Tungsten-copper alloy preparation method and tungsten-copper alloy

Abstract

The invention relates to the technical field of powder metallurgy, in particular to a tungsten-copper alloy preparation method and a tungsten-copper alloy. The preparation method of the tungsten-copper alloy comprises the following steps: mixing double-scale compound tungsten powder containing nanocrystals and ultra-fine grains or double-scale compound tungsten-tungsten oxide powder containing nanocrystals and ultra-fine grains with copper oxide powder to obtain precursor slurry; drying the precursor slurry to obtain precursor composite powder; the precursor composite powder is subjected to segmented reduction, tungsten-copper composite powder is obtained, and tungsten crystal grains in the tungsten-copper composite powder are distributed in a double-scale mode of nanocrystals and ultra-fine crystals; and the tungsten-copper composite powder is prepared into a blank and sintered, and the tungsten-copper alloy is obtained. The heat conductivity and density of the tungsten-copper alloy can be improved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of powder metallurgy, and in particular to a tungsten-copper alloy preparation method and a tungsten-copper alloy. Background Art

[0002] Tungsten copper alloy is a pseudo alloy material composed of tungsten and copper. It has the low thermal expansion of tungsten and the high thermal conductivity of copper. At the same time, the thermal expansion coefficient and thermal conductivity of tungsten copper alloy can be comprehensively designed by adjusting the composition of the material, which makes tungsten copper alloy as a thermal conductive and heat dissipating material, and has been widely used in high-power electronic devices such as wireless communications, optical communications, semiconductor lasers, etc. In recent years, with the continuous expansion of the electronic consumer market and the trend of related fields to develop to a higher level, the demand for tungsten copper alloy has continued to rise.

[0003] However, the current methods for preparing tungsten-copper alloys can be mainly divided into powder metallurgy and melt infiltration, but the prepared tungsten-copper alloys have the disadvantages of insufficient density and insufficient thermal conductivity.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present disclosure is to provide a tungsten-copper alloy preparation method and a tungsten-copper alloy, thereby improving the thermal conductivity and density of the tungsten-copper alloy at least to a certain extent.

[0006] According to one aspect of the present disclosure, a method for preparing a tungsten-copper alloy is provided, comprising: mixing a composite tungsten powder containing a dual scale of nanocrystals and ultrafine crystals or a composite tungsten-tungsten oxide powder containing a dual scale of nanocrystals and ultrafine crystals with copper oxide powder to obtain a precursor slurry; drying the precursor slurry to obtain a precursor composite powder; performing stepwise reduction on the precursor composite powder to obtain a tungsten-copper composite powder, wherein the tungsten grains in the tungsten-copper composite powder have a dual scale distribution of nanocrystals and ultrafine crystals; and making the tungsten-copper composite powder into a billet and sintering the billet to obtain a tungsten-copper alloy.

[0007] In an exemplary embodiment of the present disclosure, if a composite tungsten powder containing dual scales of nanocrystals and ultrafine crystals is mixed with copper oxide powder to obtain a precursor slurry, the method also includes: compounding nano tungsten powder and ultrafine tungsten powder to obtain a composite tungsten powder containing dual scales of nanocrystals and ultrafine crystals; wherein the particle size of the nano tungsten powder is 20 to 100 nm, the particle size of the ultrafine tungsten powder is 100 to 500 nm, and the mass ratio of the nano tungsten powder to the ultrafine tungsten powder is 1:1 to 5:1.

[0008] In an exemplary embodiment of the present disclosure, if a composite tungsten-tungsten oxide powder containing dual scales of nanocrystals and ultrafine crystals is mixed with copper oxide powder to obtain a precursor slurry, the method also includes: compounding nano tungsten powder and ultrafine tungsten oxide powder to obtain a composite tungsten-tungsten oxide powder containing dual scales of nanocrystals and ultrafine crystals, and the mass ratio of nano tungsten powder to ultrafine tungsten oxide powder is 1:2 to 4:1; wherein the particle size of the nano tungsten powder is 20 to 100 nm, the particle size of the ultrafine tungsten oxide powder is 150 to 700 nm, and the ultrafine tungsten oxide powder is selected from any one of yellow tungsten oxide, blue tungsten oxide, purple tungsten oxide and tungsten dioxide.

[0009] In an exemplary embodiment of the present disclosure, the copper oxide powder is cupric oxide or cuprous oxide, the particle size of the copper oxide powder is 30-800 nm, and the purity of the copper oxide powder is ≥99.9%.

[0010] In an exemplary embodiment of the present disclosure, a precursor composite powder is subjected to staged reduction to obtain a tungsten-copper composite powder, including: heating the precursor composite powder to 200-350°C at 5-20°C / min and then keeping it warm for 0.5-1h, heating it to 450-600°C at 5-20°C / min and then keeping it warm for 0.5-2.5h, and then heating it to 600-800°C at 3-10°C / min and then keeping it warm for 0.5-3h to obtain a tungsten-copper composite powder; wherein the atmosphere for the staged reduction is any one of hydrogen, decomposed ammonia and argon-hydrogen mixed gas.

[0011] In an exemplary embodiment of the present disclosure, the forming pressure of the tungsten-copper composite powder into a blank is 100-350 MPa, and the holding time is 5-30 min; wherein the forming method is selected from any one of unidirectional pressing, bidirectional pressing or cold isostatic pressing.

[0012] In an exemplary embodiment of the present disclosure, a tungsten-copper composite powder is made into a blank and sintered to obtain a tungsten-copper alloy, including: heating the blank made of the tungsten-copper composite powder to 750-850°C at 10-15°C / min and keeping it warm for 0.5-1h, and heating it to 850-1000°C at 5-10°C / min and keeping it warm for 0.5-1h, then heating it to 1150-1500°C at 3-5°C / min and keeping it warm for 0.5-4h, and then cooling it to 600-900°C at 5-7°C / min and cooling it with the furnace; wherein the sintering atmosphere is selected from any one of hydrogen, decomposed ammonia, argon-hydrogen mixed gas and vacuum, and the sintering environment is normal pressure sintering.

[0013] In an exemplary embodiment of the present disclosure, a composite tungsten powder containing dual scales of nanocrystals and ultrafine crystals or a composite tungsten-tungsten oxide powder containing dual scales of nanocrystals and ultrafine crystals is ball-milled with copper oxide powder to obtain a precursor slurry; wherein the ball milling mixing is wet milling, the ball milling medium is any one of deionized water, anhydrous ethanol and acetone, the ball milling speed is 100-500 r / min, and the ball milling time is 12-36 h.

[0014] In an exemplary embodiment of the present disclosure, the method of drying the precursor slurry is selected from any one of air drying, spray drying, rotary evaporation, freeze drying and vacuum drying.

[0015] According to one aspect of the present disclosure, a tungsten-copper alloy is provided, which is prepared by any one of the above-mentioned tungsten-copper alloy preparation methods.

[0016] In the technical solution provided in the embodiment of the present disclosure, on the one hand, compared with the use of a single particle size powder, the powder with a dual-scale distribution has better fluidity, is not easy to bond and agglomerate, and helps to improve the density and uniformity of the blank during the molding process. On the other hand, during the sintering process, particles of different particle sizes shrink at different rates, and small particles can fill the pores between large particles. At the same time, the interaction between large and small tungsten particles can inhibit the abnormal growth of tungsten grains, which helps to maintain the uniformity of the microstructure of the alloy, improve the density of the alloy, and improve the comprehensive properties of the alloy such as thermal conductivity. In addition, compared with the direct compounding of tungsten powder with copper powder, the surface functional groups of copper oxide powder are richer and the dispersibility is better, which helps to improve the composite uniformity of tungsten and copper powders, thereby further improving the uniformity of the organizational structure of tungsten-copper alloys, reducing interface thermal resistance, and improving the density and thermal conductivity of tungsten-copper alloys. Therefore, the embodiment of the present disclosure can provide a method for preparing a tungsten-copper alloy with uniform organizational distribution, high density, and high thermal conductivity and a tungsten-copper alloy.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0019] Figure 1 A flow chart of a method for preparing a tungsten-copper alloy according to an embodiment of the present disclosure is schematically shown.

[0020] Figure 2 A flow chart of performing segmented reduction of a precursor composite powder to obtain a tungsten-copper composite powder according to an embodiment of the present disclosure is schematically shown.

[0021] Figure 3 A flow chart of preparing a tungsten-copper composite powder into a blank and sintering the blank to obtain a tungsten-copper alloy according to an embodiment of the present disclosure is schematically shown.

[0022] Figure 4 A scanning electron microscope image (SEM image) of the surface of a W90Cu10 alloy prepared by Example 1 according to an embodiment of the present disclosure is schematically shown.

[0023] Figure 5 An energy spectrum diagram (EDS distribution diagram) of tungsten and copper in the W90Cu10 alloy prepared by Example 1 according to an embodiment of the present disclosure is schematically shown.

[0024] Figure 6 A scanning electron microscope image (SEM image) of the surface of a W80Cu20 alloy prepared by Example 2 according to an embodiment of the present disclosure is schematically shown.

[0025] Figure 7 An energy spectrum diagram (EDS distribution diagram) of tungsten and copper in the W80Cu20 alloy prepared by Example 2 according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0026] The following is an explanation of the implementation of the present disclosure by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification.

[0027] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0028] In addition, it should be understood that one or more method steps mentioned in the present disclosure do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present disclosure does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. Changes or adjustments in their relative relationships, without substantial changes in the technical content, should also be regarded as the scope of the present disclosure.

[0029] In the method of preparing tungsten-copper alloy by first mixing tungsten and copper powder in a certain proportion and then pressing and forming, and then sintering under a protective atmosphere, although the method is simple to operate and can prepare tungsten-copper alloy with any copper content, the characteristics of tungsten and copper powder have a significant impact on the performance of the alloy. Ordinary commercial tungsten and copper powders are generally micron-grade (2-5μm), with coarse particle size and low sintering activity, resulting in low density (90%-95%) of the sintered body and insufficient thermal conductivity, which is difficult to meet the use requirements as electronic packaging thermal conductive heat dissipation materials. However, tungsten powder or tungsten powder mixed with induced copper powder is first made into a blank, and then sintered into a porous matrix skeleton with a certain density and strength, and then melt-infiltrated, so that liquid copper penetrates into the porous tungsten skeleton under the action of capillary force, thereby preparing tungsten-copper alloy. The tungsten-copper alloy prepared in this way has a high density and relatively ideal thermal conductivity, but the copper content in the tungsten-copper alloy prepared by the melt-infiltration method can only be limited to a certain range (10-40wt%). In addition, since the pore connectivity and size consistency of the tungsten skeleton are difficult to control, the uniform distribution of the copper phase after infiltration is difficult to ensure. The intuitive manifestation is that the structure of the tungsten-copper alloy is generally coarse and uneven, and there are many closed pores that cannot be eliminated during the infiltration process, which affects the requirements of the heat sink material for the airtightness of the tungsten-copper alloy.

[0030] Considering the shortcomings of insufficient density and thermal conductivity of the prepared tungsten-copper alloy, a method is provided in which lanthanum oxide powder and cobalt powder are added to the tungsten-copper alloy to fill the pores between tungsten and copper, and between tungsten and tungsten, thereby improving the wettability between tungsten and copper and improving the sintering performance of the overall alloy powder. However, the introduction of additives will hinder the connection between tungsten and the copper skeleton, thereby affecting the density and thermal conductivity of the tungsten-copper alloy. A tungsten-copper powder is prepared by a three-dimensional mixing-high-speed crushing-hydrogen reduction process, and then a tungsten-copper alloy with high density and uniform structure is prepared by a hot isostatic pressing-thermoplastic processing-heat treatment process, avoiding the phenomenon of component segregation caused by the preparation of tungsten-copper alloy by the melt infiltration method. However, the complex process flow and expensive process cost limit the large-scale promotion and application of this method in the industrial field. In addition, it is also considered to add coarse-grained tungsten powder to a mixed solution of tungsten salt and copper salt, and prepare a tungsten-copper composite powder containing coarse-grained tungsten powder and fine-grained tungsten powder by spray pyrolysis-hydrogen reduction, and sinter to prepare a high-performance tungsten-copper alloy material with a bimodal structure. However, on the one hand, the particle size of tungsten grains in the tungsten-copper composite powder obtained by this method is still relatively large, and the temperature and time required for sintering to be dense are high, which leads to problems such as poor sintering performance of the alloy, coarse and uneven grain structure, insufficient density and thermal conductivity of the alloy. On the other hand, this process method for preparing composite powder by spray pyrolysis of liquid precursors is complicated to operate and has a long process, making it difficult to promote and achieve large-scale application.

[0031] Based on this, the tungsten-copper alloy prepared by the above-mentioned tungsten-copper alloy preparation method has the disadvantages of insufficient density and insufficient thermal conductivity, high process complexity, high cost, and limited application scope. The embodiment of the present disclosure provides a tungsten-copper alloy preparation method.

[0032] It should be noted that the tungsten-copper alloy prepared by the tungsten-copper alloy preparation method of the embodiment of the present disclosure can be used as a thermal conductive heat dissipation material and applied to high-power electronic devices such as wireless communication, optical communication, and semiconductor lasers. Of course, the tungsten-copper alloy prepared by the embodiment of the present disclosure can also be applied to other application fields that require thermal conductive heat dissipation materials, without limitation.

[0033] Figure 1 A flow chart of a method for preparing a tungsten copper alloy is shown, which may include:

[0034] In step S110, a composite tungsten powder containing both nanocrystals and ultrafine crystals or a composite tungsten-tungsten oxide powder containing both nanocrystals and ultrafine crystals is mixed with copper oxide powder to obtain a precursor slurry.

[0035] In step S120, the precursor slurry is dried to obtain a precursor composite powder.

[0036] In step S130, the precursor composite powder is reduced in stages to obtain a tungsten-copper composite powder, wherein the tungsten grains in the tungsten-copper composite powder have a dual-scale distribution of nanocrystalline and ultrafine crystals.

[0037] In step S140, the tungsten-copper composite powder is made into a blank and sintered to obtain a tungsten-copper alloy.

[0038] In the technical solution provided in the embodiment of the present disclosure, on the one hand, compared with the use of a single particle size powder, the powder with a dual-scale distribution has better fluidity, is not easy to bond and agglomerate, and helps to improve the density and uniformity of the blank during the molding process. On the other hand, during the sintering process, particles of different particle sizes shrink at different rates, and small particles can fill the pores between large particles. At the same time, the interaction between large and small tungsten particles can inhibit the abnormal growth of tungsten grains, which helps to maintain the uniformity of the microstructure of the alloy, improve the density of the alloy, and improve the comprehensive properties of the alloy such as thermal conductivity. In addition, compared with the direct compounding of tungsten powder with copper powder, the surface functional groups of copper oxide powder are richer and the dispersibility is better, which helps to improve the composite uniformity of tungsten and copper powders, thereby further improving the uniformity of the organizational structure of tungsten-copper alloys, reducing interface thermal resistance, and improving the density and thermal conductivity of tungsten-copper alloys. Therefore, the embodiment of the present disclosure can provide a method for preparing a tungsten-copper alloy with uniform organizational distribution, high density, and high thermal conductivity and a tungsten-copper alloy.

[0039] Next, the method for preparing the tungsten-copper alloy in the embodiment of the present disclosure is specifically described.

[0040] In step S110, a composite tungsten powder containing both nanocrystals and ultrafine crystals or a composite tungsten-tungsten oxide powder containing both nanocrystals and ultrafine crystals is mixed with copper oxide powder to obtain a precursor slurry.

[0041] In the embodiments of the present disclosure, optionally, a dual-scale composite tungsten powder of nanocrystalline and ultrafine crystal may be used, and the composite tungsten powder may be obtained by combining tungsten powders of different particle sizes and different proportions.

[0042] The nano tungsten powder and the ultrafine tungsten powder can be compounded to obtain a compound tungsten powder containing nanocrystals and ultrafine crystals. The particle size of the nano tungsten powder is 20-100nm, and the particle size of the ultrafine tungsten powder is 100-500nm.

[0043] Optionally, the mass ratio of nano tungsten powder to ultrafine tungsten powder is 1:1 to 5:1.

[0044] Based on this, the combination of tungsten powders of different particle sizes and proportions can help improve the fluidity of tungsten-copper composite powders, improve the uniformity and density of the blanks, and during the sintering process, small particles can fill the pores between large particles to form a dense stack. At the same time, the interaction between large and small tungsten particles can inhibit the abnormal growth of tungsten grains, help maintain the uniformity of the alloy microstructure, improve the density of tungsten-copper alloys, and improve the comprehensive properties of the alloys such as thermal conductivity.

[0045] Optionally, nano tungsten powder and ultrafine tungsten oxide powder may be compounded to obtain a composite tungsten-tungsten oxide powder containing both nano crystals and ultrafine crystals.

[0046] The mass ratio of nano tungsten powder to ultrafine tungsten oxide powder is 1:2 to 4:1.

[0047] Optionally, the particle size of the nano tungsten powder is 20-100 nm, and the particle size of the ultrafine tungsten oxide powder is 150-700 nm.

[0048] Optionally, the ultrafine tungsten oxide powder is selected from yellow tungsten oxide (WO3), blue tungsten oxide, purple tungsten oxide (WO 2.72 ) and tungsten dioxide (WO2).

[0049] By selecting nano-tungsten powder and ultrafine tungsten oxide powder of appropriate particle size and proportion for compounding, it is helpful to achieve in-situ uniform compounding with copper oxide powder, and further obtain high-quality tungsten-copper composite powder with dual-scale tungsten grain distribution characteristics through step-by-step reduction, thereby improving the comprehensive properties of the sintered tungsten-copper alloy such as density, organizational uniformity and thermal conductivity.

[0050] In the embodiment of the present disclosure, the copper oxide powder is cupric oxide or cuprous oxide, the particle size of the copper oxide powder is 30-800 nm, and the purity of the copper oxide powder is ≥99.9%. Of course, other types of copper oxide powder can also be selected according to actual conditions.

[0051] It should be understood that the mass of copper oxide added during the preparation process of the embodiment of the present disclosure can be determined according to the mass ratio of tungsten and copper in the tungsten-copper alloy actually required. For example, if a tungsten-copper alloy of model W90Cu10 is to be prepared, that is, a tungsten-copper alloy containing 90% by mass of tungsten and 10% by mass of copper is to be prepared, the mass of copper oxide added can be determined as needed. Correspondingly, if a tungsten-copper alloy of model W80Cu20 is to be prepared, that is, a tungsten-copper alloy containing 80% by mass of tungsten and 20% by mass of copper is to be prepared, the mass of copper oxide added and the mass ratio of the tungsten-containing composite powder and the copper oxide can also be selected as needed.

[0052] Tungsten-copper composite powder is prepared by mixing copper oxide powder with high dispersion characteristics with tungsten / tungsten oxide powder. Compared with direct compounding with copper powder, the surface functional groups of copper oxide powder are richer and the dispersion is better, which helps to avoid phase agglomeration and improve the composite uniformity of powder, thereby improving the organizational uniformity of tungsten-copper alloy and increasing density and thermal conductivity.

[0053] In the embodiments of the present disclosure, a composite tungsten powder containing nanocrystals and ultrafine crystals or a composite tungsten-tungsten oxide powder containing nanocrystals and ultrafine crystals can be ball-milled with copper oxide powder to obtain a precursor slurry.

[0054] Optionally, the ball milling is wet milling, the ball milling medium is any one of deionized water, anhydrous ethanol and acetone, the ball milling speed is 100-500 r / min, and the ball milling time is 12-36 hours. It should be understood that other mixing methods can also be used according to actual needs.

[0055] By adopting wet ball milling to achieve uniform mixing of tungsten or tungsten oxide and copper powder oxide, compared with the dry method, it can effectively avoid the agglomeration of the phases, and further achieve uniform compounding of tungsten copper precursor powder by adjusting parameters such as ball milling medium, rotation speed and time.

[0056] In step S120, the precursor slurry is dried to obtain a precursor composite powder.

[0057] In the embodiment of the present disclosure, the method of drying the precursor slurry is selected from any one of air drying, spray drying, rotary evaporation, freeze drying and vacuum drying, which can be flexibly selected according to actual needs.

[0058] By controlling the drying system of the tungsten-copper precursor slurry, promoting the rapid evaporation of the solvent, and avoiding the segregation and agglomeration of components during the solution drying process, it is beneficial to obtain a tungsten-copper precursor powder with a loose structure and uniformly distributed components, laying the raw material foundation for obtaining high-quality tungsten-copper composite powders and sintering high thermal conductivity tungsten-copper alloys.

[0059] In step S130, the precursor composite powder is reduced in stages to obtain a tungsten-copper composite powder, wherein the tungsten grains in the tungsten-copper composite powder have a dual-scale distribution of nanocrystalline and ultrafine crystals.

[0060] In the embodiments of the present disclosure, staged reduction refers to decomposing a complex chemical reaction process into several relatively simple steps, each of which is carried out under specific conditions to ultimately achieve the purpose of the overall reaction, thereby gradually improving the selectivity and efficiency of the reaction.

[0061] Among them, Figure 2 As shown, the precursor composite powder is subjected to segmented reduction to obtain the tungsten-copper composite powder, which may include steps S210 to S230 performed sequentially:

[0062] Step S210: heating the precursor composite powder to 200-350° C. at a rate of 5-20° C. / min and then keeping the temperature for 0.5-1 h.

[0063] Step S220: Raise the temperature to 450-600°C at a rate of 5-20°C / min and keep the temperature for 0.5-2.5h.

[0064] Step S230: heating to 600-800° C. at a rate of 3-10° C. / min and then maintaining the temperature for 0.5-3 h to obtain tungsten-copper composite powder.

[0065] Optionally, the atmosphere for staged reduction is any one of hydrogen, decomposed ammonia and argon-hydrogen mixed gas, which can be flexibly selected according to demand.

[0066] Through the staged reduction process, including the reduction of copper oxide powder and the reduction of tungsten / tungsten oxide powder, the copper oxide powder is first reduced in the low temperature stage, and then the tungsten / tungsten oxide powder is fully reduced and deoxidized through a stepped two-stage reduction to avoid the agglomeration and growth of tungsten powder, which is beneficial to reduce the particle size of the composite powder and obtain tungsten-copper composite powder with high sintering activity.

[0067] In step S140, the tungsten-copper composite powder is made into a blank and sintered to obtain a tungsten-copper alloy.

[0068] In the disclosed embodiment, the forming pressure of the blank made of tungsten-copper composite powder is 100-350 MPa, and the holding time is 5-30 min.

[0069] Optionally, the molding method is selected from any one of unidirectional pressing, bidirectional pressing or cold isostatic pressing, and can be flexibly selected according to actual needs.

[0070] By controlling the billet forming method, pressure and holding time, it is beneficial to obtain high-quality tungsten-copper alloy billets with high strength, high density and uniform distribution.

[0071] like Figure 3 As shown, the tungsten-copper composite powder is made into a blank and sintered to obtain a tungsten-copper alloy, including steps S310 to S330 performed sequentially:

[0072] Step S310: heating the blank made of tungsten-copper composite powder to 750-850° C. at a rate of 10-15° C. / min and keeping the temperature for 0.5-1 h.

[0073] Step S320: Raise the temperature to 850-1000° C. at a rate of 5-10° C. / min and keep the temperature for 0.5-1 h.

[0074] Step S330: Raise the temperature to 1150-1500° C. at a rate of 3-5° C. / min and keep the temperature for 0.5-4 h.

[0075] Step S340: Cooling the temperature to 600-900°C at 5-7°C / min and then cooling in the furnace to obtain a tungsten copper alloy. Optionally, cooling the temperature to 800°C at 5-7°C / min and then cooling in the furnace to obtain a tungsten copper alloy.

[0076] The sintering atmosphere is selected from any one of hydrogen, decomposed ammonia, argon-hydrogen mixed gas and vacuum, and can be flexibly selected according to needs. The sintering environment is normal pressure sintering.

[0077] By controlling the sintering temperature, time, atmosphere and other conditions of the alloy, the gas removal, impurity removal and pore shrinkage during the sintering process are promoted, which is beneficial to achieve full sintering and densification of the tungsten copper alloy.

[0078] Furthermore, the embodiment of the present disclosure also provides a tungsten-copper alloy, which is prepared by the tungsten-copper alloy preparation method of the above exemplary embodiment. For this, please refer to the above embodiment for details, which will not be described in detail here.

[0079] Through the technical solution of the embodiment of the present disclosure, on the one hand, the use of tungsten-copper composite powder with nano / ultrafine dual-scale tungsten grain distribution characteristics, compared with the use of single-size powder, the dual-scale distribution of powder has better fluidity, is not easy to stick together, and helps to improve the density and uniformity of the blank during the molding process. During the sintering process, particles of different particle sizes shrink at different rates, and small particles can fill the pores between large particles. At the same time, the interaction between large and small tungsten particles can inhibit the abnormal growth of tungsten grains, which helps to maintain the uniformity of the alloy microstructure, improve the density of the tungsten-copper alloy, and improve the comprehensive properties of the alloy such as thermal conductivity.

[0080] On the other hand, compared with direct mixing with copper powder, the surface functional groups of copper oxide powder are richer and the dispersion is better, which helps to avoid phase agglomeration and improve the composite uniformity of tungsten and copper powders, thereby effectively improving the uniformity of the organizational structure of tungsten-copper alloy, reducing interface thermal resistance, and improving the density, thermal conductivity and other properties of the material.

[0081] On the other hand, a high-density tungsten-copper alloy can be obtained by sintering at a lower sintering temperature, a shorter sintering time and a normal pressure sintering environment, which helps to reduce the sintering cost and improve the density, thermal conductivity and other comprehensive properties of the tungsten-copper alloy. In addition, compared with the tungsten-copper alloy prepared by the infiltration method and sintering of a single-size tungsten powder, the tungsten-copper alloy prepared by the embodiment of the present disclosure has a high density (≥98%), a fine and uniform tungsten grain structure (average grain size of 0.5-3.5 μm), and the tungsten and copper phases are highly connected in three-dimensional space. The tungsten-copper alloy has significantly higher comprehensive properties such as thermal conductivity.

[0082] In addition, the preparation method of the embodiment of the present disclosure is simple to operate, and the equipment used are all commonly used industrial devices. The relevant process technology can be industrially promoted on a large scale, and the prepared tungsten-copper alloy has broad application prospects in many fields such as high-power device packaging and heat dissipation materials.

[0083] The tungsten-copper alloy preparation method and the tungsten-copper alloy disclosed in the present invention are specifically described below through specific embodiments.

[0084] Example 1

[0085] The method for preparing tungsten copper alloy comprises the following steps:

[0086] Step 1: 75g of tungsten powder with an average particle size of 30nm, 18.9g of tungsten trioxide powder with an average particle size of 300nm and 12.5g of copper oxide powder with an average particle size of 300nm are placed in a zirconia ball mill, and zirconia grinding balls and anhydrous ethanol are added, and wet-milled for 12h on a planetary ball mill at 200r / min and a ball-to-material ratio of 5:1;

[0087] Step 2: After the precursor slurry obtained in step 1 is separated from the grinding balls, it is transferred to a vacuum drying oven and dried at 60° C. in a vacuum atmosphere to obtain a precursor composite powder;

[0088] Step 3: Reduce the precursor composite powder obtained in step 2 to obtain W90Cu10 composite powder (tungsten-copper composite powder). The reduction process is: first increase the temperature to 200°C at 10°C / min and keep it for 0.5h, then increase the temperature to 550°C at 10°C / min and keep it for 0.5h, and finally increase the temperature to 750°C at 5°C / min and keep it for 0.5h. The atmosphere for the reduction treatment is hydrogen.

[0089] Step 4: Use a cold isostatic press to press the W90Cu10 composite powder obtained in step 3 to obtain a W90Cu10 alloy blank, and then transfer it to a sintering furnace for sintering to obtain a W90Cu10 alloy (tungsten copper alloy). The molding pressure is 300MPa and the holding time is 10min. The sintering process is: first increase the temperature to 850℃ at 15℃ / min and keep it for 0.5h, then increase the temperature to 1000℃ at 10℃ / min and keep it for 0.5h, then increase the temperature to 1350℃ at 3℃ / min and keep it for 2h, and finally cool it to 800℃ at 7℃ / min and cool it with the furnace to obtain a tungsten copper alloy. The sintering atmosphere is hydrogen, and the sintering environment is normal pressure sintering.

[0090] Example 2

[0091] The method for preparing tungsten copper alloy comprises the following steps:

[0092] Step 1: Put 50g of tungsten powder with an average particle size of 50nm, 35.2g of tungsten dioxide powder with an average particle size of 500nm and 45g of cuprous oxide powder with an average particle size of 500nm into a zirconia ball mill, and add zirconia grinding balls and deionized water, and wet grind for 12h on a planetary ball mill at 180r / min and a ball-to-material ratio of 5:1.

[0093] Step 2: After separating the precursor slurry obtained in step 1 from the grinding balls, drying them in a forced air drying oven at 80° C. to obtain a precursor composite powder;

[0094] Step 3: Reduce the precursor composite powder obtained in step 2 to obtain W80Cu20 composite powder (tungsten-copper composite powder). The reduction process is: first increase the temperature to 250°C at 15°C / min and keep it for 0.5h, then increase the temperature to 500°C at 10°C / min and keep it for 0.5h, and finally increase the temperature to 750°C at 5°C / min and keep it for 1h, wherein the atmosphere of the reduction treatment is decomposed ammonia.

[0095] Step 4: Use a cold isostatic press to press the W80Cu20 composite powder obtained in step 3 to obtain a W80Cu20 alloy blank, and then transfer it to a sintering furnace for sintering to obtain a W80Cu20 alloy (tungsten copper alloy). The molding pressure is 250MPa and the holding time is 10min. The sintering process is: first increase the temperature to 800℃ at 15℃ / min and keep it for 0.5h, then increase the temperature to 1000℃ at 10℃ / min and keep it for 0.5h, then increase the temperature to 1250℃ at 5℃ / min and keep it for 2h, and finally cool it to 800℃ at 7℃ / min and cool it with the furnace to obtain a tungsten copper alloy. The sintering atmosphere is decomposed ammonia, and the sintering environment is normal pressure sintering.

[0096] Example 3

[0097] The method for preparing tungsten copper alloy comprises the following steps:

[0098] Step 1: Mix 50g of tungsten powder with an average particle size of 70nm and 18.6g of purple tungsten oxide (WO 2.72 ) powder and 43.75g of copper oxide powder with an average particle size of 400nm were placed in a zirconia ball mill, and zirconia grinding balls and deionized water were added, and wet grinding was carried out on a planetary ball mill at 200r / min and a ball-to-material ratio of 5:1 for 16h.

[0099] Step 2: After the precursor slurry obtained in step 1 is separated from the grinding balls, the precursor slurry is centrifugally spray-dried at an outlet air temperature of 120° C. to obtain a precursor composite powder.

[0100] Step 3: Reduce the precursor composite powder obtained in step 2 to obtain W65Cu35 composite powder (tungsten copper composite powder). The reduction process is: first increase the temperature to 300°C at 10°C / min and keep it for 0.75h, then increase the temperature to 500°C at 10°C / min and keep it for 0.5h, and finally increase the temperature to 700°C at 5°C / min and keep it for 0.5h. The atmosphere of the reduction treatment is decomposed ammonia.

[0101] Step 4: Use a cold isostatic press to press the W65Cu35 composite powder obtained in step 3 to obtain a W65Cu35 alloy blank, and then transfer it to a sintering furnace for sintering to obtain a W65Cu35 alloy (tungsten copper alloy). The molding pressure is 230MPa and the holding time is 10min. The sintering process is: first increase the temperature to 750℃ at 15℃ / min and keep it for 0.5h, then increase the temperature to 1000℃ at 10℃ / min and keep it for 0.5h, then increase the temperature to 1200℃ at 5℃ / min and keep it for 2h, and finally cool it to 800℃ at 7℃ / min and cool it with the furnace to obtain a tungsten copper alloy. The sintering atmosphere is an argon-hydrogen mixture, and the sintering environment is normal pressure sintering.

[0102] Example 4

[0103] The method for preparing tungsten copper alloy comprises the following steps:

[0104] Step 1: Put 40g of tungsten powder with an average particle size of 80nm, 10g of tungsten powder with an average particle size of 450nm and 62.5g of copper oxide powder with an average particle size of 600nm into a zirconia ball mill, and add zirconia grinding balls and anhydrous ethanol, and wet grind them for 12h on a planetary ball mill at 200r / min and a ball-to-material ratio of 5:1.

[0105] Step 2: After separating the precursor slurry obtained in step 1 from the grinding balls, the precursor slurry is dried in a vacuum drying oven at 75° C. to obtain a precursor composite powder.

[0106] Step 3: Reduce the precursor composite powder obtained in step 2 to obtain W50Cu50 composite powder (tungsten copper composite powder). The reduction process is: first increase the temperature to 300°C at 10°C / min and keep it for 1 hour, then increase the temperature to 450°C at 10°C / min and keep it for 0.2 hours, and finally increase the temperature to 600°C at 5°C / min and keep it for 0.2 hours. The atmosphere for the reduction treatment is hydrogen.

[0107] Step 4: Use a cold isostatic press to press the W50Cu50 composite powder obtained in step 3 to obtain a W50Cu50 alloy blank, and then transfer it to a sintering furnace for sintering to obtain a W50Cu50 alloy (tungsten copper alloy). The molding pressure is 200MPa and the holding time is 8min. The sintering process is: first increase the temperature to 800℃ at 15℃ / min and keep it for 0.5h, then increase the temperature to 1000℃ at 10℃ / min and keep it for 0.5h, then increase the temperature to 1150℃ at 7℃ / min and keep it for 2h, and finally cool it to 800℃ at 7℃ / min and cool it with the furnace to obtain a tungsten copper alloy. The sintering atmosphere is an argon-hydrogen mixture, and the sintering environment is normal pressure sintering.

[0108] After the tungsten copper alloy was prepared by the preparation method of Examples 1 to 4, the density of the tungsten copper alloy was measured, and the thermal conductivity of the tungsten copper alloy was measured. Among them, the density of the W90Cu10 alloy prepared in Example 1 was measured to be 17.12 g / cm 3 , which translates to a density of 98.8% and a thermal conductivity of 198W / (m·K).

[0109] like Figure 4 The SEM image of the W90Cu10 alloy surface prepared in Example 1 is shown. Figure 4 It can be seen that the grain structure of the W90Cu10 alloy is fine and uniform, without segregation. Figure 5 The energy spectrum (EDS distribution diagram) of tungsten and copper in the W90Cu10 alloy prepared in Example 1 is shown. Figure 5 It can be seen that the tungsten and copper phases in the W90Cu10 alloy are evenly distributed.

[0110] The density of the W80Cu20 alloy prepared in Example 2 is 15.53 g / cm 3 , which is converted into a density of 98.9% and a thermal conductivity of 226W / (m·K). Figure 6 The SEM image of the W80Cu20 alloy surface prepared in Example 2 is shown. Figure 6 It can be seen that the grain structure of the W80Cu20 alloy is fine and uniform, without segregation. Figure 7 The energy spectrum (EDS distribution diagram) of tungsten and copper in the W80Cu20 alloy prepared in Example 2 is shown. Figure 7 It can be seen that the tungsten and copper phases in the W80Cu20 alloy are evenly distributed.

[0111] The density of the W65Cu35 alloy prepared in Example 3 is 13.62 g / cm 3 , which is converted to a density of 99.0% and a thermal conductivity of 252 W / (m·K). The density of the W50Cu50 alloy prepared in Example 4 is 12.12 g / cm 3 , which translates to a density of 98.9% and a thermal conductivity of 298W / (m·K).

[0112] From the above, it can be seen that the tungsten-copper alloy prepared by the tungsten-copper alloy preparation method of the embodiment of the present invention has a high density (≥98%), a fine and uniform tungsten grain structure (the average grain size is 0.5-3.5 μm), and the tungsten and copper phases are evenly distributed. The uniformity of the alloy microstructure is beneficial to improving the density of the tungsten-copper alloy and improving the thermal conductivity of the alloy.

[0113] The technical solution provided by the embodiment of the present disclosure, on the one hand, compared with the use of single-size powder, the powder with dual-scale distribution has better fluidity and is not easy to stick and agglomerate, which helps to improve the density and uniformity of the blank during the molding process. On the other hand, during the sintering process, particles of different particle sizes shrink at different rates, and small particles can fill the pores between large particles. At the same time, the interaction between large and small tungsten particles can inhibit the abnormal growth of tungsten grains, which helps to maintain the uniformity of the alloy microstructure, improve the density of the alloy, and improve the comprehensive properties of the alloy such as thermal conductivity. In addition, compared with the direct composite of tungsten powder and copper powder, the surface functional groups of copper oxide powder are richer and the dispersibility is better, which helps to improve the composite uniformity of tungsten and copper powders, thereby further improving the uniformity of the organizational structure of tungsten-copper alloy, reducing the interface thermal resistance, and improving the density and thermal conductivity of tungsten-copper alloy.

[0114] It should be noted that the above embodiments are only illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure should still be covered by the claims of the present disclosure.

Claims

1. A method for preparing a tungsten-copper alloy, characterized in that: include: The composite tungsten powder containing nanocrystals and ultrafine crystals or the composite tungsten-tungsten oxide powder containing nanocrystals and ultrafine crystals is mixed with copper oxide powder to obtain a precursor slurry; Drying the precursor slurry to obtain a precursor composite powder; The precursor composite powder is subjected to staged reduction to obtain a tungsten-copper composite powder, wherein the tungsten grains in the tungsten-copper composite powder have a dual-scale distribution of nanocrystalline and ultrafine crystals; The tungsten-copper composite powder is made into a blank and sintered to obtain a tungsten-copper alloy.

2. The method according to claim 1, characterized in that If the composite tungsten powder containing nanocrystals and ultrafine crystals in dual scales is mixed with copper oxide powder to obtain a precursor slurry, the method further comprises: Compounding nano tungsten powder and ultrafine tungsten powder to obtain the compound tungsten powder containing nanocrystals and ultrafine crystals in dual scales; The particle size of the nano tungsten powder is 20-100 nm, the particle size of the ultrafine tungsten powder is 100-500 nm, and the mass ratio of the nano tungsten powder to the ultrafine tungsten powder is 1:1-5:

1.

3. The method according to claim 1, characterized in that If the composite tungsten-tungsten oxide powder containing nanocrystals and ultrafine crystals in dual scales is mixed with copper oxide powder to obtain a precursor slurry, the method further comprises: Compounding the nano tungsten powder with the ultrafine tungsten oxide powder to obtain the compound tungsten-tungsten oxide powder containing nanocrystals and ultrafine crystals in dual scales, wherein the mass ratio of the nano tungsten powder to the ultrafine tungsten oxide powder is 1:2 to 4:1; The particle size of the nano tungsten powder is 20-100 nm, the particle size of the ultrafine tungsten oxide powder is 150-700 nm, and the ultrafine tungsten oxide powder is selected from any one of yellow tungsten oxide, blue tungsten oxide, purple tungsten oxide and tungsten dioxide.

4. The method according to claim 1, characterized in that The copper oxide powder is cupric oxide or cuprous oxide, the particle size of the copper oxide powder is 30-800nm, and the purity of the copper oxide powder is ≥99.9%.

5. The method according to claim 1, characterized in that: The step of reducing the precursor composite powder in stages to obtain tungsten-copper composite powder comprises: The precursor composite powder is heated to 200-350°C at 5-20°C / min and then kept warm for 0.5-1h, and then heated to 450-600°C at 5-20°C / min and then kept warm for 0.5-2.5h, and then heated to 600-800°C at 3-10°C / min and then kept warm for 0.5-3h to obtain the tungsten-copper composite powder; Wherein, the atmosphere of the staged reduction is any one of hydrogen, decomposed ammonia and argon-hydrogen mixed gas.

6. The method according to claim 1, characterized in that The forming pressure of the tungsten-copper composite powder into a blank is 100-350 MPa, and the holding time is 5-30 minutes; The forming method is selected from any one of unidirectional pressing, bidirectional pressing or cold isostatic pressing.

7. The method according to claim 1, characterized in that The step of preparing the tungsten-copper composite powder into a blank and sintering the blank to obtain a tungsten-copper alloy comprises: The blank made of the tungsten-copper composite powder is heated to 750-850°C at 10-15°C / min and kept at this temperature for 0.5-1h, and then heated to 850-1000°C at 5-10°C / min and kept at this temperature for 0.5-1h, then heated to 1150-1500°C at 3-5°C / min and kept at this temperature for 0.5-4h, and then cooled to 600-900°C at 5-7°C / min and cooled with the furnace; The sintering atmosphere is selected from any one of hydrogen, decomposed ammonia, argon-hydrogen mixed gas and vacuum, and the sintering environment is normal pressure sintering.

8. The method according to claim 1, characterized in that The composite tungsten powder containing nanocrystals and ultrafine crystals in dual scales or the composite tungsten-tungsten oxide powder containing nanocrystals and ultrafine crystals in dual scales is ball-milled and mixed with the copper oxide powder to obtain the precursor slurry; The ball milling is wet milling, the ball milling medium is any one of deionized water, anhydrous ethanol and acetone, the ball milling speed is 100 to 500 r / min, and the ball milling time is 12 to 36 hours.

9. The method according to claim 1, characterized in that: The method of drying the precursor slurry is selected from any one of air drying, spray drying, rotary evaporation, freeze drying and vacuum drying.

10. A tungsten copper alloy, characterized in that: The tungsten-copper alloy is prepared by the tungsten-copper alloy preparation method according to any one of claims 1 to 9.

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