Preparation method of multi-particle-size-ratio aluminum-based diamond composite material

Abstract

The invention discloses a preparation method of a multi-particle-size ratio aluminum-based diamond composite material, which adopts an integrated process of multi-particle-size diamond optimization, metal coating modification, acoustic resonance uniform coating and vacuum air pressure efficient infiltration. The problems that diamond particles in a single or simple proportion are low in stacking density and a heat conduction channel is discontinuous are solved, multi-particle-size collaborative optimization is achieved to improve the heat conduction efficiency, the wettability of a diamond and aluminum interface is poor, a Cr / Ti / W plating layer is plated through magnetron sputtering / vacuum micro-deposition, the interface thermal resistance is reduced, and the bonding strength is improved; the problems that aluminum powder and diamond particles, especially multi-particle-size particles, are not uniformly mixed and are easy to agglomerate are solved, and uniform coating is realized through acoustic resonance mixing; the problems that traditional infiltration molten aluminum is insufficient in infiltration and low in density are solved, the molten aluminum is driven to penetrate into gaps of the multi-particle-size diamond through the vacuum air pressure difference, and the density and reliability of the composite material are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal matrix composites, and particularly relates to a preparation method of a multi-particle-size ratio aluminum-based diamond composite material. BACKGROUND

[0002] Diamond is an ideal reinforcing phase of aluminum-based thermal dissipation composite materials due to its extremely high thermal conductivity (≈2200 W·m⁻¹·K⁻¹) and low thermal expansion coefficient, and is widely used in the field of electronic packaging. However, the existing technology has the following core problems: Firstly, the single particle size selection of diamond easily leads to low particle packing density (<65%) and discontinuous heat conduction channels, or only simple double-particle-size matching is adopted, and multi-particle-size collaborative optimization is not achieved.

[0003] Secondly, diamond has poor wettability with aluminum, and the existing magnetic control sputtering is used to coat tungsten and zirconium metal layers, and the application of vacuum micro-deposition technology in diamond surface modification lacks targeted process design.

[0004] Thirdly, in the powder mixing stage, traditional mechanical mixing is difficult to solve the agglomeration problem of aluminum powder and diamond particles (especially multi-particle-size combinations).

[0005] Fourthly, the melting process mostly adopts pressureless or single vacuum infiltration, lacks a gas pressure difference driving mechanism, and the aluminum liquid is difficult to fully penetrate the interstitial gaps of multi-particle-size diamond particles, resulting in a density of less than 97%, which affects the reliability of the composite material.

[0006] The invention disclosed in the publication number CN117773111A discloses a diamond composite material and a preparation method thereof. The technical solution points include placing diamond powder and metal powder in an acoustic resonance mixer under a vacuum acoustic resonance mixing pressure of 1×10 -3 ~1000 Pa, then performing vacuum heat treatment under a vacuum heat treatment pressure of 1×10 -3 ~1000 Pa and a temperature of 800-1500 ℃, to obtain first plated diamond powder; plating copper on the surface of the first plated diamond powder to obtain second plated diamond powder; and performing discharge plasma sintering on the second plated diamond powder and copper powder to obtain the diamond composite material.

[0007] The invention disclosed in the publication No. CN120394882A discloses an aluminum-based diamond layered composite material and a preparation method thereof. The technical solution points include an aluminum layer, an aluminum-based diamond layer and an aluminum layer from top to bottom. The surface of the diamond powder in the aluminum-based diamond layer is plated with titanium, and the plating layer has a thickness of 10-100 nm. The mass of the titanium-plated diamond powder accounts for 25-55% of the mass of the aluminum-based diamond layer. The thickness of the aluminum layer is 0.5-1.5 mm, and the thickness of the aluminum-based diamond layer is 1-4 mm. The main method is to plate titanium on the surface of the diamond powder, reduce the micro-protrusion structure on the surface of the diamond powder, reduce the surface roughness, improve the interfacial wettability of the diamond powder, make the surface of the composite material meet the flatness requirement of the plating process, and improve the bonding force between the aluminum-based diamond layer and the upper and lower aluminum layers, as well as the thermal conductivity and heat dissipation capacity of the composite material. However, it only mentions a single vacuum evaporation method and mechanical mixing, and does not involve multi-particle size matching and vacuum air pressure infiltration.

[0008] In summary, the existing technology has not formed an integrated process of "multi-particle size diamond optimization-metal plating modification-acoustic resonance uniform coating-vacuum air pressure efficient infiltration", which is difficult to meet the stringent requirements of high-power electronic packaging on the thermal conductivity (≥500 W·m⁻¹·K⁻¹) and density (≥99%) of the composite material. SUMMARY

[0009] The purpose of the present application is to overcome the shortcomings of the prior art and provide a multi-particle size aluminum-based diamond composite material preparation method, which realizes multi-particle size optimization to improve the heat conduction efficiency.

[0010] To solve the above technical problems, the technical scheme adopted by the present application is as follows: A multi-particle size aluminum-based diamond composite material preparation method, comprising the following steps: (1) Diamond particle pretreatment and particle size matching Select diamond particles with a particle size of 3-6 μm fine particles, 8-12 μm medium particles and 15-30 μm coarse particles. Single particle size or multi-particle size matching can be used, and the matching range is fine particles:medium particles:coarse particles=1-2:3:5; The diamond particles are ultrasonically cleaned in acetone for 15-20 min to remove surface dirt, and then dried for standby use; (2) Cr / Ti / W plating on the surface of the diamond particles The surface of the diamond particles is plated with Cr / Ti / W by magnetic sputtering or vacuum micro-deposition; (3) Acoustic resonance mixing to prepare aluminum powder coated diamond particles Select aluminum powder with a purity of ≥99.7%, and mix it with the plated diamond particles at a mass ratio of 3:7-5:5, and then put it into an acoustic resonance mixing instrument; The mixing parameters of the acoustic resonance mixer are a resonance frequency of 20-30 Hz, an amplitude of 5-8 mm, and a mixing time of 3-5 min. (4) Vacuum gas pressure infiltration for preparing aluminum-based diamond composite material a. Mould preparation: graphite mould is adopted, and the inner wall is coated with boron nitride release agent; b. Laying: the pure aluminum ingot is placed at the bottom of the mould, and the diamond particle preform coated with aluminum powder prepared in step (3) is uniformly laid above; c. Infiltration process: the mould is placed into a vacuum gas pressure infiltration furnace, vacuum is first extracted to ≤1 Pa, and heating is carried out to 680-750 DEG C to completely melt the aluminum ingot; then nitrogen is introduced, and a gas pressure of 2-8 MPa is applied, and pressure is maintained for 15-20 min; the aluminum liquid is driven to fully infiltrate the interstitial space of the diamond particles by using the gas pressure difference, and the infiltration resistance caused by the accumulation of multiple particle sizes is overcome; d. Cooling forming: cooling to room temperature with the furnace, and demoulding to obtain the aluminum-based diamond composite material.

[0011] When the magnetron sputtering coating is selected, a multi-target magnetron sputtering device is adopted, and the target materials are pure Cr, pure Ti and pure W respectively; The vacuum degree is ≤0.5 Pa, the argon gas flow is 20-30 sccm, the target-to-substrate distance is 8-10 cm, the sputtering power is 150-200 W, the deposition time is 10-15 min, and the coating thickness is controlled to be 0.5-1 mu m; And the coating can be selected as a single coating or a composite coating according to requirements.

[0012] When the vacuum micro-deposition coating is selected, a resistance heating vacuum micro-deposition device is adopted, and the evaporation source is a Cr / Ti / W metal wire; The vacuum degree is ≤1*10-3 Pa, the heating power is 300-400 W, the deposition rate is 5-10 nm / s, and the coating thickness is 0.3-0.8 mu m.

[0013] The diamond particle size is selected to be 5 mu m fine particles, 10 mu m medium particles and 20 mu m coarse particles.

[0014] The aluminum powder particle size is 5-10 mu m.

[0015] In step (4), the thickness of the diamond particle preform is 10-20 mm.

[0016] The ratio of the diamond particles is mixed according to fine particles: medium particles: coarse particles = 2:3:5.

[0017] The beneficial effects of the present application are: (1) The application discloses a preparation method of a multi-particle size ratio aluminum diamond composite material, and solves the problems of low single or simply ratioed diamond particle packing density, discontinuous heat conduction channel, and poor diamond and aluminum interface wettability by adopting an integrated process of "multi-particle size diamond optimization-metal coating modification-acoustic resonance uniform coating-vacuum air pressure efficient infiltration", realizing multi-particle size collaborative optimization to improve heat conduction efficiency, and reducing the interface thermal resistance and improving the bonding strength by magnetron sputtering / vacuum micro-deposition Cr / Ti / W coating; the problems of uneven mixing and easy agglomeration of aluminum powder and diamond particles, especially multi-particle size, are solved by acoustic resonance mixing to realize uniform coating; the problems of insufficient penetration of traditional infiltration aluminum liquid and low density are solved, and the aluminum liquid is driven into the multi-particle size diamond gap by utilizing the vacuum air pressure difference to improve the density and reliability of the composite material.

[0018] (2) The thermal performance is significantly improved: the multi-particle size diamond ratio (2:3:5) makes the packing density reach 75%±3%, the Cr / Ti / W coating reduces the interface thermal resistance (≤10 m²・K / W), the thermal conductivity of the composite material is ≥520 W・m⁻¹・K⁻¹, which is 20%-30% higher than that of the existing single particle size product, and meets the demand of high-power electronic packaging.

[0019] (3) The mechanical performance and reliability are optimized: the acoustic resonance mixing realizes uniform coating of aluminum powder (coating rate ≥95%), and the vacuum air pressure infiltration (5 MPa) makes the density ≥99.2%, the bending strength of the composite material ≥350 MPa, and the interface bonding strength ≥45 MPa, which is 2%-3% higher than that of the traditional pressureless infiltration product.

[0020] (4) The process efficiency and applicability are enhanced: the acoustic resonance mixing time is only 3-5 min, which is 5-8 times higher than that of mechanical mixing; the multi-particle size ratio and differential coating design can adapt to different heat dissipation scenes (such as 5 mu m fine particles for micro packaging and 20 mu m coarse particles for high-power devices).

[0021] (5) Economy and environmental protection: the process does not need complex equipment modification, the utilization rate of magnetron sputtering / vacuum micro-deposition coating is more than 90%, the aluminum liquid recovery rate is ≥95%, there is no harmful waste gas emission, and it meets the green manufacturing demand. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the preparation flow chart of the aluminum diamond composite material of the application. DETAILED DESCRIPTION

[0023] The embodiments of the application are described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the application from the content disclosed in the specification.

[0024] The application provides a preparation method of a multi-particle-size proportioning aluminum-based diamond composite material. Figure 1 As shown in the figure.

[0025] The application provides a preparation method of a multi-particle-size proportioning aluminum-based diamond composite material, which comprises the following steps: (1) Pretreatment and particle size proportioning of diamond particles Fine particles, medium particles and coarse particles of diamond particles with particle sizes of 3-6 μm, 8-12 μm and 15-30 μm are selected, and single particle size or multi-particle-size proportioning can be used, and the proportioning range is 1-2:3:5 of fine particles:medium particles:coarse particles. The proportioning fills the gaps between the medium and coarse particles with the fine particles, so that the bulk density is increased to 72%-78%, and a continuous heat conduction channel is laid. Then the diamond particles are cleaned by ultrasonic cleaning in acetone for 15-20 min, the surface oil stains are removed, and the diamond particles are dried for standby. Preferably, 5 μm fine particles, 10 μm medium particles and 20 μm coarse particles are used.

[0026] (2) Cr / Ti / W plating on the surface of the diamond particles The surface of the diamond particles is plated with Cr / Ti / W by using magnetron sputtering or vacuum micro-deposition. When the magnetron sputtering plating is selected, a multi-target magnetron sputtering device is used, and the target materials are pure Cr, pure Ti and pure W. The vacuum degree is ≤0.5 Pa, the argon flow is 20-30 sccm, the target-to-substrate distance is 8-10 cm, the sputtering power is 150-200 W, the deposition time is 10-15 min, and the plating layer thickness is controlled to be 0.5-1 μm. The Cr plating layer improves the interfacial adhesion between the diamond and the aluminum, the Ti plating layer promotes the chemical reaction at the interface to generate a TiC transition layer, and the W plating layer reduces the interfacial thermal resistance. The plating layer can be selected as a single plating layer or a composite plating layer, such as a Cr / Ti double-layer.

[0027] When the vacuum micro-deposition plating is selected, a resistance-heating vacuum micro-deposition device is used, and the evaporation source is a Cr / Ti / W metal wire with a diameter of 1-2 mm. The vacuum degree is ≤1×10⁻³ Pa, the heating power is 300-400 W, the deposition rate is 5-10 nm / s, and the plating layer thickness is 0.3-0.8 μm. This method is suitable for fine diamond particles, such as 5 μm, to avoid particle damage in the sputtering process.

[0028] (3) Preparation of aluminum powder coated diamond particles by acoustic resonance mixing Aluminum powder with a purity of ≥99.7% and a particle size of 5-10 μm is selected, mixed with the plated diamond particles at a mass ratio of 3:7-5:5, and then put into an acoustic resonance mixing instrument. The mixing parameters of the acoustic resonance mixer are a resonance frequency of 20-30 Hz, an amplitude of 5-8 mm, and a mixing time of 3-5 min; the high-speed impact and shearing of the aluminum powder on the diamond particles are realized by using low-frequency high-intensity acoustic waves, a uniform coating layer (coating rate ≥ 95%) is formed, and the agglomeration problem is completely solved, thereby providing a uniform preform for subsequent infiltration.

[0029] (4) Preparation of aluminum-based diamond composite material by vacuum gas pressure infiltration a. Mould preparation: graphite mould, inner wall coated with boron nitride release agent; b. Laying: place the pure aluminum ingot at the bottom of the mould, and evenly lay the coated aluminum powder diamond particle preform prepared in step (3) on top, with a thickness of 10-20 mm; c. Infiltration process: place the mould into the vacuum gas pressure infiltration furnace, first vacuumize to ≤1 Pa, heat to 680-750 ℃ to completely melt the aluminum ingot; then introduce nitrogen gas, apply a gas pressure of 2-8 MPa, and maintain the pressure for 15-20 min; use the gas pressure difference to drive the aluminum liquid to fully infiltrate the interstitial spaces between the diamond particles, overcoming the infiltration resistance caused by the accumulation of multiple particle sizes; d. Cooling and forming: cool down to room temperature in the furnace, and demould to obtain the aluminum-based diamond composite material.

[0030] The following is further illustrated by specific examples: Example 1: Select multiple particle size diamond particles, fine particles 5 μm: medium particles 10 μm: coarse particles 20 μm, and mix according to the ratio of 2:3:5, and use magnetic control sputtering Cr coating layer, the preparation method includes the following steps: 1. Raw material preparation: 5 μm diamond 20 g, 10 μm diamond 30 g, 20 μm diamond 50 g, ultrasonic cleaning with acetone for 18 min, and drying at 80 ℃; pure Cr target (99.99%), 5 μm pure aluminum powder 50 g, pure aluminum ingot (100 g, purity 99.9%).

[0031] 2. Magnetic control sputtering Cr: vacuum degree 0.3 Pa, argon flow rate 25 sccm, target-to-substrate distance 9 cm, power 180 W, deposition time 12 min, coating thickness 0.8 μm.

[0032] 3. Acoustic resonance mixing: frequency 25 Hz, amplitude 6 mm, mixing time 4 min, to obtain aluminum powder coated diamond particles (coating rate 96.5%).

[0033] 4. Vacuum gas pressure infiltration: graphite mould (inner diameter 50 mm), aluminum ingot at the bottom, preform on top (thickness 15 mm); vacuum degree of the infiltration furnace 0.8 Pa, heating to 720 ℃, nitrogen gas pressure 5 MPa, pressure maintaining for 18 min; cooling in the furnace.

[0034] The performance test results of the prepared product are: thermal conductivity 532 W m-1 K-1, density 99.5%, bending strength 362 MPa, and interface bonding strength 48 MPa.

[0035] Example 2 The multi-particle-size diamond particles are selected, the fine particles 5 μm, the medium particles 10 μm, and the coarse particles 20 μm are proportioned according to the ratio 3:5:2, and a vacuum micro-deposition Ti coating is used, and the preparation method comprises the following steps: 1. Raw material preparation: 5 μm diamond 30 g, 10 μm diamond 50 g, 20 μm diamond 20 g, ultrasonic cleaning with acetone for 18 min, and drying at 80°C; Ti wire (diameter 1.5 mm, 99.99%), aluminum powder (10 μm, 60 g), and aluminum ingot (120 g).

[0036] 2. Vacuum micro-deposition of Ti: vacuum degree 5×10⁻ 4 Pa, heating power 350 W, deposition rate 8 nm / s, and coating thickness 0.6 μm.

[0037] 3. Acoustic resonance mixing: frequency 28 Hz, amplitude 7 mm, time 3.5 min, and coating rate 95.8%.

[0038] 4. Sintering: vacuum degree 0.5 Pa, temperature 700°C, gas pressure 6 MPa, and pressure maintaining time 16 min.

[0039] The performance test results of the prepared product are: thermal conductivity 518 W m-1 K-1, density 99.3%, bending strength 355 MPa.

[0040] Example 3 The single diamond particles are selected, the medium particles with a particle size of 10 μm are selected, and a W coating is prepared by magnetron sputtering, and the preparation method comprises the following steps: 1. Raw material preparation: 10 μm diamond 100 g, cleaning and drying; W target material, aluminum powder (8 μm, 40 g), and aluminum ingot 80 g.

[0041] 2. Magnetron sputtering of W: power 200 W, time 15 min, and coating thickness 1 μm.

[0042] 3. Mixing: frequency 22 Hz, amplitude 5 mm, time 5 min, and coating rate 97.2%.

[0043] 4. Sintering: gas pressure 4 MPa, temperature 730°C, and pressure maintaining time 20 min.

[0044] The performance test results of the prepared product are: thermal conductivity 505 W m-1 K-1, density 99.1%, bending strength 348 MPa.

[0045] In summary, the aluminum-based diamond composite material prepared by the method has the following significant advantages. 1. Significant improvement in thermal performance: The multi-particle size diamond ratio (2:3:5) makes the bulk density reach 75%±3%, combined with the Cr / Ti / W plating layer to reduce the interface thermal resistance (≤10 m²・K / W), the thermal conductivity of the composite material is ≥520 W・m⁻¹・K⁻¹, which is 20%-30% higher than the existing single-particle size product, meeting the demand for high-power electronic packaging.

[0046] 2. Optimization of mechanical performance and reliability: Acoustic resonance mixing realizes uniform coating of aluminum powder (coating rate ≥95%), vacuum air pressure infiltration (5MPa) makes the density ≥99.2%, the bending strength of the composite material is ≥350MPa, and the interface bonding strength is ≥45MPa, which is 2%-3% higher than the traditional pressureless infiltration product.

[0047] 3. Process efficiency and applicability enhancement: The acoustic resonance mixing time is only 3-5min, which is 5-8 times higher than the mechanical mixing efficiency; multi-particle size ratio and differential plating layer design can adapt to different heat dissipation scenarios (such as 5μm fine particles for micro packaging, 20μm coarse particles for high-power devices).

[0048] 4. Economic and environmental: The process does not require complex equipment modification, the utilization rate of magnetron sputtering / vacuum micro-deposition plating layer is more than 90%, the aluminum liquid recovery rate is ≥95%, there is no harmful exhaust gas emission, which meets the green manufacturing demand.

[0049] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed invention. The scope of protection of the present application is defined by the appended claims and equivalents thereof.

[0050] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to be approximations that allow for significant variation. Various ranges of values that are stated herein are considered to be approximate values that can vary by a small amount. Endpoints of various ranges of values, endpoints of various ranges of values and individual point values, and individual point values can be combined with each other to form one or more new ranges of values, which should be considered to be specifically disclosed herein.

[0051] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A method for preparing a multi-particle-size aluminum-based diamond composite material, characterized in that, Includes the following steps: (1) Pretreatment and particle size distribution of diamond particles Select diamond particles with a particle size of 3~6μm fine particles, 8~12μm medium particles and 15~30μm coarse particles. Single particle size or multi-particle size ratio can be used. The ratio range is 1~2:3:5 for fine particles: medium particles: coarse particles. Diamond particles are ultrasonically cleaned with acetone for 15-20 minutes to remove surface oil and then dried for later use. (2) Cr / Ti / W coating on the surface of diamond particles Cr / Ti / W is deposited on the surface of diamond particles using magnetron sputtering or vacuum microdeposition. (3) Preparation of aluminum powder coated diamond particles by acoustic resonance mixing Aluminum powder with a purity of ≥99.7% was selected and mixed with coated diamond particles at a mass ratio of 3:7 to 5:5, and then put into an acoustic resonance mixer. The mixing parameters of the acoustic resonance mixer are: resonance frequency 20~30Hz, amplitude 5~8mm, and mixing time 3~5min; (4) Preparation of aluminum-based diamond composite materials by vacuum pressure melting infiltration a. Mold preparation: Graphite molds are used, with the inner wall coated with boron nitride release agent; b. Material laying: Place the pure aluminum ingot at the bottom of the mold and evenly lay the diamond particle preform coated with aluminum powder obtained in step (3) on top; c. Melting and infiltration process: Place the mold into a vacuum pressure melting and infiltration furnace, first evacuate to ≤1Pa, heat to 680~750℃ to completely melt the aluminum ingot; then introduce nitrogen gas, apply a pressure of 2~8MPa, and hold the pressure for 15~20min; use the pressure difference to drive the aluminum liquid to fully penetrate the gaps between diamond particles, overcoming the penetration resistance caused by the accumulation of multiple particle sizes. d. Cooling and molding: Cool to room temperature in the furnace and demold to obtain aluminum-based diamond composite material.

2. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: When magnetron sputtering is selected for coating, a multi-target magnetron sputtering equipment is used, with targets being pure Cr, pure Ti, and pure W. Vacuum degree ≤0.5Pa, argon flow rate 20~30sccm, target-substrate distance 8~10cm, sputtering power 150~200W, deposition time 10~15min, coating thickness controlled at 0.5~1μm; Furthermore, the coating can be selected as a single coating or a composite coating according to the requirements.

3. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: When vacuum micro-deposition coating is selected, a resistance heating vacuum micro-deposition device is used, and the evaporation source is a Cr / Ti / W metal wire; Vacuum degree ≤1×10⁻³Pa, heating power 300~400W, deposition rate 5~10nm / s, coating thickness 0.3~0.8μm.

4. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: The diamond grain size is selected as 5μm fine grain, 10μm medium grain and 20μm coarse grain.

5. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: The aluminum powder has a particle size of 5~10μm.

6. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: In step (4), the thickness of the diamond particle preform is 10-20 mm.

7. The method for preparing a multi-particle-size aluminum-based diamond composite material according to claim 1, characterized in that: The diamond particles are mixed in a ratio of fine: medium: coarse particles of 2:3:5.

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