CN112941431B - Powder metallurgy preparation method of fine-particle diamond copper-based composite heat dissipation material - Google Patents
Powder metallurgy preparation method of fine-particle diamond copper-based composite heat dissipation material Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
- C22C47/14—Making alloys containing metallic or non-metallic fibres or filaments by powder metallurgy, i.e. by processing mixtures of metal powder and fibres or filaments
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
- C22C47/02—Pretreatment of the fibres or filaments
- C22C47/04—Pretreatment of the fibres or filaments by coating, e.g. with a protective or activated covering
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
- C22C49/02—Alloys containing metallic or non-metallic fibres or filaments characterised by the matrix material
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
- C22C49/14—Alloys containing metallic or non-metallic fibres or filaments characterised by the fibres or filaments
Abstract
The invention discloses a powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material, which comprises the following steps: s1, weighing the following materials in percentage by weight: 4.2-11.6 wt% of fine-particle diamond, 1-5 wt% of water atomized superfine CuSn15 bronze powder, 0.1-0.5 wt% of composite nickel/copper plated carbon fiber/silicon carbide whisker and the balance of electrolytic copper powder. The invention relates to a powder metallurgy production technology for preparing a composite heat dissipation substrate with the heat conductivity larger than 550W/mK by mixing fine-particle diamond and copper powder and sintering the mixture twice, which has the characteristics of low cost, stable process and capability of realizing quantitative production and can solve the engineering application difficulty that the heat dissipation substrate with the thickness less than or equal to 2mm is difficult to realize the quantitative production in the prior art.
Description
Technical Field
The invention relates to the technical field of powder metallurgy, in particular to a powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material.
Background
With the rapid development of electronic technology, modern electronic and photoelectric devices are becoming more miniaturized, highly integrated, and high powered, and the requirements for heat dissipation performance of electronic devices are becoming higher and higher. Copper is a metal with good heat conduction performance, diamond transfers heat by phonons, and the heat conductivity can reach 1500-2600W/mK at normal temperature and is about 5 times of that of copper, so that the diamond/copper composite heat dissipation material is an ideal novel electronic packaging material and has attracted wide attention in recent years.
At present, two technologies of solid phase forming and liquid phase forming are mainly used for preparing the diamond/copper composite material, the main preparation methods comprise a high-temperature high-pressure method, discharge plasma sintering, a pressure infiltration method and the like, and the composite heat dissipation material with the thickness of more than or equal to 4mm is prepared by mainly adopting coarse-grain diamond (45/50 meshes are coarse). Patent CN105483423A discloses a method for preparing a copper/diamond composite material with high thermal conductivity by air pressure infiltration, which provides a better solution for high-efficiency heat dissipation of high-power devices, but has a higher production cost, and the prepared heat dissipation material is thicker (about 4mm), and cannot be applied to some small devices. In the aspect of metallurgical factors, because the wettability of copper to diamond is extremely poor and the difference of the shrinkage coefficients of the diamond and the copper is large, the interface between the diamond and the copper is basically free of bonding strength and is easy to generate gaps when the diamond and the copper are directly compounded, so that the thermal resistance is large when heat is transmitted between the diamond and the copper, and the heat conduction performance is reduced. Therefore, reducing/eliminating the interface gap between the diamond and the copper substrate is one of the key factors for obtaining high thermal conductivity. The diamond surface metallization (chromium/nickel/titanium plating) can effectively improve the interface bonding effect between the diamond and the copper matrix and improve the heat conducting property of the composite heat dissipation material, wherein titanium plated diamond is one of the common materials. However, a considerable amount of elemental metal titanium without TiC chemical bonds is always present on the surface of the titanium-plated diamond, and solid solution is easily formed between the elemental titanium and copper during high-temperature sintering, so that titanium on the surface of the diamond is rapidly diffused into the copper matrix, the titanium-removing phenomenon is caused on the diamond/copper interface, the wettability of the diamond-copper matrix interface is reduced, and the application effect of the titanium-plated diamond is weakened; therefore, how to effectively prevent the titanium-removing phenomenon from occurring in the high-temperature preparation process of the titanium-plated diamond/copper heat dissipation material is also one of the key technologies influencing the heat conductivity of the composite heat dissipation material.
The powder metallurgy method is one of the efficient production methods for preparing the composite material, and the thin-sheet heat radiator is more suitable for preparing the thin-particle diamond (120/140 meshes are fine) by the powder metallurgy method, in particular to a thin sheet body with the thickness of less than 2 mm. At present, technical achievements (such as a discharge plasma sintering method and an SPS method) for preparing diamond/copper heat dissipation materials by adopting a powder metallurgy method and utilizing fine-particle plated diamonds (120/140 meshes and 325/400 meshes) are reported (the thermal conductivity is about 650W/mK), but the method is only limited to preparation of test samples at present and cannot be applied to batch device production. Meanwhile, when the diamond/copper composite heat dissipation material is prepared by adopting a powder metallurgy technology, fine-particle diamonds are easy to aggregate in the mixing and sintering processes, so that metal materials among diamond particles in an aggregation area cannot be filled or cannot be filled sufficiently, the number of pores among the diamond particles is large, the density of a heat dissipation body is insufficient, and the heat conduction performance of the heat dissipation body is greatly reduced; therefore, when using fine diamond particles, it must be considered that they can be dispersed effectively to prevent aggregation, which is difficult to solve effectively in the prior art.
In summary, the existing preparation methods are difficult to prepare the sheet-shaped heat dissipation materials in batches at low cost, and in order to overcome the defects of the prior art, a preparation technology which adopts fine-particle diamond and can produce the sheet-shaped diamond/copper heat dissipation substrate in batches in a large scale is urgently needed to be developed.
Disclosure of Invention
The invention aims to provide a powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides a powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material, which comprises the following steps:
s1, weighing the following materials in percentage by weight: 4.2-11.6 wt% of fine-particle diamond, 1-5 wt% of water atomized superfine CuSn15 bronze powder, 0.1-0.5 wt% of composite nickel/copper plated carbon fiber/silicon carbide whisker and the balance of electrolytic copper powder, and then weighing polyvinylpyrrolidone alcoholic solution which is 1.5-3.0 wt% of the total weight of the mixed granulation raw materials as a granulating agent;
s2, cold pressing blank making: mixing and granulating the raw material powder by taking K90 alcohol solution as a granulating adhesive, and then cold-pressing the mixture into a sheet blank in a steel die;
s3: high-temperature reduction and pre-sintering: placing the cold-pressed sheet body into a hydrogen reduction furnace for high-temperature reduction and pre-sintering;
s4: high-temperature high-pressure densification sintering: and then the pre-reduced sintered body is filled into a graphite mould to be sintered into a sheet-shaped finished product through high-temperature densification in a four-column hot-pressing sintering machine or a cubic press.
Preferably, the powder metallurgy preparation method comprises the steps of mixing and granulating various raw material powders by taking K90 as a binder, carrying out cold pressing on the granulated materials in a steel mold to prepare a blank, then putting the cold-pressed blank into a hydrogen reduction furnace for carrying out pre-reduction sintering, then putting the pre-reduction sintered blank into a graphite mold, carrying out densification sintering in a four-column hot pressing sintering machine or a cubic press to prepare the flaky composite heat sink, and carrying out mechanical polishing treatment on the surface of the flaky composite heat sink.
Preferably, the diamond has the granularity of 120/140 meshes, and the weight gain of the physical vapor plating titanium is 0.3-0.5% of the weight of the diamond to be plated; and coating nickel hydroxide on the surface of the titanium-plated diamond particles by adopting a chemical coating technology, and reducing the nickel-plated diamond particles for 20 to 30 minutes by using hydrogen at the temperature of 850 to 900 ℃ to form composite diamond particles with titanium/nickel coated on the surface, wherein the coating weight of the nickel is increased by 20 to 30 percent of the weight of the titanium-plated diamond.
Preferably, the granularity of the electrolytic copper powder is 300 meshes or less, the purity is more than or equal to 99.9 percent, and the apparent density is 1.4-1.7 g/cm3And the oxygen content is less than 0.07 percent.
Preferably, the laser particle size D50 value of the superfine CuSn15 bronze powder prepared by the water atomization method is 5-7 mu m, and the oxygen content is less than 0.08%.
Preferably, the composite nickel/copper-plated carbon fiber is an asphalt-based carbon fiber with a high thermal conductivity, the length of the asphalt-based carbon fiber is 74-150 μm, and the length of the composite nickel/copper-plated silicon carbide whisker is 74-150 μm; the nickel plating amount is 50-100% of the mass of the silicon carbide whiskers to be plated, and the copper is coated by a chemical method after nickel plating, wherein the coating amount of the copper is 50-100% of the weight of the coated material.
Preferably, the polyvinylpyrrolidone (K90) granulating agent is prepared by dissolving K90 particles in absolute alcohol to prepare a viscous alcohol solution with the mass concentration of 1.0-1.5%.
Preferably, the cold pressing blank making is to cold press the mixed granulating material taking K90 as a granulating agent in a steel cold pressing die to make a sheet blank body with the pressing density of 60-65%.
Preferably, the pre-reduction sintering is to place the cold-pressed blank into a graphite mold with a balance weight, send the blank into a hydrogen reduction furnace, keep the temperature at 850-900 ℃ for 20-30 minutes, cool the blank to room temperature along with the furnace, and place the reduction sintered sheet body into a bin filled with high-purity nitrogen for storage and standby.
Preferably, the densification sintering is to place the pre-reduced sintered body into a graphite mold, and sinter the pre-reduced sintered body in a four-column hot-pressing sintering machine at the sintering temperature of 920-950 ℃ and the sintering pressure of more than or equal to 350kg/cm2And (3) carrying out high-temperature heat preservation for 5-7 minutes or carrying out heating and pressurizing sintering in a cubic press at the sintering temperature of 880-950 ℃ under the sintering pressure of 4.5-5.0 GPa for 2-5 minutes to obtain the diamond/copper composite sintered sheet body with the density of 98.5-100%.
Compared with the prior art, the invention has the following beneficial effects:
in order to solve the defects of the prior art, the invention adopts the composite titanium/nickel-coated fine-particle diamond (120/140 meshes are fine) to reduce the preparation thickness of the heat dissipation material; in order to control the titanium removal of the diamond surface, a layer of nickel is compositely coated on the surface of the titanium-plated diamond for isolating and limiting the solid solution effect between titanium and copper; adding a proper amount of water atomized superfine CuSn15 bronze powder into the copper powder to form a partial Cu-Sn solid solution phase in a copper matrix, so as to improve the sintering compactness of the composite material; meanwhile, a small amount of carbon fiber/silicon carbide whiskers are added to enhance the strength of a sintered matrix and reduce the cooling shrinkage coefficient of the sintered matrix, so that the quantitative production of the diamond/copper composite heat sink with the thickness less than 2mm can be realized, and the engineering application problem that the thin-wall diamond/copper composite heat sink body is difficult to produce in a large scale by the existing production technology is solved;
a powder metallurgy production technology for preparing a composite heat dissipation substrate with the heat conductivity larger than 550W/mK by mixing fine-particle diamond and copper powder and sintering the mixture twice has the characteristics of low cost, stable process and capability of realizing quantitative production, and can solve the engineering application difficulty that the heat dissipation substrate with the thickness less than or equal to 2mm is difficult to realize the quantitative production in the prior art.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material comprises the following steps:
s1, weighing the following materials in percentage by weight: 4.2-11.6 wt% of fine-particle diamond, 1-5 wt% of water atomized superfine CuSn15 bronze powder, 0.1-0.5 wt% of composite nickel/copper plated carbon fiber/silicon carbide whisker, 1.5-3.0 wt% of polyvinylpyrrolidone alcoholic solution and the balance of electrolytic copper powder;
s2, cold pressing blank making: mixing and granulating the raw material powder by taking K90 alcohol solution as a granulating adhesive, and then cold-pressing the mixture into a sheet blank in a steel die;
s3: high-temperature reduction and pre-sintering: placing the cold-pressed sheet body into a hydrogen reduction furnace for high-temperature reduction and pre-sintering;
s4: high-temperature high-pressure densification sintering: and then the pre-reduced sintered body is filled into a graphite mould to be sintered into a sheet-shaped finished product through high-temperature densification in a four-column hot-pressing sintering machine or a cubic press.
The powder metallurgy preparation method of the embodiment includes mixing and granulating various raw material powders together by using K90 as a binder, cold-pressing the granulated materials in a steel mold to prepare a blank, then placing the cold-pressed blank into a hydrogen reduction furnace for pre-reduction sintering, then placing the pre-reduction sintered blank into a graphite mold, performing densification sintering in a four-column hot-pressing sintering machine or a six-sided press machine to prepare a sheet-shaped composite heat sink, and performing mechanical polishing treatment on the surface of the heat sink.
The diamond of the embodiment has the granularity of 120/140 meshes, and the weight gain of the physical vapor plating titanium is 0.3-0.5% of the weight of the diamond to be plated, namely the composite titanium/nickel-plated diamond with single granularity or combined granularity; and coating nickel hydroxide on the surface of the titanium-plated diamond particles by adopting a chemical coating technology, and reducing the nickel-plated diamond particles for 20 to 30 minutes by using hydrogen at the temperature of 850 to 900 ℃ to form composite diamond particles with titanium/nickel coated on the surface, wherein the coating weight of the nickel is increased by 20 to 30 percent of the weight of the titanium-plated diamond.
The electrolytic copper powder of the embodiment has a granularity of 300 meshes, a purity of not less than 99.9 percent and a bulk density of 1.4-1.7 g/cm3And the oxygen content is less than 0.07 percent.
The laser particle size D50 value of the superfine CuSn15 bronze powder prepared by the water atomization method in the embodiment is 5-7 mu m, and the oxygen content is less than 0.08%.
The composite nickel/copper-plated carbon fiber is an asphalt-based carbon fiber with a high heat conductivity coefficient, the length of the asphalt-based carbon fiber is 74-150 mu m, and the length of the composite nickel/copper-plated silicon carbide whisker is 74-150 mu m; the nickel plating amount is 50-100% of the mass of the material to be plated, and the copper is coated by a chemical method after nickel plating, wherein the coating amount of the copper is 50-100% of the weight of the material to be coated.
The polyvinylpyrrolidone (K90) granulating agent of the embodiment is prepared by dissolving K90 particles in absolute alcohol to prepare a viscous alcohol solution with the mass concentration of 1.0-1.5%.
The cold pressing blank manufacturing method is characterized in that a mixed granulating material taking K90 as a granulating agent is cold pressed in a steel cold pressing die to manufacture a flaky blank body with the pressing density of 60-65%.
The pre-reduction sintering of the embodiment is to place the cold-pressed blank into a graphite mold with a balance weight, send the blank into a hydrogen reduction furnace, keep the temperature at 850-900 ℃ for 20-30 minutes, cool the blank along with the furnace to room temperature, and place the reduction sintered sheet body into a bin filled with high-purity nitrogen for storage and standby.
The densification sintering of the embodiment is to place the pre-reduced sintered body into a graphite mold, and sinter the pre-reduced sintered body in a four-column hot-pressing sintering machine at a sintering temperature of 920-950 ℃ and a sintering pressure of more than or equal to 350kg/cm2The sintering temperature is 880-950 ℃ in a high-temperature heat preservation for 5-7 minutes or the sintering pressure is 4.5-5.0 GPa in a cubic press, and the high-temperature heat preservation time is 2-5 minutes for heating and pressurizing sintering to obtain the productAnd obtaining the diamond/copper composite sintered sheet body with the density of 98.5-100%.
Example 1
A four-column hot-pressing sintering machine is adopted to prepare sheet diamond/copper composite radiating substrates with the specification of 15mm (length) multiplied by 15mm (width) multiplied by 1mm (thickness), and the total number of the diamond/copper composite radiating substrates is 160, 16 sheets/die (4 layers of materials/die, and 4 single-layer charging sheets). Wherein, the designed addition of diamond is described by taking volume concentration as measurement (4.4 carat diamond is added into 1 cubic centimeter of volume and defined as 100% volume concentration), and when the diamond is actually added, the volume concentration is converted into weight after being converted. In this example, the mass ratio of diamond was 7.7% (corresponding to a design volume concentration of 60%) for composite titanium/nickel plating (0.3% increase in plating weight of titanium and 20% increase in coating weight of nickel), 1% for ultrafine CuSn15 powder, 0.5% for composite nickel/copper-coated carbon fiber (length 74 μm), and the balance for electrolytic copper powder. All the materials are mixed and granulated, and the addition amount of a granulating agent K90 (alcohol solution with the mass concentration of 1.5%) is 1.5 percent of the total weight of the materials. The present example was carried out as follows:
(1) the surface of the titanium-plated diamond is coated with nickel (the coating weight gain is 20 percent of the total weight of the coating material):
a) weighing NiSO452.54 g of solid particles are placed in a No. 1 beaker, distilled water is added, and the mixture is stirred until the solid particles are completely dissolved, so that 300mL of nickel sulfate solution is prepared for standby;
b) weighing 27.12 g of NaOH solid particles, placing the NaOH solid particles in a No. 2 beaker, adding distilled water, stirring until the NaOH solid particles are completely dissolved, and preparing 150mL of sodium hydroxide solution for later use;
c) weighing 100 g of diamond micro powder plated with titanium (plating weight gain is 0.3%) and placing the diamond micro powder into a No. 3 beaker, and adding the prepared nickel sulfate solution into the No. 3 beaker;
d) putting the magnetons into a No. 3 beaker, putting the beaker on a magnetic stirrer, setting the temperature to be 30 ℃, and stirring for 10 min;
e) repeatedly carrying out suction filtration on the solution for multiple times by using a vacuum water circulation suction filter to wash off redundant impurity ions;
f) putting the cleaned sample into an oven, and drying for 3 hours at 100 ℃;
g) reducing the sample in a hydrogen reducing furnace at 900 ℃ for 30 minutes, so that partial Ti-C chemical bonds can be formed on the surface of the diamond, and diamond composite particles with titanium-plated surfaces and nickel-coated surfaces are formed, wherein the oxygen content of the reduced material is less than 0.05%, and after reduction and cooling, vacuum packaging the material for later use.
(2) Coating copper on the surface of the nickel-plated carbon fiber/silicon carbide whisker (the coating increment of the copper is 100%):
carrying out chemical copper-clad treatment on the carbon fiber plated with nickel (the plating weight gain of nickel is 100%) according to the following steps h) to m), wherein the clad weight gain of copper is 100%:
h) weighing CuSO4Putting 13 g of solid powder into a No. 1 beaker, adding distilled water, stirring until the solid powder is completely dissolved, and preparing 200mL of copper sulfate solution for later use;
i) weighing 6.5 g of NaOH solid particles, placing the NaOH solid particles in a No. 2 beaker, adding distilled water, stirring until the NaOH solid particles are completely dissolved, and preparing 200mL of sodium hydroxide solution for later use;
j) weighing 5.2 g of nickel-plated carbon fiber, placing the nickel-plated carbon fiber in a No. 3 beaker, and adding the prepared copper sulfate solution into the No. 3 beaker;
k) putting the magnetons into a No. 3 beaker, putting the beaker on a magnetic stirrer, setting the temperature to be 30 ℃, and stirring until the solution is uniform;
l) adding the prepared sodium hydroxide solution into a No. 3 beaker, and stirring for 10 min;
m) carrying out repeated suction filtration on the solution for multiple times by using a vacuum water circulation suction filter to wash off redundant impurity ions;
putting the cleaned sample into an oven, and drying for 3 hours at 100 ℃;
n) reducing the dried material obtained in the step m) in a hydrogen reduction furnace for 20 minutes at 850 ℃, wherein the oxygen content of the reduced finished product material is less than 0.07%.
(3) Preparing a cold-pressed blank: weighing 23 g of the composite diamond particles prepared in the step (1), 267.5 g of electrolytic copper powder, 3g of superfine CuSn15 powder and 1.5 g of composite nickel/copper plated carbon fiber, adding 4.5g of K90 adhesive for mixing and granulating, then dividing 160 parts of dried mixed granulated materials, and respectively putting the materials into a steel die to be cold-pressed into a sheet blank with the thickness of 15mm multiplied by 1.6 mm.
(4) Reduction and pre-sintering: and (3) placing the cold-pressed green body into a graphite die with a balance weight, carrying out reduction treatment in a push type reduction furnace at 860 ℃ for 30 minutes, and then placing the cooled and discharged reduced sintered body into a bin filled with high-purity nitrogen for storage for later use.
(5) Hot-pressing sintering densification: and (3) putting the reduced sintered body into a graphite assembly die, and carrying out densification sintering treatment in a four-column hot pressing sintering machine, wherein 4 layers are charged in each die, and each layer is 4 sheets. The sintering temperature is 950 ℃, and the sintering pressure is 350kg/cm2And (5) preserving heat for 5 minutes at high temperature, naturally cooling after sintering, and removing the mold to take the workpiece.
(6) Cleaning and polishing: the workpiece is fixed on a rotary polishing device, soft polishing cloth with short fiber and polishing liquid are adopted to carry out polishing treatment by taking clear water as a medium, and then the polished workpiece is dried and sealed after being subjected to ultrasonic cleaning treatment in industrial alcohol solution. The prepared composite heat dissipation substrate has the spot inspection thermal conductivity of 609-632W/mK, which is basically equivalent to that of a discharge plasma sintering method (SPS) reported in the literature (about 650W/mK).
Example 2
The diamond/copper heat-dissipating substrate with the same specification and ratio as those in example 1 was prepared by densification sintering using a cubic press.
Adopting the steps (1) to (4) in the embodiment 1 to prepare a pre-reduction sintered diamond/copper heat dissipation sheet body;
placing the pre-reduced sintered sheet bodies into a pyrophyllite assembly block, 10 sheets/group, taking graphite with the thickness of 2mm as an isolation sheet among the sheet bodies, sintering and densifying at high temperature and high pressure in a cubic press, preserving heat for 3 minutes under the conditions that the temperature is 950 ℃ and the pressure is 4.5GPa, naturally cooling, and then removing a mold and taking out a piece;
the workpiece is fixed on a rotary polishing device, soft polishing cloth with short fiber and polishing liquid are adopted to carry out polishing treatment by taking clear water as a medium, and then the polished workpiece is dried and sealed after being subjected to ultrasonic cleaning treatment in industrial alcohol solution. The prepared composite heat dissipation substrate has the sampling thermal conductivity of 629-652W/mK.
Example 3
A four-column hot-pressing sintering machine is adopted to prepare 200 diamond/copper radiating substrates with the specification of 20mm (length) multiplied by 20mm (width) multiplied by 1.5mm (thickness), and the substrate components are as follows: the composite heat dissipation substrate is prepared by the following implementation steps of 9.2% by weight (corresponding volume concentration is 70%) of titanium-plated diamond (140/170 meshes, titanium plating weight gain is 0.3%), 88.8% by weight of electrolytic copper powder, 1.5% by weight of superfine CuSn15 powder and 0.5% by weight of composite nickel/copper-plated silicon carbide whisker.
(1) Coating copper by compounding the nickel-plated silicon carbide whisker: weighing 5g of nickel-plated silicon carbide whisker (with the length of 74 mu m and the weight gain of nickel plating of 100 percent), carrying out surface chemical copper coating treatment, wherein the weight gain of copper coating is 100 percent, and carrying out the following steps a) to h):
a) weighing CuSO4Putting 12.5 g of solid powder into a No. 1 beaker, adding distilled water, stirring until the solid powder is completely dissolved, and preparing 150mL of copper sulfate solution for later use;
b) weighing 6.25 g of NaOH solid particles, placing the NaOH solid particles in a No. 2 beaker, adding distilled water, stirring until the NaOH solid particles are completely dissolved, and preparing 150mL of sodium hydroxide solution for later use;
c) putting 5g of nickel-plated silicon carbide whiskers into a No. 3 beaker, and adding the prepared copper sulfate solution into the No. 3 beaker;
d) putting the magnetons into a No. 3 beaker, putting the beaker on a magnetic stirrer, setting the temperature to be 30 ℃, and stirring until the solution is uniform;
e) adding the prepared sodium hydroxide solution into a No. 3 beaker, and continuously stirring until the solution is uniform until the chemical reaction CuSO4+2NaOH＝Cu(OH)2↓+Na2SO4 is fully complete;
f) repeatedly carrying out suction filtration on the solution for multiple times by using a vacuum water circulating suction filter, and washing out soluble substances in the solution;
g) putting the cleaned sample into an oven, and drying for 3 hours at 100 ℃;
h) reducing the dried sample in a hydrogen reduction furnace at 850 ℃ for 20 minutes to obtain the composite nickel/copper-coated silicon carbide whisker, wherein the oxygen content of the composite is less than 0.05 percent;
(2) mixing and granulating: 89 g of the composite coated titanium/nickel-plated diamond, 861 g of electrolytic copper powder, 15 g of superfine CuSn15 powder and 5g of composite nickel/copper-coated silicon carbide whisker are weighed, the materials are mixed, then a K90 adhesive with 2 percent (19 g) of the total amount of the raw material powder is added for mixing granulation, and the mixture is divided into 200 parts after being dried;
(3) cold pressing to form a blank: cold-pressing the granulated material obtained in the step (2) into a cold-pressed green body with the length of 20mm multiplied by 2.5mm multiplied by the thickness of the steel mould;
(4) pre-reduction sintering: placing the cold-pressed green body in the step (3) in a graphite die with a balance weight, reducing and sintering for 30 minutes in a hydrogen reduction furnace at 880 ℃, and after reducing and cooling, placing the sintered green body in a bin protected by nitrogen for storage for later use;
(5) hot-pressing, compacting and sintering: loading the reduction sintering blank in the step (4) into a graphite die, and placing the graphite die on a four-column hot pressing sintering machine at 950 ℃ and 350kg/cm of pressure2Keeping the temperature at high temperature for 5 minutes, maintaining the pressure, naturally and slowly cooling, releasing the pressure, removing the die, and taking out the workpiece;
(6) cleaning and polishing the substrate: the workpiece is fixed on a rotary polishing device, soft polishing cloth with short fiber and polishing liquid are adopted to carry out polishing treatment by taking clear water as a medium, and then the polished workpiece is dried and sealed after being subjected to ultrasonic cleaning treatment in industrial alcohol solution. The prepared composite heat dissipation substrate has the sampling inspection thermal conductivity of 589-621W/mK.
Example 4
A diamond/copper heat-dissipating substrate having the same composition and specifications as those of example 3 was prepared by using a cubic press.
The steps (1) to (4) in example 3 are adopted to prepare a pre-reduction sintered diamond/copper heat dissipation sheet body;
placing the pre-reduced sintered sheet bodies into a pyrophyllite assembly block, 10 sheets/group, taking graphite with the thickness of 2mm as an isolation sheet among the sheet bodies, sintering and densifying at high temperature and high pressure in a cubic press, preserving heat for 3 minutes under the conditions that the temperature is 950 ℃ and the pressure is 5GPa, naturally cooling, and then removing a mold to take out a piece;
the workpiece is fixed on a rotary polishing device, soft polishing cloth with short fiber and polishing liquid are adopted to carry out polishing treatment by taking clear water as a medium, and then the polished workpiece is dried and sealed after being subjected to ultrasonic cleaning treatment in industrial alcohol solution. The prepared composite heat dissipation substrate has the sampling inspection thermal conductivity of 613-652W/mK.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (10)
1. A powder metallurgy preparation method of a fine-particle diamond copper-based composite heat dissipation material is characterized by comprising the following steps: the method comprises the following steps:
s1, weighing the following materials in percentage by weight: 4.2-11.6 wt% of fine-particle diamond, 1-5 wt% of water atomized superfine CuSn15 bronze powder, 0.1-0.5 wt% of composite nickel and copper plated carbon fiber and composite nickel and copper plated silicon carbide whisker, and the balance of electrolytic copper powder, wherein the K90 polyvinylpyrrolidone alcoholic solution with the weight percentage of 1.5-3.0 wt% of the total weight of the mixed granulation raw materials is used as a granulating agent;
s2, cold pressing blank making: mixing and granulating the raw material powder by taking K90 polyvinylpyrrolidone alcoholic solution as a granulating agent, and then cold-pressing the mixture into a flaky blank in a steel die;
s3: high-temperature reduction and pre-sintering: placing the cold-pressed sheet body into a hydrogen reduction furnace for high-temperature reduction and pre-sintering;
s4: high-temperature high-pressure densification sintering: and then the pre-reduced sintered body is filled into a graphite mould to be sintered into a sheet-shaped finished product through high-temperature densification in a four-column hot-pressing sintering machine or a cubic press.
2. The powder metallurgy preparation method of the fine-grained diamond copper-based composite heat dissipation material as claimed in claim 1, wherein the powder metallurgy preparation method comprises the steps of mixing and granulating various raw material powders together by using a K90 polyvinylpyrrolidone alcoholic solution as a granulating agent, carrying out cold pressing on the granulated material in a steel mold to prepare a blank, then placing the cold-pressed blank into a hydrogen reduction furnace for pre-reduction sintering, then placing the pre-reduced sintered blank into a graphite mold, carrying out densification sintering in a four-column hot-pressing sintering machine or a cubic press to prepare the flaky composite heat dissipation body, and carrying out mechanical polishing treatment on the surface of the flaky composite heat dissipation body.
3. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as claimed in claim 1, wherein the diamond is 120 or 140-mesh composite titanium/nickel-plated diamond with fine single-particle size or combined particle size, and the weight gain of the physical vapor plating titanium is 0.3-0.5% of the weight of the diamond to be plated; and coating nickel hydroxide on the surface of the titanium-plated diamond particles by adopting a chemical coating technology, and reducing the nickel-plated diamond particles for 20 to 30 minutes by using hydrogen at the temperature of 850 to 900 ℃ to form composite diamond particles with titanium/nickel coated on the surface, wherein the coating weight of the nickel is increased by 20 to 30 percent of the weight of the titanium-plated diamond.
4. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as recited in claim 1, wherein the electrolytic copper powder is fine with a particle size of 300 meshes, has a purity of not less than 99.9%, and has a bulk density of 1.4-1.7 g/cm3Oxygen, oxygenThe content is less than 0.07 percent.
5. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as recited in claim 1, wherein the laser particle size D50 value of the superfine CuSn15 bronze powder prepared by the water atomization method is 5-7 μm, and the oxygen content is less than 0.08%.
6. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as claimed in claim 1, wherein the composite nickel-plated and copper-plated carbon fiber is an asphalt-based carbon fiber with a thermal conductivity of 600-900W/mK, the length of the asphalt-based carbon fiber is 74-150 μm, and the length of the composite nickel-plated and copper-plated silicon carbide whisker is 74-150 μm; the nickel plating amount is 50-100% of the mass of the silicon carbide whiskers to be plated, the silicon carbide whiskers are coated with copper by a chemical method after being plated with nickel, and the copper coating amount is 50-100% of the weight of the material subjected to nickel plating treatment in the previous working procedure.
7. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as claimed in claim 1, wherein the K90 polyvinylpyrrolidone alcoholic solution granulating agent is prepared by dissolving K90 polyvinylpyrrolidone particles in absolute alcohol to prepare a viscous alcoholic solution with a mass concentration of 1.0-1.5%.
8. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material according to claim 1, wherein the cold pressing blank is prepared by cold pressing a mixed granulation material using K90 polyvinylpyrrolidone alcoholic solution as a granulating agent in a steel cold pressing mold to prepare a sheet blank with a pressing density of 60-65%.
9. The powder metallurgy preparation method of the fine-particle diamond copper-based composite heat dissipation material as recited in claim 1, wherein the pre-reduction sintering is that the cold-pressed blank is loaded into a graphite mold with a balance weight, sent into a hydrogen reduction furnace, kept at 850-900 ℃ for 20-30 minutes, cooled to room temperature along with the furnace, and then the reduction sintered sheet body is placed into a bin filled with high-purity nitrogen gas for storage and standby.
10. The powder metallurgy preparation method of the fine-grained diamond copper-based composite heat dissipation material as claimed in claim 1, wherein the densification sintering is to place the pre-reduced sintered body into a graphite mold, and sinter the pre-reduced sintered body in a four-column hot-pressing sintering machine at a sintering temperature of 920-950 ℃ and a sintering pressure of not less than 350kg/cm2And (3) carrying out high-temperature heat preservation for 5-7 minutes or carrying out heating and pressurizing sintering in a cubic press at the sintering temperature of 880-950 ℃ under the sintering pressure of 4.5-5.0 GPa for 2-5 minutes to obtain the diamond/copper composite sintered sheet body with the density of 98.5-100%.
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