Preparation method of material with high thermal conductivity and low thermal expansion coefficient

Abstract

The invention discloses a preparation method of a high-thermal-conductivity and low-thermal-expansion-coefficient material, and relates to the field of metal-based composites.The preparation method comprises the steps that high-purity aluminum is infiltrated into pores of silicon carbide foamed ceramic with the equal volume fraction; the silicon carbide foamed ceramic serves as a framework of the aluminum-silicon carbide composite material, the wettability of the silicon carbide foamed ceramic and aluminum is improved through a method for improving and controlling parameters in the infiltration process, and the poor interface reaction in the preparation process is reduced; the porosity of the silicon carbide foamed ceramic is controlled, pure aluminum with the calculated volume is placed below the silicon carbide foamed ceramic, and a heavy object is added above the silicon carbide foamed ceramic, so that an aluminum block is melted at high temperature and permeates into silicon carbide pores, and an aluminum-silicon carbide composite material is prepared; through the method, the aluminum silicon carbide composite material has high thermal conductivity and low thermal expansion coefficient.

Description

Technical Field

[0001] The invention belongs to the technical field of metal-based composite materials, and in particular relates to a method for preparing a material with high thermal conductivity and low thermal expansion coefficient. Background Art

[0002] According to different main materials, composite materials in the field of electronic packaging mainly include polymer-based composite materials, ceramic-based composite materials, and metal-based composite materials; among metal-based composite materials, aluminum-based composite materials are widely used; for aluminum-based composite materials, there are two preparation methods, namely powder metallurgy and melt infiltration; both methods have some disadvantages. Powder metallurgy can flexibly and accurately control the content of the reinforcing phase, but the disadvantage is that the powder mixing is uneven and the sintering process is not easy to control; the melt infiltration method has a simple process flow, low raw material price, no need for expensive equipment, and a short production cycle, but the wettability of silicon carbide and aluminum liquid is relatively poor, so silicon carbide needs to be pretreated; therefore, composite materials with high thermal conductivity, small thermal expansion coefficient and low price are difficult to obtain; therefore, it is necessary to design an inexpensive material with high thermal conductivity and low thermal expansion coefficient.

[0003] Foam ceramic is a new type of porous ceramic material with high and controllable porosity, low bulk density, high temperature resistance, corrosion resistance, light weight and other excellent properties. It can be used as thermal insulation, sound insulation material, filter, refractory material, etc.; SiC foam ceramic has excellent characteristics such as large specific surface area, high porosity, good chemical stability and strong corrosion resistance. It shows broad application prospects in molten metal filtration, automobile exhaust treatment, sound absorption and noise reduction, catalyst carrier, heat exchanger, biomedicine and other fields; but silicon carbide and aluminum have poor surface wettability, uneven dispersion, and particle agglomeration. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing a material with high thermal conductivity and low thermal expansion coefficient, so as to reduce the cost, enhance the thermal conductivity of the original thermal conductive material and reduce its thermal expansion coefficient.

[0005] The present invention adopts the following technical solutions to achieve the above-mentioned purpose: A method for preparing a material with high thermal conductivity and low thermal expansion coefficient, wherein the preparation method comprises infiltrating high-purity aluminum into the pores of silicon carbide foam ceramic with a medium volume fraction; using the silicon carbide foam ceramic as the skeleton of the aluminum-silicon carbide composite material, and improving its wettability with aluminum and reducing undesirable interface reactions during the preparation process by improving the parameter method for controlling the infiltration process; the specific preparation steps are as follows: 1) The porosity, bulk density and true density of silicon carbide foam ceramics were calculated using the Archimedean drainage method. The porosity of silicon carbide foam ceramics was controlled at 70%-80%, the pore size was 3-4mm, and the pores were interconnected and all were through holes. The measured silicon carbide foam ceramics were placed in a 110°C oven and completely dried; 2) Place a high-purity aluminum block in a graphite boat, and place silicon carbide foam ceramics on the high-purity aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. Heat the high-temperature furnace to 800°C at a heating rate of 4°C / min, with a melting and infiltration time of 30 minutes. Slowly cool to room temperature and take out to obtain an aluminum-silicon carbide composite material.

[0006] The melting temperature of the high-purity aluminum is 660°C.

[0007] The present invention proposes a method for preparing a material with high thermal conductivity and low thermal expansion coefficient. Compared with the prior art, the present invention has the following beneficial effects: 1) the silicon carbide foam ceramic used has high strength, low thermal conductivity, low density and low price; 2) the method of the present invention is simple, easy to operate and does not require expensive instruments; 3) infiltrating aluminum into the pores of silicon carbide foam ceramic effectively reduces the thermal expansion coefficient of the material, while fully demonstrating the excellent thermal conductivity of aluminum; 4) silicon carbide has high hardness, and aluminum improves its hardness and other physical properties by being compounded with the silicon carbide foam ceramic skeleton. DETAILED DESCRIPTION

[0008] The embodiments of the present invention are described in further detail below. Embodiment 1:

[0009] The porosity of silicon carbide foam ceramics is controlled at 70%, the pore size is about 3-4mm, the pores are interconnected, and all are open. The porosity, volume density and true density of silicon carbide foam ceramics are roughly calculated using the Archimedes drainage method, and after measurement, they are placed in a 110°C oven for complete drying. A high-purity aluminum block is placed in a graphite boat, and the silicon carbide foam ceramics are placed on the aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. The high-temperature furnace is heated to 800°C at a heating rate of 4°C / min, the infiltration time is 30min, and the aluminum silicon carbide composite material is obtained after slowly cooling to room temperature. Embodiment 2:

[0010] The porosity of silicon carbide foam ceramics is controlled at 80%, the pore size is about 4-5mm, the pores are interconnected, and all are through holes. The porosity, volume density and true density of silicon carbide foam ceramics are calculated using the Archimedes drainage method, and after measurement, they are placed in a 110°C oven for complete drying. A high-purity aluminum block is placed in a graphite boat, and the silicon carbide foam ceramics are placed on the aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. The high-temperature furnace is heated to 800°C at a heating rate of 4°C / min, the infiltration time is 30min, and the aluminum silicon carbide composite material is obtained after slowly cooling to room temperature. Embodiment 3:

[0011] The porosity of silicon carbide foam ceramics is controlled at 80%, the pore size is about 4-5mm, the pores are interconnected, and all are through holes. The porosity, volume density and true density of silicon carbide foam ceramics are calculated using the Archimedes drainage method, and after measurement, they are placed in a 110°C oven for complete drying. A high-purity aluminum block is placed in a graphite boat, and the silicon carbide foam ceramics are placed on the aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. The high-temperature furnace is heated to 1000°C at a heating rate of 4°C / min, the infiltration time is 30min, and the aluminum silicon carbide composite material is obtained after slowly cooling to room temperature. Embodiment 4:

[0012] The porosity of silicon carbide foam ceramics is controlled at 70%, the pore size is about 3-4mm, the pores are interconnected, and all are through holes. The porosity, volume density and true density of silicon carbide foam ceramics are roughly calculated using the Archimedes drainage method, and after measurement, they are placed in a 110°C oven for complete drying. A high-purity aluminum block is placed in a graphite boat, and the silicon carbide foam ceramics are placed on the aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. The high-temperature furnace is heated to 1000°C at a heating rate of 4°C / min, the infiltration time is 30min, and the aluminum silicon carbide composite material is obtained after slowly cooling to room temperature.

[0013] This method will improve the thermal conductivity and strength of the composite material and reduce the thermal expansion coefficient. The reason is that silicon carbide has low density, high hardness, poor thermal conductivity, and a small thermal expansion coefficient. When it is used as a skeleton and forms a composite material with aluminum, it can inhibit the thermal expansion of aluminum. The porosity of silicon carbide foam ceramic is large and evenly distributed, which fully reflects the thermal conductivity of aluminum and improves the thermal conductivity of aluminum-silicon carbide composite materials.

Claims

1. A method for preparing a material with high thermal conductivity and low thermal expansion coefficient, characterized in that: The preparation method is to infiltrate high-purity aluminum into the pores of silicon carbide foam ceramic with a medium volume fraction; use silicon carbide foam ceramic as the skeleton of aluminum-silicon carbide composite material, improve its wettability with aluminum and reduce adverse interface reactions during the preparation process by improving the parameter method of controlling the infiltration process; the specific preparation steps are as follows: 1) The porosity, bulk density and true density of silicon carbide foam ceramics were calculated using the Archimedean drainage method. The porosity of silicon carbide foam ceramics was controlled at 70%-80%, the pore size was 3-4mm, and the pores were interconnected and all were through holes. The measured silicon carbide foam ceramics were placed in a 110°C oven and completely dried; 2) Place a high-purity aluminum block in a graphite boat, and place silicon carbide foam ceramics on the high-purity aluminum block. The aluminum penetration capacity is increased by adding weights to the silicon carbide foam ceramics. Heat the high-temperature furnace to 800°C at a heating rate of 4°C / min, with a melting and infiltration time of 30 minutes. Slowly cool to room temperature and take out to obtain an aluminum-silicon carbide composite material.

2. The method for preparing a material with high thermal conductivity and low thermal expansion coefficient as claimed in claim 1, characterized in that: The melting temperature of the high-purity aluminum is 660°C.