CN1782111A

CN1782111A - Method for preparing smelting cast-in-site synthetic alpha-Al2O3 granule reinforced copper base composite material

Info

Publication number: CN1782111A
Application number: CN 200510086723
Authority: CN
Inventors: 崔华; 杨滨; 张济山; 孙淼; 黄赞军
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2005-10-26
Filing date: 2005-10-26
Publication date: 2006-06-07

Abstract

The present invention relates to fusion casting-in-site synthesis process of preparing alpha-Al2O3 grain reinforced copper base composite material, and belongs to the field of metal base composite material. The technological process includes: compounding materials based on reaction formula 2Al+3CuO-->3Cu+Al2O3; mixing materials Al and CuO in a material mixing machine and forming; heating matrix material Cu of over 99.0 % purity in MF inducing furnace to the temperature of 50-150 deg.c over the smelting point of Cu; pressing the fabricated blocks on 1-10 wt% of the melt into the melt and maintaining; casting to obtain in-site reacted alpha-Al2O3 grain reinforced copper base composite material. The advantages include shortened technological process, low manufacture cost and wide application as high strength and high conductivity electronic and electric material.

Description

Fusion casting-in-situ synthesis α -Al2O3Preparation method of particle reinforced copper-based composite material

Technical Field

The invention belongs to the field of metal-based composite materials, and particularly provides fusion casting-in-situ synthesis α -Al₂O₃The preparation method of the particle reinforced copper-based composite material can synchronously carry out the smelting of the matrix alloy and the generation of the reinforced phase, obviously shortens the preparation process flow of the composite material, reduces the manufacturing cost of the copper-based composite material, and can be widely applied to the fields of electronics, electrical engineering technology and the like which require high strength and high conductivity.

Background

Since the mid-eighties of the 20 th century, under the promotion of application and market demands, the research focus of metal matrix composites is shifted from the aspect of continuous fiber reinforced metal matrix composites to the aspect of discontinuous fiber reinforced metal matrix composites which have lower cost but wide industrial application prospect. In recent years, in-situ reaction synthesis ofmetal matrix composites (in-situ metal matrix composites, in situ MMCs for short) has been rapidly developed. The in-situ synthesis of the metal matrix composite refers to the generation of a reinforcing phase different from a matrix in a metal matrix (solid or liquid) through chemical reactions (combination reactions, redox reactions and the like) among substances, so as to achieve the purpose of improving certain properties of the matrix. The method for preparing the in-situ metal matrix composite material corresponds to the external composite method. The additional phases of the additive composite method need to be separately synthesized and added to the matrix during subsequent processes, such as infiltration, powder metallurgy, etc. The reinforcing phase in the in-situ compounding method is generated in the matrix during the preparation process. In general, the in situ compounding process can produce reinforcements in a variety of morphologies (from continuous to discontinuous reinforcements), and the reinforcements can be either plastic or ceramic phases. For metal matrices, the emphasis of current research is mainly on ceramic reinforcing phases, including oxides, carbides, nitrides, silicides, borides, etc., in order to strengthen the matrix and increase the modulus.

The earliest in situ composite technology came fromHigh temperature self-propagating synthesis (SHS). XD was subsequently developed by Martin Marietta laboratories in the United states, inspired by SHS technology^TM(Exothermic dispersion, XD) technique, the company Lanxide invented DIMOX^TM(direct metal oxidation, DIMOX) technology. Thereafter, research on in-situ synthesis of composite materials has been carried out in various countries. By introducing in-situ synthesis technology in each link of composite material preparation and cutting and grafting various methods in a bold way, various novel methods appear in succession.

Methods for preparing in-situ metal matrix composites can generally be classified into two broad categories, liquid and solid, depending on the state of the reactants during the formation of the reinforcement phase. The former mainly includes reaction hot pressing, reaction sintering, SHS method and XD^TMMethods, and the like. The latter mainly comprising DIMOX^TMA method, a reaction gas injection method, an alloy liquid mixed reaction method, a reaction jet deposition method, a mixed salt reaction method, and the like. Each of these methods has its advantages and disadvantages. For example, the SHS method has the following advantages: (1) the reaction is spontaneously sustained with only an ignition heat source. Therefore, the method has the advantages of low energy consumption and high production efficiency; (2) at certain high levelIn a heat system, the high temperature (3000-4000 ℃) which cannot be achieved by a conventional heating method can be achieved, which is very beneficial to synthesizing high-temperature materials. XD^TMThe method has the advantages that: (1) the reinforced phase particles are uniformly distributed in the matrix, and the interface between the particles and the matrix is clean and well combined; (2) the volume fraction of the reinforcing phase particles can be adjusted by in-situ reaction parameters; (3) the reinforcing phase particles, because they are formed by the high temperature exothermic reaction, maintain a high degree of stability both in subsequent processing and in high temperature use environments. DIMOX^TMThe method has the advantages that: (1) the cheap and wide-range aluminum is adopted, the oxidizing atmosphere is air, and the heating furnace can adopt a common electric furnace, so the cost is low. (2) Al (Al)₂O₃The green compact grows in the green compact, and the dimensional change of the green compact is below 10 percent, so that the subsequent processing is hardly needed; (3) can be made into complex and large composite material parts; (4) the technological parameters are adjusted to ensure that a certain amount of Al is remained in the product, so that the toughness of the product can be improved. However, theseThe method has the common problem that the reaction generates the required reinforcing phase and simultaneously brings unnecessary byproducts, and the byproducts are easy to segregate in the solidification process and are distributed on the grain boundaries, so that the performance of the material is deteriorated.

The in-situ reinforced particles are obtained by adopting cheap raw materials such as oxides and the like, and the preparation cost of the composite material is favorably reduced. Al production by exothermic reaction (thermite reaction) in which metal oxide is reduced by Al₂O₃The particle reinforced metal matrix composite material has attracted the attention of researchers at home and abroad. The oxides used in the in situ thermite reaction studied included: fe₂O₃、SiO₂、ZnO、TiO₂、Ni₂O₃、MnO₂、CuO、SnO₂And the like.

Chengang, Zhuzheng et Al (Chengang, Zhuzheng, Sunpong, journal of metals, 34(5) (1998)531), the solid Physics of Chinese academy of sciences, studied the reaction mechanism between CuO and Al by pressing a mixture of CuO and Al powders into a billet under the conditions of air and pure Al medium, respectively, heating at different temperatures for 10 minutes and 30 minutes, and found that the intermediate transition product Cu existed in the reaction₂O。

Shiqiao Zhen et Al (Shiqiao Zhen, light metals, 42(1992)138), university of Japan famous ancient House, utilizes a higher free energy than Al₂O₃Some oxides of (2), e.g. CuO, SnO₂，ZnO，Cr₂O₃And the like, one of the oxides (MeO) is stirred into the aluminum alloy melt to obtain Al₂O₃a/Al composite material.

P.c. maity et al (m.c. maity, p.n.chakraborty, s.c. panigrahi, j.mater.sci.letters, 16 (1997)) 1224, institute for casting and forging, india, add Fe to an aluminium melt₂O₃Particles, Al produced₂O₃The particle size is 0.5-1 μm. X-ray diffraction studies have shown that Fe is displaced to form Fe-containing intermetallic compounds.

The direct addition of powder to the metal melt, although a simple process, has the disadvantage that the amount of reinforcement is difficult to control, especially when the powder has poor wettability with the metal melt. To solve this problem, the present inventors also prepared in situ composites by pre-compacting elemental powders into a mass and then pressing into a metal melt (B.Yang, F.Wang, J.S.Zhang, Acta Materialia, 2003, 51 (17): 4977. times. 4989, Bin Yang, Guoxing Chen, Jishan Zhang, Materials&Design 22(8) (2001) 645). The technology of pressing the powder prefabricated block into the metal melt and synthesizing the required reinforcing phase in situ is called as fusion casting-in situ reaction synthesis technology.

FIG. 1 shows that the inventors obtained 5% Al using Al + CuO in situ reactants₂O₃Microstructure photographs of the/Al-10 Cu (wt.%) composite. It can be seen that in order to obtain 5 wt.% Al₂O₃The body carries about 10 wt.% Cu. Furthermore, to further improve Al₂O₃With the number of particles, more Cu will be produced. They are brittleThe network compounds are concentrated at the grain boundaries, and this structure greatly impairs the properties of the composite material. In order to reduce and eliminate the unnecessary excess element(s) and even harmful element(s), the invention changes the matrix aluminum or aluminum alloy into copper, and realizes thein-situ reaction of the prefabricated block in the copper melt to generate Al₂O₃The reinforcing phase simultaneously reinforces the matrix.

Disclosure of Invention

The invention aims to provide in-situ α -Al₂O₃The preparation method of the particle reinforced copper-based composite material can synchronously carry out the smelting of the matrix alloy and the generation of the reinforced phase, obviously shorten the preparation process flow of the composite material, reduce the manufacturing cost of the copper-based composite material, and can be widely applied to the fields of electronics, electrical engineering technology and the like which require high strength and high conductivity.

The technological process of the present invention includes two stages of preparing prefabricated block and smelting copper-base composite material.

1. Preparation of precast blocks

According to the reaction formula Proportioning raw materials. Wherein Al and CuO are powder with particle size range of 10 to100 μm, purity greater than 96.0 wt.%. Putting Al and CuO raw materials into a mixer according to a stoichiometric ratio, uniformly mixing, and then pressing and molding the uniformly mixed raw materials at the temperature of 10-30 ℃ under the pressure range of 25-40 MPa;

2. the method for melting the copper-based composite material comprises the steps of putting a proper amount of base material Cu with the purity of more than 99.0 weight percent into a medium-frequency induction furnace for heating at the temperature of 50-150 ℃ above the melting point of the copper, pressing a prefabricated block accounting for 1-10 weight percent of a melt into the melt, keeping the temperature for 1-30 minutes, pouring the prefabricated block into a metal mold or a sand mold for molding, and molding by using methods such as extrusion and the like to obtain an in-situ reaction α -Al₂O₃The particle reinforced copper-based composite material.

Compared with the currently generally adopted in-situ synthesis technology of the metal matrix composite material, the invention has the following remarkable advantages:

1. the utilization rate of the reinforced particles is high, and the particles are uniformly distributed in the alloy matrix.

2. Simple process, low cost and easy realization of industrialization. The invention can synchronously carry out the smelting of the matrix alloy, the generation of the particles and the preparation of the metal matrix composite material, thereby obviously shortening the preparation process flow of the composite material, reducing the preparation cost of the material and being easy to realize industrialization.

3. The refining and modification treatment technology in the cast alloy can be repeatedly used, and the comprehensive performance of the composite material is improved. Our existing research shows that the fusion casting-in-situ synthesis of Al₂O₃The particles in the particle reinforced metal matrix composite material are fine (the average diameter is less than 0.5 mu m), and the particles are not easy to float upwards along with bubbles in the matrix alloy and are brought to the surface of the molten liquid, so that the master alloy melt can repeatedly use the refining and modification treatment technology in the cast alloy to improve the comprehensive performance of the composite material.

Drawings

FIG. 1 shows 5 wt.% Al in the present invention₂O₃Photograph of structure scan of/Al-10 (wt%) Cu composite.

FIG. 2 shows in situ α -Al in the present invention₂O₃And (3) a tissue scanning photo of the particle reinforced copper-based composite material.

Detailed Description

Example 1

Preparation of 3 wt.% Al₂O₃A copper composite material. Weighing the purities according to the proportion of Al to CuO of 9 to 35 (weight percent)96% and 98%, and Al powder and CuO powder having a particle size of 75 μm, which were uniformly mixed. Pressing into cylindrical prefabricated block of phi 20X 30mm at 26 MPa. 2 kg of pure copper are placed in a medium frequency induction furnace for melting and heating to 1160 ℃. And pressing 0.16 kg of precast block into the copper liquid by using a graphite bell jar, and keeping the temperature for 15 minutes. Pouring into a metal mold at a melt temperature of 1150 ℃ to obtain about 3 wt% Al₂O₃A copper composite material.

Example 2

Preparation of 6 wt.% Al₂O₃A copper composite material. Al powder and CuO powder with purity of 96% and 98% and particle size of 75 μm are weighed according to the weight ratio of Al to CuO of 9: 39, and are mixed uniformly. Pressing into cylindrical prefabricated block of phi 20X 30mm at 33 MPa. 2 kg of pure copper are melted in a medium frequency induction furnace and heated to 1170 ℃. And pressing 0.32 kg of precast block into the copper liquid by using a graphite bell jar, and keeping the temperature for 20 minutes. Pouring into a metal mold at a melt temperature of 1160 ℃ to obtain about 6 weight percent Al₂O₃A coppercomposite material.

Example 3

Preparation of 9 wt.% Al₂O₃A copper composite material. Al powder and CuO powder with purity of 96% and 98% and particle size of 75 μm are weighed according to the weight ratio of Al to CuO of 9: 37, and are mixed uniformly. Pressing into cylindrical prefabricated block of phi 20X 30mm at 37 MPa. 2 kg of pure copper is placed in a medium frequency induction furnace for melting and heating to 1200 ℃. And pressing 0.48 kg of precast block into the copper liquid by using a graphite bell jar, and keeping the temperature for 25 minutes. Pouring into a sand mold when the melt temperature is 1170 ℃ to obtain about 9 weight percent Al₂O₃Copper compositeA material.

Claims

1. Fusion casting-in-situ synthesis α -Al₂O₃The preparation method of the particle reinforced copper-based composite material is characterized by comprising the following steps: the process comprises the following steps:

a. preparing a precast block: according to the reaction formula The raw materials are proportioned, wherein Al and CuO are both powdery, the granularity range is 10-100 mu m, and the purity is more than 96.0 weight percent. Putting Al and CuO raw materials into a mixer according to a stoichiometric ratio, uniformly mixing, and then pressing and molding the uniformly mixed raw materials at the temperature of 10-30 ℃ under the pressure range of 25-40 MPa;

b. the method for melting the copper-based composite material comprises the steps of putting a base material Cu with the purity of more than 99.0 weight percent into a medium-frequency induction furnace for heating at the temperature of 50-150 ℃above the melting point of the copper, pressing a prefabricated block accounting for 1-10 weight percent of a melt into the melt, keeping the temperature for 1-30 minutes, pouring the prefabricated block into a metal mold or a sand mold to obtain an in-situ reaction α -Al₂O₃The particle reinforced copper-based composite material.