CN113737045A

CN113737045A - Method for preparing bicontinuous phase SiC/Cu composite material

Info

Publication number: CN113737045A
Application number: CN202111064068.2A
Authority: CN
Inventors: 傅丽华; 周孟; 张永振; 杜三明; 刘建; 贺甜甜; 岳赟; 倪锋; 毛艳珊
Original assignee: Henan University of Science and Technology
Current assignee: Henan University of Science and Technology
Priority date: 2021-09-10
Filing date: 2021-09-10
Publication date: 2021-12-03
Anticipated expiration: 2041-09-10
Also published as: CN113737045B

Abstract

The invention relates to a method for preparing a bicontinuous phase SiC/Cu composite material, belonging to the technical field of pressureless infiltration. The method for preparing the double continuous phase SiC/Cu composite material comprises the following steps: taking SiC porous ceramic and copper-based metal as pre-infiltrants; and then, burying the pre-impregnated body by using silicon carbide sand to ensure that the silicon carbide sand is distributed at the bottom and around the pre-impregnated body, heating in an oxygen-free environment to carry out non-pressure impregnation, and cooling after the non-pressure impregnation is finished to obtain the double continuous phase SiC/Cu composite material. The method has simple process, easy realization and simple operation process, takes the silicon carbide sand as the die material, is beneficial to avoiding the deoxidation reaction of the oxide sand in the high-temperature anaerobic environment to cause the die collapse failure when the mechanical property of the copper-based composite material is improved by pressureless infiltration under the high-temperature anaerobic condition; meanwhile, the reaction of the die material and the SiC porous ceramic in the pre-impregnated body can be reduced.

Description

Method for preparing bicontinuous phase SiC/Cu composite material

Technical Field

The invention relates to a method for preparing a bicontinuous phase SiC/Cu composite material, belonging to the technical field of pressureless infiltration.

Background

The copper-based composite material (such as SiC/Cu) not only has the characteristics of good electric and thermal conductivity, corrosion resistance, processability and the like, but also has moderate price, becomes an important material for preparing electric contact parts and brake discs, and is widely applied to the fields of electronic equipment, rail transit and the like. In the service environment, the friction and the abrasion are one of the main failure modes of the copper-based composite material. With the rapid development of the fields of electronic technology, rail transit, weaponry and the like in China, the variety and the demand of copper-based composite components are increased rapidly, and the service environment of the components is increasingly harsh (the components are developed towards the directions of high power, high frequency, integration, miniaturization and the like), so that the copper-based composite material not only needs to have better electric and thermal conductivity, but also needs to have more excellent mechanical properties and wear resistance. The traditional copper-based composite material belongs to a typical 1-3 (one-dimensional friction component and three-dimensional matrix) connection type composite material, and reinforcing particles dispersed in a copper alloy matrix cannot effectively dissipate current heating and friction heating in time, so that the capability of the material for resisting high-temperature deformation and adhesive wear is weakened, and the development requirements of modern materials on structural function integration and efficient heat dissipation cannot be met.

Compared with the traditional composite material structure, the bicontinuous phase composite material has the 3-3 type connection characteristic, is beneficial to rapid transmission and dispersion of stress and heat in a spatial range in the using process, and can also effectively restrain plastic deformation and high-temperature softening of a metal matrix, thereby being used for preparing wear-resistant parts in various fields. An important link in the preparation process of the bicontinuous phase composite material is that the metal melt is impregnated into the porous material. Common methods of infiltration of molten metals include extrusion infiltration, vacuum pressure infiltration, and pressureless infiltration. Wherein, the pressureless infiltration does not need special vacuum or pressure devices, is a simple and easy-to-operate process method with excellent material performance, and is widely regarded. For the double continuous phase SiC/copper alloy composite material, if a mould with an internal space larger than the size of a pre-impregnated body is adopted in the non-pressure impregnation process, the impregnation metal melt is easy to flow and run off towards four sides, and the impregnation effect is seriously influenced. In addition, due to the high melting point of the copper alloy, if a mold with an internal space consistent with the size of the pre-impregnated body is adopted, various chemical, physical and diffusion reactions can occur between the copper alloy and the mold at high temperature, so that the demolding of the material is difficult.

At present, modified quartz sand is adopted to bury SiC and aluminum alloy pre-infiltration bodies, a breathable and liquid-tight mould shell is formed by utilizing the modified quartz sand at high temperature, the size of the inner space of the mould shell is consistent with that of the pre-infiltration body, the loss of molten metal can be reduced, the infiltration efficiency is improved, and the mould shell is easy to remove. However, when the copper-based composite material is prepared by the method, the mold shell formed by the modified quartz sand is easy to collapse.

Disclosure of Invention

The invention aims to provide a preparation method of a bicontinuous phase SiC/Cu composite material, which can solve the problem that a shell of a mold is easy to collapse.

In order to realize the purpose, the preparation method of the double continuous phase SiC/Cu composite material adopts the technical scheme that:

a method for preparing a bicontinuous phase SiC/Cu composite material comprises the following steps: taking SiC porous ceramic and copper-based metal as pre-infiltrants; and then, burying the pre-impregnated body by using silicon carbide sand to ensure that the silicon carbide sand is distributed at the bottom and around the pre-impregnated body, heating in an oxygen-free environment to carry out non-pressure impregnation, and cooling after the non-pressure impregnation is finished to obtain the double continuous phase SiC/Cu composite material.

According to the method for preparing the bicontinuous phase SiC/Cu composite material, the silicon carbide sand is skillfully selected to bury the pre-impregnated body to form the simple die with the inner space being consistent with the size of the pre-impregnated body, and then the die is breathable and liquid-tight in the non-pressure impregnation process, so that on one hand, the formation of an oxygen-free environment around a metal melt is facilitated, on the other hand, the metal melt is effectively prevented from flowing and losing from four sides and can only permeate into the SiC porous ceramic under the action of self weight, the impregnation effect of the metal melt can be promoted while the using amount of the metal to be impregnated is reduced, and the cost and the efficiency for preparing the bicontinuous phase SiC/Cu composite material under the non-pressure impregnation condition are improved.

In addition, the method for preparing the bicontinuous phase SiC/Cu composite material has the advantages of simple process, easy realization and simple operation process, takes the silicon carbide sand as the mold material, and is beneficial to avoiding the collapse failure of the mold caused by the deoxidation reaction of oxide sand (such as quartz sand) in a high-temperature oxygen-free environment when the mechanical property of the copper-based composite material is improved by pressureless infiltration under the high-temperature oxygen-free condition; meanwhile, the reaction of the die material and the SiC porous ceramic in the pre-impregnated body can be reduced.

It will be appreciated that the silicon carbide distributed at the bottom and around the pre-infiltrant forms a gas-permeable, liquid-impermeable mold shell during infiltration. After the pre-impregnated body is buried with the silicon carbide sand, the device for heating may be an atmosphere furnace.

Preferably, before the copper-based metal and the SiC porous ceramic are used as the pre-impregnated body, the copper-based metal is polished and cleaned to remove surface dirt, and the SiC porous ceramic is calcined to remove free carbon. The temperature of the calcination treatment is preferably 600 ℃ and the time is preferably 1 h.

In order to further improve the air permeability and liquid impermeability of the mold shell, the average particle size of the silicon carbide sand is preferably 1-1.5 mm.

The silicon carbide sand is used as a raw material of the die, so that the decomposition failure of the die in an oxygen-free environment can be reduced, the chemical reaction between the die material and SiC porous ceramic can also be reduced, and preferably, the silicon carbide sand is black silicon carbide sand.

In order to improve the effect of pressureless infiltration and ensure the comprehensive performance of the bicontinuous phase SiC/Cu composite material prepared by pressureless infiltration in an oxygen-free environment, the pressureless infiltration temperature is preferably 50-300 ℃ above the melting point of copper-based metal.

In order to further improve the infiltration effect and obtain the bicontinuous phase SiC/Cu composite material with excellent performance, the porosity of the SiC porous ceramic is 80-90%. The pore density of the SiC porous ceramic is 10-20 ppi. The average pore diameter of the SiC porous ceramic is 1.6-2.5 mm.

The following reactions occur among quartz sand, SiC and nitrogen at high temperature: 3SiC +2N₂＝Si₃N₄+3C and 3SiC +3SiO₂+4N₂＝2Si₃N₄+3CO₂So that the quartz sand mould collapses and fails and the SiC porous ceramic is decomposed. In order to avoid reaction of other inert gases (such as nitrogen) with the silicon carbide sand and the SiC porous ceramic, the oxygen-free environment is preferably formed by charging argon into the environment. Because the mold shell formed by the silicon carbide sand in the pressureless infiltration process is permeable and impermeable to liquid (water or melt), the inert gas argon can enter the mold shell in the pressureless infiltration process, an oxygen-free environment is formed around the copper metal melt, and the performance of a composite material product is improved.

The copper-based metal is a copper bar. The copper-based metal is copper alloy or pure copper. Preferably, the copper-based metal is tin bronze. Preferably, the copper alloy is tin bronze QSN 6-6-3. The melting point of tin bronze QSN6-6-3 is about 1019 ℃. The tin bronze QSN6-6-3 comprises, by mass, 5-7% of Sn, 5-7% of Zn and 2-4% of Pb. The tin bronze QSN6-6-3 also contains a small amount of P, Ni and Fe elements. The volume ratio of the copper-based metal to the SiC porous ceramic is preferably 2-3: 1 in order to ensure sufficient infiltration and control the cost well because the copper-based metal has high density and heavy weight and is easy to infiltrate, and the cost is wasted due to excessive consumption of the copper alloy.

In order to further improve the impregnation effect, the non-pressure impregnation temperature under the anaerobic environment is preferably 1100-1200 ℃; the non-pressure infiltration time under the anaerobic environment is 30-90 min.

In order to reduce cracks of the SiC porous ceramic caused by an excessively high temperature rise speed and simultaneously give consideration to efficiency and time cost, the temperature rise speed is preferably 4-6 ℃/min. The cooling rate in the pressureless infiltration process is not limited, and for example, the temperature is reduced in a furnace cooling mode.

When the pre-impregnated body is buried with the silicon carbide sand, the crucible can be used as a container for the silicon carbide sand and the pre-impregnated body. Preferably, the landfill is realized by the following modes: and paving a layer of silicon carbide sand at the bottom of the crucible, then placing the pre-impregnated body on the silicon carbide sand at the bottom of the crucible, filling the silicon carbide sand around the pre-impregnated body, and compacting. The silicon carbide sand is filled in the gap between the pre-impregnated body and the crucible, so that the chemical, physical or diffusion reaction between the copper metal melt and the wall of the crucible container in a high-temperature environment can be reduced, and the phenomenon that demoulding cannot be carried out is avoided. It is understood that the crucible material is only required to withstand the temperature used for pressureless infiltration, and for example, an alumina crucible may be used.

In order to fill the silicon carbide sand around the pre-impregnated body, the selected crucible volume is slightly larger than the volume of the pre-impregnated body, a layer of silicon carbide sand is firstly paved at the bottom of the crucible, then the pre-impregnated body is placed on the silicon carbide sand, SiC porous ceramics can be placed firstly, then the metal to be impregnated is placed on the SiC porous ceramics, after the pre-impregnated body is placed, the pre-impregnated body has a certain distance with the inner wall of the crucible, then the gap between the pre-impregnated body and the crucible is filled with the silicon carbide sand, and the silicon carbide sand is compacted.

In order to enable the silicon carbide sand to form a gas-permeable liquid-tight mold shell and facilitate demolding, the silicon carbide sand is preferably paved at the bottom of the crucible to a thickness of 10-15 mm. The filling thickness of the silicon carbide sand around the pre-impregnated body in the crucible is 10-15 mm.

Drawings

FIG. 1 is a schematic diagram of a bicontinuous SiC/Cu composite prepared by burying silica sand in example 1;

FIG. 2 is a structural diagram of a bicontinuous phase SiC/Cu composite obtained in example 1 of Experimental example 1;

FIG. 3 is a structural diagram of a bicontinuous phase SiC/Cu composite material obtained by the comparative example in Experimental example 1.

Detailed Description

The technical solution of the present invention will be further described with reference to the following embodiments.

Example 1

The method for preparing the double continuous phase SiC/Cu composite material comprises the following steps:

1) polishing, degreasing and ultrasonically cleaning the surface of the tin bronze alloy with the mark of QSN 6-6-3; the length x width x height of the tin bronze alloy is 50mm x 30 mm;

2) heating the SiC porous ceramic at 600 ℃ for 1h to remove free carbon; the SiC porous ceramic has a pore density of 20ppi, a porosity of 82% and an average pore diameter of 1.6 mm; the length, width and height of the SiC porous ceramic are 50mm, 50mm and 15 mm;

3) paving silicon carbide sand with the thickness of 10-15 mm at the bottom of an alumina crucible, placing a tin bronze alloy on SiC porous ceramic, and placing the SiC porous ceramic in the crucible paved with the silicon carbide sand; then, burying the tin bronze alloy and the SiC porous ceramic in the crucible by using silicon carbide sand, so that the tin bronze alloy and the SiC porous ceramic and the inner wall of the crucible form silicon carbide sand with the thickness of 10-15 mm;

the carborundum sand adopted in the step 3) is black carborundum sand, and the average grain diameter is 1 mm;

4) putting the crucible in which the pre-impregnated body is embedded into an atmosphere furnace, introducing argon for protection, heating at a heating rate of 5 ℃/min, when the temperature reaches the melting point of the tin bronze alloy, melting the tin bronze alloy, and preserving heat for 60min after heating to 1150 ℃, wherein in the heat preservation process, the tin bronze alloy melt is gradually impregnated into the SiC porous ceramic downwards under the self-weight and capillary action;

5) and after the infiltration is finished, stopping heating, cooling the sample along with the furnace, and finally obtaining the bicontinuous phase SiC/Cu composite material without obvious macroscopic defects and with good performance.

The method for preparing the double-continuous-phase SiC/Cu composite material in the embodiment in the year is specifically as shown in figure 1, wherein a tin bronze alloy and SiC porous ceramics are placed in a crucible, and black silicon carbide sand is filled around a pre-impregnated body in the crucible.

Example 2

1) polishing, degreasing and ultrasonically cleaning the surface of the tin bronze alloy with the mark of QSN 6-6-3; the length x width x height of the tin bronze alloy is 50mm x 45 mm;

2) heating the SiC porous ceramic at 600 ℃ for 1h to remove free carbon; the SiC porous ceramic has the pore density of 15ppi, the porosity of 80 percent and the average pore diameter of 2.5 mm; the length, width and height of the SiC porous ceramic are 50mm, 50mm and 15 mm;

the silicon carbide sand adopted in the step 3) is black silicon carbide sand, and the average grain diameter is 1.5 mm.

4) Putting the crucible in which the pre-impregnated body is embedded into an atmosphere furnace, introducing argon for protection, heating at the heating rate of 4 ℃/min, melting the tin bronze alloy when the temperature reaches the melting point of the tin bronze alloy, and preserving heat for 90min after heating to 1100 ℃, wherein in the heat preservation process, the tin bronze alloy melt is gradually impregnated into the SiC porous ceramic downwards under the self-weight and capillary action.

Example 3

1) polishing, degreasing and ultrasonically cleaning the surface of the tin bronze alloy with the mark of QSN 6-6-3; the length, width and height of the copper alloy are 50mm, 50mm and 36 mm;

2) heating the SiC porous ceramic at 600 ℃ for 1h to remove free carbon; the SiC porous ceramic has the pore density of 10ppi, the porosity of 90 percent and the average pore diameter of 2 mm; the length, width and height of the SiC porous ceramic are 50mm, 50mm and 15 mm;

3) paving silicon carbide sand with the thickness of 10-15 mm at the bottom of an alumina crucible, placing a copper alloy on SiC porous ceramic, and placing the SiC porous ceramic in the crucible where the silicon carbide sand is paved; then, burying the copper alloy and the SiC porous ceramic in the crucible by using silicon carbide sand, so that the copper alloy and the SiC porous ceramic and the inner wall of the crucible form the silicon carbide sand with the thickness of 10-15 mm;

the silicon carbide sand adopted in the step 3) is black silicon carbide sand, and the average grain diameter is 1 mm.

4) Putting the crucible in which the pre-impregnated body is embedded into an atmosphere furnace, introducing argon for protection, heating at the heating rate of 6 ℃/min, melting the copper alloy when the temperature reaches the melting point of the tin bronze alloy, and preserving heat for 30min after the copper alloy is heated to 1200 ℃, wherein in the heat preservation process, the copper alloy melt is gradually impregnated into the SiC porous ceramic downwards under the self-weight and capillary action.

Comparative example

The method for producing the bicontinuous phase SiC/Cu composite material of this comparative example was conducted by replacing argon gas introduced into the atmospheric furnace in step 4) of the method for producing the bicontinuous phase SiC/Cu composite material of example 1 with air.

Experimental example 1

The morphology of the bicontinuous phase SiC/Cu composite materials prepared in example 1 and the comparative example was characterized by a digital camera, wherein the morphology of the bicontinuous phase SiC/Cu composite material prepared in example 1 is shown in FIG. 2, the morphology of the bicontinuous phase SiC/Cu composite material prepared in the comparative example is shown in FIG. 3, in FIGS. 2 and 3, the dark color corresponds to the SiC phase, and the light color corresponds to the copper alloy matrix phase. Wherein the copper alloy matrix of the double continuous phase SiC/Cu composite material prepared in the example 1 is yellowish brown, and the copper alloy matrix of the double continuous phase SiC/Cu composite material prepared in the comparative example is bright yellow.

Experimental example 2

The results of the frictional wear test on the bicontinuous SiC/Cu composite materials obtained in example 1 and the comparative example are shown in Table 1. The friction and wear test is completed on a QG-700 atmosphere friction and wear tester, wherein the selected motion mode is a pin-disc rotation mode. For the counter grinding pin, GCr15 bearing steel with a diameter of 6.35mm was used, and the bicontinuous phase SiC/C composite materials prepared in example 1 and comparative example were used as counter grinding disks, respectively. The friction and wear conditions are as follows: the load was 30N, the rotating diameter was 14mm, the rotating speed was 400rev/min, and the wear time was 30 min. And friction wear equipment automatically collects the friction coefficient in real time in the experimental process. Before the frictional wear test, the bicontinuous phase SiC/C composite materials prepared in example 1 and comparative example were weighed to have a mass m₁The mass of the product after abrasion is m₂Then, the volumetric wear rate was calculated by the following formula:

in the formula m₁Is the mass m before abrasion of the double continuous phase SiC/C composite material₂Is the mass rho (g/cm) of the double continuous phase SiC/C composite material after abrasion³) Is the bulk density of the sample, F (N) is the load, S (m) is the wear path.

TABLE 1 results of frictional wear test

	Wear Rate/(cm)³·m^-1·N^-1)	Coefficient of friction
			Example 1	1.33×10^-6	0.31
Comparative example	3.25×10^-6	0.38

As can be seen from Table 1, the rate of wear of the bicontinuous SiC/Cu composite obtained in example 1 was lower than that of the bicontinuous SiC/Cu composite obtained in the comparative example, and the coefficient of friction of the bicontinuous SiC/Cu composite obtained in example 1 was also lower than that of the bicontinuous SiC/Cu composite obtained in the comparative example. Therefore, the bicontinuous phase SiC/Cu composite material prepared by the pressureless infiltration in the oxygen-free environment has good frictional wear performance.

Claims

1. A method for preparing a bicontinuous phase SiC/Cu composite material is characterized by comprising the following steps:

taking SiC porous ceramic and copper-based metal as pre-infiltrants; and then, burying the pre-impregnated body by using silicon carbide sand to ensure that the silicon carbide sand is distributed at the bottom and around the pre-impregnated body, heating in an oxygen-free environment to carry out non-pressure impregnation, and cooling after the non-pressure impregnation is finished to obtain the double continuous phase SiC/Cu composite material.

2. The method of claim 1, wherein the average particle size of the silicon carbide sand is 1 to 1.5 mm.

3. The method of the bicontinuous phase SiC/Cu composite material of claim 1, wherein the pressureless infiltration is at a temperature 50-300 ℃ above the melting point of the copper-based metal.

4. The method of claim 1, wherein the porosity of the SiC porous ceramic is 80-90%.

5. The method of a bicontinuous phase SiC/Cu composite material as claimed in any one of claims 1 to 4, characterized in that said SiC porous ceramic has a pore density of 10 to 20 ppi; the average pore diameter of the SiC porous ceramic is 1.6-2.5 mm.

6. The method of bicontinuous phase SiC/Cu composite material of any one of claims 1-4, characterized in that said oxygen-free environment is formed by filling an environment with argon.

7. The method of bicontinuous phase SiC/Cu composite according to claim 1, characterized in that said copper-based metal is tin bronze.

8. The method of the bicontinuous phase SiC/Cu composite material of claim 1 or 7, wherein the pressureless infiltration temperature in the oxygen-free environment is 1100-1200 ℃; the non-pressure infiltration time under the anaerobic environment is 30-90 min.

9. The method of making a bicontinuous phase SiC/Cu composite material as claimed in any one of claims 1 to 4, wherein said temperature rise is at a rate of 4 to 6 ℃/min.

10. The method of bicontinuous phase SiC/Cu composite material according to any one of claims 1 to 4, characterized in that said landfill is carried out by: and paving a layer of silicon carbide sand at the bottom of the crucible, then placing the pre-impregnated body on the silicon carbide sand at the bottom of the crucible, filling the silicon carbide sand around the pre-impregnated body, and compacting.