of the tin bronze powders prepared in Examples 1-6 were observed and analyzed using a Hitachi SU8000 scanning electron microscope. Figure 3 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 1 of the present invention. Figure 4 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 2 of the present invention. Figure 5 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 4 of the present invention. Figure 6 This is a 1000x SEM micrograph of the tin bronze powder prepared according to Example 5 of the present invention. Figure 7 The energy spectrum distribution of copper, tin, and zinc elements and the total elemental distribution spectrum of the tin bronze powder prepared according to Example 2 of the present invention are shown.

[0088] like Figures 3 to 6As shown, the tin bronze powder prepared by the present invention through mixing, metallurgical transformation, crushing, and sieving processes still retains a well-developed dendritic morphology. This morphological feature stems from the effective inheritance of the morphology of copper powder, and the diffusion alloying during the metallurgical transformation process does not destroy its dendritic framework structure. The well-developed dendritic morphology endows the tin bronze powder with excellent pressing and forming properties, which is beneficial for achieving close contact and bonding between particles during subsequent sintering, thereby improving the final density and mechanical properties of the product.

[0089] like Figure 7 As shown, the tin bronze powder prepared in this embodiment of the invention exhibits a highly uniform elemental distribution with no segregation or enrichment. Through metallurgical transformation, tin and zinc elements have been fully diffused and dissolved in the copper matrix, achieving a high degree of alloying. The homogeneity of the composition distribution not only ensures the consistency of the powder particles' properties but also lays the foundation for the uniformity of the microstructure during subsequent forming and sintering, effectively avoiding local performance differences caused by compositional segregation.

[0090] The bulk density and flowability of the tin bronze powder prepared in Examples 1-6 of this invention were measured using a Hall flowmeter. The particle size distribution of the tin bronze powder prepared in Examples 1-4 of this invention was measured using a Taylor analytical sieve. The median diameter (D50) of the tin bronze powder prepared in Examples 1-4 was measured using a Dandong Baite BT9300-ST laser particle size analyzer. The measurement results are shown in Table 1.

[0091] Table 1

[0092]

[0093] As shown in Table 1, the embodiments of the present invention can effectively prepare tin bronze powder with uniform composition and high alloying degree. The loose packing density is loosely controlled at 1.8-2.24 g / cm³. 3 The fine particle size, with a median diameter controlled within the range of 20.50-23.82 μm, ensures uniform dispersion of the metal skeleton in the polymer matrix. The micro-dendritic morphology provides excellent molding support for the powder, offering abundant physical interfaces for subsequent mechanical anchoring with PTFE polymers, thus significantly improving the tensile toughness and overall density of the composite material. Simultaneously, the high alloying and uniformity of the microstructure work synergistically to eliminate localized performance defects caused by phase segregation, ensuring improved material hardness and compressive strength. The powders obtained in the examples are all non-flowing, allowing for good venting during sintering and reducing product defects. Furthermore, as a base material for filler compounds, they are easily and uniformly mixed with other fillers, reducing segregation and ensuring uniform mixing and excellent product performance.

[0094] The mechanical properties of the composite plate made of tin bronze powder and PTFE prepared in Example 7 were determined using a German Zwick high and low temperature tensile testing machine. The tensile strength and compressive strength were tested, and the hardness value of the prepared composite plate was determined using a Shore D hardness tester. The test results are shown in Table 2.

[0095] Table 2

[0096]

[0097] As shown in Table 2, the composite plate made using the tin bronze powder prepared according to this invention as a filler has a tensile strength of not less than 22.8 MPa, a compressive strength of not less than 51.4 MPa, and a hardness of not less than 55.2 (Shore D), exhibiting excellent comprehensive mechanical properties. The dendritic crystal structure of the powder is in close contact and bond with the PTFE matrix during sintering, promoting mechanical interlocking with the matrix and effectively transferring stress during tensile testing, significantly improving the tensile strength of the plate. The high uniformity of the composition ensures the uniformity of the microstructure of the sintered body, making the stress distribution under compressive load more stable, thus obtaining reliable compressive strength. The high degree of alloying endows the particles with higher load-bearing capacity, which, combined with the uniform dispersion of fine particle size in the matrix, enhances the compressive strength and surface hardness of the plate. Surface hardness, as a macroscopic characterization of a material's resistance to local plastic deformation, also indicates the material's ability to resist creep deformation under constant stress. Therefore, the plate prepared according to this invention also has good creep resistance, effectively maintaining dimensional stability and mechanical reliability under long-term load conditions.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing tin bronze powder for PTFE filling, characterized in that, The method includes: preparing a uniform mixed powder composed of copper powder, tin powder and zinc powder; metallurgically transforming the mixed powder into a Cu-Sn-Zn alloy in a reducing atmosphere; and obtaining tin bronze powder for PTFE filling by crushing and sieving.

2. The method for preparing tin bronze powder for PTFE filling according to claim 1, characterized in that, The mixed powder contains 7-12% tin powder, 1-5% zinc powder, and the balance is copper powder by mass percentage.

3. The method for preparing tin bronze powder for PTFE filling according to claim 1, characterized in that, The particle size of tin powder is -500 mesh, zinc powder is -300 mesh, and copper powder is -300 mesh.

4. The method for preparing tin bronze powder for PTFE filling according to claim 3, characterized in that, The purity of tin powder is not less than 99.9%, the purity of zinc powder is not less than 99%, and the purity of copper powder is not less than 99.8%.

5. The method for preparing tin bronze powder for PTFE filling according to claim 1, characterized in that, The reducing atmosphere consists of a nitrogen-hydrogen mixture with a hydrogen to nitrogen flow rate ratio of 0.6:

2.

6. The method for preparing tin bronze powder for PTFE filling according to claim 1, characterized in that, The mixed powder is metallurgically transformed into a Cu-Sn-Zn alloy in the following manner: the mixed powder is placed in a reducing atmosphere, heated to 350-500℃, and held for 60-180 minutes.

7. The method for preparing PTFE-filled tin bronze powder according to claim 6, characterized in that, Heat to the holding temperature at a rate of 30℃ / min.

8. The method for preparing PTFE-filled tin bronze powder according to claim 6, characterized in that, After the heat preservation is completed, the atmosphere is switched to nitrogen protective gas and cooled to 25°C to obtain Cu-Sn-Zn alloy.

9. The method for preparing tin bronze powder for PTFE filling according to claim 1, characterized in that, The Cu-Sn-Zn alloy is crushed by roller crushing, and tin bronze powder with a particle size distribution of -45μm is screened out from the crushed material through sieving.

10. A tin bronze powder for PTFE filling, characterized in that, The tin bronze powder for PTFE filling is prepared according to any one of claims 1 to 9.

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