Amorphous-coated copper powder and preparation method thereof

Abstract

An amorphous coated copper powder and its preparation method belong to the technical field of powder metallurgy powder preparation. The copper powder is a 10-30nm thick amorphous film covered on the surface of the copper powder particles. The chemical composition formula of the coating layer is Al 100‑a (Cu 100‑b Y b ) a , where 10≤a≤25, 25≤b≤45 are the atomic percentage compositions. First, Al with a melting point below 700°C is prepared by arc melting combined with melt atomization technology. 100‑a (Cu 100‑b Y b ) a Amorphous alloy powder is mixed with copper powder as the master material of the coating layer and subjected to high-energy ball milling, resulting in Al 100‑a (Cu 100‑b Y b ) a The amorphous material adheres and spreads on the surface of the copper powder, ultimately forming a nanometer-thick film on the surface of the copper powder particles. This method successfully produces copper powder coated with a nanometer-thick amorphous layer. By adjusting the amount of the coating matrix material added, the amorphous coating layer of varying thickness can be obtained on the surface of the copper powder particles. This method also enables liquid-solid reaction sintering of the copper powder material, significantly reducing the sintering temperature and increasing the density of the sintered body, which is beneficial for improving the performance and production efficiency of ODS-Cu copper-based sintered materials.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy powder preparation, and relates to Cu powder coated with an amorphous layer and a preparation method thereof. Background Art

[0002] Oxide dispersion-strengthened (ODS) copper alloys offer high electrical and thermal conductivity, resistance to arc erosion and wear, and excellent high-temperature mechanical and processing properties. They are used in a wide range of applications, including resistance welding electrodes, plasma cutting gun nozzles, high-speed train asynchronous traction motor rotors, low-voltage electrical contacts and supports, relay copper sheets, integrated circuit lead frames, conductive elastic materials, high-temperature conductive bars, and combustion chamber liners. Currently, the production of ODS-Cu alloys primarily relies on internal oxidation powder metallurgy technology: internal oxidation is used to obtain a dispersed oxide in the Cu matrix. After the powder sintering process is completed, multiple processes such as hot extrusion, cold drawing, and annealing are required to improve the microstructure and properties. Currently, commercially available ODS-Cu is primarily Al2O3-Cu, marketed as the Gildcop series from SCM (USA).

[0003] Powder modification is beneficial for improving the oxide state (size, morphology, and distribution) in ODS-Cu sintered bodies, as well as the material's microstructure uniformity and performance. Existing powder modification methods primarily focus on directly obtaining composite powders of ideal size. For example, Aghamiria et al. used copper powder and Y2O3 powder as raw materials, using stearic acid as a process control agent, to prepare Y2O3-Cu reinforced with 28nm nano-oxide particles through mechanical alloying. Regarding surface modification of single powders, due to the poor affinity between oxides and metals, chemical methods have been used to modify the surface of hard oxide particles. To date, no research has been reported on the surface coating and modification of soft copper particles. For example, Xiong Weihao et al. used electroless plating to obtain Ni-coated Y2O3 powders; LU et al. also achieved electroless copper plating on Al2O3 particles. Existing powder surface modification technologies generally suffer from limitations such as numerous control parameters, complex production processes, long cycle times, and poor process controllability and reproducibility. In particular, the type and content of impurities are difficult to control. These issues can affect the subsequent sintering of alloy powders.

[0004] Based on the fact that there is currently no physical method for coating and modifying the surface of copper powder particles, this application proposes to utilize the characteristics of Al-Y-Cu amorphous alloy, such as high structural and compositional uniformity, low melting point, and easy rheological behavior in the supercooled liquid phase, as a surface coating. Through mechanical ball milling, a special type of Cu powder material coated with a nanometer-thick amorphous layer has been successfully developed. This material not only enables high-density sintering of embryonic bodies at relatively low temperatures, but also overcomes the various shortcomings of existing powder metallurgy methods for preparing ODS-Cu materials. It can be used to sinter and produce dense ODS-Cu sintered bodies with a uniform distribution of oxide dispersed phases. Summary of the Invention

[0005] The purpose of the present invention is to provide an amorphous-coated copper powder and a preparation method thereof, so as to solve the following problems existing in the current preparation of ODS-Cu materials by powder metallurgy: (1) physical surface coating modification of the main copper powder soft particles has not yet been achieved; (2) the existing common chemical methods for powder surface modification have the disadvantages of many control parameters, complex production processes, long cycles, poor process controllability and reproducibility, and difficulty in controlling the types and contents of impurities; (3) the crystalline modified layer has the disadvantages of high melting point and poor fluidity, which will lead to problems such as high subsequent powder sintering temperature, coarse grains and weak interface bonding.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An amorphous coated copper powder, that is, the surface of the copper powder particles is covered with a layer of nanometer-thick amorphous film. The chemical composition formula of the amorphous film coating is Al 100-a (Cu 100-b Y b ) a , including Y, Cu, and Al elements, where 10≤a≤25, 25≤b≤45 are atomic percentage compositions.

[0008] Furthermore, the thickness of the nano-amorphous coating layer (ie, the alloy film) is between 10 and 30 nm, and the size of the copper powder particles can vary in the range of 10 to 30 μm.

[0009] A method for preparing copper powder coated with a nano-amorphous layer, firstly preparing Al with a melting point below 700 ° C by arc melting combined with melt atomization technology 100-a (Cu 100-b Y b ) a Amorphous alloy powder is mixed with copper powder as the master material of the coating layer and subjected to high-energy ball milling, resulting in Al 100-a (Cu 100-b Y b ) a The amorphous material adheres to and spreads on the surface of the copper powder, eventually forming a nanometer-thick film on the surface of the copper powder particles. When the copper powder, coating matrix material, and ball milling process are constant, the thickness of the amorphous film on the copper powder particle surface can be controlled by varying the amount of coating matrix material added.

[0010] The specific steps are as follows:

[0011] (1) The first step is to prepare Al 100-a (Cu 100-b Y b ) a Powder materials

[0012] First, industrial pure metal is used as raw material, and the atomic percentage composition is Cu 100-b Y b The alloy was placed in a water-cooled copper crucible in a non-consumable arc melting furnace and vacuumed to ≤5×10 -2 Pa, and filled with 0.01 ~ 0.02MPa of industrial pure Ar gas for non-consumable arc melting, the working current of the melting is 150 ~ 180A; the alloy is turned upside down and repeatedly melted 3 times to obtain a uniform composition of Cu 100-b Y b alloy ingot; then, Cu 100-b Y b The alloy ingot is crushed and mixed with industrial pure Al to form an atomic percentage composition of Al 100-a (Cu 100-b Y b ) a The alloy is placed in a non-consumable arc melting furnace and melted into an ingot. The melting current is 100-120A. The alloy is turned upside down and melted repeatedly for 3 times to make Al 100-a (Cu 100-b Y b ) a The alloy ingot has uniform composition.

[0013] Al 100-a (Cu 100-b Y b ) a The alloy ingot is crushed and placed in a graphite crucible for atomization and powdering: it is heated by medium frequency induction to a certain temperature (slightly higher than Al 100-a (Cu 100-b Y b ) a The mixture was then cooled using atomization technology (atomizing gas pressure of 1-5 MPa and a guide rod nozzle aperture of 1 mm) to produce a spherical powder with a particle size ranging from 5 μm to 50 μm. The powder's appearance was observed using a scanning electron microscope, and its amorphous structure was confirmed using X-ray diffraction (XRD) and electron microscopy.

[0014] (2) The second step is to prepare the amorphous layer coated copper powder

[0015] First, based on the particle size of the selected copper powder (commercial, commercially available), sieve and select Al 100-a (Cu 100-b Y b ) aWeigh and mix the amorphous powder according to the desired ratio. Then, place it in a ball mill with grinding balls (material-to-ball ratio of 1:5-1:10) and perform high-energy ball milling at a speed of 100-150 rpm for 10-30 hours. Remove the milled powder and set aside.

[0016] The powder obtained in step 2 was observed by scanning electron microscopy and electron microscopy (with energy spectrum attachment). The results showed that an amorphous film was formed on the surface of the copper particles, and the composition of the film was close to that of Al 100-a (Cu 100-b Y b ) a The thickness of the amorphous coating layer of the cladding layer mother material is between 10 and 30 nm, and the size of the copper particles can vary within the range of 10 to 30 μm.

[0017] The beneficial effects of the present invention are:

[0018] (1) The present invention successfully prepared copper powder coated with a nano-thick amorphous layer;

[0019] (2) By adjusting the amount of the coating layer parent material added, an amorphous coating layer of different thicknesses can be obtained on the surface of the copper powder particles;

[0020] (3) This nano-amorphous layer-coated copper powder material can realize liquid-solid reaction sintering of copper powder material, which can significantly reduce the sintering temperature of copper material and improve the density of sintered body, which is beneficial to improving the performance and production efficiency of ODS-Cu copper-based sintered material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 shows the Al prepared in Example 1 75 (Cu 55 Y 45 ) 25 SEM secondary electron image (a) and XRD spectrum (b) of the coating layer base material powder. The XRD spectrum shows the typical diffuse package characteristics of the amorphous structure.

[0022] Figure 2 shows the SEM morphology and TEM high-resolution image of the Cu powder coated with the amorphous film in Example 1. The dotted line shown in Figure 2(b) is the boundary between the regular striped copper grains and the disordered amorphous film layer. DETAILED DESCRIPTION

[0023] The following describes in detail the copper powder coated with a nano-amorphous layer and its implementation in the present invention. The specific preparation process of this powder is described using three typical components as examples.

[0024] Example 1A1 75 (Cu 55 Y 45 ) 25 Copper powder coated with amorphous layer

[0025] Step 1: Prepare the parent material of the coating layer - Al 75 (Cu 55 Y 45 ) 25 Amorphous powder

[0026] Industrial pure Cu (>99.9%) and Y (>99.5%) are used as raw materials, and the atomic percentage composition is Cu 55 Y 45 The raw materials are mixed and placed in a water-cooled copper crucible in a non-consumable arc melting furnace, and then vacuumed to 2×10 -2 Pa, filled with 0.02MPa industrial pure Ar gas for arc melting, the melting current is 180A; the alloy is turned upside down and repeatedly melted 3 times to obtain a uniform composition of Cu 55 Y 45 The alloy ingot is taken out, crushed, and mixed with industrial pure Al to form an atomic percentage composition of Al 75 (Cu 55 Y 45 ) 25 Alloy, continue to use the above non-consumable arc melting process to obtain Al with uniform composition 75 (Cu 55 Y 45 ) 25 Alloy ingot, the melting current in this stage is 120A, and the weight loss of the alloy before and after melting is less than one thousandth.

[0027] Next, Al 75 (Cu 55 Y 45 ) 25 After the alloy ingot is crushed, it is placed in a graphite crucible in a gas atomization powder production unit. The crucible is then heated to 800°C in an induction heating coil and held at that temperature for 5 minutes. The ingot is then atomized and cooled using gas atomization technology (atomizing gas pressure of 5 MPa, with a guide rod nozzle aperture of 1 mm). This produces a nearly spherical powder material, as shown in Figure 1(a). The powder particle size ranges from 5 μm to 30 μm. Figure 1(b) shows the X-ray diffraction spectrum of the powder, which displays the typical diffuse packet characteristics of an amorphous structure, with no sharp crystalline diffraction peaks.

[0028] Step 2: Prepare Al 75 (Cu 55 Y 45 ) 25 Amorphous film coated copper powder material

[0029] Use 600 mesh and 800 mesh sieves to separate Al2O3 with a particle size of 18 to 23 μm. 75 (Cu 55 Y45 ) 25 The powder was weighed and mixed with commercially available copper powder with a particle size of 20 μm at a mass ratio of 1:90. The mixed powder and grinding balls (material-to-ball ratio of 1:10) were placed in a ball mill and subjected to high-energy ball milling at a ball mill speed of 150 rpm for 10 hours.

[0030] The powder after high-energy ball milling is taken out. The obtained powder is observed and characterized by scanning electron microscopy and transmission electron microscopy (with energy spectrum accessories). Figure 2 (a) shows the scanning electron microscope (SEM) morphology of the powder, indicating that the particle size of the powder particles is between 10 and 20 μm; further transmission electron microscope (TEM) analysis shows that: the powder has a shell structure, the main body of the particles is a copper grain with an orderly structure, and the surface is wrapped with a thin film with a thickness of about 10 nm, which is disordered and amorphous. The atomic percentage composition of the film measured by energy spectrum is close to Al 75 (Cu 55 Y 45 ) 25 Attached Figure 2(b) shows the TEM high-resolution image of the powder material. Above the dotted line in the figure are regular stripes of crystalline copper particles, and below the dotted line are disordered Al 75 (Cu 55 Y 45 ) 25 Amorphous film.

[0031] The above results show that the powder finally obtained in this embodiment is nano-thick Al 75 (Cu 55 Y 45 ) 25 Amorphous film coated copper particle powder material, which is a special nano-amorphous layer coated copper powder, is made of soft low melting point Al 75 (Cu 55 Y 45 ) 25 The amorphous material is gradually spread and coated on the surface of copper powder particles through high-energy ball milling.

[0032] Example 2A1 90 (Cu 75 Y 25 ) 10 Copper powder coated with amorphous layer

[0033] Step 1: Prepare the parent material of the coating layer - Al 90 (Cu 75 Y 25 ) 10 Amorphous powder

[0034] Industrial pure Cu (>99.9%) and Y (>99.5%) are used as raw materials, and the atomic percentage composition is Cu 75 Y 25 The raw materials are mixed and placed in a water-cooled copper crucible in a non-consumable arc melting furnace, and then vacuumed to 5×10 -2 Pa, filled with 0.01MPa industrial pure Ar gas for arc melting, the melting current is 170A; the alloy is turned upside down and repeatedly melted 3 times to obtain a uniform composition of Cu 75 Y 25 The alloy ingot is taken out, crushed, and mixed with industrial pure Al to form an atomic percentage composition of Al 90 (Cu 75 Y 25 ) 10 Alloy, continue to use the above non-consumable arc melting process to obtain Al with uniform composition 90 (Cu 75 Y 25 ) 10 Alloy ingot, the melting current in this stage is 110A, and the weight loss of the alloy before and after melting is less than one thousandth.

[0035] Next, Al 90 (Cu 75 Y 25 ) 10 After the alloy ingot is crushed, it is placed in a graphite crucible in a gas atomization powder making device. The crucible is then placed in an induction heating coil, heated to 700°C, and held at that temperature for 3 minutes. It is then sprayed and cooled using gas atomization technology (the atomizing gas pressure is 1 MPa, and the nozzle aperture of the guide rod is 1 mm). This produces a nearly spherical powder material with a particle size of 20 to 50 μm. Its X-ray diffraction spectrum shows the typical diffuse packet characteristics of an amorphous structure.

[0036] Step 2: Prepare Al 90 (Cu 75 Y 25 ) 10 Amorphous film coated copper powder material

[0037] Use 400 mesh and 600 mesh sieves to separate Al2O3 with a particle size of 23 to 38 μm. 90 (Cu 75 Y 25 ) 10 The powder was weighed and mixed with commercially available copper powder with a particle size of 45 μm at a mass ratio of 1:25. The mixed powder and grinding balls (material-to-ball ratio of 1:5) were placed in a ball mill and subjected to high-energy ball milling at a ball mill speed of 100 rpm for 30 hours.

[0038] The powder after high-energy ball milling was taken out. The obtained powder was observed by scanning electron microscopy and transmission electron microscopy (with energy spectrum accessories). The scanning electron microscope (SEM) morphology showed that the powder particle size was between 15 and 30 μm; the transmission electron microscope (TEM) analysis showed that the main body of the powder was copper grains with an orderly structure, which was covered with an amorphous alloy film with a thickness of about 30 nm. The atomic percentage composition measured by the energy spectrum was close to Al 90 (Cu 75 Y 25 ) 10 The final product of this embodiment is Al 90 (Cu 75 Y 25 ) 10 Copper powder material coated with nano-amorphous film.

[0039] Example 3A1 85 (Cu 60 Y 40 ) 15 Copper powder coated with amorphous layer

[0040] Step 1: Prepare the parent material of the coating layer - Al 85 (Cu 60 Y 40 ) 15 Amorphous powder

[0041] Industrial pure Cu (>99.9%) and Y (>99.5%) are used as raw materials, and the atomic percentage composition is Cu 60 Y 40 The raw materials are mixed and placed in a water-cooled copper crucible in a non-consumable arc melting furnace, and then vacuumed to 3×10 -2 Pa, filled with 0.01MPa industrial pure Ar gas for arc melting, the melting current is 150A; the alloy is turned upside down and repeatedly melted 3 times to obtain a uniform composition of Cu 60 Y 40 The alloy ingot is taken out, crushed, and mixed with industrial pure Al to form an atomic percentage composition of Al 85 (Cu 60 Y 40 ) 15 Alloy, continue to use the above non-consumable arc melting process to obtain Al with uniform composition 85 (Cu 60 Y 40 ) 15 Alloy ingot, the melting current in this stage is 100A, and the weight loss of the alloy before and after melting is less than one thousandth.

[0042] Next, Al 85 (Cu 60Y 40 ) 15 After the alloy ingot is crushed, it is placed in a graphite crucible in a gas atomization powder making device. The crucible is then placed in an induction heating coil and heated to 680°C for 2 minutes. It is then sprayed and cooled using gas atomization technology (the atomizing gas pressure is 3 MPa, and the nozzle aperture of the guide rod is 1 mm). This produces a nearly spherical powder material with a particle size ranging from 15 to 35 μm. Its X-ray diffraction spectrum shows the typical diffuse packet characteristics of an amorphous structure.

[0043] Step 2: Prepare Al 85 (Cu 60 Y 40 ) 15 Amorphous film coated copper powder material

[0044] Use 500 mesh and 800 mesh sieves to separate Al2O3 with a particle size of 18 to 25 μm. 85 (Cu 60 Y 40 ) 15 The powder was weighed and mixed with commercially available copper powder with a particle size of 30 μm at a mass ratio of 1:50. The mixed powder and grinding balls (material-to-ball ratio of 1:5) were placed in a ball mill and subjected to high-energy ball milling at a ball mill speed of 120 rpm for 20 hours.

[0045] The powder after high-energy ball milling was taken out. The obtained powder was observed by scanning electron microscopy and transmission electron microscopy (with energy spectrum accessories). The scanning electron microscope (SEM) morphology showed that the powder particle size was between 10 and 25 μm; the transmission electron microscope (TEM) analysis showed that the main body of the powder was copper grains with an orderly structure, which was covered with an amorphous alloy film with a thickness of about 20 nm. The atomic percentage composition measured by the energy spectrum was close to Al 85 (Cu 60 Y 40 ) 15 The final product of this embodiment is Al 85 (Cu 60 Y 40 ) 15 Copper powder material coated with nano-amorphous film.

[0046] In order to reveal and verify the beneficial effects of the amorphous coated Cu composite powder provided by the present invention, we used it as the final powder to prepare an ODS-copper-based alloy. Specifically, the composite powder obtained in the second step of Example 1 was used to prepare an ODS-copper-based alloy sintered body by hot pressing sintering technology. The sintering temperature was 880°C and the temperature was kept for 2 hours. During the sintering process, the amorphous coating layer melted into a liquid phase, fully filling the gaps between the Cu powder particles, and Al and Y adsorbed the free O impurities in the main copper powder to form oxides in situ. The final sintered density of the ODS-copper-based alloy can be as high as 98% or more. Observation under a scanning electron microscope found that the ODS-copper sintered body had fine grains, and (Al, Y)2O3 particles were formed both inside the grains and at the grain boundaries, and were uniformly and dispersedly distributed with a size between 10 and 100 nm, achieving the expected results and well solving the technical problems that the present invention is intended to solve as mentioned above. At the same time, the amorphous coated copper powder prepared by the present invention can also be used as a raw material for preparing ODS-copper materials by a melt casting method, wherein the amorphous film coating can effectively reduce the melting temperature and improve the wettability of the melt and the reinforcement particles.

[0047] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. An amorphous-coated copper powder, characterized in that: The copper powder is a copper powder particle surface covered with a layer of nano-thick amorphous film, the chemical composition formula of the nano-amorphous film coating is Al 100-a (Cu 100-b Y b ) a , including Y, Cu, and Al elements, where 10≤a≤25, 25≤b≤45 are atomic percentage compositions.

2. The amorphous-coated copper powder according to claim 1, characterized in that: The thickness of the nano-amorphous thin film coating layer is between 10 and 30 nm, and the size of the copper powder particles varies in the range of 10 to 30 μm.

3. A method for preparing the amorphous-coated copper powder according to claim 1 or 2, characterized in that: Preparation of Al with melting point below 700℃ by arc melting combined with melt atomization technology 100-a (Cu 100-b Y b ) a Amorphous alloy powder; mix it with copper powder as the master material of the coating layer and perform high-energy ball milling to make Al 100-a (Cu 100-b Y b ) a The amorphous material adheres and spreads on the surface of the copper powder, eventually forming a nano-thick film on the surface of the copper powder particles; when the copper powder, coating layer mother material and ball milling process are constant, the thickness of the amorphous film on the surface of the copper powder particles can be controlled by changing the addition amount of the coating layer mother material.

4. The method for preparing an amorphous-coated copper powder according to claim 3, wherein: The specific steps are as follows: (1) The first step is to prepare Al 100-a (Cu 100-b Y b ) a Powder materials First, industrial pure metal is used as raw material, and the atomic percentage composition is Cu 100-b Y b The alloy is placed in a water-cooled copper crucible of a non-consumable arc melting furnace, which is then evacuated and filled with industrial pure Ar gas for non-consumable arc melting; The alloy is turned upside down and smelted repeatedly to obtain a uniform composition of Cu 100-b Y b alloy ingot; secondly, Cu 100-b Y b Alloy ingot crushing and industrial pure Al, with atomic percentage composition of Al 100-a (Cu 100-b Y b ) a The alloy is placed in a non-consumable arc melting furnace to be melted into an ingot. The alloy is turned upside down and repeatedly melted many times to make Al 100-a (Cu 100-b Y b ) a The alloy ingot has uniform composition; finally, the Al 100-a (Cu 100-b Y b ) a The alloy ingot is crushed, placed in a graphite crucible, and atomized to obtain spherical powder material with a particle size between 5 μm and 50 μm. (2) The second step is to prepare the amorphous layer coated copper powder First, based on the selected copper powder particle size, sieve and select Al 100-a (Cu 100-b Y b ) a The amorphous powder is weighed and mixed according to the required proportion; then, it is placed in a ball mill with grinding balls for high-energy ball milling. The ball mill speed is 100-150 rpm and the ball milling time is 10-30 h. Finally, the ball-milled powder is taken out to obtain the product.

5. The method for preparing an amorphous-coated copper powder according to claim 4, characterized in that: In the step (1), Cu 100-b Y b During the smelting process of the alloy ingot, the working current is 150~180A; 100-a (Cu 100-b Y b ) a During the smelting process of the alloy ingot, the working current is 100~120 A.

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