CN119566315A

CN119566315A - Micron-sized Cu powder and preparation method thereof

Info

Publication number: CN119566315A
Application number: CN202510134984.0A
Authority: CN
Inventors: 谢上川
Original assignee: Hangzhou Xinchuan Electronic Materials Co ltd
Current assignee: Hangzhou Xinchuan Electronic Materials Co ltd
Priority date: 2025-02-07
Filing date: 2025-02-07
Publication date: 2025-03-07

Abstract

The present application discloses a micron-sized Cu powder and a preparation method thereof, the method comprising placing a raw material in a heating chamber, vacuumizing the heating chamber to make the vacuum degree reach 80-150KPa, and introducing an inert gas; heating the raw material, the temperature of the heating treatment is 1300-1700 degrees Celsius, and the holding time is 10-20min; cooling the Cu vapor, the cooling treatment comprising mixing the Cu vapor and the inert gas, and supplying them to a closed space with a condenser, the flow rate of the Cu vapor and the inert gas supplied to the inside of the closed space is not less than 500ml/s, and the temperature difference of the cooling medium in the condenser before and after the cooling treatment is not more than 30°C. The method can obtain a micron-sized Cu powder with a relatively uniform size distribution and good roundness through simple operation.

Description

Micron-sized Cu powder and preparation method thereof

Technical Field

The application relates to the field of materials, in particular to micron-sized Cu powder and a preparation method thereof.

Background

Micron-sized copper powder is widely applied to various conductive adhesives, conductive coatings, conductive electrode materials and solar slurries due to its excellent electrical properties and relatively low cost (compared with silver powder, palladium powder and the like), such as relatively high conductivity. With the development of the electronic industry and the solar industry, the ultra-thin film paste prepared from the micron-sized copper powder plays an important role in application scenes such as large-scale integrated circuits, solar silicon wafers and the like.

The condensation evaporation method is often used to prepare high quality Cu powder because it is advantageous to obtain powder with a clean interface. However, the existing condensation evaporation method generally has the defects of higher equipment cost, slower production speed and complicated operation to control the uniformity of the produced powder. Moreover, since the current preparation process is relatively complex to operate, the uniformity and roundness of the prepared powder are difficult to maintain relatively good consistency in different production batches, and thus, the current micron-sized Cu powder and the preparation method thereof still need to be improved.

Disclosure of Invention

In view of the above, the present application provides a micron-sized Cu powder and a method for preparing the same.

In one aspect of the application, a method of preparing a micron-sized Cu powder is presented. The method comprises heating treatment and cooling treatment, wherein inert gas is introduced and the vacuum degree is increased before heating treatment and heating, so that the temperature of the molten Cu raw material can be reduced, the impurity content is reduced, cu vapor and the inert gas are mixed, and the dispersion of crystal nucleus is assisted and the flow rate of the raw material entering a cooling space is increased. Meanwhile, the condenser colleagues arranged in parallel are adopted to control the flow of the condensing medium, so that the materials can form particles more uniformly and rapidly in the condensing unit. Under the combined action of the conditions, the micron-sized Cu powder with uniform size distribution and good roundness can be obtained through simple operation.

In one aspect of the application, a method of preparing a micron-sized Cu powder is presented. The method comprises the steps of placing raw materials in a heating chamber, vacuumizing the heating chamber to enable the vacuum degree to reach 80-150KPa, introducing inert gas to perform atmosphere replacement, heating the raw materials, wherein the heating temperature is 1300-1700 ℃ and the heat preservation time is 10-20min to form Cu vapor, cooling the Cu vapor, mixing the Cu vapor and the inert gas, then, feeding the mixture into a closed space with a condenser, wherein the flow rate of the Cu vapor and the inert gas fed into the closed space is not lower than 500ml/s, and the temperature difference of a cooling medium in the condenser before and after the cooling process is not more than 30 ℃. Thus, the nano Cu powder with lower impurity content and better roundness can be simply formed.

According to an embodiment of the present application, the heating process further comprises heating at a heating rate of 20-50 ℃ per minute, the heating process having a temperature of 1500-1680 ℃.

According to an embodiment of the application, the vacuum degree is 100-150KPa.

According to an embodiment of the present application, the flow rate of the Cu-containing mixture is 500-800ml/s, the inert gas is He gas, and the mixing of the inert gas and Cu vapor is performed at the entrance of the closed space.

According to the embodiment of the application, the closed space comprises a plurality of condensers, the condensers are plate-type condensers, the condensers are distributed at intervals, and the cooling medium inlets of the condensers are arranged in parallel.

According to the embodiment of the application, the plate-type condenser is internally provided with the turbulence columns which are regularly arranged, the plate-type condenser is provided with the cooling medium inlet and the cooling medium outlet, the cooling medium inlet and the cooling medium outlet are respectively provided with a temperature sensor, and the method further comprises the step of adjusting the flow rate of condensate based on the temperature measured by the temperature sensors so that the temperature difference between the cooling medium outlet and the cooling medium inlet is not higher than 30 ℃.

According to an embodiment of the application, the micron-sized Cu powder has a Dv50 of 1-2 μm and a sphericity of >90%.

In another aspect of the application, the application provides a micron-sized Cu powder. The micron-sized Cu powder contains 0.005-0.05wt% of carbon, the oxygen content is 0.08-2.0wt%, the Dv50 is 1-2 mu m, and the sphericity is more than 90%. The micron-sized Cu powder has low impurity content and good roundness, and can meet the requirements of various conductive slurries.

According to the embodiment of the application, the micron-sized Cu powder has the iron content of <0.01wt%, the aluminum content of <0.01wt%, the silicon content of <0.01wt%, the calcium content of <0.01wt%, the magnesium content of <0.01wt% and the zirconium content of <0.01wt%.

According to an embodiment of the present application, the micro-sized Cu powder is obtained using the method described previously.

Drawings

In order to more clearly illustrate the technical solution of the present application, the following description will briefly explain the drawings used in the present application. It is apparent that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained from the drawings without inventive work for those skilled in the art.

FIG. 1 is a flow chart of a method of making some embodiments of the present application;

FIG. 2 is a scanning electron microscope image of Cu powder prepared in example 1 of the present application;

FIG. 3 is a thermogravimetric analysis curve of Cu powder prepared in example 1 of the present application.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the application, and the terms "comprising" and "having" and any variations thereof in the description of the application and in the claims are intended to cover non-exclusive inclusions.

In the description of embodiments of the present application, the technical terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiment of the present application, the term "and/or" is merely an association relationship describing the association object, and indicates that three relationships may exist, for example, a and/or B, and may indicate that a exists alone, while a and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two), and "plural sheets" means two or more (including two).

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "upper", "lower", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the apparatus or element in question must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

In a first aspect of the present application, the present application provides a method for preparing micron-sized Cu powder, by introducing inert gas, reducing the temperature of molten Cu raw material, reducing impurity content, and increasing vacuum degree, increasing particle size of the obtained Cu powder. In the cooling treatment step, the flow rate of the Cu raw material is increased, and a plurality of condensers connected in parallel are utilized for cooling, so that the yield is improved, and the material can be more uniformly formed into micron particles. Under the combined action of the conditions, the micron-sized Cu powder with uniform size distribution and good roundness can be obtained through simple operation.

In one aspect of the application, a method of preparing a micron-sized Cu powder is presented. Referring to FIG. 1, the method comprises the steps of controlling the vacuum degree in a heating unit to be 80-150KPa, introducing inert gas, heating a Cu-containing raw material, wherein the temperature of the heating treatment is 1200-1500 ℃ to form a Cu-containing mixture, supplying the Cu-containing mixture to a condensing unit for cooling treatment to obtain the micron-sized Cu powder, wherein a plurality of condensers are arranged in the condensing unit at intervals, flowable cooling medium is arranged in the condensers, the cooling treatment comprises the steps of controlling the flow rate of the Cu-containing mixture to ensure that the residence time of materials in the condensing unit is not less than 5min, and/or controlling the flow rate of the cooling medium to ensure that the temperature difference between a cooling medium outlet of the condensers and a cooling medium inlet is not higher than 45 ℃. Thus, the nano Cu powder with lower impurity content and better roundness can be simply formed.

For the convenience of understanding, the principle of the present application capable of achieving the above-mentioned advantageous effects will be briefly described below:

The method provided by the application can reduce the evaporation temperature and inhibit part of impurity atoms from being mixed into the mixture containing Cu by controlling the evaporation conditions, improving the vacuum degree and introducing inert gas. Secondly, the inert gas with a certain flow rate is utilized to increase the speed of the material entering the condensing unit, so that Cu in the mixture containing Cu can be more uniformly distributed on one hand, the nucleation rate is prevented from forming large particles too fast, and on the other hand, the yield of the method can be increased. Meanwhile, the cooling rate can be optimized by synchronously controlling the flow rate of the Cu-containing mixture in the condensing unit and the flow rate of the cooling medium, so that the roundness and uniformity of Cu powder are regulated and controlled. Therefore, under the combined action of the parameters, the Cu powder with better quality can be obtained under the simpler operation condition. The Cu powder prepared by the method provided by the application has good roundness and low impurity content.

According to an embodiment of the application, the heating treatment may be performed in a sealable heating chamber, for example in a heating chamber of a heating unit. The specific structure and materials of the heating unit are not particularly limited as long as the foregoing heating temperature can be endured. To facilitate control of the pressure within the heating chamber of the heating unit, in some examples, the heating chamber may be of a closable construction so as to remain relatively closed during the phase of the heat treatment to form the Cu-containing mixture, thereby reducing the equipment costs required to maintain the vacuum.

Specifically, the heating treatment may be to place the raw material in a heating chamber, vacuum-pumping the heating chamber to make the vacuum degree reach 80-150KPa, and introducing inert gas to perform atmosphere placement. The inert gas may be He gas. The residual air in the cavity can be replaced by the inert gas, so that oxidation of the Cu-containing raw material in the subsequent heating process is avoided, meanwhile, the temperature of vapor formed by the Cu-containing raw material can be reduced, and on the other hand, the residual air can be reduced to react with Cu in the subsequent high-temperature heating process, so that the impurity element content in the product is improved. Specifically, the flow rate of the inert gas can be controlled to maintain the vacuum degree and for a period of time to realize the replacement of the atmosphere in the cavity. Subsequently, the heating treatment may be started.

According to the embodiment of the application, the vacuum degree of the heating treatment is controlled to 80-150KPa, and the temperature is 1300-1700 ℃ so as to be favorable for obtaining micron-sized Cu powder with good roundness and uniformity. Since the heating temperature needs to be maintained at a high temperature to obtain Cu vapor, the heating-condensing process for preparing Cu metal powder generally requires precise temperature control, thus involving precise monitoring of temperature and more complicated operations. In addition, when deviation occurs in parameter control of heating and cooling treatment, the difference between particle size distribution conditions of different batches is also large, and further the stability of the conductive paste prepared by using the Cu powder is affected. The temperature required for the formation of Cu vapor can be reduced by the operation of first evacuating and then performing the atmosphere replacement. In addition, when the atmosphere is replaced, the change of the vacuum degree is maintained to be not more than 10% of the preset value, so that a stable evaporation environment is obtained.

Higher temperatures and lower vacuum levels are advantageous for obtaining relatively large sized nuclei, forming micron sized particles, but the ever increasing vacuum levels and heating temperatures can significantly increase production costs. Thus, in some embodiments, the temperature may be raised at a rate of 20-50 ℃ per minute, the temperature of the heat treatment is 1500-1680 ℃, and the incubation is for 10-20 minutes to obtain Cu vapor. The above process is advantageous in obtaining Cu vapor capable of forming micron-sized particles. The evaporation rate is greatly influenced by the vacuum degree and the temperature, so that the proper evaporation rate can be obtained by controlling the vacuum degree and the temperature of the heating treatment, and finally the micron-sized Cu powder with the particle size meeting the requirement is obtained. In addition, the pressure in the heating treatment stage has a larger influence on the morphology of the formed Cu powder, and when the vacuum degree is higher, the Cu powder with better roundness can be obtained more favorably. Therefore, properly lifting the vacuum degree is beneficial to obtaining micron-sized copper powder with better roundness. However, the increase of the vacuum degree will cause a significant increase in equipment cost, and the maintenance of the vacuum degree under the condition of continuously introducing inert gas also requires a relatively complicated operation, i.e. real-time monitoring of the vacuum degree. Therefore, the application chooses to raise the temperature of the heating treatment more, and obtain micron-sized particles with uniform granularity. In some embodiments, the heating temperature may be 1600 degrees celsius or higher and the vacuum degree may be not less than 100KPa

As described above, the particle size of Cu powder is affected by the nucleation rate and the crystal nucleus growth rate, and the decrease in temperature during formation increases the supercooling degree, thereby increasing the nucleation rate, but the decrease in temperature simultaneously decreases the diffusion rate, which is an important step in the crystallization process, and the decrease in diffusion rate is unfavorable for increasing the nucleation rate. Therefore, the nucleation rate is greatly affected by temperature, and generally increases and then decreases with increasing supercooling degree. The increase in nucleation rate results in more new nucleation, and thus the nucleation rate and the growth rate of the crystals together affect the size and uniformity of the finally formed nanoparticles.

The inventors found that by controlling the vacuum degree and the heating temperature of the heating treatment and performing the heat-preserving treatment for a period of time, it is advantageous to sufficiently gasify the Cu-containing raw material and to control the rate of Cu vapor formed appropriately. In continuous production, the conditions are favorable for making the obtained Cu powder particles more uniform in the subsequent condensation treatment, and prolonging the heat preservation time is also favorable for obtaining particles with larger particle diameters. In some embodiments, the incubation time may be 10-20min and the Dv50 of the resulting particles may be around 1.5 μm.

According to an embodiment of the present application, the raw material may be a metal raw material such as a Cu bar. In order to enhance the purity of the obtained powder, the Cu-containing raw material may also be subjected to operations including, but not limited to, water washing, degreasing, ultrasonic treatment, and the like, prior to the treatment. The Cu-containing raw material is gasified after the heat treatment to form Cu vapor for the subsequent cooling treatment.

The Cu vapor may be supplied to a region having a closed space such as a condensing unit for cooling. In order to improve the contact between the Cu vapor and the condenser uniformly when the Cu vapor enters the condensing unit and to improve the production efficiency, the Cu vapor may be mixed with an inert gas and then supplied to the condensing unit. Specifically, after the heat preservation is performed for a certain period of time, cu vapor and an inert gas may be mixed and supplied to the condensing unit by using a nozzle.

As previously described, the heating unit may be in a relatively airtight state during the heat treatment stage. In particular, at the beginning of production, the heating unit can be rapidly brought to the desired vacuum level and temperature by closing the passage between the heating unit and the condensing unit. When it is desired to supply material to the condensing unit, a passageway between the two may be opened, such as by opening a nozzle, and adding a second gas, such as an inert gas, through the nozzle.

For example, in some embodiments, the amount of mixture supplied to the condensing unit may be controlled by adjusting the flow rate of the inert gas at the nozzle. The flow velocity of cooling medium in the condenser is matched, so that the crystal nucleus aggregation can be prevented from producing oversized particles, particles with narrower particle size distribution can be obtained, and the roundness of formed Cu powder can be improved.

In some embodiments, the Cu-containing gas may be regulated to be supplied to the condensing unit at a rate of not less than 500 ml/s. In some embodiments, the velocity may be controlled by the flow of the second gas. The problems of wide particle size distribution and poor particle roundness of the micron-sized Cu powder prepared in the related technology generally exist, so that the prepared Cu powder has large difference in different production batches. As described above, since Cu has a high melting point, a certain temperature and vacuum degree are required for the heat treatment. Therefore, through regulating and controlling the step of cooling treatment, on one hand, the granularity and roundness of the obtained powder can be improved, and on the other hand, the operation difficulty can be reduced as well: the cooling treatment part can better adjust the morphology of the obtained particles by controlling the flow rates of the second gas and the condensing medium, and the flow rates of the air flow and the cooling medium are controlled relatively more easily relative to the regulation and control of the vacuum degree.

In some embodiments, the nozzle may have a second gas inlet therein to mix the second gas with the Cu-containing mixture. In some embodiments, the flow rate of the material into the condensing unit may be controlled by adjusting the flow rate of the second gas. Thereby being beneficial to keeping a relatively stable atmosphere in the heating treatment link. Thereby, it is advantageous to more easily optimize the cooling rate and maintain the stability of the heat treatment process.

According to the embodiment of the application, in order to more effectively realize condensation, meanwhile, cu powder is reduced to be accumulated on the surface of the condenser, so that the particle size of the prepared Cu powder is not controlled, and the arrangement direction of the plate type condenser can be the same as the movement direction of materials in the condensing unit. Therefore, the material with a certain speed can be utilized to impact the surface of the plate-type condenser, the heat exchange efficiency is improved, and the formation of particles with overlarge particle size caused by accumulation of the material on the surface of the condenser is prevented. For example, the material may be sprayed into the condensing unit through a nozzle in a vertical direction, and the plate condensers may be arranged at intervals in the vertical direction. Compared with the inclined arrangement or the horizontal staggered arrangement, the vertical arrangement is more beneficial to reducing the temperature difference among the condensers and is also convenient to provide cooling medium for the condensers in a parallel connection mode. The plurality of condensers which are connected in parallel can reduce the temperature difference between two adjacent condensers, and a more uniform cooling environment is obtained.

According to the embodiment of the application, the plate type condenser can be internally provided with the turbulence columns which are regularly arranged so as to improve the heat exchange efficiency. In some embodiments, the height of the turbulator column may be consistent with or slightly less than the height of the cooling medium channel inside the condenser. The specific structure of the plate condenser can be designed according to the size of the condensing unit.

The inventor finds that if the residence time of the material in the condensing unit is too short, the material cannot be sufficiently cooled and grown in the condensing unit, which is unfavorable for obtaining particles with the particle size of micrometers and also unfavorable for obtaining uniformly distributed powder. If the temperature difference of the condensing medium before and after condensation is large, the material can also experience a large temperature difference when contacting with the condenser, which is also unfavorable for obtaining particles with narrower particle size distribution. When the flow rate of the Cu vapor and the second gas supplied to the space is not less than 500ml/s, the temperature difference of the cooling medium in the condenser is not more than 30 ℃ before and after the cooling treatment, the roundness of the obtained particles can reach more than 90%, and the particle size distribution is relatively narrow.

In order to control the flow rate of the cooling medium simply, temperature sensors may be provided at both the cooling medium inlet and the cooling medium outlet of the plate-type condensing appliance. Based on the temperature measured by the temperature sensor, the flow rate of the condensate is adjusted, so that the Cu-containing mixture forms micron-sized powder on the surface of the condenser at a better cooling rate. In some embodiments, the temperature difference at the cooling medium outlet and the cooling medium inlet may be made not higher than 30 ℃.

According to embodiments of the present application, the formed micron-sized Cu powder may have a Dv50 of 1-2 μm and a sphericity of >90%. The micron-sized copper powder has low impurity content, for example, the micron-sized copper powder contains 0.005-0.05wt% of carbon and the oxygen content is 0.08-2.0wt%.

In some embodiments, the micron-sized Cu powder surface may have a thinner oxide layer. The thickness of the oxide layer is tens of micrometers, and the main components of the oxide layer can be CuO, cu (OH) ₂ and the like. The oxidation resistance of the micron-sized Cu powder can be improved by the proper oxidation layer. And on the premise of not influencing the main performance parameters of the Cu powder, the oxide layer with proper thickness can also reduce the requirements on equipment and a method for preparing the Cu powder, thereby being beneficial to reducing the production cost.

According to the embodiment of the application, the Cu powder has the iron content of <0.01wt%, the aluminum content of <0.01wt%, the silicon content of <0.01wt%, the calcium content of <0.01wt%, the magnesium content of <0.01wt% and the zirconium content of <0.01wt%.

Therefore, the micron-sized Cu powder has all the features and advantages of the Cu powder obtained by the foregoing method, and will not be described herein.

Hereinafter, embodiments of the present application are described. The following examples are illustrative only and are not to be construed as limiting the application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Unless otherwise indicated, terms used in the present application have well-known meanings commonly understood by those skilled in the art. Unless otherwise indicated, the numerical values of the parameters set forth in the present application may be measured by various measurement methods commonly used in the art (e.g., may be tested according to the methods set forth in the examples of the present application).

Example 1

And (3) heating, namely closing the nozzle, controlling the vacuum degree in the heating unit to be 100KPa, introducing inert gas He, starting programmed heating after introducing the inert gas for 15min, heating to 1550 ℃, and preserving heat for 15min.

And (3) condensing, namely opening a nozzle, introducing He gas from the nozzle, controlling the flow rate of the gas-liquid mixture to be 550ml/s, entering a condensing unit, controlling the flow rate of condensate to be 600ml/s, maintaining the temperature difference between an inlet and an outlet of a condenser to be 25+/-2 ℃, and condensing for 10min.

Example 2

And (3) heating, namely closing the nozzle, controlling the vacuum degree in the heating unit to be 85KPa, introducing inert gas He, starting programmed heating after introducing the inert gas for 15min, heating to 1700 ℃, and preserving heat for 15min.

And (3) condensing, namely opening the nozzle, introducing He gas from the nozzle, controlling the flow rate of the gas-liquid mixture to be 600ml/s, entering a condensing unit, controlling the flow rate of condensate to be 800ml/s, maintaining the temperature difference between the inlet and the outlet of the condenser to be 20+/-2 ℃, and condensing for 10min.

Example 3

And (3) heating, namely closing the nozzle, controlling the vacuum degree in the heating unit to be 150KPa, introducing inert gas He, starting programmed heating after introducing the inert gas for 15min, heating to 1500 ℃, and preserving heat for 10min.

And (3) condensing, namely opening the nozzle, introducing He gas from the nozzle, controlling the flow speed of the gas-liquid mixture to be 450ml/s, entering the condensing unit, controlling the flow speed of condensate to be 400ml/s, maintaining the temperature difference between the inlet and the outlet of the condenser to be 30+/-2 ℃, and condensing for 15min.

Example 4

And (3) heating, namely closing the nozzle, controlling the vacuum degree in the heating unit to be 120KPa, introducing inert gas He, starting programmed heating after introducing the inert gas for 15min, heating to 1500 ℃, and preserving heat for 10min.

And (3) condensing, namely opening a nozzle, introducing He gas from the nozzle, controlling the flow rate of the gas-liquid mixture to be 450ml/s, entering a condensing unit, controlling the flow rate of condensate to be 600ml/s, maintaining the temperature difference between an inlet and an outlet of a condenser to be 28+/-2 ℃, and condensing for 10min.

Comparative example 1

The rest of the operations were the same as in example 1, except that no inert gas was introduced into the heating unit, and the heating temperature was 1600 ℃.

Comparative example 2

The rest of the operation was the same as in example 1, except that the condensate flow rate was 200ml/s, the condenser inlet-outlet temperature difference was 50.+ -. 2 ℃ and the condensation treatment was 10min.

Comparative example 3

The other operations were the same as in example 1 except that He gas was not introduced at the nozzle, and the Cu-containing mixture was introduced into the condensing unit at 100 ml/s.

The performance of the Cu powder prepared in the above examples and comparative examples was examined. The particle size is detected by a laser particle sizer, and Dv10, dv50 and Dv90 of the sample are obtained. The C content is measured by a carbon-sulfur analyzer, and the O content is measured by an oxygen analyzer.

Roundness is measured by methods conventional in the art, as well as the surface area of the particle, and the ratio of the surface area of the sphere to the equivalent volume of the particle. The roundness of a perfect sphere is 1, i.e., 100%, and the roundness of a particle approximately approaching a sphere is approximately 100%, and the calculation formula for roundness I is as follows:

Where Vp is the particle volume and Sp is the surface area of the particle.

The roundness of the application is an average value of the roundness of the particles.

Thermogravimetric analysis and detection were performed on the Cu powder prepared in example 1, and the test results are shown in fig. 2.

The partial test results of the above examples and comparative examples are shown in table 1 below:

TABLE 1

As can be seen from Table 1, higher heating treatment temperature is favorable for obtaining micron-sized Cu powder with better roundness and narrower particle size distribution, and the uniformity of Cu powder is favorable for improving when the flow rate of the material sprayed into the condensing unit and the cooling water is higher. And the inert atmosphere of the heat treatment is also favorable for reducing the impurity element content.

Referring to fig. 2 and 3, the Cu powder prepared in example 1 was more uniform in particle size and higher in roundness. Thermogravimetric analysis showed that the DTA curve of Cu powder had a more pronounced exothermic peak around 217 ℃, and the TGA curve also appeared to be inflection point around 217 ℃, which may be related to the oxidation of Cu powder. A broad peak appears in the DTA curve around 365 ℃, which may be related to the oxidation of the impurity element in the Cu powder. The peak occurs at a higher temperature and a broader peak width, possibly associated with oxidation of various impurities.

From the data of comparative examples 1-3 and examples, it is known that introducing inert gas into the heating unit, maintaining the material sprayed into the cooling unit at a certain rate, and maintaining a small condensate temperature difference is a key influencing factor in obtaining micron-sized Cu powder with good roundness.

It should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit the technical solution of the present application, and although the detailed description of the present application is given with reference to the above embodiments, it should be understood by those skilled in the art that the technical solution described in the above embodiments may be modified or some or all technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application, and all the modifications or substitutions are included in the scope of the claims and the specification of the present application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing micron-sized Cu powder, comprising:

The raw materials are placed in a heating chamber, and the heating chamber is evacuated to a vacuum degree of 80-150 KPa, and an inert gas is introduced to replace the atmosphere;

The raw material is subjected to a heating treatment at a temperature of 1300-1700 degrees Celsius and a holding time of 10-20 minutes to form Cu vapor;

The Cu vapor is subjected to a cooling treatment, wherein the cooling treatment comprises mixing the Cu vapor and the second gas and supplying the mixture to a closed space having a condenser, wherein the flow rate of the Cu vapor and the second gas supplied to the space is not less than 500 ml/s, and the temperature difference of the cooling medium in the condenser before and after the cooling treatment is not greater than 30°C.

2. The method according to claim 1 is characterized in that the heating treatment further comprises: heating at a heating rate of 20-50°C/min, and the temperature of the heating treatment is 1500-1680 degrees Celsius.

3. The method according to claim 1, characterized in that the vacuum degree is 100-150 KPa.

4. The method according to claim 1, characterized in that the flow rate of the Cu-containing mixture is 500-800 ml/s, the inert gas is He gas, and the mixing of the inert gas and Cu vapor is carried out at the entrance of the closed space.

5. The method according to claim 4 is characterized in that the enclosed space includes a plurality of condensers, the plurality of condensers are plate condensers, the plurality of condensers are arranged at intervals, and the cooling medium inlets of the plurality of condensers are arranged in parallel.

6. The method according to claim 5, characterized in that the plate condenser is provided with regularly arranged spoiler columns, the plate condenser has the cooling medium inlet and the cooling medium outlet, and the cooling medium inlet and the cooling medium outlet are both provided with temperature sensors, and the method further comprises:

Based on the temperature measured by the temperature sensor, the flow rate of the condensate is adjusted so that the temperature difference between the cooling medium outlet and the cooling medium inlet is not higher than 30°C.

7. The method according to any one of claims 1 to 6, characterized in that the Dv50 of the micron-sized Cu powder is 1-2 μm and the sphericity is greater than 90%.

8. A micron-sized Cu powder, characterized in that the micron-sized Cu powder contains 0.005-0.05wt% carbon, an oxygen content of 0.08-2.0wt%, a Dv50 of 1-2μm, and a sphericity of >90%.

9. The micron-sized Cu powder according to claim 8, characterized in that the iron content, aluminum content, silicon content, calcium content, magnesium content, and zirconium content in the micron-sized Cu powder are less than 0.01wt%, less than 0.01wt%, less than 0.01wt%, less than 0.01wt%, and less than 0.01wt%.

10 . The micron-sized Cu powder according to claim 8 or 9 , characterized in that the micron-sized Cu powder is obtained by the method according to any one of claims 1 to 7 .