Negative thermal expansion material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of negative thermal expansion materials, and discloses a negative thermal expansion material and a preparation method and application thereof. And the negative thermal expansion material is Cu3 (MoO4) 2 (OH) 2. The nano-sheet alkali Cu3 (MoO4) 2 (OH) 2 with the negative thermal expansion characteristic not only can tolerate higher temperature, but also has a wide NTE temperature range of the negative thermal expansion material.

Description

Technical Field

[0001] This invention belongs to the field of negative thermal expansion materials technology, and more specifically, relates to a negative thermal expansion material, its preparation method, and its application. Background Technology

[0002] Most engineering materials expand in volume when heated (positive thermal expansion, PTE), a common phenomenon caused by increased vibration of atoms or crystal lattices within the material as temperature rises. This thermal expansion effect presents significant technical challenges in fields such as precision engineering, microelectronics, optoelectronics, aerospace, precision instruments, and optical devices. When components composed of materials with different coefficients of thermal expansion (such as multilayer ceramic capacitors, chip packages, optical system lens groups, and composite material structures) experience temperature changes, the varying degrees of expansion / contraction generate enormous thermal stress, leading to device cracking, delamination, performance drift, or even complete failure. In high-precision applications (such as lithography machine lenses, space telescope mirrors, laser resonant cavities, and precision measurement references), the dimensions of materials change with temperature fluctuations, severely reducing the system's accuracy, stability, and reliability.

[0003] Negative thermal expansion (NTE) materials are a class of special functional materials that shrink in volume when heated within a specific temperature range. Introducing NTE materials into conventional positive thermal expansion (PTE) material systems allows for the design of composite materials with near-zero or even tunable coefficients of thermal expansion (CTE), fundamentally solving or mitigating the aforementioned thermal expansion problems. Developing high-performance, easily integrated, and cost-effective NTE materials is one of the key requirements for achieving high-precision, high-stability, and high-reliability advanced devices and systems. NTE materials generally suffer from one or more of the following problems: complex / high-cost synthesis processes, insufficient chemical / thermal stability, limited NTE temperature range, and poor environmental friendliness. Therefore, there is an urgent need to develop novel NTE materials with more balanced performance and greater practical potential. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a negative thermal expansion material, its preparation method, and its applications. The nanosheet-like basic Cu3(MoO4)2(OH)2 of this invention, possessing negative thermal expansion properties, not only withstands higher temperatures, but also exhibits a wide NTE (negative thermal expansion) temperature range.

[0005] To achieve the above objectives, the first aspect of the present invention provides a negative thermal expansion material, wherein the negative thermal expansion material is Cu3(MoO4)2(OH)2.

[0006] According to the present invention, preferably, the microstructure of Cu3(MoO4)2(OH)2 is a parallelogram nanosheet.

[0007] According to the present invention, preferably, the Cu3(MoO4)2(OH)2 nanosheets have a side length of 450-550 nm and a thickness of 30-50 nm.

[0008] According to the present invention, preferably, the NTE temperature range of Cu3(MoO4)2(OH)2 is 125-325℃.

[0009] A second aspect of the present invention provides a method for preparing the aforementioned negative thermal expansion material, the method comprising the following steps:

[0010] S1: Nano Cu2(OH)2CO3 and nano Mo5O 42 Stir and mix, then carry out one reaction to obtain a one-time reaction system;

[0011] S2: The primary reaction system is cooled and stirred sequentially, and then a secondary reaction is carried out to obtain the negative thermal expansion material Cu3(MoO4)2(OH)2.

[0012] According to the present invention, preferably, the nano-Cu2(OH)2CO3 and nano-Mo5O 42 The mass ratio is (2.5-3.5):1.

[0013] In this invention, the primary reaction system comprises, by weight, 1-3% unreacted nano-Cu2(OH)2CO3.

[0014] According to the present invention, preferably, in step S1:

[0015] The stirring time is 0.5-1.5 minutes;

[0016] The temperature of the first reaction is 105-115℃, and the time is 3.5-4.5h.

[0017] According to the present invention, preferably, in step S2:

[0018] The stirring time is 0.5-1.5 minutes;

[0019] The secondary reaction is carried out at a temperature of 105-115℃ for 3.5-4.5 hours.

[0020] In this invention, both the primary and secondary reactions are carried out in an eleven-tube furnace.

[0021] The third aspect of the present invention provides the application of the negative thermal expansion material or the negative thermal expansion material prepared by the preparation method described above in the thermal insulation coating of aerospace vehicles.

[0022] According to the present invention, preferably, the heat-insulating coating is provided on the surface of the aerospace vehicle body; the heat-insulating coating includes a negative thermal expansion material layer and a heat-resistant layer arranged sequentially from bottom to top;

[0023] The material of the negative thermal expansion material layer is the negative thermal expansion material described above or the negative thermal expansion material prepared by the preparation method described above.

[0024] In this invention, such as Figure 1 As shown, the negative thermal expansion material of this invention is located between the surface of the aerospace vehicle body and the heat-resistant layer. The material used in the heat-resistant layer is a material that expands and contracts with temperature changes. If it comes into direct contact with the surface of the aerospace vehicle body, the coating will crack due to the difference in expansion coefficients between the material and the surface of the aerospace vehicle body. By using the negative thermal expansion material of this invention as an intermediate interlayer (negative thermal expansion material layer), its negative thermal expansion characteristics can prevent the heat-resistant layer from cracking.

[0025] The beneficial effects of the technical solution of the present invention are as follows:

[0026] The nanosheet-shaped basic Cu3(MoO4)2(OH)2 of the present invention, which has negative thermal expansion properties, can not only withstand higher temperatures, but also has a wide NTE temperature range.

[0027] The nanosheet-shaped basic Cu3(MoO4)2(OH)2 of the present invention, which has negative thermal expansion characteristics, can be prepared on a large scale industrially and can be used to construct thermal insulation coatings for aerospace vehicles.

[0028] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0029] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0030] Figure 1 A schematic diagram of the structure of the aerospace vehicle heat insulation coating provided by the present invention is shown.

[0031] Figure 2 The image shows a microstructure (SEM) of a negative thermal expansion material provided in Embodiment 1 of the present invention.

[0032] Figure 3The diagram shows a test graph of the coefficient of thermal expansion of a negative thermal expansion material provided in Embodiment 1 of the present invention ("Temperature", dL: the change in length of the material during the temperature change (ΔL), Lo: the original length of the material at the initial temperature, dL / Lo: the length change corresponding to a unit of original length, used to calculate the linear coefficient of thermal expansion (α=(dL / Lo) / ΔT)).

[0033] Figure 4 The XRD pattern (“Intensity”, “2θ (degree)”) of a negative thermal expansion material provided in Embodiment 1 of the present invention is shown.

[0034] The annotations in the attached figures are explained as follows:

[0035] 1-Heat-resistant layer; 2-Negative thermal expansion material layer; 3-Surface of aerospace vehicle body. Detailed Implementation

[0036] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0037] Example 1

[0038] This embodiment provides a negative thermal expansion material, wherein the negative thermal expansion material is Cu3(MoO4)2(OH)2.

[0039] The preparation method of the negative thermal expansion material Cu3(MoO4)2(OH)2 includes the following steps:

[0040] S1: Nano Cu2(OH)2CO3 and nano Mo5O 42 Stir the mixture thoroughly in a stirrer at a mass ratio of 3:1 for 1 minute. Place the uniformly mixed material into an eleven-tube furnace and react at 110°C for 4 hours to obtain a primary reaction system (based on the total weight of the primary reaction system, the primary reaction system includes: 1-3% of unreacted nano-Cu2(OH)2CO3).

[0041] S2: After cooling the primary reaction system, it is reintroduced into the stirrer and stirred at high speed for 1 minute. The reaction is then carried out again at 110°C for 4 hours to obtain the negative thermal expansion material—basic Cu3(MoO4)2(OH)2 nanosheets, whose microstructure is as follows: Figure 2 As shown, the nanosheets are parallelograms with a side length of approximately 500 nm and a thickness of approximately 40 nm, and they are arranged relatively closely.

[0042] like Figure 3 As shown, by testing the coefficient of thermal expansion of the basic Cu3(MoO4)2(OH)2 nanosheets obtained in this embodiment, it can be seen that: from room temperature to 134.8℃, the length of the material increases with increasing temperature, showing obvious positive thermal expansion characteristics, but the slope of the curve shows that the degree of positive thermal expansion is low; from 134.8℃ to 210℃, it shows negative thermal expansion characteristics; in the range of 210℃ to 225℃, a brief positive thermal expansion phenomenon occurs, and the coefficient of positive thermal expansion is also low; from 225℃ to 280℃, it is negative thermal expansion; in the range of 280℃ to 329.3℃, it exhibits extremely excellent negative thermal expansion characteristics.

[0043] like Figure 4 As shown, the basic Cu3(MoO4)2(OH)2 nanosheets obtained in this embodiment were subjected to high-temperature XRD testing. The results show that the diffraction peaks of the basic Cu3(MoO4)2(OH)2 nanosheets did not disappear with increasing temperature, which proves that the material in this embodiment did not decompose due to increased temperature.

[0044] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A negative thermal expansion material, characterized in that, The negative thermal expansion material is Cu3(MoO4)2(OH)2.

2. The negative thermal expansion material according to claim 1, wherein, The microstructure of Cu3(MoO4)2(OH)2 is parallelogram-shaped nanosheets.

3. The negative thermal expansion material according to claim 2, wherein, The Cu3(MoO4)2(OH)2 nanosheets have a side length of 450-550 nm and a thickness of 30-50 nm.

4. The negative thermal expansion material according to claim 1, wherein, The NTE temperature range of Cu3(MoO4)2(OH)2 is 125-325℃.

5. The method for preparing the negative thermal expansion material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1: Nano Cu2(OH)2CO3 and nano Mo5O 42 Stir and mix, then carry out one reaction to obtain a one-time reaction system; S2: The primary reaction system is cooled and stirred sequentially, and then a secondary reaction is carried out to obtain the negative thermal expansion material Cu3(MoO4)2(OH)2.

6. The method for preparing the negative thermal expansion material according to claim 5, wherein, The nano-Cu2(OH)2CO3 and nano-Mo5O 42 The mass ratio is (2.5-3.5):

1.

7. The method for preparing the negative thermal expansion material according to claim 5, wherein, In step S1: The stirring time is 0.5-1.5 minutes; The temperature of the first reaction is 105-115℃, and the time is 3.5-4.5h.

8. The method for preparing the negative thermal expansion material according to claim 5, wherein, In step S2: The stirring time is 0.5-1.5 minutes; The secondary reaction is carried out at a temperature of 105-115℃ for 3.5-4.5 hours.

9. The application of the negative thermal expansion material according to any one of claims 1-4 or the negative thermal expansion material prepared by the preparation method according to any one of claims 5-8 in the thermal insulation coating of aerospace vehicles.

10. The application according to claim 9, wherein, The heat-insulating coating is applied to the surface of the aerospace vehicle body; the heat-insulating coating includes a negative thermal expansion material layer and a heat-resistant layer arranged sequentially from bottom to top. The material of the negative thermal expansion material layer is the negative thermal expansion material according to any one of claims 1-4 or the negative thermal expansion material prepared by the preparation method according to any one of claims 5-8.

Images