阅读说明：本技术 一种高导热高可靠性的金刚石/铝复合材料及其制备工艺 (Diamond/aluminum composite material with high heat conductivity and high reliability and preparation process thereof ) 是由 丁伟 李荣福 李学伟 李诗菁 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种高导热、高可靠、低成本的金刚石/铝复合材料及其制备工艺,该制备工艺包括以下步骤：在金刚石粉表面镀上金属和陶瓷的混合膜,膜厚30～300nm；在灌装金刚石粉后的模具上,放置铝合金锭,在压强0.08～0.15MPa的氮气气氛中加热,得到金刚石/铝复合材料。本发明以金属和陶瓷混合膜的形式对膜层进行了优化,因而复合材料的耐候性更好,在湿热、冷热冲击等条件下不易发生衰减,产品热导率的衰减小于3％,这说明金刚石粉表面的金属和陶瓷混合膜可以起到抑制有害相碳化铝的生成,提高了材料服役的可靠性。(The invention discloses a diamond/aluminum composite material with high heat conductivity, high reliability and low cost and a preparation process thereof, wherein the preparation process comprises the following steps: plating a mixed film of metal and ceramic on the surface of diamond powder, wherein the film thickness is 30-300 nm; and placing an aluminum alloy ingot on the mold filled with the diamond powder, and heating in a nitrogen atmosphere with the pressure of 0.08-0.15 MPa to obtain the diamond/aluminum composite material. The film layer is optimized in the form of the metal and ceramic mixed film, so that the composite material has better weather resistance, is not easy to attenuate under the conditions of damp heat, cold and hot shock and the like, and the attenuation of the heat conductivity of the product is less than 3 percent, which shows that the metal and ceramic mixed film on the surface of diamond powder can inhibit the generation of harmful phase aluminum carbide and improve the reliability of the service of the material.)

1. A pressureless infiltration preparation process of a diamond/aluminum composite material is characterized by comprising the following steps:

(1) plating a metal film or a silicon dioxide film on the surface of diamond powder, and then placing the diamond powder under a vacuum condition and keeping the temperature at 1350 ℃ for 1.5 to 7.0 hours to generate a mixed film of metal and ceramic, wherein the film thickness is 20 to 300 nm;

(2) and placing an aluminum alloy ingot on the mold filled with the diamond powder, and heating in a nitrogen atmosphere with the pressure of 0.08-0.15 MPa to obtain the diamond/aluminum composite material.

2. The process according to claim 1, characterized in that: the metal film in the step (1) comprises Ti, W, Mo, Zr, Cr and Nb; the ceramic membrane is a carbon compound, and the ceramic membrane comprises titanium carbide, molybdenum carbide, silicon carbide, chromium carbide, zirconium carbide and neodymium carbide.

3. The process according to claim 1, characterized in that: and (2) plating a mixed film of metal and ceramic in the step (1), wherein the plating method adopts magnetron sputtering, chemical plating, chemical vapor deposition, sol-gel or salt bath plating.

4. The process according to claim 1, characterized in that: in the step (1), the diamond powder has a particle size of 10-300 μm.

5. The process according to claim 1, characterized in that: the aluminum alloy in the step (2) is Al-Mg-Si alloy, wherein the mass fraction of Mg is 2-15%, and the mass fraction of Si is 5-25%.

6. The process according to claim 1, characterized in that: and (3) heating, namely preserving the heat at 780-1100 ℃ for 0.5-3.0 h.

7. A diamond/aluminum composite characterized by: is prepared by the method of any one of claims 1 to 6.

Technical Field

The invention relates to a diamond/aluminum composite material with high heat conductivity, high reliability and low cost and a preparation process thereof.

Background

Consumer demand has driven the design of new products in the electronics industry, which is also responding to market expectations to provide smaller and smaller sized, yet more powerful products. The demand for further miniaturization and ever increasing performance will exponentially increase power consumption and heat generation within the system. The extremely high heat generated has an adverse effect on the health of the user as well as the reliability and performance of the product, creating a central need for thermal management in all electronic products. In particular, in industries related to the national civilian population, such as the national defense electronic technology industry represented by advanced radar and the high-technology national industry represented by new energy, big data operation, and 5G communication, the requirement for electronic packaging materials is increasing.

The diamond aluminum composite material takes diamond powder as a reinforcement body, the aluminum alloy as a continuous matrix, the heat conduction performance, the thermal expansion coefficient and the strength of the diamond and the aluminum alloy are organically coordinated, the thermal conductivity higher than that of the electronic packaging materials of the previous generations is obtained, the thermal expansion coefficient more matched with a semiconductor material is also obtained, and if the cost can be reduced and the production efficiency is improved, the diamond aluminum composite material becomes an extremely competitive electronic packaging material in the market.

The composite material is usually prepared by adopting an air pressure infiltration technology, can realize the full contact of diamond and liquid aluminum alloy, is beneficial to strengthening interface combination, and the prepared diamond/aluminum composite material usually has excellent performance. However, the method has high requirements on equipment, is not easy to produce on a large scale, and greatly limits the cost and the production efficiency of the composite material. Compared with the diamond aluminum composite material prepared by the pressure infiltration process, the pressureless infiltration process does not need pressurization, so that the requirement on equipment is low, the utilization rate of a furnace chamber is high, the targeted design can be performed, and the prepared diamond aluminum composite material has the outstanding advantages of low cost and high efficiency and is an industrialized technical scheme with more superiority.

Chinese invention patent ZL 201110194213.9 discloses a preparation method of a high volume fraction diamond/aluminum heat conduction function composite material, which adopts a salt bath coating method to coat Ti or Cr on diamond particles to obtain a coating with the thickness of 0.1-0.3 mu m, then diamond particle preforms are prepared, aluminum alloy is added, and the composite material is prepared under the nitrogen pressure of 0.6-1.5 MPa. The method has the advantages of high air pressure and high requirement on equipment, and is easy to cause uneven material preparation and poor density, thereby causing unstable material performance.

Disclosure of Invention

In order to overcome the defect that the thermal conductivity of the existing diamond/aluminum composite material is unstable, the invention aims to provide a preparation process of a metal and ceramic mixed film modified diamond/aluminum composite material.

It is another object of the present invention to provide a diamond/aluminum composite material produced by the above process.

The purpose of the invention is realized by the following technical scheme:

a pressureless infiltration preparation process of a diamond/aluminum composite material comprises the following steps:

(1) surface treatment of diamond powder

Plating a metal film or a silicon dioxide film on the surface of diamond powder, and then placing the diamond powder under a vacuum condition and keeping the temperature at 1350 ℃ for 1.5 to 7.0 hours to generate a metal and ceramic mixed film with the thickness of 20 to 300 nm; the surface treatment of diamond powder is one of the important solutions to the degradation of the properties of composite materials.

The metal film comprises Ti, W, Mo, Zr, Cr and Nb;

the ceramic membrane is a carbon compound, and the ceramic membrane comprises titanium carbide, tungsten carbide, molybdenum carbide, silicon carbide, chromium carbide, zirconium carbide and neodymium carbide;

the coating method can adopt the methods of the prior art such as magnetron sputtering, chemical plating, chemical vapor deposition, sol-gel and salt bath plating;

the bonding force between diamond and matrix aluminum alloy is weak, which is the main reason for poor performance of the diamond/aluminum composite material. The ceramic film on the surface of the diamond is a key transition phase, so that the interface bonding force can be effectively improved, the performance of the composite material is further improved, and the interface harmful phase Al can be inhibited₄C₃And (4) generating.

(2) Pressureless infiltration for preparing composite material

The diamond/aluminum composite material has a certain size and shape when used as a product. Due to the addition of diamond powder, the processability of the composite material is poor, and therefore, a direct forming mode is adopted, and the subsequent processing is reduced as much as possible.

According to the forming mode, diamond powder is filled in a mold, the mold is utilized to obtain a product with a certain shape, and the mold is removed after the metal is cooled.

Placing an aluminum alloy ingot on a mold filled with diamond powder, heating the aluminum alloy ingot in a nitrogen atmosphere with the pressure of 0.08-0.15 MPa, spontaneously infiltrating the aluminum alloy into pores among the diamond powder after the aluminum alloy is molten, and cooling to obtain a diamond/aluminum composite material; the heating temperature and time are related to the type of alloy and the quality of the aluminum ingot;

the nitrogen gas has the function of reacting with magnesium element in the aluminum alloy, breaking a surface oxidation film which obstructs the flow of molten aluminum and promoting the penetration of aluminum liquid in the diamond powder prefabricated body. The invention adopts lower nitrogen pressure, which not only meets the reaction requirement, but also avoids the residue of nitrogen in the composite material, thereby reducing the density and the heat conductivity of the composite material.

In the step (1), the particle size of the diamond powder is 10-300 μm;

the mould is designed and prepared according to the drawing of a product. The mould may be made of ceramic, refractory metal or graphite material, e.g. Al₂O₃Ceramics, molybdenum alloys, tungsten alloys and various types of graphite such as electrode graphite, high purity graphite, isostatic graphite and various types of graphite impregnated with chemical adjuvants. Which material is selected for making the moldThe function and application occasion to be realized.

The filling is to fill diamond powder with good fluidity into the inner mold of the mold through gravity action or in combination with vibration, injection and other modes through a pouring channel reserved for the mold.

The Al-Mg-Si alloy is preferably selected as the aluminum alloy in the step (2), wherein the mass fraction of Mg is 2-15%, and the mass fraction of Si is 5-25%;

the heating in the step (2) is carried out for 0.5-3.0 h at 780-1100 ℃; the temperature and time of heat preservation are related to the type of alloy and the quality of the aluminum ingot.

Compared with the prior art, the invention has the following advantages and effects:

1. the film layer is optimized in the form of the metal and ceramic mixed film, so that the composite material has better weather resistance, is not easy to attenuate under the conditions of damp heat, cold and hot shock and the like, and the attenuation of the heat conductivity of the product is less than 3 percent, which shows that the metal and ceramic mixed film on the surface of diamond powder can inhibit the generation of harmful phase aluminum carbide and improve the reliability of the service of the material.

2. The invention solves the problems of high cost and low efficiency of the diamond aluminum composite material and the product thereof in the production and preparation process. The diamond aluminum composite material prepared by the pressureless infiltration process has excellent performance, meets the heat conduction and heat dissipation requirements of high-power electronic equipment, and is easy to control the product quality and stability.

Drawings

FIG. 1 is a scanning electron micrograph of the diamond/aluminum composite obtained in example 1.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.