A fine-grain pure copper material with high temperature resistance and a preparation method thereof

Abstract

The application provides a fine-grain pure copper material resistant to high temperature and a preparation method thereof, and belongs to the field of metal processing. The method comprises the following steps: obtaining pure copper powder; performing cold isostatic pressing forming on the pure copper powder to obtain an initial blank; performing sintering on the initial blank to obtain an ingot; performing hot rolling on the ingot to obtain a hot-rolled plate; performing first cold rolling on the hot-rolled plate and then performing first annealing to obtain a first cold-rolled plate; performing second cold rolling on the first cold-rolled plate and then performing second annealing to obtain a second cold-rolled plate; performing third cold rolling on the second cold-rolled plate and then performing third annealing to obtain a fine-grain pure copper material. The pure copper material obtained by the application can realize an average grain size of < 150 mu m and an electrical conductivity of ≥ 100 % IACS at 1063 DEG C for 30 min, and better consideration is given to electrical conductivity and high-temperature microstructure stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal processing, in particular to a fine-grain pure copper material resistant to high temperature and a preparation method thereof. BACKGROUND

[0002] Oxygen-free copper has a wide application value in the electronic communication industry due to high electrical conductivity and thermal conductivity. As a key conductive and thermal material in the structure of ceramic copper-clad plate, oxygen-free copper has become an indispensable basic material in IGBT modules and is widely used in the fields of new energy vehicles, wind power and high-speed rail.

[0003] However, in actual application, the grains in the oxygen-free copper layer will significantly grow after the oxygen-free copper is compounded with the ceramic at high temperature, and the grain size can reach millimeter level, which cannot meet the requirements of subsequent use performance. In order to solve this problem, usually, a method of adding trace alloying elements is used to inhibit the growth of grains at high temperature, but the alloying elements have a great influence on the electrical conductivity of pure copper, and with the increase of the content of the alloying elements, the electrical conductivity of copper will be reduced, and it is difficult to well balance the electrical conductivity and heat resistance of pure copper. Chinese patent CN113186415A discloses a heat-resistant oxygen-free copper, but the material is suitable for use at 900 DEG C, and the compounding temperature of oxygen-free copper and aluminum oxide is usually above 1060 DEG C. How to obtain a copper material with high electrical conductivity and a fine-grain structure with a compounding temperature above 1060 DEG C has become an important direction in the field of research on high-performance pure copper. SUMMARY

[0004] The application provides a fine-grain pure copper material resistant to high temperature and a preparation method thereof, to solve the technical problem of how to balance the electrical conductivity and high-temperature organizational stability of the pure copper material.

[0005] In a first aspect, the application provides a preparation method of a fine-grain pure copper material resistant to high temperature, and the method comprises the following steps:

[0006] obtaining pure copper powder; the mass percentage of Y element in the pure copper powder is 10ppm-20ppm, the purity of the pure copper powder is 99.990%-99.999%, and the particle size is 0.5-1.0 microns;

[0007] cold isostatic pressing the pure copper powder to obtain an initial blank; the pressure of the cold isostatic pressing is 200-250 MPa, and the pressure holding time is 4-6 minutes;

[0008] sintering the initial blank to obtain an ingot;

[0009] hot rolling the ingot to obtain a hot-rolled plate;

[0010] The hot-rolled plate is first cold-rolled, and then first annealed to obtain a first cold-rolled plate;

[0011] The first cold-rolled plate is second cold-rolled, and then second annealed to obtain a second cold-rolled plate;

[0012] The second cold-rolled plate is third cold-rolled, and then third annealed to obtain a fine-grained pure copper material.

[0013] Optionally, the sintering temperature is 500-600 DEG C, and the holding time is 4-6 min.

[0014] Optionally, the hot-rolling starting temperature is 880-900 DEG C, the final rolling temperature is 700-800 DEG C, and the total deformation amount is 70-80%.

[0015] Optionally, the first cold-rolling deformation amount is 55-65%.

[0016] Optionally, the first annealing temperature is 700-750 DEG C, and the holding time is 1-2 min.

[0017] Optionally, the second cold-rolling deformation amount is 16-20%.

[0018] Optionally, the second annealing temperature is 700-750 DEG C, and the holding time is 0.5-1 min.

[0019] Optionally, the third cold-rolling deformation amount is 50-55%.

[0020] Optionally, the third annealing temperature is 180-200 DEG C, and the holding time is 30-60 min.

[0021] In a second aspect, the embodiments of the present application provide a fine-grained pure copper material prepared by the method of any one of the embodiments of the first aspect, and the fine-grained pure copper material satisfies the following performances: the average grain size after holding at 1063 DEG C for 30 min is <150 mu m, and the conductivity is ≥100% IACS.

[0022] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0023] The embodiment of the present application provides a preparation method of a fine-grain pure copper material resistant to high temperature, on the one hand, by virtue of the advantages of powder metallurgy, pure copper powder containing a trace amount of Y elements is subjected to cold isostatic pressing and sintering, so that an initial billet with ultra-fine grains can be obtained, and then uniform organization and chemical composition are realized. Meanwhile, the pure copper powder with a purity of 99.990% to 99.999% is selected, the high purity lays a foundation for high conductivity of the final material, and by controlling the mass percentage of Y elements in the powder raw material to be 10ppm to 20ppm, appropriate chemical composition and initial organization are obtained, and the subsequent deformation and annealing process is cooperated, so that the abnormal grain growth under high temperature is effectively inhibited; on the other hand, the cold rolling (first cold rolling, second cold rolling) with multiple medium deformation amounts and the recrystallization annealing are adopted, so that appropriate recrystallization grain size is obtained; the final third cold rolling and recovery annealing are combined, so that the recrystallization nucleation and growth are inhibited, and stable organization conditions for inhibiting grain boundary migration of the material under high temperature are provided. Therefore, the conductivity and high-temperature organization stability of the pure copper material are taken into account. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without any creative labor under the premise of the drawings.

[0026] Figure 1 A flowchart of a preparation method of a fine-grain pure copper material resistant to high temperature provided by the embodiment of the present application;

[0027] Figure 2 A metallographic photograph of a pure copper material provided by the embodiment 1 of the present application after being kept at 1063 DEG C for 30 min;

[0028] Figure 3 A metallographic photograph of a pure copper material provided by the embodiment 2 of the present application after being kept at 1063 DEG C for 30 min;

[0029] Figure 4 A metallographic photograph of a pure copper material provided by the embodiment 3 of the present application after being kept at 1063 DEG C for 30 min;

[0030] Figure 5 A metallographic photograph of a pure copper material provided by the embodiment 4 of the present application after being kept at 1063 DEG C for 30 min;

[0031] Figure 6The metallographic photo of the pure copper material provided for the comparative example 1 of the present application after holding at 1063℃ for 30 min;

[0032] Figure 7 The metallographic photo of the pure copper material provided for the comparative example 2 of the present application after holding at 1063℃ for 30 min;

[0033] Figure 8 The metallographic photo of the pure copper material provided for the comparative example 3 of the present application after holding at 1063℃ for 30 min;

[0034] Figure 9 The metallographic photo of the pure copper material provided for the comparative example 4 of the present application after holding at 1063℃ for 30 min;

[0035] Figure 10 The metallographic photo of the pure copper material provided for the comparative example 5 of the present application after holding at 1063℃ for 30 min. DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0037] The range descriptions described herein, such as numerical range, ratio range, etc., all include all possible sub-ranges and single values within the range, for example, the range description of "1 to 6" or "1-6" covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "include", "contain" and the like used herein mean "include but not limited to"; the relationship terms "first", "second" and the like are only used to distinguish different entities or operations, and do not imply actual sequence or relationship; "and / or" means that multiple cases can exist independently or simultaneously; "at least one", "multiple", "at least one" and the like refer to any combination of the corresponding objects, including single or multiple combinations. The ratio relationship involved herein, such as mass ratio, molar ratio, etc., should be understood as the corresponding relationship between the front and the rear in the ratio. The raw materials, reagents, instruments and equipment used herein can be purchased or prepared by existing methods.

[0038] Figure 1 The flowchart of the preparation method of a high-temperature-resistant fine-grain pure copper material provided by the embodiments of the present application.

[0039] As Figure 1 The embodiment of the present application provides a preparation method of fine-grain pure copper material with high temperature resistance, and the method comprises the following steps:

[0040] S1, obtaining pure copper powder;

[0041] In some embodiments, the mass percentage of Y element in the pure copper powder is 10ppm-20ppm, the purity of the pure copper powder is 99.990%-99.999%, and the particle size is 0.5-1.0μm.

[0042] The mass percentage of Y element in the pure copper powder is limited to 10ppm-20ppm, Y element can inhibit migration through pinning grain boundaries, so as to effectively play the role of inhibiting grain growth; meanwhile, the content range can avoid the problem of the decrease of the conductivity caused by the too high content of Y element, and then realize the good consideration of the conductivity and the high temperature stability of the pure copper material. If the mass percentage of Y element is >20ppm, two adverse effects will be produced: on the one hand, the conductivity of the pure copper will be reduced; on the other hand, it is difficult to make Y element obtain uniform content in the material, finally leading to the too large grain size of the material at high temperature. Exemplarily, the mass percentage of Y element in the pure copper powder can be 10ppm, 12ppm, 15ppm, 18ppm, 20ppm and the like.

[0043] The purity of the pure copper powder is limited to 99.990%-99.999%, which is the basis for ensuring the high conductivity of the final pure copper material. Exemplarily, the purity of the pure copper powder can be 99.990%, 99.992%, 99.995%, 99.997%, 99.999% and the like.

[0044] The particle size of the pure copper powder is limited to 0.5-1.0μm, so that more uniform structure and chemical composition can be obtained, and the uniformity of the structure in the subsequent process is ensured. Exemplarily, the particle size of the pure copper powder can be 0.5μm, 0.6μm, 0.7μm, 0.8μm, 1μm and the like.

[0045] S2, the pure copper powder is cold isostatic pressed to obtain an initial blank;

[0046] In some embodiments, the pressure of the cold isostatic pressing is 200-250MPa, and the pressure holding time is 4-6min;

[0047] The pressure of the cold isostatic compaction is limited to 200MPa-250MPa, and the pressure holding time is 4min-6min, which can ensure the uniform densification of the pure copper powder, avoid defects in the structure, and ensure the uniform distribution of the chemical composition, thereby providing a high-quality initial blank for subsequent sintering and processing. For example, the pressure of the cold isostatic compaction can be 200MPa, 210MPa, 230MPa, 240MPa, 250MPa, etc., and the pressure holding time can be 4min, 4.5min, 5min, 5.5min, 6min, etc.

[0048] S3, sintering the initial blank to obtain an ingot;

[0049] The initial blank after cold isostatic pressing is sintered into an ingot in the embodiments of the present application, which can obtain an initial ingot with ultra-fine grains in combination with the advantages of powder metallurgy.

[0050] In some embodiments, the sintering temperature is 500℃-600℃, and the holding time is 4min-6min.

[0051] The sintering temperature is limited to 500℃-600℃, and the holding time is 4min-6min, which can realize the combination of powder particles while avoiding excessive grain growth, and in combination with the fine particle size characteristics of the pure copper powder, an ingot with ultra-fine grains and uniform structure is finally obtained, thereby providing a good foundation for subsequent deformation processing. For example, the sintering temperature can be 500℃, 520℃, 550℃, 580℃, 600℃, etc., and the holding time can be 4min, 4.5min, 5min, 5.5min, 6min, etc.

[0052] S4, hot rolling the ingot to obtain a hot-rolled plate;

[0053] The initial structure can be controlled by hot rolling in the embodiments of the present application, thereby providing a suitable initial state for grain regulation in subsequent multiple deformation and annealing processes.

[0054] In some embodiments, the opening rolling temperature is 880℃-900℃, the final rolling temperature is 700℃-800℃, and the total deformation amount is 70%-80%.

[0055] The opening rolling temperature is limited to 880℃-900℃, the final rolling temperature is 700℃-800℃, and the total deformation amount is 70%-80%, which can refine or adjust the initial grain structure of the ingot, thereby ensuring the stability of the structure evolution in subsequent processes. For example, the opening rolling temperature can be 880℃, 885℃, 890℃, 895℃, 900℃, etc., the final rolling temperature can be 700℃, 720℃, 750℃, 780℃, 800℃, etc., and the total deformation amount can be 70%, 72%, 75%, 78%, 80%, etc.

[0056] S5, performing first cold rolling on the hot-rolled plate, and then performing first annealing to obtain a first cold-rolled plate;

[0057] It should be noted that the present application obtains appropriate recrystallized grain size through multiple medium deformation amounts and recrystallization heat treatment, and in combination with final recovery annealing, recrystallization nucleation and growth can be inhibited, and organizational conditions for inhibiting grain boundary migration at high temperature are provided.

[0058] The first cold rolling and the first annealing belong to the first step of the multiple medium deformation amounts and recrystallization heat treatment, and the purpose is to obtain appropriate recrystallized grain size.

[0059] In some embodiments, the deformation amount of the first cold rolling is 55% to 65%.

[0060] The first cold rolling deformation amount is limited to 55% to 65%, and the medium deformation amount provides sufficient energy storage for subsequent recrystallization and promotes recrystallization nucleation. For example, the deformation amount of the first cold rolling can be 55%, 57%, 60%, 63%, 65%, etc.

[0061] In some embodiments, the temperature of the first annealing is 700°C to 750°C, and the holding time is 1 min to 2 min.

[0062] The first annealing temperature is limited to 700°C to 750°C, and the holding time is limited to 1 min to 2 min. Under this condition, the recrystallization heat treatment can adjust the grain size after recrystallization to a suitable range, laying a foundation for subsequent steps. For example, the temperature of the first annealing can be 700°C, 710°C, 730°C, 740°C, 750°C, etc., and the holding time can be 1 min, 1.2 min, 1.5 min, 1.8 min, 2 min, etc.

[0063] S6, performing second cold rolling on the first cold-rolled plate, and then performing second annealing to obtain a second cold-rolled plate;

[0064] The second cold rolling and the second annealing are the second step of the multiple medium deformation amounts and recrystallization heat treatment, which further adjusts the recrystallized grain size and optimizes the uniformity of the structure.

[0065] In some embodiments, the deformation amount of the second cold rolling is 16% to 20%.

[0066] The second cold rolling deformation amount is limited to 16% to 20%, and the energy storage is continued through the medium deformation amount to refine or adjust the structure. For example, the deformation amount of the second cold rolling can be 16%, 17%, 18%, 19%, 20%, etc.

[0067] In some embodiments, the second annealing temperature is 700-750℃, and the holding time is 0.5-1min.

[0068] The second annealing temperature is limited to 700-750℃, and the holding time is limited to 0.5-1min, so that the grain size is further optimized by recrystallization heat treatment, the uniformity of the structure is ensured, and the high-temperature stability is supported. For example, the second annealing temperature can be 700℃, 710℃, 730℃, 740℃, 750℃, etc., and the holding time can be 0.5min, 0.6min, 0.8min, 0.9min, 1min, etc.

[0069] S7, the second cold-rolled plate is subjected to third cold rolling, and then subjected to third annealing to obtain a fine-grained pure copper material.

[0070] The third cold rolling and the third annealing inhibit recrystallization nucleation and growth by final deformation and recovery annealing, and provide a structural condition for inhibiting grain boundary migration at high temperatures.

[0071] In some embodiments, the deformation amount of the third cold rolling is 50-55%.

[0072] The third cold rolling deformation amount is limited to 50-55%, so that the energy is accumulated by a large deformation amount, but the structural defects caused by excessive deformation are avoided. For example, the deformation amount of the third cold rolling can be 50%, 51%, 53%, 54%, 55%, etc.

[0073] In some embodiments, the third annealing temperature is 180-200℃, and the holding time is 30-60min.

[0074] The third annealing temperature is limited to 180-200℃, and the holding time is limited to 30-60min, so that the temperature is a recovery annealing temperature, part of the internal stress can be eliminated, and recrystallization nucleation and growth are inhibited, so that a stable structure that can resist grain boundary migration at high temperatures is finally formed, and the average grain size of the material is ensured to be <150μm after being kept at 1063℃ for 30min. For example, the third annealing temperature can be 180℃, 185℃, 190℃, 195℃, 200℃, etc., and the holding time can be 30min, 40min, 50min, 55min, 60min, etc.

[0075] Therefore, by adopting the powder metallurgy method, an initial billet with ultra-fine grains can be obtained, and uniform structure and chemical composition can be realized. In addition, by controlling the content of trace alloying elements in high-purity copper, such as the addition of Y element, a suitable chemical composition and initial structure can be obtained, and the subsequent deformation and annealing process can be controlled to inhibit abnormal grain growth at high temperatures. At the same time, the process adopted by the method is easy to control, low in cost, and suitable for industrial production.

[0076] Based on the overall inventive concept, the embodiment of the present application provides a fine-grained pure copper material prepared by the method described in any one of the above embodiments, wherein the fine-grained pure copper material satisfies the following performance: the average grain size after heat preservation at 1063℃ for 30min is <150μm, and the conductivity is ≥100%IACS.

[0077] The pure copper material prepared by the embodiment of the present application is a copper strip or a copper foil, which can realize the average grain size of <150μm and the conductivity of ≥100%IACS after heat preservation at 1063℃ for 30min, and better balances the electrical conductivity and high-temperature microstructure stability, the method is easy to control, low in cost, and suitable for industrial production.

[0078] The fine-grained pure copper material is realized based on the preparation method of the fine-grained pure copper material, and the specific steps of the preparation method of the fine-grained pure copper material can be referred to the above embodiments. Since the fine-grained pure copper material adopts part or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0079] In summary, the present application realizes the balance between the electrical conductivity and the high-temperature microstructure stability of the pure copper material through multi-linkage synergistic regulation, and the specific mode is as follows:

[0080] (1) Raw material control lays the foundation: pure copper powder with a purity of 99.990% to 99.999% is selected, and high purity is the basis for ensuring high conductivity of the final material; at the same time, the mass percentage of Y element is controlled to be 10ppm to 20ppm, which not only pins the grain boundary through Y element to inhibit high-temperature grain growth (to ensure high-temperature stability), but also avoids the decrease of electrical conductivity due to too high Y element content, in addition, fine particle size (0.5μm to 1.0μm) pure copper powder ensures uniform organization and chemical composition, providing a prerequisite for the balance of the two.

[0081] (2) Powder metallurgy and forming process optimization of initial organization: uniform and fine initial blank is obtained by cold isostatic pressing (200MPa to 250MPa, pressure holding for 4min to 6min); at the same time, through low-temperature short-time sintering (500℃ to 600℃, heat preservation for 4min to 6min) combined with fine powder, ultra-fine grain and uniform organization blank is formed, providing a high-quality matrix for subsequent performance regulation.

[0082] (3) Multi-step deformation and annealing process synergistically regulates the stability of the microstructure: The initial microstructure is controlled by hot rolling (opening rolling 880-900℃, final rolling 700-800℃, total deformation 70-80%) to ensure the stability of subsequent grain regulation; at the same time, through multiple cold rolling with moderate deformation (first 55-65%, second 16-20%) and recrystallization annealing (700-750℃), appropriate recrystallized grain size is obtained to optimize the uniformity of the microstructure; finally, through the third cold rolling (50-55%) to accumulate energy storage, combined with low temperature recovery annealing (180-200℃, holding for 30-60min) to inhibit recrystallization nucleation and growth, a stable microstructure that can resist high temperature grain boundary migration is formed, ensuring that the average grain size is <150μm after 1063℃ holding for 30min.

[0083] (4) Performance guarantee result: The final prepared copper strip / copper foil ensures the electrical conductivity ≥100%IACS through high-purity raw materials and low Y element content, and realizes the stability of the grain size at high temperature (<150μm) through the above microstructure regulation, so as to balance the electrical conductivity and high-temperature microstructure stability.

[0084] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples without specific conditions are generally determined according to the industry standards. If there is no corresponding industry standard, it is determined according to the general international standards, conventional conditions, or according to the conditions suggested by the manufacturer.

[0085] Example 1

[0086] The present embodiment provides a method for preparing a high-temperature-resistant fine-grained pure copper material, which comprises the following steps:

[0087] S11, obtaining a pure copper powder;

[0088] wherein the mass percentage of Y element in the pure copper powder is 10ppm, the purity of the pure copper powder is 99.999%, and the particle size is 0.5-1.0μm;

[0089] S21, cold isostatic pressing the pure copper powder to obtain an initial billet;

[0090] wherein the pressure of the cold isostatic pressing is 250MPa, and the holding time is 5min;

[0091] S31, sintering the initial billet to obtain an ingot;

[0092] wherein the sintering temperature is 500℃, and the holding time is 5min;

[0093] S41, hot-rolling the blank ingot to obtain a hot-rolled plate;

[0094] The hot-rolling has a starting rolling temperature of 900 DEG C and a final rolling temperature of 700 DEG C, and a total deformation of 70%;

[0095] S51, first cold-rolling the hot-rolled plate and then first annealing to obtain a first cold-rolled plate;

[0096] The first cold-rolling has a deformation of 55%;

[0097] The first annealing has a temperature of 700 DEG C and a holding time of 2 min;

[0098] S61, second cold-rolling the first cold-rolled plate and then second annealing to obtain a second cold-rolled plate;

[0099] The second cold-rolling has a deformation of 16%;

[0100] The second annealing has a temperature of 700 DEG C and a holding time of 1 min;

[0101] S71, third cold-rolling the second cold-rolled plate and then third annealing to obtain a fine-grained pure copper material;

[0102] The third cold-rolling has a deformation of 50%;

[0103] The third annealing has a temperature of 190 DEG C and a holding time of 30 min.

[0104] The metallographic photograph of the pure copper material obtained in this example after holding at 1063 DEG C for 30 min is shown in FIG. 2. Figure 2 The grain size distribution is uniform, and the average grain size is less than 150 μm.

[0105] Example 2

[0106] This example provides a method for preparing a high-temperature-resistant fine-grained pure copper material, which comprises the following steps:

[0107] S11, obtaining a pure copper powder;

[0108] The pure copper powder has a purity of 99.990%, a particle size of 0.5 μm to 1.0 μm, and a mass percentage of Y element of 20 ppm;

[0109] S21, cold isostatic pressing the pure copper powder to obtain an initial blank;

[0110] The cold isostatic pressing has a pressure of 200 MPa and a holding time of 5 min;

[0111] S31, sintering the initial blank to obtain an ingot;

[0112] The sintering temperature is 600 DEG C, and the holding time is 5 min.

[0113] S41, hot rolling the ingot to obtain a hot-rolled plate;

[0114] The hot rolling temperature is 880 DEG C, the final rolling temperature is 800 DEG C, and the total deformation amount is 80%.

[0115] S51, first cold rolling the hot-rolled plate, and then first annealing to obtain a first cold-rolled plate;

[0116] The first cold rolling deformation amount is 65%.

[0117] The first annealing temperature is 750 DEG C, and the holding time is 1 min.

[0118] S61, second cold rolling the first cold-rolled plate, and then second annealing to obtain a second cold-rolled plate;

[0119] The second cold rolling deformation amount is 20%.

[0120] The second annealing temperature is 750 DEG C, and the holding time is 0.5 min.

[0121] S71, third cold rolling the second cold-rolled plate, and then third annealing to obtain a fine-grained pure copper material;

[0122] The third cold rolling deformation amount is 52%.

[0123] The third annealing temperature is 190 DEG C, and the holding time is 60 min.

[0124] The metallographic photograph of the pure copper material obtained in this embodiment after holding at 1063 DEG C for 30 min is shown in Figure 3 The grain size distribution is uniform, and the average grain size is less than 150 μm.

[0125] Example 3

[0126] The embodiment provides a preparation method of a high-temperature-resistant fine-grained pure copper material, and the method comprises the following steps:

[0127] S11, obtaining a pure copper powder;

[0128] The mass percentage of Y element in the pure copper powder is 15 ppm, the purity of the pure copper powder is 99.995%, and the particle size is 0.5-1.0 μm.

[0129] S21, cold isostatic pressing the pure copper powder to obtain an initial blank;

[0130] The pressure of the cold isostatic pressing is 220 MPa, and the pressure holding time is 5 min.

[0131] S31, sintering the initial blank to obtain an ingot;

[0132] The temperature of the sintering is 550 DEG C, and the holding time is 5 min.

[0133] S41, hot rolling the ingot to obtain a hot-rolled plate;

[0134] The open rolling temperature of the hot rolling is 900 DEG C, the finish rolling temperature is 750 DEG C, and the total deformation amount of rolling is 75%.

[0135] S51, first cold rolling the hot-rolled plate, and then first annealing to obtain a first cold-rolled plate;

[0136] The deformation amount of the first cold rolling is 60%.

[0137] The temperature of the first annealing is 720 DEG C, and the holding time is 1.5 min.

[0138] S61, second cold rolling the first cold-rolled plate, and then second annealing to obtain a second cold-rolled plate;

[0139] The deformation amount of the second cold rolling is 18%.

[0140] The temperature of the second annealing is 720 DEG C, and the holding time is 1 min.

[0141] S71, third cold rolling the second cold-rolled plate, and then third annealing to obtain a fine-grained pure copper material;

[0142] The deformation amount of the third cold rolling is 55%.

[0143] The temperature of the third annealing is 190 DEG C, and the holding time is 50 min.

[0144] The metallographic photograph of the pure copper material obtained in this embodiment after holding at 1063 DEG C for 30 min is shown in FIG. 2. Figure 4 The grain size distribution is uniform, and the average grain size is less than 150 μm.

[0145] Example 4

[0146] The embodiment provides a preparation method of a high-temperature-resistant fine-grained pure copper material.

[0147] S11, obtaining a pure copper powder;

[0148] The mass percentage of the element Y in the pure copper powder is 17 ppm, the purity of the pure copper powder is 99.995%, and the particle size is 0.5-1.0 μm.

[0149] S21, cold isostatic pressing the pure copper powder to obtain an initial blank;

[0150] The pressure of the cold isostatic pressing is 220 MPa, and the pressure holding time is 5 min.

[0151] S31, sintering the initial blank to obtain an ingot;

[0152] The sintering temperature is 580°C, and the holding time is 5 min.

[0153] S41, hot rolling the ingot to obtain a hot-rolled plate;

[0154] The hot rolling temperature is 900°C, the final rolling temperature is 750°C, and the total deformation amount of rolling is 80%.

[0155] S51, first cold rolling the hot-rolled plate, and then first annealing to obtain a first cold-rolled plate;

[0156] The deformation amount of the first cold rolling is 60%.

[0157] The first annealing temperature is 720°C, and the holding time is 1.5 min.

[0158] S61, second cold rolling the first cold-rolled plate, and then second annealing to obtain a second cold-rolled plate;

[0159] The deformation amount of the second cold rolling is 18%.

[0160] The second annealing temperature is 720°C, and the holding time is 1 min.

[0161] S71, third cold rolling the second cold-rolled plate, and then third annealing to obtain a fine-grained pure copper material;

[0162] The deformation amount of the third cold rolling is 55%.

[0163] The third annealing temperature is 190°C, and the holding time is 50 min.

[0164] The metallographic photograph of the pure copper material obtained in this example after holding at 1063°C for 30 min is shown in Figure 5 The grain size distribution is uniform, and the average grain size is less than 150 μm.

[0165] Comparative Example 1

[0166] The present comparative example provides a preparation method of a pure copper material, comprising the following steps:

[0167] S11, obtaining a pure copper ingot by casting;

[0168] The mass percentage of Y element in the pure copper ingot is 10ppm, and the purity of the pure copper ingot is 99.999%.

[0169] S21, hot rolling the pure copper ingot to obtain a hot-rolled plate;

[0170] The opening rolling temperature of the hot rolling is 900℃, the final rolling temperature is 700℃, and the total deformation amount of rolling is 70%.

[0171] S31, first cold rolling the hot-rolled plate, and then first annealing to obtain a first cold-rolled plate;

[0172] The deformation amount of the first cold rolling is 55%.

[0173] The temperature of the first annealing is 700℃, and the holding time is 2min.

[0174] S41, second cold rolling the first cold-rolled plate, and then second annealing to obtain a second cold-rolled plate;

[0175] The deformation amount of the second cold rolling is 16%.

[0176] The temperature of the second annealing is 700℃, and the holding time is 1min.

[0177] S71, third cold rolling the second cold-rolled plate, and then third annealing to obtain a pure copper material;

[0178] The deformation amount of the third cold rolling is 50%.

[0179] The temperature of the third annealing is 190℃, and the holding time is 30min.

[0180] The metallographic photograph of the pure copper material obtained by the comparative example after holding at 1063℃ for 30min is shown in FIG. 2. Figure 6 The grain size distribution is uneven, and the size of individual grains reaches 1mm or more.

[0181] Comparative Example 2

[0182] The present comparative example is based on Example 2, and the specific adjustments are as follows:

[0183] The pure copper powder does not contain Y element, and the purity of the pure copper powder is 99.990%, and the particle size is 0.5μm-1.0μm.

[0184] The metallographic photograph of the pure copper material obtained from the comparative example after holding at 1063°C for 30 min is shown in FIG. 2, and the grain size distribution is relatively uniform, but most of the grain sizes are close to 1 mm. Figure 7

[0185] Comparative Example 3

[0186] The present comparative example provides a preparation method of a pure copper material, and the method comprises the following steps:

[0187] S11, obtaining a pure copper powder;

[0188] The mass percentage of the element Y in the pure copper powder is 17 ppm, the purity of the pure copper powder is 99.990%, and the particle size is 0.5-1.0 μm.

[0189] S21, cold isostatic pressing the pure copper powder to obtain an initial blank;

[0190] The pressure of the cold isostatic pressing is 200 MPa, and the pressure holding time is 5 min.

[0191] S31, sintering the initial blank to obtain an ingot;

[0192] The sintering temperature is 600°C, and the holding time is 5 min.

[0193] S41, hot rolling the ingot to obtain a hot-rolled plate;

[0194] The opening rolling temperature is 880°C, the final rolling temperature is 800°C, and the total deformation amount of rolling is 80%.

[0195] S51, cold rolling the hot-rolled plate and then annealing to obtain a pure copper material;

[0196] The deformation amount of the cold rolling is 85%.

[0197] The annealing temperature is 190°C, and the holding time is 60 min.

[0198] The metallographic photograph of the pure copper material obtained from the comparative example after holding at 1063°C for 30 min is shown in FIG. 2, and the grain size distribution is relatively uniform, but most of the grain sizes are close to 1 mm. Figure 8

[0199] Comparative Example 4

[0200] The present comparative example provides a preparation method of a pure copper material, and the method comprises the following steps:

[0201] S11, obtaining a pure copper powder; ​​

[0202] The mass percentage of the element Y in the pure copper powder is 17 ppm, the purity of the pure copper powder is 99.990%, and the particle size is 0.5-1.0 μm.

[0203] S21, cold isostatic pressing the pure copper powder to obtain an initial blank;

[0204] The pressure of the cold isostatic pressing is 200 MPa, and the pressure holding time is 5 min.

[0205] S31, sintering the initial blank to obtain an ingot;

[0206] The sintering temperature is 600°C, and the holding time is 5 min.

[0207] S41, hot rolling the ingot to obtain a hot-rolled plate;

[0208] The hot rolling temperature is 880°C, the finish rolling temperature is 800°C, and the total deformation amount of rolling is 80%.

[0209] S51, first cold rolling the hot-rolled plate, and then first annealing to obtain a first cold-rolled plate;

[0210] The deformation amount of the first cold rolling is 65%.

[0211] The first annealing temperature is 750°C, and the holding time is 1 min.

[0212] S61, second cold rolling the first cold-rolled plate, and then second annealing to obtain a second cold-rolled plate;

[0213] The deformation amount of the second cold rolling is 20%.

[0214] The second annealing temperature is 750°C, and the holding time is 0.5 min.

[0215] S71, third cold rolling the second cold-rolled plate to obtain a pure copper material;

[0216] The deformation amount of the third cold rolling is 52%.

[0217] The metallographic photograph of the pure copper material after holding at 1063°C for 30 min is shown in Figure 9 Most of the grain sizes are more than 1 mm.

[0218] Comparative Example 5

[0219] This comparative example is based on Example 2, and the specific adjustments are as follows:

[0220] The mass percentage of Y element in the pure copper powder is 25ppm, the purity of the pure copper powder is 99.990%, and the particle size is 0.5μm-1.0μm.

[0221] The metallographic photograph of the pure copper material obtained by the comparative example after holding at 1063℃ for 30min is shown in FIG. 1, and the grain size distribution is relatively uniform, but most of the grain sizes are close to 1mm. Figure 10

[0222] The grain information of the pure copper materials prepared in Examples 1-4 and Comparative Examples 1-5 after holding at 1063℃ for 30min is summarized, and the electrical conductivity of each pure copper material is measured, and the related results are shown in Table 1.

[0223]

[0224] As shown in Table 1, the average grain size of the fine-grained pure copper materials in Examples 1-4 after holding at 1063℃ for 30min is <150μm, and the electrical conductivity is ≥100%IACS.

[0225] Comparative Example 1 uses casting to obtain pure copper ingot, and the casting process cannot obtain ultra-fine grains and uniform structure as powder metallurgy, and the initial blank has coarse or uneven grain structure. Although the same hot rolling, cold rolling and annealing process is used, the initial structure is defective, and the abnormal growth of grains at high temperature cannot be inhibited, which finally leads to uneven grain size distribution after holding at 1063℃, and individual grain size is more than 1mm.

[0226] Comparative Example 2 does not add Y element, which lacks the key grain boundary pinning effect. Even if the purity, particle size of the pure copper powder and the subsequent process are consistent, the grain boundary migration at high temperature cannot be effectively inhibited, which finally leads to most of the grain sizes close to 1mm.

[0227] Comparative Example 3 only performs one cold rolling with large deformation (85%) and one annealing, and does not undergo multiple intermediate deformation and recrystallization heat treatment, so that it cannot form suitable recrystallized grain size and uniform structure, which leads to difficulty in stabilizing the grains at high temperature, and most of the grain sizes are close to 1mm.

[0228] Comparative Example 4 does not perform annealing after the third cold rolling, which cannot inhibit recrystallization, and the internal structure of the material cannot form a stable high-temperature growth-resistant structure, which finally leads to most of the grain sizes exceeding 1mm after holding at 1063℃ for 30min.

[0229] Comparative Example 5 will induce grain growth at high temperature when the Y content exceeds a certain content, so that the final grain size reaches mm level.

[0230] ​The foregoing detailed description of the application has been presented for purposes of illustration and description. Various modifications and changes can be made to these embodiments without departing from the spirit and scope of the application. It is intended that the scope of the application should not be limited by the particular representative embodiments described above.

Claims

1. A method for producing a fine-grained pure copper material resistant to high temperatures, characterized in that, The method comprises: obtaining pure copper powder; the mass percentage of Y element in the pure copper powder is 10 ppm to 20 ppm, the purity of the pure copper powder is 99.990% to 99.999%, and the particle size is 0.5 μm to 1.0 μm; the pure copper powder is cold isostatic pressed to obtain an initial blank; the pressure of the cold isostatic pressing is 200 MPa to 250 MPa, and the pressure maintaining time is 4 min to 6 min; the initial blank is sintered to obtain an ingot; the ingot is hot rolled to obtain a hot-rolled plate; the opening rolling temperature of the hot rolling is 880 ℃ to 900 ℃, the final rolling temperature is 700 ℃ to 800 ℃, and the total deformation amount of rolling is 70% to 80%; the hot-rolled plate is first cold rolled and then first annealed to obtain a first cold-rolled plate; the deformation amount of the first cold rolling is 55% to 65%; the temperature of the first annealing is 700 ℃ to 750 ℃, and the holding time is 1 min to 2 min; the first cold-rolled plate is second cold rolled and then second annealed to obtain a second cold-rolled plate; the deformation amount of the second cold rolling is 16% to 20%; the temperature of the second annealing is 700 ℃ to 750 ℃, and the holding time is 0.5 min to 1 min; the second cold-rolled plate is third cold rolled and then third annealed to obtain a fine-grained pure copper material; the deformation amount of the third cold rolling is 50% to 55%; the temperature of the third annealing is 180 ℃ to 200 ℃, and the holding time is 30 min to 60 min; the fine-grained pure copper material satisfies the following performances: the average grain size after being kept at 1063 ℃ for 30 min is less than 150 μm, and the conductivity is greater than or equal to 100% IACS.

2. The method of claim 1, wherein, The temperature of the sintering is 500 ℃ to 600 ℃, and the holding time is 4 min to 6 min.

3. A fine-grained pure copper material produced by the method as claimed in claim 1 or 2, characterized in that The fine-grained pure copper material satisfies the following performances: the average grain size after being kept at 1063 ℃ for 30 min is less than 150 μm, and the conductivity is greater than or equal to 100% IACS. The fine-grained pure copper material satisfies the following performances: the average grain size after being kept at 1063 ℃ for 30 min is less than 150 μm, and the conductivity is greater than or equal to 100% IACS.

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