Method for preparing multi-component carbide ceramic nanowire by molten salt method

Abstract

The invention discloses a method for preparing a multi-element carbide ceramic nanowire by a molten salt method. The multi-element carbide ceramic nanowire is prepared from the following raw materials: a carbon nanotube, potassium halide and IVB group metal powder, the method for preparing the multi-element carbide ceramic nanowire by the molten salt method comprises the following steps: mixing preparation raw materials and sintering. The preparation method is simple and feasible, and can be used for industrial production; in addition, the prepared multi-component carbide ceramic nanowire is high in phase purity and uniform in distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of multi-component carbide ceramic nanowires, in particular to a method for preparing multi-component carbide ceramic nanowires by a molten salt method. Background Art

[0002] Compared with bulk ceramics, one-dimensional (1D) nanoceramics have become attractive nanomaterials due to their unique 1D characterization and favorable properties, including high aspect ratio, large specific surface area, extremely low dislocation density, excellent mechanical properties and chemical stability. Ultrahigh temperature ceramic nanowires have been used to improve interface bonding, coating toughening, structural composite reinforcement materials, etc. Similarly, 1D high entropy ceramics have excellent physical, chemical and mechanical properties due to their small size and unique microstructure, which also shows the potential for toughening materials under high temperature conditions.

[0003] However, multi-element ultra-high temperature ceramics are difficult to dissolve at low temperatures due to factors such as crystal structure, atomic size and charge balance, while the preparation of nanowires at high temperatures is easily affected by the nanosize effect. This limits the application of 1D HECs as composite materials or ceramic reinforcement materials.

[0004] To solve this problem, the present invention utilizes the advantages of molten salt in providing a liquid phase environment and ion melt at a relatively low temperature, dissolves metal components into the molten salt at a low temperature, and reacts in situ with carbon nanotubes as templates, thereby synthesizing single-phase high-purity multi-component carbide ceramic nanowires at a low temperature and at a low cost. Summary of the invention

[0005] The present invention overcomes the above technical problems and provides a method for preparing multi-component carbide ceramic nanowires by a molten salt method. The preparation method of the present invention is simple and feasible and can be industrially produced. In addition, the multi-component carbide ceramic nanowires prepared by the present invention have high phase purity and uniform distribution.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention discloses a method for preparing multi-component carbide ceramic nanowires by a molten salt method. The multi-component carbide ceramic nanowires include preparation raw materials: carbon nanotubes, potassium halide and IVB group metal powder;

[0008] The method for preparing multi-component carbide ceramic nanowires by a molten salt method comprises the following steps:

[0009] The raw materials are mixed and then sintered.

[0010] In the present invention, the mass ratio of the IVB group metal powder: carbon nanotube: potassium halide is 4-9: 0.5-1: 8-10.5; preferably, the mass ratio of the IVB group metal powder: carbon nanotube: potassium halide is 4.5-8: 0.5-1: 8.5-10.

[0011] In the present invention, the carbon base content of the carbon nanotube (CNT) is ≥95%.

[0012] In the present invention, the outer diameter of the carbon nanotubes is 10-40 nm.

[0013] In the present invention, the length of the carbon nanotubes is 0.5 to 1.5 mm.

[0014] In the present invention, the potassium halide is KCl and KF.

[0015] In the present invention, the mass ratio of KCl:KF in the potassium halide is 8-9:0.5-1.

[0016] In the present invention, the IVB metal powder is Zr powder, Hf powder and Ti powder.

[0017] In the present invention, the mass ratio of Zr:Hf:Ti in the IVB group metal powder is 1-2:3-5:0.5-1.

[0018] In the present invention, the mass ratio of the components in the carbon nanotubes, potassium halide and IVB group metal powder is Zr:Hf:Ti:CNT:KCl:KF=1-2:3-5:0.5-1:0.5-1:8-9:0.5-1; for example, Zr:Hf:Ti:CNT:KCl:KF=2:3:1:0.5:9:1.

[0019] In the present invention, the mixing further includes a drying operation.

[0020] In the present invention, after sintering, the molten salt needs to be cooled to room temperature (20° C.), and filtered with water and alcohol respectively to wash away excess molten salt.

[0021] Furthermore, the drying temperature is 100-150°C, for example 130°C.

[0022] Furthermore, the drying time is 8 to 16 hours, preferably 10 to 12 hours, for example 12 hours.

[0023] Furthermore, the vacuum degree of the drying is 10-90Pa, for example, 10Pa.

[0024] In the present invention, the heating rate before sintering is 5-15°C / min, preferably 8-12°C / min, such as 10°C / min.

[0025] In the present invention, the sintering temperature is 800-950°C, preferably 900-950°C, such as 900°C or 950°C.

[0026] In the present invention, the sintering time is 1 to 5 hours, preferably 1 to 3 hours, for example 1 hour;

[0027] In the present invention, the vacuum degree of sintering is 10-90Pa, preferably 10-50Pa, such as 10Pa.

[0028] In the present invention, the room temperature is 20-25°C, for example 20°C.

[0029] In the present invention, after cooling to room temperature, water and alcohol are used for filtration three or more times to wash away excess molten salt.

[0030] In the present invention, the multi-component carbide ceramic nanowires include a single-phase solid solution.

[0031] In the present invention, the composition of the multi-component carbide ceramic nanowires includes (Zr a Hf b Ti c )C d ; Among them, a=2~9at%, b=2~7at%, c=2.5~15at%, d=45~75at%; preferably, a=2.5~6.8at%, b=2.5~6.5at%, c=2.5~13.5at%, d=48~73at%.

[0032] The multi-component carbide ceramic nanowires prepared by the aforementioned molten salt method are used in the fields of toughening materials, thermal insulation materials or protective materials.

[0033] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The preparation method of the present invention utilizes the solubility of metal powder in molten salt to achieve uniform distribution of metal powder in molten salt, and reacts with carbon nanomaterials in situ to prepare multi-component carbide ceramic nanowires. Compared with the in-situ catalytic growth by vapor deposition, the molten salt in-situ reaction method has the advantages of simple experimental steps, low powder cost, and short preparation cycle. In addition, the multi-component carbide ceramic nanowires synthesized by the method of the present invention are a single solid solution phase, with high phase purity and uniform distribution of nanowires.

[0036] 2. The multinary carbide ceramic nanowires prepared by the method of the present invention not only have uniform physical distribution, but also have high phase purity and uniform element distribution. Since no substrate and catalyst are required in the preparation process, the obtained nanowires have high purity. Multinary carbides can be directly applied to substrates such as C / C composite materials and graphite, and can also be used for toughening treatment of multinary ultra-high temperature ceramic blocks.

[0037] 3. The preparation method of the present invention is simple, feasible, low-cost and can be industrially produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in Example 1;

[0039] Figure 2 is a BES diagram of the multi-component carbide ceramic nanowires prepared in Example 1;

[0040] Figure 3 This is a scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in Example 2;

[0041] Figure 4 is a BES diagram of the multi-component carbide ceramic nanowires prepared in Example 2;

[0042] Figure 5 This is a scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in Comparative Example 1;

[0043] Figure 6 is a BES diagram of the multi-component carbide ceramic nanowires prepared in Comparative Example 1;

[0044] Figure 7 This is a scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in Comparative Example 2;

[0045] Figure 8 This is the BES diagram of the multi-component carbide ceramic nanowires prepared in Comparative Example 2.

[0046] Fig. 9 This is the XRD pattern of the multi-component carbide ceramic nanowires prepared in Example 1. DETAILED DESCRIPTION

[0047] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0048] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0049] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range defined in this way can be inclusive or exclusive of end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0051] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0052] If not otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0053] If there is no special explanation, the "include" and "comprising" mentioned in the present invention represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0054] If not specifically stated, in the present invention, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0055] In the following examples and comparative examples, carbon nanotubes were purchased from Aladdin (the carbon base content of the carbon nanotubes (CNT) was ≥ 95%; the outer diameter of the carbon nanotubes was 10-40 nm; and the length of the carbon nanotubes was 0.5-1.5 mm).

[0056] Example 1

[0057] 1. Raw materials for preparing multi-component carbide ceramic nanowires of this embodiment:

[0058] The mass ratio of Zr:Hf:Ti:CNT:KCl:KF is 2:3:1:0.5:9:1.

[0059] 2. Preparation method of multi-component carbide ceramic nanowires of this embodiment:

[0060] S1. The carbon nanotubes, potassium halide and IVB group metal powder are mixed and ground according to the desired ratio to obtain a mixture;

[0061] S2. The mixture was dried at 130 ° C for 12 h to obtain a dry material;

[0062] S3. The dried material is heated to 900°C at a heating rate of 10°C / min, sintered at this temperature for 1 hour, and then naturally cooled to room temperature. Finally, it is filtered with water and alcohol for more than three times to wash away excess molten salt, thereby obtaining multi-carbide ceramic nanowires.

[0063] The scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in this example is shown in Figure 1 (“+” in the figure indicates the scanned selected area), BES diagram, see Figure 2 . Figure 1 Uniformly distributed nanowires can be observed. Figure 2 There is also no obvious element segregation, and the EDS results show that the nanowires contain Zr, Hf, and Ti elements (EDS results show that this position contains: 72.73at% C, 19.06at% O, 2.67at% Zr, 2.81at% Ti, 2.73at% Hf). Fig. 9 : is the XRD diagram of the multi-component carbide ceramic nanowires prepared in this example. XRD shows a group of diffraction peaks indicating that it is a single-phase solid solution.

[0064] Example 2

[0065] The difference between this embodiment and embodiment 1 is that:

[0066] In this embodiment S3, the sintering temperature is 950°C.

[0067] The scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in this example is shown in Figure 3 、BES diagram see Figure 4 . Figure 3 Uniformly distributed nanowires can be observed. Figure 4 There is no obvious element segregation. The EDS results show that the nanowires contain Zr, Hf, and Ti elements (EDS results show that the multi-carbide ceramic nanowires contain: 48.91at% C, 25.37at% O, 6.72at% Zr, 13.04at% Ti, 5.97at% Hf, among which, due to the rounding error during equipment measurement, the content may be close to but not equal to 100%) and a solid solution phase is formed.

[0068] Comparative Example 1

[0069] The difference between this comparative example and Example 1 is:

[0070] In this comparative example S3, the sintering temperature is 1000°C.

[0071] The scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in this comparative example is shown in Figure 5 (“+” in the figure indicates the selected area), BES diagram, see Figure 6 . Combined Figure 5 It can be seen that the rapid dissipation of molten salt will cause the nanowires to curl up; Figure 6 The results show that the multi-component carbide ceramic nanowires contain: 48.46at% C, 23.99at% O, 6.80at% Zr, 14.27at% Ti, 6.48at% Hf, and the three elements Zr, Hf and Ti are all distributed in the solid, which indicates that the roll is still a solid solution.

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is:

[0074] In this comparative example S3, the sintering temperature is 1100°C.

[0075] The scanning electron microscope image of the multi-component carbide ceramic nanowires prepared in this comparative example is shown in Figure 7 、BES diagram see Figure 8 . Combined Figure 7 It can be seen that the rapid dissipation of molten salt will cause the nanowires to curl up; Figure 8The results show that the multi-carbide ceramic nanowires contain: 54.82at% C, 19.14at% O, 8.51at% Zr, 10.88at% Ti, 6.64at% Hf, among which, due to the rounding error during equipment measurement, the content may be close to but not equal to 100%; Zr, Hf, and Ti are all distributed in the solid, which shows that the coiling is still a solid solution. It can be observed that the coiling effect intensifies as the temperature rises. Obviously, the temperature mainly affects the morphology and distribution of the nanowires.

[0076] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing multi-component carbide ceramic nanowires by a molten salt method, characterized in that: The multi-component carbide ceramic nanowires include preparation raw materials: carbon nanotubes, potassium halide and IVB group metal powder; The method for preparing multi-component carbide ceramic nanowires by a molten salt method comprises the following steps: The raw materials are mixed and then sintered.

2. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: The mass ratio of the IVB group metal powder: carbon nanotube: potassium halide is 4-9: 0.5-1: 8-10.

5.

3. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: The potassium halide is KCl and KF; And / or, the IVB metal powder is Zr powder, Hf powder and Ti powder.

4. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 3, characterized in that: The mass ratio of KCl:KF in the potassium halide is 8-9:0.5-1; And / or, the mass ratio of Zr:Hf:Ti in the IVB group metal powder is 1-2:3-5:0.5-1.

5. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 3, characterized in that: The mass ratio of each component in the preparation raw material is Zr:Hf:Ti:CNT:KCl:KF=1-2:3-5:0.5-1:0.5-1:8-9:0.5-1.

6. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: The mixing also includes a drying operation; And / or, after sintering, the molten salt needs to be cooled to room temperature, and filtered with water and alcohol respectively to wash away excess molten salt.

7. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 6, characterized in that: Satisfy at least one of the following conditions ① to ③: ① The drying temperature is 100-150°C; ② The drying time is 8 to 16 hours; ③ The vacuum degree of the drying is 10-90Pa.

8. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: Satisfy at least one of the following conditions ① to ④: ① The heating rate before sintering is 5-15°C / min; ② The sintering temperature is 800-950°C; ③ The sintering time is 1 to 5 hours; ④ The vacuum degree of the sintering is 10-90Pa.

9. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: Satisfy at least one of the following conditions ① to ④: ① The heating rate before sintering is 8-12°C / min; ② The sintering temperature is 900-950°C; ③ The sintering time is 1 to 3 hours; ④ The vacuum degree of the sintering is 10-50Pa.

10. The method for preparing multi-component carbide ceramic nanowires by molten salt method according to claim 1, characterized in that: The multi-component carbide ceramic nanowires include a single-phase solid solution.

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