A powder metallurgy composite material and preparation method thereof

Abstract

The present application belongs to the field of powder metallurgy technology, specifically discloses a kind of powder metallurgy composite material and preparation method thereof, including copper powder and aluminum powder are respectively subjected to low-energy ball milling, after obtaining smaller powder, cold-pressed into copper thin sheet blank and aluminum thin sheet blank respectively;In an oxygen-free box, thin sheet blank is sequentially placed in acetone, ethanol, water, dilute hydrochloric acid to ultrasonically remove surface oxide film, then sequentially cleaned with water, ethanol and acetone, dried;Copper thin sheet blank is transferred in a tube furnace, methane, hydrogen and argon are passed through to carry out the in-situ vapor deposition of graphene, the graphene-copper thin sheet blank after deposition is transferred in an oxygen-free box and stacked with aluminum thin sheet blank at intervals, then sealed and coated out of the box;After hot pressing and sintering in a sintering machine, it is put into a vacuum furnace and densified and sintered under an argon atmosphere. This method can effectively reduce the material cost of copper materials.

Description

Technical Field

[0001] The present application belongs to the technical field of powder metallurgy, and specifically relates to a powder metallurgy composite material and a preparation method thereof. Background Art

[0002] Copper and aluminum are good conductors of heat and are widely used in various electronic products, especially heat dissipation substrates. Since copper is relatively expensive, but aluminum has relatively low thermal conductivity, if the two can be mixed in a certain proportion, a low-cost composite material with good heat dissipation effect can be obtained. The advantage of the powder metallurgy method is that it can prepare metal composite materials with simple shapes and structures such as heat dissipation substrates at a lower cost. However, a disadvantage of powder metallurgy is that the prepared materials have a high porosity and more grain boundaries, which leads to reduced heat transfer efficiency, limiting the application prospects of the powder metallurgy method.

[0003] Therefore, the existing technology still needs to be further developed and improved. Summary of the Invention

[0004] In view of the various deficiencies of the existing technology and in order to solve the above problems, a powder metallurgy composite material and its preparation method are proposed. This application provides the following technical solutions:

[0005] A powder metallurgy composite material comprises aluminum sheets and copper sheets which are laminated in sequence, wherein a single layer of graphene is attached to the surface of the copper sheet.

[0006] Furthermore, the outermost layer of the composite material is a copper sheet.

[0007] A method for preparing a powder metallurgy composite material, comprising:

[0008] The copper powder and aluminum powder are subjected to low-energy ball milling to obtain smaller powders, which are then cold-pressed into copper sheet blanks and aluminum sheet blanks respectively.

[0009] In an oxygen-free chamber, the sheet blanks were placed in acetone, ethanol, water, and dilute hydrochloric acid in sequence to remove the surface oxide film by ultrasonic treatment, and then washed with water, ethanol, and acetone in sequence and dried.

[0010] The copper sheet blank is transferred to a tube furnace, and methane, hydrogen and argon are introduced to perform in-situ vapor deposition of graphene. The deposited graphene-copper sheet blank is transferred to an oxygen-free box and stacked with the aluminum sheet blank, and then sealed and coated before being taken out of the box.

[0011] After hot pressing and sintering in a sintering machine, the product is placed in a vacuum furnace for densification and sintering under an argon atmosphere.

[0012] Furthermore, the rotation speed of the low-energy ball mill is 100-150 r / min, anhydrous ethanol is used as a dispersant, and the ball milling time is 4 h.

[0013] Furthermore, the thickness of the sheet blank after cold pressing is 0.5-1 mm.

[0014] Furthermore, when ultrasonically removing the surface oxide film, the thin-sheet blank was ultrasonically treated in acetone, ethanol and water for 5 min, respectively, and in dilute hydrochloric acid for 10 min.

[0015] Furthermore, the gas flow ratio of methane, hydrogen and argon is 1:30:30-1:5:5, and the vapor deposition temperature is 1050°C.

[0016] Furthermore, the methane gas flow rate was initially 5 sccm during vapor deposition and increased to 30 sccm after 10 minutes.

[0017] Furthermore, the hot pressing sintering temperature is 700-900 °C and the pressure is 500 kgf / cm 2 , hot pressing sintering time is 4min.

[0018] Furthermore, the densification sintering temperature is 1100° C., and the densification sintering time is 30 min.

[0019] Beneficial effects:

[0020] 1. By combining copper and aluminum sheets, heat dissipation efficiency is improved while material costs are reduced;

[0021] 2. By vapor-depositing graphene on the surface of the copper sheet, oxidation of the copper sheet is prevented, thereby improving thermal conductivity;

[0022] 3. Improve thermal conductivity by removing the oxide layer of the thin sheet blank;

[0023] 4. Processing and synthesis in an oxygen-free environment to avoid the formation of a secondary oxide layer;

[0024] 5. By controlling the gas flow ratio, thin-layer graphene deposition is achieved to compensate for the heat conduction loss at the grain boundary between the copper and aluminum sheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a powder metallurgy composite material and a preparation method thereof in a specific embodiment of the present application;

[0026] Figure 2 This is the Raman spectrum of the vapor deposition product in the specific embodiment of the present application;

[0027] Figure 3 These are the different thermal conductivities corresponding to different sintering temperatures in the specific embodiments of this application. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present application, the following is a clear and complete description of the technical solution of the present application in conjunction with the drawings of the present application. Based on the embodiments in the present application, other similar embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present application. In addition, the directional terms mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the drawings. Therefore, the directional terms used are used to illustrate rather than limit the invention of the present application.

[0029] A powder metallurgy composite material comprises aluminum sheets and copper sheets which are laminated in sequence, wherein a single layer of graphene is attached to the surface of the copper sheet.

[0030] Furthermore, the outermost layer of the composite material is a copper sheet.

[0031] like Figure 1 As shown, a method for preparing a powder metallurgy composite material comprises:

[0032] S1. The copper powder and aluminum powder are separately subjected to low-energy ball milling to obtain smaller powders, which are then cold-pressed into copper sheet blanks and aluminum sheet blanks, respectively;

[0033] S2. In an oxygen-free chamber, the sheet blanks were placed in acetone, ethanol, water, and dilute hydrochloric acid to ultrasonically remove the surface oxide film, and then sequentially washed with water, ethanol, and acetone and dried;

[0034] S3. The copper sheet blank is transferred to a tube furnace, and graphene is in-situ vapor-deposited by passing methane, hydrogen, and argon. The deposited graphene-copper sheet blank is transferred to an oxygen-free box and stacked with aluminum sheet blanks, and then sealed and packaged before being taken out of the box. After the graphene-copper sheet blank is corroded with sulfuric acid solution, a transparent film is found floating above the solution, which is identified as graphene by Raman analysis. Figure 2 shown.

[0035] S4. After hot pressing and sintering in a sintering machine, the product is placed in a vacuum furnace and densified and sintered under an argon atmosphere.

[0036] Furthermore, the rotation speed of the low-energy ball mill is 100-150 r / min, anhydrous ethanol is used as a dispersant, and the ball milling time is 4 h.

[0037] Furthermore, the thickness of the sheet blank after cold pressing is 0.5-1 mm.

[0038] Furthermore, when ultrasonically removing the surface oxide film, the thin-sheet blank was ultrasonically treated in acetone, ethanol and water for 5 min, respectively, and in dilute hydrochloric acid for 10 min.

[0039] Furthermore, the gas flow ratio of methane, hydrogen and argon is 1:30:30-1:5:5, and the vapor deposition temperature is 1050°C.

[0040] Furthermore, the methane gas flow rate was initially 5 sccm during vapor deposition and increased to 30 sccm after 10 minutes.

[0041] Furthermore, the hot pressing sintering temperature is 700-900 °C and the pressure is 500 kgf / cm 2 , hot pressing sintering time is 4min.

[0042] Furthermore, the densification sintering temperature is 1100° C., and the densification sintering time is 30 min.

[0043] The thermal conductivity of the heat dissipation materials prepared in the following examples was tested and analyzed using the laser flash point method of the LFA1000 thermal conductivity tester.

[0044] Example 1

[0045] A method for preparing a powder metallurgy composite material, comprising:

[0046] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0047] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0048] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0049] S4. After hot pressing in the sintering machine, the product was placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing temperature was 700°C and the pressure was 500 kgf / cm 2The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 50 W / mK.

[0050] Example 2

[0051] A method for preparing a powder metallurgy composite material, comprising:

[0052] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0053] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0054] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0055] S4. After hot pressing in the sintering machine, the material is placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing temperature is 750°C and the pressure is 500 kgf / cm 2 The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 54 W / mK.

[0056] Example 3

[0057] A method for preparing a powder metallurgy composite material, comprising:

[0058] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0059] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0060] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0061] S4. After hot pressing in the sintering machine, the product was placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing temperature was 800°C and the pressure was 500 kgf / cm 2 The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 57 W / mK.

[0062] Example 4

[0063] A method for preparing a powder metallurgy composite material, comprising:

[0064] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0065] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0066] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0067] S4. After hot pressing sintering in a sintering machine, the material is placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing sintering temperature is 850°C and the pressure is 500 kgf / cm 2 The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 59 W / mK.

[0068] Example 5

[0069] A method for preparing a powder metallurgy composite material, comprising:

[0070] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0071] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0072] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0073] S4. After hot pressing in the sintering machine, the product was placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing temperature was 900°C and the pressure was 500 kgf / cm 2The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 58 W / mK.

[0074] Example 6

[0075] A method for preparing a powder metallurgy composite material, comprising:

[0076] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0077] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0078] S3. The copper sheet was transferred to a tube furnace and in-situ graphene vapor deposition was performed using methane, hydrogen, and argon. The gas flow rates of methane, hydrogen, and argon were 5 sccm, 150 sccm, and 150 sccm, respectively, maintained for 10 minutes, and then increased to 30 sccm, 150 sccm, and 150 sccm. The vapor deposition temperature was 1080°C. The deposited graphene-copper sheet was transferred to an oxygen-free oven and stacked with the aluminum sheet. The sheet was then sealed and packaged before being removed from the oven.

[0079] S4. After hot pressing in the sintering machine, the material is placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing temperature is 950°C and the pressure is 500 kgf / cm 2 The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 57 W / mK.

[0080] Comparative Example

[0081] A method for preparing a powder metallurgy composite material, comprising:

[0082] S1. Copper and aluminum powders were separately subjected to low-energy ball milling at a speed of 100-150 r / min using anhydrous ethanol as a dispersant for 4 h. After obtaining smaller powders, they were cold-pressed into copper and aluminum sheet blanks, respectively. The cold-pressed sheet blanks had a thickness of 0.5-1 mm.

[0083] S2. In an oxygen-free chamber, ultrasonically remove the surface oxide film by placing the wafer in acetone, ethanol, water, and dilute hydrochloric acid, respectively. To remove the surface oxide film, ultrasonically sonicate the wafer in acetone, ethanol, and water for 5 minutes each, and in dilute hydrochloric acid for 10 minutes. The wafer is then ultrasonically cleaned in water, ethanol, and acetone for 30 seconds each, and air-dried.

[0084] S3. The copper sheet blank and the aluminum sheet blank are stacked in an oxygen-free box at intervals and then sealed and coated out of the box;

[0085] S4. After hot pressing sintering in a sintering machine, the material is placed in a vacuum furnace for densification sintering under an argon atmosphere. The hot pressing sintering temperature is 850°C and the pressure is 500 kgf / cm 2 The hot pressing sintering time is 4 min, the densification sintering temperature is 1100 ℃, and the densification sintering time is 30 min. The thermal conductivity is 48 W / mK.

[0086] like Figure 3 The test results of the above thermal conductivity are shown. In the comparative example without adding graphene, the copper grain boundaries cannot be completely fused with the aluminum grain boundaries, resulting in low thermal conductivity. The addition of graphene fills the gaps in the copper grain boundaries, allowing the heat at the grain boundaries to be quickly transferred out through the graphene. As the sintering temperature increases, the density of the composite material continues to increase, which is conducive to the fusion between the grain boundaries, thereby reducing the number of gaps and improving the thermal conductivity. However, after the temperature reaches a certain level, the grain boundaries no longer fuse and the density no longer increases. At this time, continuing to increase the temperature will cause thermal cracks in the sintered structure, thereby leading to a decrease in thermal conductivity.

[0087] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and all variations that come within the meaning and range of equivalents of the claims are intended to be included in this application.

[0088] The present application has been described in detail above. The above description is only a preferred embodiment of the present application and should not limit the scope of implementation of the present application. That is, all equivalent changes and modifications made within the scope of the present application should still fall within the scope of the present application.

Claims

1. A powder metallurgy composite material, characterized in that: The method comprises sequentially stacked aluminum sheets and copper sheets, wherein a single layer of graphene is attached to the surface of the copper sheet; A method for preparing a powder metallurgy composite material, characterized by comprising: The copper powder and aluminum powder are subjected to low-energy ball milling to obtain smaller powders, which are then cold-pressed into copper sheet blanks and aluminum sheet blanks respectively. In an oxygen-free chamber, the sheet blanks were placed in acetone, ethanol, water, and dilute hydrochloric acid in sequence to remove the surface oxide film by ultrasonic treatment, and then washed with water, ethanol, and acetone in sequence and dried. The copper sheet blank is transferred to a tube furnace, and methane, hydrogen and argon are introduced to perform in-situ vapor deposition of graphene. The deposited graphene-copper sheet blank is transferred to an oxygen-free box and stacked with the aluminum sheet blank, and then sealed and coated before being taken out of the box. After hot pressing sintering in a sintering machine, it is placed in a vacuum furnace for densification sintering under an argon atmosphere; The hot pressing sintering temperature is 700-900 ℃ and the pressure is 500 kgf / cm 2 , hot pressing sintering time 4 min; As the sintering temperature increases, the density of the composite material continues to increase, which is conducive to the fusion between grain boundaries, thereby reducing the number of gaps and improving thermal conductivity. However, when the temperature reaches a certain level, the grain boundaries no longer fuse and the density no longer increases. At this time, continuing to increase the temperature will cause thermal cracks in the sintered structure, resulting in a decrease in thermal conductivity.

2. The powder metallurgy composite material according to claim 1, characterized in that: The outermost layer of the composite material is a copper sheet.

3. The powder metallurgy composite material according to claim 1, characterized in that: The low-energy ball milling speed is 100-150 r / min, anhydrous ethanol is used as a dispersant, and the ball milling time is 4 h.

4. The method for preparing a powder metallurgy composite material according to claim 1, characterized in that: The thickness of the sheet blank after cold pressing is 0.5-1 mm.

5. The powder metallurgy composite material according to claim 1, characterized in that: When ultrasonically removing the surface oxide film, the thin sheet was ultrasonically treated in acetone, ethanol and water for 5 min respectively, and in dilute hydrochloric acid for 10 min.

6. The powder metallurgy composite material according to claim 1, characterized in that: The gas flow ratio of methane, hydrogen and argon is 1:30:30-1:5:5, and the vapor deposition temperature is 1050 °C.

7. The powder metallurgy composite material according to claim 6, characterized in that: The methane gas flow rate was initially 5 sccm during vapor deposition and was increased to 30 sccm after 10 minutes.

8. The powder metallurgy composite material according to claim 1, characterized in that: The densification sintering temperature is 1100° C., and the densification sintering time is 30 minutes.

Images