Single crystal graphite and preparation method thereof
By growing single-crystal graphite on a graphite substrate in a non-oxidizing atmosphere and consuming or peeling off the metal substrate, the wrinkling problem caused by the difference in thermal expansion coefficients during the cooling process of single-crystal graphite was solved, realizing the preparation of wrinkle-free large-size single-crystal graphite, simplifying the process and reducing costs.
Patent Information
- Application Number
- CN202511284294.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2025-11-04
AI Technical Summary
In existing technologies, large-size single-crystal graphite wrinkles during cooling due to the difference in thermal expansion coefficients between graphite and the metal substrate, which limits its application.
Using graphite substrate as carbon source, single-crystal graphite is grown in a non-oxidizing atmosphere using heating equipment, and wrinkles caused by the difference in thermal expansion coefficients are avoided by consuming or peeling off the single-crystal metal substrate and graphite substrate.
Large-size single-crystal graphite without wrinkles was obtained, which simplified the preparation process, reduced costs and improved safety, and avoided the need to use highly toxic etching gases.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of material preparation, in particular to a single crystal graphite and a preparation method thereof. BACKGROUND
[0002] In some application scenarios, large-size single crystal graphite needs to be used. At present, large-size single crystal graphite is generally obtained by growing on a single crystal nickel substrate. However, due to the difference in thermal expansion coefficients between graphite and nickel, the graphite grown on nickel at high temperature will wrinkle during the cooling process, causing the graphite to split into small flat areas, which greatly limits the size of the graphite and affects its application.
[0003] Therefore, how to obtain large-size single crystal graphite without wrinkles is a technical problem to be solved by those skilled in the art. SUMMARY
[0004] The purpose of the present application is to provide a single crystal graphite and a preparation method thereof to obtain single crystal graphite without wrinkles.
[0005] To solve the above technical problems, the present application provides a preparation method of single crystal graphite, comprising:
[0006] placing a single crystal metal substrate on the surface of a graphite base material, and placing the single crystal metal substrate and the graphite base material in the cavity of a heating device; wherein the graphite base material serves as a carbon source for the growth of single crystal graphite;
[0007] heating the single crystal metal substrate and the graphite base material when the cavity is in a non-oxidizing atmosphere, to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and removing the single crystal metal substrate and the graphite base material to obtain single crystal graphite.
[0008] Optionally, any one of single crystal nickel, single crystal iron, single crystal cobalt, single crystal platinum, single crystal palladium, single crystal nickel-based alloy, single crystal iron-based alloy, and single crystal cobalt-based alloy.
[0009] Optionally, when the ratio of the thickness of the graphite base material to the thickness of the single crystal metal substrate is Q, Q≥5, heating the single crystal metal substrate and the graphite base material to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and removing the single crystal metal substrate and the graphite base material comprises:
[0010] heating the single crystal metal substrate and the graphite base material to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material by heating the single crystal metal substrate and the graphite base material to a first temperature and maintaining the temperature.
[0011] The heating device continues to increase temperature to a second temperature and keeps constant, and the nickel in the single-crystal metal substrate is penetrated into the graphite base material to be consumed and removed; the first temperature is less than the second temperature.
[0012] The graphite base material is removed.
[0013] Optionally, when the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, Q≥5, the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material, and the single-crystal metal substrate and the graphite base material are removed, comprising:
[0014] The heating device increases temperature to a second temperature and keeps constant, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material, and the metal in the single-crystal metal substrate is penetrated out of the graphite base material to be consumed and removed;
[0015] The graphite base material is removed.
[0016] Optionally, when the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, 0.5≤Q<5, the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material, and the single-crystal metal substrate and the graphite base material are removed, comprising:
[0017] The heating device increases temperature to a first temperature and keeps constant, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material;
[0018] The heating device continues to increase temperature to a second temperature and keeps constant to consume and remove the graphite base material, and further to volatilize and remove the metal in the single-crystal metal substrate; the first temperature is less than the second temperature.
[0019] Optionally, when the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, 0.5≤Q<5, the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material, and the single-crystal metal substrate and the graphite base material are removed, comprising:
[0020] The heating device increases temperature to a second temperature and keeps constant, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite base material, and the graphite base material is dissolved into the single-crystal metal substrate, and the metal in the single-crystal metal substrate is further volatilized and removed.
[0021] Optionally, the first temperature is in the range of 1100-1350℃, and the holding time is at least 10 hours; the second temperature is in the range of 1380-1450℃, and the holding time is at least 10 hours.
[0022] Optionally, the second temperature is in the range of 1450-2500℃, and the holding time is at least 10 hours, preferably, the temperature is in the range of 1800-2200℃, and the holding time is at least 5 hours.
[0023] Optionally, after the metal in the single-crystal metal substrate is removed by volatilization, the method further comprises:
[0024] immersing the single-crystal graphite in a solution to remove the metal and metal-containing substances on the surface of the single-crystal graphite;
[0025] removing the solution and graphite attachments remaining on the surface of the single-crystal graphite.
[0026] Optionally, after the graphite substrate is removed, and before the nickel in the single-crystal metal substrate is removed by volatilization, the method further comprises:
[0027] reducing the pressure in the cavity to a target low pressure.
[0028] Optionally, the target low pressure is less than or equal to 0.2 Pa.
[0029] Optionally, the heating rate is in the range of 0.05-30℃ / min.
[0030] Optionally, after the single-crystal metal substrate and the graphite substrate are removed, the method further comprises:
[0031] cooling the heating device to room temperature, wherein the cooling rate is less than 10℃ / min.
[0032] Optionally, before the single-crystal metal substrate and the graphite substrate are heated, the method further comprises:
[0033] using a vacuum pump to pump the cavity of the heating device to reduce the pressure in the cavity to a target low pressure;
[0034] introducing hydrogen and inert gas into the cavity to normal pressure, so that the atmosphere in the cavity is hydrogen and inert gas.
[0035] Optionally, the target low pressure is less than or equal to 0.2 Pa.
[0036] The application also provides a single-crystal graphite prepared by any one of the above-mentioned methods.
[0037] The application provides a single crystal graphite preparation method, which comprises the following steps: placing a single crystal metal substrate on the surface of a graphite base material, and placing the single crystal metal substrate and the graphite base material in the cavity of a heating device; wherein the graphite base material serves as the carbon source of the single crystal graphite; when the cavity is in a non-oxidizing atmosphere, the single crystal metal substrate and the graphite base material are heated, so that the single crystal graphite is grown on the surface of the single crystal metal substrate away from the graphite base material, and the single crystal metal substrate and the graphite base material are removed in situ, thereby obtaining the single crystal graphite, which does not need to replace the device, reduces the contamination possibility and improves the efficiency.
[0038] It can be seen that in the application, the graphite base material is used as the carbon source when the single crystal graphite is prepared, the single crystal metal substrate is placed on the surface of the graphite base material, and then the single crystal metal substrate and the graphite base material are placed in the heating device for heating, so that the single crystal graphite is grown at high temperature, and then the single crystal metal substrate is consumed, and the graphite base is consumed or peeled off. The method provided in the application can avoid the wrinkles of the single crystal graphite caused by the difference in the thermal expansion coefficient between the single crystal graphite grown on the single crystal metal substrate and the single crystal metal substrate during the cooling process, so that the single crystal graphite without wrinkles is obtained.
[0039] In addition, the application also provides single crystal graphite without wrinkles. BRIEF DESCRIPTION OF DRAWINGS
[0040] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.
[0041] Figure 1 A flow chart of the single crystal graphite preparation method provided by the embodiments of the application is provided.
[0042] Figure 2 A single crystal graphite preparation method provided by the embodiments of the application is shown in the figure. Figure One ;
[0043] Figure 3 A single crystal graphite preparation method provided by the embodiments of the application is shown in the figure. Figure Two . DETAILED DESCRIPTION
[0044] For the person skilled in the art to better understand the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application.
[0045] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.
[0046] As described in the background section, at present, large-size single crystal graphite is generally grown on a single crystal metal substrate, but due to the difference in thermal expansion coefficient between graphite and metal, the graphite grown on the metal at high temperature will wrinkle during cooling, causing the graphite to split into small flat areas, greatly limiting the size of the graphite and affecting its application.
[0047] Therefore, the present application provides a preparation method of single crystal graphite, please refer to Figure 1 The method can include:
[0048] Step S101: placing a single crystal metal substrate on the surface of a graphite base material, and placing the single crystal metal substrate and the graphite base material in the cavity of a heating device; wherein the graphite base material serves as a carbon source for single crystal graphite.
[0049] The graphite base material refers to an object whose material is graphite, such as graphite paper, ordinary graphite sheet, pyrolytic graphite plate, and sheet material pressed from graphite powder, etc.
[0050] The heating device can be a high-temperature tube furnace, a joule heating device, and a box furnace, etc., which is not specifically limited in the present embodiment.
[0051] The material of the single crystal metal substrate can be any one of single crystal nickel, single crystal iron, single crystal cobalt, single crystal platinum, single crystal palladium, single crystal nickel-based alloy, single crystal iron-based alloy, and single crystal cobalt-based alloy; for example, single crystal nickel-iron, single crystal nickel-copper, single crystal nickel-cobalt, etc.
[0052] The thickness relationship between the single crystal metal substrate and the graphite base material is not limited in the present embodiment, which is different according to the different functions of the single crystal metal substrate, which will be described in the following embodiments.
[0053] Step S102: heating the single-crystal metal substrate and the graphite substrate to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite substrate and remove the single-crystal metal substrate and the graphite substrate, to obtain single-crystal graphite.
[0054] The graphite substrate can be removed or not removed by dissolving, peeling, etc.
[0055] The pressure in this step is atmospheric pressure. The non-oxidizing atmosphere is used to grow and promote the growth of single-crystal graphite. The non-oxidizing atmosphere can be a mixture of hydrogen and inert gas (such as argon, etc.).
[0056] The heating process in this embodiment is not specifically limited. The purpose of heating is to grow single-crystal graphite and consume the single-crystal metal substrate, as long as it can achieve this purpose.
[0057] In an embodiment of the present application, before heating the single-crystal metal substrate and the graphite substrate, it can further include:
[0058] The cavity of the heating device is pumped by a vacuum pump to reduce the pressure in the cavity to a target low pressure;
[0059] Hydrogen and inert gas are introduced into the cavity to atmospheric pressure, so that the atmosphere in the cavity is hydrogen and inert gas.
[0060] The target low pressure is less than or equal to 0.2 Pa. After pumping, the vacuum pump is turned off, then hydrogen and inert gas are introduced to atmospheric pressure, and then the exhaust valve is opened. The temperature is raised in the hydrogen and inert gas atmosphere.
[0061] The flow rate of hydrogen can be 0.1-200 sccm, and the flow rate of argon can be 10-1500 sccm.
[0062] After introducing argon and hydrogen to atmospheric pressure, the exhaust valve is opened, and the temperature is raised in the argon and hydrogen atmosphere.
[0063] Since the temperature in the heating device is high, after the growth of single-crystal graphite is completed, the single-crystal graphite can be taken out when the heating is reduced to room temperature.
[0064] As an implementable manner, after removing the single-crystal metal substrate and the graphite substrate, it further includes:
[0065] The heating device is cooled to room temperature, wherein the cooling rate is less than 10℃ / min.
[0066] In the embodiment, the cooling rate is less than 10℃ / min, and the cooling rate is relatively slow, so that the corundum tube of the heating device can be prevented from being broken, and the single crystal graphite can be prevented from being wrinkled due to thermal stress and the like.
[0067] In the prior art, when the single crystal graphite is prepared by using the nickel substrate, the nickel substrate is removed by introducing an etching gas (such as chlorine or hydrogen chloride) to react with the metal nickel at a high temperature. The etching gas is highly toxic, and a complex professional device is required, and the cost is high. In the scheme, the single crystal graphite is directly obtained in the high-temperature device, and no special requirement is needed, and the scheme is simple and easy to implement, and the etching gas is not required, and the cost is low, and the safety factor is higher.
[0068] In the embodiment, when the single crystal graphite is prepared, the graphite base material is used as a carbon source, the single crystal metal substrate is placed on the surface of the graphite base material, and then the single crystal metal substrate and the graphite base material are placed in the heating device to be heated, the single crystal graphite is grown at a high temperature, and then the single crystal metal substrate is consumed. The method can prevent the single crystal graphite grown on the single crystal metal substrate from being wrinkled due to the difference in the thermal expansion coefficient between the single crystal graphite and the single crystal metal substrate during the cooling process, and the single crystal graphite without wrinkles is obtained.
[0069] In the embodiment, when the thickness ratio of the graphite base material to the single crystal metal substrate is Q, and Q≥5, the single crystal metal substrate and the graphite base material are heated to grow the single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and the single crystal metal substrate and the graphite base material are removed, and the method comprises the following steps.
[0070] In step S201, the heating device is heated to a first temperature and kept at the first temperature, and the single crystal metal substrate and the graphite base material are heated to grow the single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material.
[0071] The first temperature is a temperature required for the growth of the single crystal graphite, and the first temperature can be in the range of 1100℃ to 1350℃.
[0072] The time for keeping the temperature constant is not limited in the step, and the length of the time for keeping the temperature constant is related to the growth thickness of the single crystal graphite. For example, the time for keeping the temperature constant can be in the range of 10 hours to 15 days, for example, the time for keeping the temperature constant can be 10 hours, 1 day, 50 hours, 3 days, 5 days, 8 days, 10 days, 12 days, 15 days, and the like.
[0073] As an implementable manner, the heating rate can be in the range of 0.05℃ / min to 30℃ / min, so that the single crystal graphite grown too fast can be prevented from being re-dissolved.
[0074] Step S202: The heating device continues to increase the temperature to a second temperature and keeps the temperature constant, so that the metal in the single-crystal metal substrate is penetrated out of the graphite substrate to be consumed and removed; the first temperature is less than the second temperature.
[0075] The second temperature can range from 1450°C to 2500°C, and the constant temperature time range is at least 10 hours. In order to achieve a relatively thick layer, the growth time is controlled to be about one week. In order to accelerate the growth rate, the second temperature can be increased to above 1450°C, and generally should be controlled to be below 1800°C. At this time, the constant temperature time range is at least 5 hours. The growth time of the graphite material of a certain thickness can be greatly shortened, and generally it can be about 3 days.
[0076] Preferably, the temperature is 1800-2200°C, and the constant temperature time range is 1-3 days. At this temperature range, the temperature is slowly increased to 1800-2200°C to realize the rapid growth of graphite (at least ten times more carbon dissolution than at 1300°C) and the preparation of wrinkle-free graphite. In this process, the rapid growth of graphite is first, and then the metal substrate is gradually dissolved into the graphite substrate to be consumed. This process is accompanied by the evaporation of the metal at high temperature to be consumed, leaving single-crystal graphite material and graphite substrate. Because the difference in the thermal expansion coefficient of the two is small, the formation of wrinkles is inhibited, and the preparation of wrinkle-free graphite is realized.
[0077] As an implementable manner, the temperature increasing rate can range from 0.05°C / min to 30°C / min to avoid the rapid temperature increase causing the single-crystal graphite that is grown first to be re-dissolved.
[0078] The time for constant temperature in this step is not limited, and is mainly determined according to the second temperature and the thickness of the single-crystal metal substrate. The constant temperature time range in this step can range from 10 hours to 7 days. For example, the constant temperature time can be 10 hours, 1 day, 50 hours, 3 days, 5 days, 7 days, etc.
[0079] The main effects of increasing the temperature to the second temperature in this embodiment include two aspects: 1. further increasing the carbon dissolution in nickel to accelerate the growth rate of graphite, which can increase the thickness of single-crystal graphite; 2. causing the metal to penetrate into the graphite substrate layer and be partially evaporated, which is consumed by the two forms.
[0080] Step S203: removing the graphite substrate.
[0081] Since the single-crystal metal substrate is consumed and removed, the single-crystal graphite is located on the graphite substrate, and the graphite substrate can be removed in the form of peeling.
[0082] The growth process of single-crystal graphite is as follows: Figure 2As shown, the single crystal graphite 3 grows out of the surface of the graphite base material 1 away from the single crystal metal substrate 2, and as the heating proceeds, the thickness of the single crystal graphite 3 gradually increases, and the single crystal metal substrate 2 gradually consumes, until it is finally consumed.
[0083] When the ratio Q of the thickness of the graphite base material to the thickness of the single crystal metal substrate is greater than or equal to 5, the method for preparing single crystal graphite can be referred to as a high-temperature metal infiltration method. The purpose of the ratio Q of the thickness of the graphite base material to the thickness of the single crystal metal substrate being greater than or equal to 5 is that the carbon source of the graphite base material does not need to be consumed, and the single crystal metal substrate is mainly consumed by infiltrating into the graphite base material at high temperature.
[0084] For example, for a single crystal metal substrate with a thickness of 100 microns, a graphite base material with a thickness of 0.5 mm or more is used. For example, the thickness of the graphite base material can range from 0.5 mm to 10 mm.
[0085] In this embodiment, the growth of the single crystal graphite is carried out in two steps, and the single crystal graphite can be grown first, and then the graphite formed by the subsequent growth of the seed is induced to form a consistent single crystal structure.
[0086] On the basis of the above embodiment, in an embodiment of the present application, when the ratio Q of the thickness of the graphite base material to the thickness of the single crystal metal substrate is greater than or equal to 5, the single crystal metal substrate and the graphite base material are heated to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and the single crystal metal substrate and the graphite base material are removed, comprising:
[0087] Step S301: The heating device is warmed to a second temperature and kept at a constant temperature, and the single crystal metal substrate and the graphite base material are heated to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and the metal in the single crystal metal substrate is infiltrated out of the graphite base material to be consumed and removed.
[0088] As an implementable manner, the warming rate can range from 0.05 ℃ / min to 30 ℃ / min, so as to avoid the single crystal graphite grown at too high a temperature from being redissolved.
[0089] The constant temperature time in this step is not limited, and is determined according to the growth of the single crystal graphite, the consumption and removal of the metal, and the melting point of the metal material.
[0090] In this embodiment, the growth of the single crystal graphite is carried out in one step, and the second temperature is higher, so as to improve the growth rate of the single crystal graphite.
[0091] The warming rate in this step is lower than that in steps S201 and S202.
[0092] Step S302: The graphite base material is removed.
[0093] Since the single-crystal metal substrate is consumed and removed, the single-crystal graphite is located on the graphite substrate, and the graphite substrate can be removed in the form of exfoliation.
[0094] On the basis of the above-mentioned embodiments, in an embodiment of the present application, when the ratio of the thickness of the graphite substrate to the thickness of the single-crystal metal substrate is Q, 0.5≤Q<5, the single-crystal metal substrate and the graphite substrate are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite substrate, and the single-crystal metal substrate and the graphite substrate are removed, comprising:
[0095] Step S401: the heating device is warmed up to a first temperature and kept at the first temperature, and the single-crystal metal substrate and the graphite substrate are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite substrate.
[0096] The first temperature is the temperature required for the growth of single-crystal graphite, and the range of the first temperature can be 1100℃-1350℃.
[0097] As an implementable manner, the range of the warming-up rate can be 0.05℃ / min-30℃ / min, so as to avoid that the single-crystal graphite grown first is re-dissolved due to too fast warming-up.
[0098] The time for keeping the temperature constant in this step is not limited, and the length of the time for keeping the temperature constant is related to the growth thickness of the single-crystal graphite. For example, the range of the time for keeping the temperature constant can be 10 hours-15 days, for example, the time for keeping the temperature constant can be 10 hours, 1 day, 50 hours, 3 days, 5 days, 8 days, 10 days, 12 days, 15 days, etc.
[0099] Step S402: the heating device continues to be warmed up to a second temperature and kept at the second temperature, so as to consume and remove the graphite substrate, and further remove the metal in the single-crystal metal substrate by volatilization; the first temperature is less than the second temperature.
[0100] As an implementable manner, the range of the warming-up rate can be 0.05℃ / min-30℃ / min, so as to avoid that the single-crystal graphite grown first is re-dissolved due to too fast warming-up.
[0101] The time for keeping the temperature constant in this step is not limited, and is mainly determined according to the second temperature and the thickness of the single-crystal metal substrate. The range of the time for keeping the temperature constant in this step can be 10 hours-7 days. For example, the time for keeping the temperature constant can be 10 hours, 1 day, 50 hours, 3 days, 5 days, 7 days, etc.
[0102] The effect of heating to the second temperature in this embodiment mainly includes two aspects, 1, further increasing the carbon solubility in the metal, and accelerating the growth rate of the graphite, which can increase the thickness of the single crystal graphite and inhibit the formation of wrinkles; 2, at high temperature, the volatility of metals such as nickel, iron, cobalt and copper is greatly improved, which promotes the consumption of the substrate.
[0103] The growth process of the single crystal graphite is as shown in Figure 3 The single crystal graphite 3 grows out of the surface of the single crystal metal substrate 2 away from the graphite base material 1, as the heating proceeds, the graphite base material 1 is gradually consumed, the single crystal metal substrate 2 is exposed, and then gradually volatilizes.
[0104] When the ratio Q of the thickness of the graphite base material to the thickness of the single crystal metal substrate is 0.5≤Q<5, the preparation method of the single crystal graphite can be called a substrate volatilization method, and the purpose of 0.5≤Q<5 is to consume the carbon source of the graphite base material, and then the single crystal metal substrate is exposed, so as to volatilize at high temperature.
[0105] For example, for a single crystal metal substrate with a thickness of 100 microns, a graphite base material with a thickness of 0.05mm-0.5mm can be used.
[0106] The growth of the single crystal graphite in this embodiment is carried out in two steps, the single crystal graphite can be grown first, and then the graphite formed by the subsequent growth is induced to form a consistent single crystal structure.
[0107] On the basis of the above embodiment, in an embodiment of the present application, when the ratio Q of the thickness of the graphite base material to the thickness of the single crystal metal substrate is 0.5≤Q<5, the single crystal metal substrate and the graphite base material are heated to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and the single crystal metal substrate and the graphite base material are removed, comprising:
[0108] The heating device is heated to a second temperature and kept at a constant temperature, and the single crystal metal substrate and the graphite base material are heated to grow single crystal graphite on the surface of the single crystal metal substrate away from the graphite base material, and the graphite base material is consumed and removed, and the metal in the single crystal metal substrate is volatilized and removed.
[0109] The heating rate of this step is lower than that in steps S401 and S402.
[0110] The constant temperature time in this step is not limited, and is determined according to the growth of the single crystal graphite and the consumption and removal of the graphite base material and the single crystal metal.
[0111] The growth of the single crystal graphite in this embodiment is carried out in one step, and the second temperature is higher, which can improve the growth rate of the single crystal graphite.
[0112] On the basis of any of the above embodiments, in an embodiment of the present application, when the ratio of the thickness of the graphite substrate to the thickness of the single-crystal metal substrate is 0.5≤Q<5, after the metal in the single-crystal metal substrate is removed by volatilization, the method can further include:
[0113] immersing the single-crystal graphite in a solution to remove the metal and metal-containing substances on the surface of the single-crystal graphite;
[0114] removing the residual solution and graphite attachments on the surface of the single-crystal graphite.
[0115] After the substrate is removed by volatilization, a small amount of metal and its compounds can be left. In order to reduce the metal content in the single-crystal graphite, further processing can be performed. The solution can be any one of ferric chloride, sulfuric acid, and nitric acid to which hydrochloric acid is added, so as to etch and remove the residual metal and metal-containing substances. Then, the residual solution and graphite attachments can be rinsed by using deionized water, and the rinsing can be performed three times. Then, the single-crystal graphite can be transferred to a target substrate and combined and dried for standby.
[0116] On the basis of any of the above embodiments, in an embodiment of the present application, when the ratio of the thickness of the graphite substrate to the thickness of the single-crystal metal substrate is 0.5≤Q<5, after the graphite substrate is removed by consumption, before the metal in the single-crystal metal substrate is removed by volatilization, the method can further include:
[0117] pumping the pressure of the cavity to a target low pressure.
[0118] The target low pressure is less than or equal to 0.2 Pa.
[0119] Since the single-crystal metal substrate is exposed, by reducing the pressure to the target low pressure, the volatilization of the metal can be promoted more quickly and uniformly.
[0120] The present application also provides a single-crystal graphite prepared by using the method for preparing a single-crystal graphite according to any of the above embodiments.
[0121] The embodiments in the present specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. The single-crystal graphite and the method for preparing the same provided by the present application are described in detail above. The principles and implementation manners of the present application are described by using specific examples. The above description of the embodiments is only used to help understand the scheme of the present application and its core idea. It should be noted that, for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the present application.
Claims
1. A method for producing a single crystal graphite, characterized by, The method comprises: placing a single-crystal metal substrate on a surface of a graphite base material, and placing the single-crystal metal substrate and the graphite base material in a cavity of a heating device; wherein the graphite base material serves as a carbon source for single-crystal graphite growth; heating the single-crystal metal substrate and the graphite base material to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and removing the single-crystal metal substrate and the graphite base material, to obtain single-crystal graphite, when a non-oxidizing atmosphere is present in the cavity.
2. The method of producing single crystal graphite according to claim 1, wherein The material of the single-crystal metal substrate is any one of single-crystal nickel, single-crystal iron, single-crystal cobalt, single-crystal platinum, single-crystal palladium, single-crystal nickel-based alloy, single-crystal iron-based alloy, and single-crystal cobalt-based alloy.
3. The method of producing single crystal graphite according to claim 1, wherein When the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, Q≥5, heating the single-crystal metal substrate and the graphite base material to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and removing the single-crystal metal substrate and the graphite base material comprises: the heating device is warmed to a first temperature and kept at the first temperature, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material; the heating device is continuously warmed to a second temperature and kept at the second temperature, and nickel in the single-crystal metal substrate is penetrated out of the graphite base material to be consumed and removed; the first temperature is less than the second temperature; the graphite base material is removed.
4. The method of producing single crystal graphite according to claim 1, wherein When the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, Q≥5, heating the single-crystal metal substrate and the graphite base material to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and removing the single-crystal metal substrate and the graphite base material comprises: the heating device is warmed to a second temperature and kept at the second temperature, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and single-crystal metal in the single-crystal metal substrate is penetrated into the graphite base material to be consumed and removed; the graphite base material is removed.
5. The method of producing single-crystal graphite according to claim 1, wherein When the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, 0.5≤Q<5, heating the single-crystal metal substrate and the graphite base material to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and removing the single-crystal metal substrate and the graphite base material comprises: the heating device is warmed to a first temperature and kept at the first temperature, and the single-crystal metal substrate and the graphite base material are heated to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material; the heating device is continuously warmed to a second temperature and kept at the second temperature, to consume and remove the graphite base material, and to volatilize and remove single-crystal metal in the single-crystal metal substrate; the first temperature is less than the second temperature.
6. The method of producing single-crystal graphite according to claim 1, wherein When the ratio of the thickness of the graphite base material to the thickness of the single-crystal metal substrate is Q, 0.5≤Q<5, heating the single-crystal metal substrate and the graphite base material to grow single-crystal graphite on a surface of the single-crystal metal substrate away from the graphite base material, and removing the single-crystal metal substrate and the graphite base material comprises: The heating device is heated to a second temperature and kept constant, and the single-crystal metal substrate and the graphite substrate are heated to grow single-crystal graphite on the surface of the single-crystal metal substrate away from the graphite substrate, and dissolve the graphite substrate into the single-crystal metal substrate, and then volatilize and remove the nickel in the single-crystal metal substrate.
7. The method of producing single-crystal graphite according to any one of claims 2 to 6, wherein The first temperature ranges from 1100℃ to 1350℃, and the constant temperature time ranges at least 10 hours; the second temperature ranges from 1380℃ to 1450℃, and the constant temperature time ranges at least 10 hours.
8. The method of producing single-crystal graphite according to any one of claims 2 to 6, wherein The second temperature ranges from 1450℃ to 2500℃, and the constant temperature time ranges at least 10 hours, preferably the temperature ranges from 1800℃ to 2200℃, and the constant temperature time ranges at least 5 hours.
9. The method of producing single-crystal graphite according to claim 5, wherein After the single-crystal metal in the single-crystal metal substrate is volatilized and removed, the method further comprises: immersing the single-crystal graphite in a solution to remove the metal and metal-containing substances on the surface of the single-crystal graphite; removing the residual solution and graphite attachments on the surface of the single-crystal graphite.
10. The method of producing single crystal graphite according to claim 5, wherein After the graphite substrate is consumed and removed, and before the single-crystal metal in the single-crystal metal substrate is volatilized and removed, the method further comprises: pumping the pressure of the cavity to a target low pressure.
11. The method of producing single crystal graphite according to claim 10, wherein The target low pressure ranges from 0.2Pa or less.
12. The method of producing single crystal graphite according to any one of claims 2 to 6, 8, 9, 10, 11, wherein The heating rate ranges from 0.05℃ / min to 30℃ / min.
13. The method of producing single crystal graphite according to claim 1, wherein After the single-crystal metal substrate and the graphite substrate are removed, the method further comprises: cooling the heating device to room temperature, wherein the cooling rate is less than 10℃ / min.
14. The method of producing single crystal graphite according to claim 1, wherein Before the single-crystal metal substrate and the graphite substrate are heated, the method further comprises: pumping the cavity of the heating device by a vacuum pump to reduce the pressure of the cavity to a target low pressure; introducing hydrogen and inert gas into the cavity to normal pressure, so that the atmosphere in the cavity is hydrogen and inert gas.
15. The method of producing single crystal graphite according to claim 14, wherein The target low pressure ranges from 0.2Pa or less.
16. A single crystal graphite characterized in that, The single-crystal graphite is prepared by the method for preparing single-crystal graphite according to any one of claims 1 to 15.