CN111101009A - High-strength high-conductivity copper material and preparation method thereof - Google Patents
High-strength high-conductivity copper material and preparation method thereof Download PDFInfo
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- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
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Abstract
The invention relates to the technical field of metal materials, in particular to a high-strength high-conductivity copper material and a preparation method thereof. The preparation method of the high-strength and high-conductivity copper material comprises the following steps: step S1: grinding copper powder into nano copper powder in a ball milling tank which takes red copper as the lining of the ball milling tank and ball milling media; step S2: pressing and molding the nano copper powder to obtain a blank; step S3: and sintering the blank to obtain the copper material. According to the invention, copper powder is placed in the ball milling tank which takes red copper as the inner lining of the ball milling tank and ball milling medium for ball milling, so that the copper material without iron impurities, magnetism and high conductivity is obtained. In addition, the copper material prepared by the preparation method of the copper material has no iron impurity, so that the conductivity is improved, and the non-magnetism of the copper material is realized.
Description
Technical Field
The invention relates to the technical field of metal materials, in particular to a high-strength high-conductivity copper material and a preparation method thereof.
Background
Copper and copper alloy have the characteristics of excellent electrical conductivity, thermal conductivity, corrosion resistance and the like, and are widely applied to the fields of marine ships, electronic appliances, aerospace, machinery manufacturing, metallurgy, national defense and military industry and the like. However, pure copper is soft, and the tensile strength in an annealing state is only 220MPa, so that the requirement cannot be met. With the development of science and technology, industry and manufacturing industry, especially the rapid development of microelectronics industry, integrated circuit and communication industry, these emerging industries put higher demands on the comprehensive performance of copper and copper alloy materials: the tensile strength is more than 600MPa, the hardness is more than 180HV, and the electric conductivity is more than 80% IACS. Therefore, it is of great significance to develop copper and copper alloy materials with high strength and high conductivity.
The conventional strengthening method mainly comprises an alloying method and a second phase strengthening method. The alloying method is to add certain alloy elements into the copper alloy matrix to form solid solution, and then change the structure and structure of the copper alloy by a mechanical processing or heat treatment method, thereby obtaining the copper alloy which not only has excellent mechanical properties, but also keeps the original excellent characteristics of electric conduction, heat conduction and the like. The strengthening means mainly comprises solid solution strengthening, aging strengthening, fine grain strengthening, deformation strengthening and the like. Second phase strengthening is the introduction of second phase particles, whiskers, or fibers to strengthen the copper matrix, such as Al2O3，Y2O3And the like. In practical production, a plurality of strengthening methods are combined to improve the strength of the material as much as possible on the premise of ensuring the conductivity.
On the premise of ensuring the conductivity of the material, the mechanical property of the copper alloy material prepared by the traditional alloying method is improved to a limited extent, the strength of the alloy material added excessively is improved, the conductivity is reduced rapidly, and the copper alloy with high strength and high conductivity is difficult to prepare. In general, the smaller the second phase particles of the copper alloy prepared by the second phase composite material method, the better the strengthening effect on metal or alloy, but the complex process of adding nano-scale particles into molten metal by the traditional method, the high requirement on the control of the production process and the difficulty in realizing the uniform distribution of the nano-scale particles. And the preparation of the three-dimensional nano-structure copper and copper alloy block is very difficult. On one hand, the preparation of the nano powder is difficult, the price is high, and the nano powder is extremely easy to oxidize and is not beneficial to transportation and storage. On the other hand, the crystal grains of the nano powder can grow rapidly in the sintering process, and the size of the crystal grains is extremely difficult to control. Mechanical alloying (high-energy ball milling) is one of effective methods for preparing nano powder, but impurities such as iron and the like are introduced in the ball milling process to greatly influence the material. For copper conductive parts, especially lead frame and other materials, non-magnetism is an important characteristic, so how to prepare the iron-free copper material is a key.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a high-strength high-conductivity copper material and a preparation method thereof.
The purpose of the invention is realized by adopting the following technical scheme:
the invention provides a preparation method of a high-strength high-conductivity copper material, which comprises the following steps: step S1: grinding copper powder into nano copper powder in a ball milling tank which takes red copper as the lining of the ball milling tank and ball milling media; step S2: pressing and molding the nano copper powder to obtain a blank; step S3: and sintering the blank to obtain the copper material.
In one embodiment, in the step S3, the sintering temperature is 350-550 ℃.
In one embodiment, in the step S3, the sintering temperature is 390 to 410 ℃.
In one embodiment, in the step S3, the sintering time is 0-5 min.
In a specific embodiment, in the step S3, the sintering time is 1 min.
In one embodiment, in the step S3, the average grain size inside the copper-niobium alloy material is 20 to 100 nm.
In one embodiment, in the step S1, the ball milling time is 60 to 180 hours.
In one embodiment, in the step S1, the ball milling time is 120 h.
In one embodiment, in step S1, the particle size of the copper nanoparticles is 10 to 20 nm.
The invention also provides the high-strength high-conductivity copper material prepared by the preparation method of the high-strength high-conductivity copper material.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, copper powder is placed in the ball milling tank which takes red copper as the inner lining of the ball milling tank and ball milling medium for ball milling, so that the copper material without iron impurities, magnetism, high conductivity and high strength is obtained.
In addition, the copper material prepared by the preparation method of the copper material has no iron impurity, so that the conductivity and the strength are improved, and the non-magnetism of the copper material is realized.
Detailed Description
The present invention will be described in more detail below, and it should be noted that the description of the present invention is only illustrative and not restrictive. The various embodiments may be combined with each other to form other embodiments not shown in the following description.
The material of the inner lining of the ball milling tank body and the ball milling medium greatly affects the impurities introduced in the powder ball milling process, so that the final performance of the material is affected; meanwhile, the hardness of the material can influence the ball milling efficiency, and is high relative to the ball milling efficiency, so that in order to reduce impurities such as iron and the like introduced into ball milling powder due to continuous collision and abrasion of the inner lining of the stainless steel ball milling tank body and a ball milling medium in the ball milling process, the invention designs to use red copper as the inner lining of the ball milling tank and red copper balls as the ball milling medium. Because red copper is relatively soft, hardening treatment needs to be carried out for about 200 hours of continuous ball milling before ball milling, and the lining of the ball milling tank and a ball milling medium have enough hardness.
The invention provides a preparation method of a high-strength high-conductivity copper material, which comprises the following steps: step S1: copper powder is placed in a ball milling tank which takes red copper as an inner lining of the ball milling tank and ball milling media, ball milling is carried out, and the copper powder is ground into the nano copper powder, wherein the ball material ratio in the ball milling process is (3-20): 1, preferably (4-10): 1, a process control agent can enable the ball milling process to be more sufficient, and can avoid agglomeration and agglomeration of the copper powder in the ball milling process, the process control agent can be stearic acid, ethyl acetate, ethane, heptane, acetone, methanol, ethanol, ethylene glycol or benzene, and the like, and in a specific embodiment, which process control agent can be selected according to specific ball milling parameters, and the invention is not limited to the method. It should be noted that before the step of ball milling the copper powder, a layer of micromolecules is grafted on the surface of the copper powder, then the parameters such as the ball milling time, the using amount of a process control agent and the like are controlled in the ball milling process to realize re-agglomeration of the nanometer components, the surface area of the agglomerated nanometer powder is greatly reduced, the protection of the nanometer powder is realized, and thus the oxidation phenomenon of the nanometer powder after ball milling after being placed in the air for a long time is reduced or avoided.
Step S2: and applying pressure to the nano copper powder to press and form the nano copper powder to obtain a blank. It should be understood that, in the process of pressure forming the nano copper powder, the higher the compactness of the nano copper powder, the more beneficial the subsequent sintering process is. In the process of pressure forming of the nano copper powder, the pressure is preferably 300 MPa.
Step S3: and sintering the blank to obtain the copper material. The invention adopts a pressure-assisted low-temperature rapid activation solid-phase sintering technology. The technology is suitable for sintering the high-activity nano copper. The specific principle is that the energy of the high-activity copper powder is released in a concentrated manner at a certain temperature, so that the instantaneous sintering of the nano copper powder at a lower temperature is realized, the growth process of crystal grains is inhibited, and the compact copper block with a three-dimensional nano structure is obtained. The specific preparation process comprises the steps of wrapping the formed blank by carbon paper, putting the wrapped blank into the middle of a hot-pressing die, and preheating in a resistance furnace for 0-30 min, preferably 0-10 min, for example, 3min, wherein the preheating aims to uniformly heat the blank to the sintering temperature. And (3) immediately pressurizing to more than 100Mpa for sintering after the sample is heated to the sintering temperature, wherein the sintering time is preferably 0-1 min, and the overlong sintering time does not influence the material densification process, but can cause the material strength to be reduced. In the whole process, under the protection of inert gas or vacuum, the final mechanical property of the material is not changed greatly, and the conductivity is slightly improved. In view of the problems of simple process and easy operation, the operation under air is preferred. It will be appreciated that the greater the pressure at which the embryo body is pressurized, the better the mould can withstand, preferably 200Mpa for the present invention.
In one embodiment, in the step S3, the sintering temperature is 350-550 ℃. Preferably, in the step S3, the sintering temperature is 390 to 410 ℃, and the low-temperature sintering is adopted to inhibit the growth of the manager, so as to obtain the copper alloy compact block with the three-dimensional nano structure. In one embodiment, in the step S3, the sintering time is 0-5 min, and the shorter sintering time can ensure the strength of the material. Preferably, in the step S3, the sintering time is 1 min. Specifically, the average grain size in the formed copper material is 20-100 nm, the grain growth is controlled by sintering below the melting point of copper and shorter sintering time, and further the grain size of the copper material is controlled, namely the copper material with a three-dimensional nano structure is prepared by a mechanical alloying and low-temperature instant activation solid-phase sintering method, and the formed copper material has higher strength and higher conductivity.
In one embodiment, the ball to feed ratio is (3-20): 1, preferably (4-10): 1. In one embodiment, the ball milling efficiency is best when the ball-to-material ratio is 4:1, and when the ball-to-material ratio is greater than or less than 4:1, the ball milling efficiency is low although nano copper powder can be obtained.
The copper material has the advantages of simple preparation process, no smelting process, almost no loss of raw materials, energy conservation, environmental protection and excellent performance.
According to the embodiment, pure copper powder is weighed according to the design and then is filled into a ball milling tank for high-energy ball milling. The material of the ball milling tank body and the ball milling medium greatly affects the impurities introduced in the powder ball milling process, and the final performance of the material is affected. Meanwhile, the ball milling efficiency can be influenced by the hardness of the ball milling tank body and the ball milling medium, and the hardness is high and the ball milling efficiency is high. In order to reduce impurities such as iron and the like introduced into ball-milling powder due to continuous collision and abrasion of a stainless steel tank and balls in the ball-milling process, red copper is used as an inner lining of a ball-milling tank, and red copper balls are used as a ball-milling medium. Since red copper is relatively soft, hardening treatment is required before ball milling. Compared with stainless steel materials, the design slightly increases the ball milling time by 5-10 hours, and slightly increases the dosage of process control agents (anti-forging agents). The powder granularity has no special requirement, the larger the initial powder granularity is, the more the required ball milling time is increased, but the final size of the ball milling powder crystal grain is not influenced. During the canning process, special atmosphere protection (such as argon, nitrogen and the like) is carried out to reduce the oxygen content of the powder, but even if no special atmosphere protection is carried out, the performance of a final sintered sample is not greatly influenced, and the atmosphere protection of a product can be omitted under no special requirement.
The ratio of the weight of the copper powder in the ball milling tank to the ball is about 1: 4, the ball milling efficiency is optimal, and the ball-material ratio is more than or less than the ratio, so that nano powder can be obtained, but the relative efficiency is reduced. The ball milling process control agent can be conventional ball milling control agent, such as stearic acid, ethyl acetate, ethane, heptane, acetone, methanol, ethanol, ethylene glycol, benzene, etc., and the corresponding process control agent can be selected according to specific ball milling parameters in specific embodiments, but the invention is not limited thereto. Acetone is preferred as a process control agent in the present invention. As the level of process control agent increases, the ball milling efficiency increases and the required ball milling time decreases, but too much process control agent can reduce the efficiency and lead to an increase in the required ball milling time. An increase in the ball to feed ratio increases the ball milling efficiency and the amount of control agent required increases. In the invention, the content of the anti-forging agent is preferably one milliliter of control agent per kilogram of copper powder, and the ball milling time is preferably 120 hours.
In one embodiment, in step S1, the process control agent is contained in an amount of 0.1 to 10 ml per kg of copper powder, preferably 1 to 6 ml per kg of copper powder, and the higher the content of the process control agent, the higher the ball milling efficiency is, the less the required ball milling time is, but the too much process control agent reduces the ball milling efficiency, resulting in an increase in the required ball milling time.
In addition, the ball-to-feed ratio is increased, the ball milling efficiency is improved, and the required process control agent is increased. Acetone is preferred as the process control agent in the present invention, and the process control agent is present in an amount of one milliliter per kilogram of copper powder.
In one embodiment, in the step S1, the ball milling time is 60 to 180 hours, and preferably 120 hours. It should be noted that as the size of the primary particles of the copper powder and the change of the ball milling medium, the ball milling time changes, and if the primary particle size of the copper powder is larger, the required ball milling time is increased; the ball milling medium is replaced by red copper from stainless steel, and the ball milling time is increased.
In one embodiment, in step S1, the particle size of the copper nanoparticles is 10 to 20 nm.
The invention also provides the high-strength high-conductivity copper material prepared by the preparation method of the high-strength high-conductivity copper material. The copper material prepared by the preparation method has no iron impurity, improves the conductivity and the strength, and realizes the non-magnetism of the copper material.
Example 1
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 200ml of process control agent and 100h of ball milling time. And (3) placing the molded blank in a high-temperature furnace, preheating for 3 minutes at the sintering temperature of 410 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.4%. Tensile strength 602MPa, electrical conductivity 83.9% IACS.
Example 2
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 200ml of process control agent and 100h of ball milling time. And (3) placing the formed blank in a high-temperature furnace, preheating for 5 minutes at the sintering temperature of 410 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.5%. Tensile strength 588MPa, electrical conductivity 84.1% IACS.
Example 3
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 120h of ball milling time. And (3) placing the formed blank in a high-temperature furnace, preheating for 3 minutes at the sintering temperature of 400 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.4%. Tensile strength 623MPa, electrical conductivity 82.1% IACS.
Example 4
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 120h of ball milling time. And (3) placing the formed blank in a high-temperature furnace, preheating for 5 minutes at the sintering temperature of 400 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.3%. Tensile strength 609MPa, electrical conductivity 82.2% IACS.
Example 5
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 140h of ball milling time. And (3) placing the molded blank in a high-temperature furnace, preheating for 3 minutes at the sintering temperature of 390 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.4%. Tensile strength 654MPa, electrical conductivity 80.6% IACS.
Example 6
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 140h of ball milling time. And (3) placing the molded blank in a high-temperature furnace, preheating for 5 minutes at the sintering temperature of 390 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 1 minute. And taking out and naturally cooling. The sample was polished to a relative density of 98.5%. Tensile strength of 633MPa, electrical conductivity of 80.5% IACS.
Example 7
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 140h of ball milling time. And (3) placing the molded blank in a high-temperature furnace, preheating for 5 minutes at the sintering temperature of 390 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 2 minutes. And taking out and naturally cooling. The sample was polished to a relative density of 98.5%. Tensile strength 626MPa, electrical conductivity 80.5% IACS.
Example 8
Weighing copper powder, mixing and filling the copper powder into a ball milling tank, wherein the total weight is 300kg, and the ball material ratio is 4:1, 300ml of process control agent and 140h of ball milling time. And (3) placing the molded blank in a high-temperature furnace, preheating for 5 minutes at the sintering temperature of 390 ℃, and pressurizing. The pressure is 200MPa, and the sintering and heat preservation are carried out for 3 minutes. And taking out and naturally cooling. The sample was polished to a relative density of 98.5%. Tensile strength 609MPa, electrical conductivity 80.6% IACS.
The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.
Claims (10)
1. A preparation method of a high-strength high-conductivity copper material is characterized by comprising the following steps:
step S1: grinding copper powder into nano copper powder in a ball milling tank which takes red copper as the lining of the ball milling tank and ball milling media;
step S2: pressing and molding the nano copper powder to obtain a blank;
step S3: and sintering the blank to obtain the copper material.
2. The method for preparing the high-strength and high-conductivity copper material according to claim 1, wherein in the step S3, the sintering temperature is 350 to 550 ℃.
3. The method for preparing the high-strength and high-conductivity copper material according to claim 2, wherein in the step S3, the sintering temperature is 390 to 410 ℃.
4. The method for preparing the high-strength and high-conductivity copper material according to claim 1, wherein in the step S3, the sintering time is 0-5 min.
5. The method for preparing the high-strength and high-conductivity copper material according to claim 4, wherein in step S3, the sintering time is 1 min.
6. The method for preparing the high-strength and high-conductivity copper material according to any one of claims 1 to 5, wherein in the step S3, the average grain size in the copper-niobium alloy material is 20 to 100 nm.
7. The method for preparing the high-strength and high-conductivity copper material according to claim 1, wherein in step S1, the ball milling time is 60 to 180 hours.
8. The method for preparing the high-strength and high-conductivity copper material according to claim 7, wherein in the step S1, the ball milling time is 120 h.
9. The method for preparing the high-strength and high-conductivity copper material according to claim 1, wherein in step S1, the particle size of the copper nanoparticles is 10 to 20 nm.
10. A copper material prepared by the method for preparing a high-strength and high-conductivity copper material according to any one of claims 1 to 9.
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