CN112981213A - Silver-iron composite material and preparation method thereof - Google Patents

Silver-iron composite material and preparation method thereof Download PDF

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Publication number
CN112981213A
CN112981213A CN202110151116.5A CN202110151116A CN112981213A CN 112981213 A CN112981213 A CN 112981213A CN 202110151116 A CN202110151116 A CN 202110151116A CN 112981213 A CN112981213 A CN 112981213A
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silver
iron
composite material
block
iron composite
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刘增乾
赵宁
张健
张哲峰
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Institute of Metal Research of CAS
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Institute of Metal Research of CAS
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0242—Making ferrous alloys by powder metallurgy using the impregnating technique
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/007—Ferrous alloys, e.g. steel alloys containing silver

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention relates to a silver-iron composite material and a preparation method thereof, and relates to the technical field of metal composite materials. The main technical scheme adopted is as follows: the preparation method of the silver-iron composite material comprises the following steps: compression molding the raw material powder into a briquette; wherein the raw material powder is iron powder or silver-iron mixed powder; wherein the pressure for compression molding is 10-25MPa, and the pressure maintaining time is 10-30 minutes; putting the compact, the silver block or the silver alloy block together to obtain a mixed block; and heating the mixed block under a protective atmosphere, raising the temperature to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material. Wherein the set temperature is higher than the melting point of silver or silver alloy and lower than the melting point of iron. The invention is mainly used for preparing the silver-iron composite material by a simple and reliable process, and the prepared silver-iron composite material has uniform components, good conductivity, electromagnetic shielding property and processability.

Description

Silver-iron composite material and preparation method thereof
Technical Field
The invention relates to the technical field of metal composite materials, in particular to a silver-iron composite material and a preparation method thereof.
Background
Silver has extremely high conductivity and oxidation resistance, and has a large market in the electrical field, particularly in the field of low-voltage electrical appliances as an electrical contact material. However, due to the characteristics of low strength and low melting point, the silver has the problems of large material transfer, easy fusion welding and the like in the use process. Therefore, the silver-based composite material is usually prepared by alloying and compounding, and the silver-iron composite material attracts attention of researchers due to the characteristics of good conductivity, small contact resistance, low temperature rise, wear resistance and the like. On the other hand, with the progress of science and technology, in order to reduce the radiation interference of the environment to the equipment or the equipment to the environment, and improve the reliability and the safety of the equipment, the requirement of the industry on the electromagnetic compatibility of the product is higher and higher. And the magnetic conductivity of iron is high, and the electromagnetic shielding performance is particularly good, so that the silver-iron composite material with high iron volume fraction has wide application prospect in the field.
Currently, there are three main related technologies for silver-iron composite materials: the first related art is: the silver ferroelectric contact material is prepared by adopting powder equipment and powder mixing integrated equipment to prepare raw materials into mixed powder particles, and the mixed powder particles are processed into the silver ferroelectric contact material through the working procedures of drying, ingot pressing, extruding and the like, and has the advantages of good particle distribution uniformity, high interface bonding strength, short production period and the like. The second related art is: firstly, melting silver into silver liquid, placing an iron core rod in the center of a casting mold, pouring the silver liquid into the casting mold in a vacuum state to obtain a silver-coated iron core composite circular ring with the diameter of 80-90 mm, and performing hot extrusion and cold drawing treatment to obtain the silver-coated iron core composite electrode wire. The technology overcomes the defects of long mixed powder preparation period, high cost, poor particle uniformity, limited performance improvement and the like existing in the traditional silver iron powder metallurgy preparation of the electric contact material. The third related art is: firstly, roasting mixed powder of high-purity ammonium rhenate and carbonyl iron powder to obtain iron-rhenium alloy powder through reduction; and then carrying out the processes of powder mixing, static pressure, sintering, extrusion, rolling, annealing, finish rolling and the like on the silver powder and the iron-rhenium alloy powder to finally obtain the silver-iron-rhenium electric contact material. The technology overcomes the problem that rhenium does not form alloy with iron and silver, and the processability and the electric contact performance of the obtained material are improved.
In the aspect of improving the performance of the silver-iron composite material, the first technology and the third technology both adopt a powder mixing process, but the first technology is to refine raw materials through improved traditional equipment so as to achieve a strengthening effect. The third technology is to preliminarily obtain alloyed metal powder by a chemical reduction method, then mix the powder and continue to prepare the material in the subsequent steps, and the main idea of material reinforcement is rare element alloying. The second technique is characterized by simple process and short preparation period, but the silver content is high (40% -90%).
However, the inventors of the present invention have found that the above-described related art has at least the following technical problems: the preparation processes of the three related technologies are complex and have high production cost; in particular, the third related art, which involves the step of reduction by baking, while effectively solving the problem that rhenium does not form an alloy with iron or silver, also uses equipment that increases the manufacturing cost (furthermore, rhenium is one of the rare metal elements in the earth's crust, and the addition of rhenium also increases the material cost). In addition, the above three related techniques have limited uniformity of components in the prepared composite material (the first related technique, the third related technique are based on a powder mixing process, and have limited uniformity; the second related technique is a silver-coated iron material).
Disclosure of Invention
In view of the above, the present invention provides a silver-iron composite material and a preparation method thereof, and mainly aims to prepare a silver-iron composite material with excellent performance by a simple process.
In order to achieve the purpose, the invention mainly provides the following technical scheme:
in one aspect, an embodiment of the present invention provides a method for preparing a silver-iron composite material, where the method for preparing the silver-iron composite material includes the following steps:
a compression molding step: compression molding the raw material powder into a briquette; wherein the raw material powder is iron powder or silver-iron mixed powder; wherein the pressure for compression molding is 10-25MPa, and the pressure maintaining time is 10-30 minutes;
and (3) high-temperature infiltration: putting the compact, silver block or silver alloy block together to obtain a mixed block; and heating the mixed block under a protective atmosphere, heating to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material. Wherein the set temperature is higher than the melting point of silver or silver alloy and lower than the melting point of iron.
Preferably, in the compression molding step: the particle size of the raw material powder is 3-200 μm.
Preferably, the step of compression molding includes: and (3) mounting the die on a hydraulic press, putting the raw material powder into the die, starting the hydraulic press, stopping pressurizing when the hydraulic pressure reaches 10-25MPa, maintaining the pressure for 10-30 minutes, resetting the hydraulic press, and taking out the billet from the die.
Preferably, in the high-temperature infiltration step:
placing the silver block or silver alloy block on the compact to obtain a mixed block; or
And placing the compact on the silver block or the silver alloy block to obtain a mixed block.
Preferably, the high-temperature infiltration step includes: placing the compact, silver block, or silver alloy block in a crucible; placing the crucible in a furnace chamber of a heating device; and after the furnace chamber is vacuumized and filled with protective gas, heating the crucible, heating the temperature of the mixed block to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material.
Preferably, the set temperature is 900-1300 ℃ and the set time is at least 10 minutes.
Preferably, in the high-temperature infiltration step, when the mixed block is heated, the temperature rise rate of the mixed block is 5-15 ℃/min.
Preferably, if the mixed block comprises a silver alloy block; wherein the difference between the melting point of the iron and the melting point of the silver alloy block is 450-600 ℃; preferably, the silver alloy block is a silver-copper alloy block; more preferably, the silver alloy block is AgCu 5.
In another aspect, embodiments of the present invention provide a silver-iron composite material, where the silver-iron composite material includes an iron phase and a silver phase; wherein, microscopically, the silver-iron composite material has a three-dimensional interpenetrating bicontinuous phase structure; preferably, the volume fraction of iron in the silver-iron composite is greater than 40%, preferably between 40 and 88%. Preferably, the silver-iron composite material is prepared by the preparation method of any one of the silver-iron composite materials.
Compared with the prior art, the silver-iron composite material and the preparation method thereof have the following beneficial effects:
on the one hand, the preparation method of the silver-iron composite material provided by the invention only needs to take the iron powder or the silver-iron mixed powder as the raw material powder to be molded into a compact, and then the compact, the silver block or the silver alloy block is subjected to high-temperature infiltration treatment, so that the silver-iron composite material can be obtained. Therefore, the silver-iron composite material provided by the invention is simple in preparation process and lower in cost. In the method of the present invention, the pressure for compression molding is controlled to be 10-25MPa, and the pressure holding time is controlled to be 10-30 minutes, under which conditions, not only the raw material powder can be molded into a billet, but also the silver or silver alloy billet in the later high-temperature infiltration step can be ensured to be uniformly infiltrated into the billet to form a three-dimensional interpenetrating continuous phase structure with iron, so that the silver-iron composite material has excellent properties (uniform component distribution, excellent conductivity, excellent processability, excellent electromagnetic shielding performance, etc.).
On the other hand, the invention provides a silver-iron composite material, which is prepared by the preparation method of the silver-iron composite material, the prepared silver-iron composite material has high iron content (the volume fraction of iron is more than 40%, preferably 70-85%), microscopically has a three-dimensional interpenetrating bicontinuous phase structure, and silver and iron phases are interpenetrated and are respectively kept continuous; the material has certain electromagnetic shielding performance, excellent conductivity, homogeneous component distribution and excellent machining performance.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
Fig. 1 is a schematic diagram of a method for preparing a silver-iron composite material according to an embodiment of the present invention;
FIG. 2A is a schematic view showing the installation of a mold for press molding according to an embodiment of the present invention;
FIG. 2B is a view showing a mold for press molding according to an embodiment of the present invention;
FIG. 3 is a macro-morphology of a compact obtained by compression molding of iron powder in example 1 of the present invention;
FIG. 4 is a macro-topography of the Ag-Fe composite prepared in example 1 of the present invention;
FIG. 5 is a microstructure diagram of a silver-iron composite material prepared in example 1 of the present invention (in which a light color is a silver phase and a dark color is an iron phase);
FIG. 6 is a macro-morphology of a compact obtained by compression molding of iron powder in example 2 of the present invention;
FIG. 7 is a macro topography of the Ag-Fe composite prepared in example 2 of the present invention;
fig. 8 is a microstructure diagram of a silver-iron composite material prepared in example 2 of the present invention (in which a light color is a silver phase and a dark color is an iron phase).
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the predetermined object, the following detailed description of the embodiments, structures, features and effects according to the present invention will be made with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "an embodiment" refers to not necessarily the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
In one aspect, embodiments of the present invention provide a silver-iron composite material, where iron is used as a framework, silver is infiltrated into the framework, and the silver and iron phases are interpenetrating and are each continuously connected. Wherein the volume fraction of iron in the silver-iron composite material is higher than 40%. As used herein, "continuous" means that the same composition is continuous and not completely separated by other compositions. This feature is evident from the method of making the silver-iron composite material of the present invention (and also from fig. 1, 5 and 8). Secondly, since the composition of the silver-iron composite material is two (silver and iron or silver alloy and iron), the silver-iron composite material is characterized by bicontinuous phases. Further, the term "three-dimensional interpenetrating" refers to "interpenetrating in three dimensions".
Here, it should be noted that: in the silver-iron composite material provided by the embodiment of the invention, both silver and iron have excellent conductivity, in the high-temperature infiltration and temperature rise process, the contact part of iron powder and iron powder is sintered (powder particles are contacted with each other and extruded with each other in the mould pressing process of the iron powder, and when the temperature rises, the contact part provides energy due to the temperature, so that the interatomic diffusion is more obvious, the powder particles are bonded together at high temperature, so that the sintering is generated), a three-dimensional interpenetrating framework is formed, and the gaps of the framework are filled after the silver is melted, so that the material components are uniformly distributed and the conductivity is good. Meanwhile, silver and iron phases in the silver-iron composite material are interpenetrated and inserted and are respectively kept continuous, and the silver has excellent plasticity and has the function of coordinated deformation in the deformation process of the composite material, so that the material has good processing performance. In addition, the volume fraction of iron in the silver-iron composite material is high, and the silver-iron composite material has outstanding electromagnetic shielding performance because the iron has excellent electromagnetic shielding performance.
On the other hand, the present invention mainly provides a method for preparing the silver-iron composite material (a specific schematic diagram illustrating the principle of the method using Fe powder as raw material powder is shown in fig. 1), wherein the silver-iron composite material prepared by the method is mainly used as an electrical contact material or an electromagnetic shielding conductive material.
Here, it should be noted that: the preparation method of the silver-iron composite material provided by the invention adopts the following raw materials: the first is iron powder or silver-iron mixed powder with the particle size range of 3-200 mu m; the second is a silver or silver alloy block (the term "silver block" in the present invention is a pure silver block). The corresponding preparation steps mainly comprise two steps of compression molding and high-temperature infiltration. The preparation method comprises the following steps:
a compression molding step: and (3) compression molding the raw material powder into a compact. Wherein the raw material powder is iron powder or silver-iron mixed powder with the granularity range of 3-200 mu m.
Specifically, the pressure for compression molding is 10-25MPa, and the pressure maintaining time is 10-30 minutes. Particular emphasis is given here to: the press molding pressure of the present application must be controlled to 10 to 25MPa, otherwise, there occurs a problem that it is difficult to form a lump (the pressure is too small), a problem that it is not easy to permeate silver or silver alloy liquid at a later stage (the pressure is too large), and even if it is possible to permeate, there is a problem in uniformity.
Preferably, the mold used in the molding step includes, but is not limited to, the mold shown in fig. 2A and 2B. Here, taking the mold shown in fig. 2A and 2B as an example, the molding process includes: firstly, selecting proper hydraulic equipment and installing a mould on a hydraulic machine, then pouring a certain amount of iron powder or silver-iron mixed powder into the mould at room temperature, starting the hydraulic machine, stopping pressurizing when the hydraulic pressure reaches a certain value, and maintaining the pressure for a period of time until the iron powder or silver-iron mixed powder is pressed into a compact. The hydraulic press is then reset, the mold is removed and the base 2 is removed. And finally, inverting the die, putting the die under a hydraulic press again, and slowly ejecting the billet clamped in the die cavity by using the male die 3.
Further, referring to fig. 2A and 2B, the compression molding step specifically includes: the compression molding begins, firstly, absorbent cotton is dipped in a small amount of alcohol to wipe the mold, particularly the inner wall of the female mold 1, the male mold 3 and the surface of the base 2, and then the female mold 1 is fixed on the base 2. Then powder is added into the female die 1, and the male die 3 is utilized for primary flattening. And then, adjusting the stroke of the hydraulic press to a complete die opening state, and placing the whole die and the iron powder at the center of the hydraulic press. And finally, manually pressurizing at 10-25MPa, after maintaining the pressure for 10-30 minutes, unloading the load, adjusting the upper die base to enable the hydraulic machine to be completely opened, and taking out the die and the billet. The billet is blocked in the female die 1 and is not easy to take out, the die is disassembled at the moment, the base 2 is taken out, the rest part of the die is placed under the hydraulic press upside down, and the billet is completely ejected out by the male die 3.
And (3) high-temperature infiltration: and putting the compact, the silver block or the silver alloy block together to obtain a mixed block, heating the mixed block under a protective atmosphere, raising the temperature to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material. Wherein the set temperature is higher than the melting point of silver and lower than the melting point of iron.
In the mixing block: the silver or silver alloy mass may be placed above or below the compact, preferably above the compact, so that the silver or silver alloy better penetrates into the compact under the influence of gravity.
Preferably, the set temperature is 900-1300 ℃, preferably 1150 ℃, and the set time is at least 10 minutes.
Preferably, the high-temperature infiltration step specifically comprises: firstly, according to the volume and the density of a compact after compression molding and the size of a crucible, selecting a silver block or a silver alloy block with a proper size, mechanically grinding and polishing, and removing a surface oxide layer. The compact and the silver or silver alloy block are then placed in a crucible (preferably the compact is down and the silver or silver alloy block is up) and the crucible is then placed in the furnace chamber of the heating apparatus. Vacuumizing the furnace, filling protective gas, heating the crucible, raising the temperature to be higher than the melting point of silver or silver alloy at a certain speed, preserving the temperature for a period of time, and obtaining the silver-iron composite material after in-situ sintering of iron powder, infiltration of silver blocks or silver alloy and furnace cooling.
Here, it should be noted that: the amount of silver ingot required is roughly estimated, preferably more and less, based on the volume of the crucible and the compact density, wherein the gap between the ingot and the crucible is visually observed (in the present invention, a cylindrical ingot is molded, the diameter of which is approximately equal to the diameter of the crucible (the inner diameter of the crucible is 25mm, and the diameter of the ingot is 25mm), and the volume V1 of the silver ingot for filling the gap between the ingots is neglected, and the density rho iron of the iron is 7.87g/cm according to the density formula (rho m/V, wherein rho, m and V represent the density, mass and volume of the material, respectively3And,) estimating:
taking a billet as an iron block as an example, if x g of iron powder is weighed, the volume of the fully dense iron block is equal to x/rho iron, and the actual volume of the iron block measured and calculated according to a volume formula after die pressing is vacal, then V1 is ═ vacal- (x/rho iron).
In addition, if the raw material powder is silver-iron mixed powder, the volume fraction of the silver powder in the silver-iron mixed powder is 0-40%, preferably 0-15%; the volume of the silver or silver alloy block is obtained by subtracting the volume of the actually prepared compact from the volume of the compact when the compact is completely densified according to the component ratio of the silver-iron mixed powder. In the impregnation, the silver or silver alloy is preferably weighed more or less.
The invention is further illustrated by the following specific experimental examples:
examples 1 to 4 were all compression-molded using the same hot press apparatus with a mold having an inner diameter of 25mm as shown in FIGS. 2A and 2B, and were subjected to high-temperature infiltration using the same heating furnace apparatus with a graphite crucible having an inner diameter of 25 mm.
Example 1
This example prepares a silver-iron composite material, wherein the raw materials used include iron powder with an average particle size of 3-5 μm, and silver lumps. The mold for preparing the silver-iron composite material in this embodiment is shown in fig. 2A and 2B, and the specific preparation steps are as follows:
a compression molding step: the compression molding begins, firstly, absorbent cotton is dipped in a small amount of alcohol to wipe the mold, particularly the inner wall of the female mold 1, the surface of the male mold 2 and the surface of the base 3, and then the female mold 1 is fixed on the base 2. Then 15g of iron powder with the average grain size of 3-5 mu m is added into the concave die 1, and the convex die 3 is utilized to carry out primary flattening. And then, adjusting the stroke of the hydraulic press to a complete die opening state, and placing the whole die and the iron powder at the center of the hydraulic press. And finally, manually pressurizing to 15MPa, after maintaining the pressure for 15 minutes, unloading the load, adjusting the upper die base to enable the hydraulic machine to be completely opened, and taking out the die and the billet. The billet is clamped in the female die 1 and is not easy to take out, the die is disassembled at the moment, the base 2 is taken out, the rest part of the die is placed under a hydraulic press upside down, the billet is completely ejected out by the male die 3, and the step is completed. Wherein the macroscopic morphology of the compact is shown in fig. 3.
And (3) high-temperature infiltration: weighing 20g of silver blocks, mechanically polishing to remove a surface oxide layer, sequentially cleaning in acetone and alcohol, and blowing to dry by using a blower. Meanwhile, the crucible is ultrasonically cleaned in an absolute ethyl alcohol solution for 5 minutes and then dried. Then, the ingot and the silver block are placed in a crucible (the ingot is below and the silver block is above), and the crucible is placed in a furnace chamber of a heating device. After the pressure in the furnace is stabilized, the temperature is raised to 1150 ℃ at the speed of 10 ℃/min, the temperature is kept for 20 minutes, and finally the furnace is cooled to the room temperature.
And (5) closing the instrument after the preparation process is finished, and taking out the sample to obtain the silver-iron composite material. The macro-morphology of the silver-iron composite material is shown in fig. 4. FIG. 5 is a microstructure diagram of a silver-iron composite material (wherein the light color is silver and the dark color is iron), and the volume fraction of iron in the silver-iron composite material is 81.7%, the average hardness value of the composite material is 78HV, and the electric conductivity is 19.64 multiplied by 106S·m-1。
Example 2
This example prepared a silver iron composite material in which the raw materials used included iron powder having an average particle size of 200 μm and a silver alloy block (AgCu 5). The mold for preparing the silver-iron composite material in this embodiment is shown in fig. 2A and 2B, and the specific preparation steps are as follows:
a compression molding step: the compression molding begins, firstly, absorbent cotton is dipped in a small amount of alcohol to wipe the mold, particularly the inner wall of the female mold 1, the male mold 3 and the surface of the base 2, and then the female mold 1 is fixed on the base 2. Then 15g of iron powder with an average particle size of 200 μm are added to the female die 1 and are initially pressed flat by means of the male die 3. And then, adjusting the stroke of the hydraulic press to a complete die opening state, and placing the whole die and the iron powder at the center of the hydraulic press. And finally, manually pressurizing to 20MPa, after maintaining the pressure for 15 minutes, unloading the load, adjusting the upper die base to enable the hydraulic machine to be completely opened, and taking out the die and the billet. The billet is clamped in the female die 1 and is not easy to take out, the die is disassembled at the moment, the base 2 is taken out, the rest part of the die is placed under a hydraulic press upside down, the billet is completely ejected out by the male die 3, and the step is completed. Wherein the macroscopic morphology of the compact is shown in fig. 6.
And (3) high-temperature infiltration: weighing 15g of silver alloy block, mechanically polishing to remove a surface oxide layer, then sequentially cleaning in acetone and alcohol, and blowing to dry by using a blower. Meanwhile, the crucible is ultrasonically cleaned in an absolute ethyl alcohol solution for 5 minutes and then dried. Then, the ingot and the silver alloy ingot are placed in a crucible (the ingot is below and the silver alloy ingot is above), and the crucible is placed in a furnace chamber of a heating device. After the pressure in the furnace is stabilized, the temperature is raised to 1150 ℃ at the speed of 10 ℃/min, the temperature is kept for 20 minutes, and finally the furnace is cooled to the room temperature.
And (5) closing the instrument after the preparation process is finished, and taking out the sample to obtain the silver-iron composite material. The macro-morphology of the silver-iron composite is shown in fig. 7. Fig. 8 is a microstructure diagram of a silver-iron composite material (in which the light color is silver and the dark color is iron), and the volume fraction of iron in the silver-iron composite material is determined to be 85% by experiment. The composite material has an average hardness value of 83HV and an electrical conductivity of 17.44 x 106S·m-1。
Example 3
This example prepares a silver-iron composite material in which the raw materials used include a silver-iron mixture powder (in which the volume ratio of silver powder to iron powder is about 1: 3) having an average particle size of 3 to 5 μm and silver lumps. The mold for preparing the silver-iron composite material in this embodiment is shown in fig. 2A and 2B, and the specific preparation steps are as follows:
a compression molding step: the compression molding begins, firstly, absorbent cotton is dipped in a small amount of alcohol to wipe the mold, particularly the inner wall of the female mold 1, the male mold 3 and the surface of the base 2, and then the female mold 1 is fixed on the base 2. Then 15g of silver-iron mixed powder with the average grain size of 3-5 mu m is added into the female die 1, and the male die 3 is utilized to carry out primary flattening. And then, adjusting the stroke of the hydraulic press to a complete die opening state, and placing the whole die and the iron powder at the center of the hydraulic press. And finally, manually pressurizing to 15MPa, after maintaining the pressure for 15 minutes, unloading the load, adjusting the upper die base to enable the hydraulic machine to be completely opened, and taking out the die and the billet. The billet is clamped in the female die 1 and is not easy to take out, the die is disassembled at the moment, the base 2 is taken out, the rest part of the die is placed under a hydraulic press upside down, the billet is completely ejected out by the male die 3, and the step is completed.
And (3) high-temperature infiltration: weighing 5g of silver blocks, mechanically polishing to remove a surface oxide layer, sequentially cleaning in acetone and alcohol, and blowing to dry by using a blower. Meanwhile, the crucible is ultrasonically cleaned in an absolute ethyl alcohol solution for 5 minutes and then dried. Then, the ingot and the silver block are placed in a crucible (the ingot is below and the silver block is above), and the crucible is placed in a furnace chamber of a heating device. After the pressure in the furnace is stabilized, the temperature is raised to 1150 ℃ at the speed of 10 ℃/min, the temperature is kept for 20 minutes, and finally the furnace is cooled to the room temperature.
And (5) closing the instrument after the preparation process is finished, and taking out the sample to obtain the silver-iron composite material. The volume fraction of iron is 76.7%, the average hardness value of the composite material is 68HV, and the conductivity is 22 multiplied by 106S·m-1。
Example 4
This example prepares a silver-iron composite material, wherein the raw materials used include a silver-iron mixed powder (in which the volume ratio of silver powder to iron powder is 15: 10) with an average particle size of 50 μm and silver lumps. The mold for preparing the silver-iron composite material in this embodiment is shown in fig. 2A and 2B, and the specific preparation steps are as follows:
a compression molding step: the compression molding begins, firstly, absorbent cotton is dipped in a small amount of alcohol to wipe the mold, particularly the inner wall of the female mold 1, the surface of the male mold 2 and the surface of the base 3, and then the female mold 1 is fixed on the base 2. Then 15g of silver-iron mixed powder with the average grain size of 50 mu m is added into the female die 1, and the male die 3 is utilized for primary flattening. And then, adjusting the stroke of the hydraulic press to a complete die opening state, and placing the whole die and the iron powder at the center of the hydraulic press. And finally, manually pressurizing to 10MPa, after maintaining the pressure for 15 minutes, unloading the load, adjusting the upper die base to enable the hydraulic machine to be completely opened, and taking out the die and the billet. The billet is clamped in the female die 1 and is not easy to take out, the die is disassembled at the moment, the base 2 is taken out, the rest part of the die is placed under a hydraulic press upside down, the billet is completely ejected out by the male die 3, and the step is completed.
And (3) high-temperature infiltration: weighing 5g of silver blocks, mechanically polishing to remove a surface oxide layer, sequentially cleaning in acetone and alcohol, and blowing to dry by using a blower. Meanwhile, the crucible is ultrasonically cleaned in an absolute ethyl alcohol solution for 5 minutes and then dried. Then, the ingot and the silver block are placed in a crucible (the ingot is below and the silver block is above), and the crucible is placed in a furnace chamber of a heating device. After the pressure in the furnace is stabilized, the temperature is raised to 1150 ℃ at the speed of 10 ℃/min, the temperature is kept for 20 minutes, and finally the furnace is cooled to the room temperature.
And (5) closing the instrument after the preparation process is finished, and taking out the sample to obtain the silver-iron composite material. The volume fraction of iron in the silver-iron composite material is 43.5%, the average hardness value of the composite material is 60HV, and the electric conductivity is 39.5 multiplied by 106S·m-1。
As is evident from the above examples: the silver-iron composite material prepared by the embodiment of the invention has excellent conductivity and good processability (lower hardness and good processability). Here, the electric conductivity of iron is good, and the electric conductivity of silver is higher than that of iron, so that the electric conductivity of the silver-iron composite material is decreased as the volume fraction of iron in the silver-iron composite material is increased.
In addition, the electromagnetic shielding performance is determined by the conductivity, the magnetic permeability, the thickness and the like of the material, and the material has excellent electromagnetic shielding performance and high conductivity and magnetic permeability. While it is acknowledged that iron has a good shielding effect against low-impedance magnetic fields, silver has the highest conductivity. Therefore, the silver-iron composite material prepared by the embodiment of the invention has excellent electromagnetic shielding performance.
In conclusion, the silver-iron composite material prepared by the embodiment of the invention has certain electromagnetic shielding performance, excellent conductivity, uniform component distribution and good processing performance.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.

Claims (10)

1. The preparation method of the silver-iron composite material is characterized by comprising the following steps of:
a compression molding step: compression molding the raw material powder into a briquette; wherein the raw material powder is iron powder or silver-iron mixed powder; wherein the pressure for compression molding is 10-25MPa, and the pressure maintaining time is 10-30 minutes;
and (3) high-temperature infiltration: putting the compact, silver block or silver alloy block together to obtain a mixed block; and heating the mixed block under a protective atmosphere, heating to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material. Wherein the set temperature is higher than the melting point of silver or silver alloy and lower than the melting point of iron.
2. The method for preparing a silver-iron composite material according to claim 1, wherein in the compression molding step: the particle size of the raw material powder is 3-200 μm.
3. The method for preparing the silver-iron composite material according to claim 1, wherein the step of compression molding comprises:
and (3) mounting the die on a hydraulic press, putting the raw material powder into the die, starting the hydraulic press, stopping pressurizing when the hydraulic pressure reaches 10-25MPa, maintaining the pressure for 10-30 minutes, resetting the hydraulic press, and taking out the billet from the die.
4. The method for preparing a silver-iron composite material according to claim 1, wherein in the high-temperature infiltration step:
placing the silver block or silver alloy block on the compact to obtain a mixed block; or
And placing the compact on the silver block or the silver alloy block to obtain a mixed block.
5. The method for preparing silver-iron composite material according to claim 1 or 4, wherein the high-temperature infiltration step comprises:
placing the compact, silver block, or silver alloy block in a crucible; placing the crucible in a furnace chamber of a heating device; and after the furnace chamber is vacuumized and filled with protective gas, heating the crucible, heating the temperature of the mixed block to a set temperature, preserving the heat at the set temperature for a set time, and cooling to obtain the silver-iron composite material.
6. The method as claimed in claim 5, wherein the set temperature is 900-1300 ℃ and the set time is at least 10 minutes.
7. The method of preparing a silver-iron composite material according to claim 5, wherein the temperature increase rate of the mixed block is 5-15 ℃/min when the mixed block is heated in the high-temperature infiltration step.
8. The method for preparing a silver-iron composite material according to any one of claims 1 to 7, wherein if the mixed mass comprises a silver alloy mass; wherein the difference between the melting point of the iron and the melting point of the silver alloy block is 450-600 ℃; preferably, the silver alloy block is a silver-copper alloy block; more preferably, the silver alloy block is AgCu 5.
9. A silver iron composite, characterized in that the silver iron composite comprises an iron phase and a silver phase; wherein, microscopically, the silver-iron composite material has a three-dimensional interpenetrating bicontinuous phase structure;
preferably, the volume fraction of iron in the silver-iron composite is greater than 40%, preferably between 40 and 88%.
10. The silver-iron composite material according to claim 9, wherein the silver-iron composite material is produced by the method for producing a silver-iron composite material according to any one of claims 1 to 8.
CN202110151116.5A 2021-02-03 2021-02-03 Silver-iron composite material and preparation method thereof Pending CN112981213A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB713982A (en) * 1952-03-07 1954-08-18 Metro Cutanit Ltd Improvements relating to the manufacture of commutator segments
CN1161380A (en) * 1996-02-27 1997-10-08 德古萨股份公司 Sticked Ag-Fe electric contact material, and method for preparing same
CN101834070A (en) * 2009-03-13 2010-09-15 上海电科电工材料有限公司 AgWC (wolfram carbide) electrical contact material and manufacturing method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB713982A (en) * 1952-03-07 1954-08-18 Metro Cutanit Ltd Improvements relating to the manufacture of commutator segments
CN1161380A (en) * 1996-02-27 1997-10-08 德古萨股份公司 Sticked Ag-Fe electric contact material, and method for preparing same
CN101834070A (en) * 2009-03-13 2010-09-15 上海电科电工材料有限公司 AgWC (wolfram carbide) electrical contact material and manufacturing method thereof

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Application publication date: 20210618