High-entropy ceramic laser protective coating and design method thereof

Abstract

The invention discloses a high-entropy ceramic laser protective coating and a design method thereof, and belongs to the technical field of laser protection, the chemical formula of the high-entropy ceramic protective coating is (Hf < x > Nb < 0.2 > Ti < 0.2 > Zr < 0.2 > Ta < 0.4-x >) C, x belongs to (0, 0.4), and the design method comprises the following steps: S1, adopting a special quasi-random structure method to construct crystal models of different element molar ratios for the high-entropy ceramic protective coating; s2, adopting a Monkhorst-Pack scheme to generate a plurality of groups of K-point grids for the crystal model, and determining an optimal K-point grid; s3, geometric optimization is carried out on the crystal model structure by adopting a density functional theory, and the crystal model structure with the lowest energy is determined; and S4, judging the stability of the crystal model structure, calculating the characteristics of the crystal model structure, and determining the final high-entropy ceramic laser protective coating. According to the method, through accurate K-point grid generation, comprehensive structure optimization, comprehensive characteristic evaluation and the like, the microstructure of the material is accurately predicted and adjusted to meet specific mechanical property indexes, the practicability and reliability of the material are ensured, and optimization of a laser protective coating scheme is achieved.

Description

Technical Field

[0001] The present invention relates to the field of laser protection technology, and in particular to a high-entropy ceramic laser protection coating and a design method thereof. Background Art

[0002] In today's laser protection field, high-fired ceramic protective coatings are developing rapidly. In order to meet the growing demand for laser protective coatings, researchers have begun to optimize the design of laser protective coating performance.

[0003] In the modern military field, high-energy laser weapons deployed on military satellites are increasingly attracting widespread attention due to their rapid attack capabilities, low costs and controllable killing effects. High-energy laser weapons have significant advantages such as rapid attack, low cost, and controllable killing. Their laser power can reach hundreds of thousands or even millions of watts, and can directly destroy or weaken targets. Laser attacks can accurately act on core components such as the satellite's optical system, solar cells, and thermal control system, thereby weakening or destroying their functions, and will not produce debris that poses a threat to the orbital safety of other spacecraft. In view of the severe threat posed by high-energy laser weapons to the safety of satellites in orbit, the development of effective laser protection technology has become an important task to ensure that satellites can operate stably and reliably in complex confrontation environments.

[0004] In the prior art, the design method of laser protective coating cannot produce protective coatings that meet specific mechanical performance indicators, nor can it adjust the microstructure of the material. Based on this, the present invention proposes a new optimization design method based on high-entropy ceramic materials to promote the development of high-entropy ceramic coatings for high-performance laser protection in the future. Summary of the invention

[0005] The purpose of the present invention is to provide a high entropy ceramic laser protective coating and a design method thereof to solve the problems in the background technology.

[0006] To achieve the above object, the present invention provides a high entropy ceramic laser protective coating, the chemical formula of the high entropy ceramic protective coating is (Hf x Nb 0.2 Ti 0.2 Zr 0.2 Ta 0.4-x )C,x∈(0,0.4).

[0007] The present invention also provides a design method for the above-mentioned high entropy ceramic laser protective coating, comprising the following steps:

[0008] S1. Use a special quasi-random structure method to construct a crystal model of high entropy ceramic protective coating with different element molar ratios;

[0009] S2, using the Monkhorst-Pack scheme to generate multiple groups of K-point grids for the crystal models with different element molar ratios constructed in S1, and determine the optimal K-point grid;

[0010] S3. Use the optimal K-point grid to configure density functional theory calculation parameters, use density functional theory to geometrically optimize the crystal model structure of different element molar ratios, adjust the atomic position and lattice parameters, and determine the crystal model structure of the lowest energy state;

[0011] S4. Determine the stability of the crystal model structure obtained in S3, calculate the elastic properties, optical properties, and high thermodynamic properties of the crystal model structure respectively, and determine the final high-entropy ceramic laser protective coating.

[0012] Preferably, in S1, the element composition of the high entropy ceramic protective coating is first determined to be Hf, Nb, Ti, Zr, and Ta, different molar ratio combinations are set for the element composition, and then a crystal model is constructed.

[0013] Preferably, in S3, the lattice constant and total energy of the crystal model structure in the lowest energy state are recorded, and the enthalpy of formation and the enthalpy of mixing are calculated.

[0014] Preferably, in S4, when the enthalpy of formation is less than zero, it is thermodynamically stable, and the enthalpy of formation is defined as:

[0015] ΔH f =(E tot -∑N i E i ) / ∑N i ;

[0016] In the formula, ΔH f is the enthalpy of formation, E tot is the total energy, N i is the number of atoms in the cell, E i is the monatomic energy of element i in a stable elementary crystal structure.

[0017] Preferably, in S3, the mixing enthalpy is less than zero and the smaller the mixing enthalpy is, the better the stability is. The mixing enthalpy is defined as:

[0018]

[0019] In the formula, ΔH mix is the mixing enthalpy, E tot is the total energy, is the number of individual metal carbides, is the energy of a single metal carbide.

[0020] Preferably, in S3, the condition for judging stability is whether the enthalpy of formation and the enthalpy of mixing are less than 0. If both the enthalpy of formation and the enthalpy of mixing are less than 0, the stability is good; if both the enthalpy of formation and the enthalpy of mixing are greater than 0, the stability is poor, and step S3 is performed again.

[0021] Preferably, in S4, the elastic properties are calculated by the Voigt-Reuss-Hill method, the optical properties are calculated by the density functional perturbation theory method, and the high thermodynamic properties are calculated by the Debye-Grüneisen model, and the high thermodynamic properties include the expansion coefficient and the Debye temperature.

[0022] Preferably, the Debye temperature is a key parameter reflecting the stiffness and thermal properties of a material and is defined as:

[0023]

[0024] In the formula, θ D is the Debye temperature, h is the Planck constant, N A is the Avogadro constant, k B is the Boltzmann constant, n is the total number of atoms in the supercell, M is the molar mass, ρ is the theoretical mass density, and v m is the average speed of sound;

[0025] The average speed of sound is calculated as:

[0026]

[0027] Among them, v t is the transverse speed of sound;

[0028]

[0029]

[0030] Where B is the bulk modulus and G is the shear modulus.

[0031] Therefore, a high-entropy ceramic laser protective coating and a design method thereof of the present invention can accurately predict and adjust the microstructure of the material to meet specific mechanical performance indicators by constructing a multi-element molar ratio model, accurately generating a K-point grid, comprehensively optimizing the structure, and evaluating comprehensive properties, thereby achieving the optimization of the laser protective coating scheme, ensuring the practicability and reliability of the material, and guiding the optimization of the design of high-entropy ceramic laser protective coatings in practical applications; and the geometric model generated by the design method has the required mechanical properties, further confirming its practicability and reliability in engineering applications.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a flow chart of an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of a high entropy ceramic crystal model according to an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of a structurally optimized EV according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0038] Example

[0039] like Figure 1 As shown, this embodiment mainly designs a high entropy ceramic laser protective coating, and the specific steps are as follows:

[0040] S1. First, determine the element composition of the high entropy ceramic protective coating, which is Hf, Nb, Ti, Zr, and Ta, and set different molar ratio combinations;

[0041] The special quasi-random structure (SQS) method was adopted to model the molar proportions of different elements using the mcsqs code based on the automated toolkit ATAT. In the model, metal cations Hf, Nb, Ti, Zr, and Ta randomly occupied the cation sublattice, while all C atoms occupied the anion sublattice.

[0042] S2, using the Monkhorst-Pack scheme to generate multiple groups of K-point grids for the crystal models with different element molar ratios constructed in S1, and determine the optimal K-point grid, specifically:

[0043] The Monkhorst-Pack scheme is used to generate multiple groups of K-point grids ranging from sparse to dense for the high entropy ceramic model, and then VASP numerical simulation is carried out. Considering the limited computer resources, after multiple groups of comparisons, a group of K-point grids with high calculation accuracy and high efficiency is determined.

[0044] S3. Use the optimal K-point grid to configure density functional theory calculation parameters, use density functional theory to geometrically optimize the crystal model structure of different element molar ratios, adjust the atomic position and lattice parameters, and determine the crystal model structure of the lowest energy state; record the lattice constant and total energy of the crystal model structure of the lowest energy state, and calculate the formation enthalpy and mixing enthalpy;

[0045] When the enthalpy of formation is less than zero, it is thermodynamically stable. The enthalpy of formation is:

[0046] ΔH f =(E tot -∑N i E i ) / ∑N i ;

[0047] In the formula, ΔH f is the enthalpy of formation, E tot is the total energy, N i is the number of atoms in the cell, E i is the monatomic energy of element i in a stable elementary crystal structure.

[0048] The mixing enthalpy is less than zero and the smaller it is, the better the stability. The mixing enthalpy is:

[0049]

[0050] In the formula, ΔH mix is the mixing enthalpy, E tot is the total energy, is the number of individual metal carbides, is the energy of a single metal carbide.

[0051] S4. Determine the stability of the crystal model structure obtained in S3. The condition for determining the stability is whether the enthalpy of formation and the enthalpy of mixing are less than 0. If both the enthalpy of formation and the enthalpy of mixing are less than 0, the stability is good; if both the enthalpy of formation and the enthalpy of mixing are greater than 0, the stability is poor.

[0052] A crystal model structure with good stability was selected, and the elastic properties were calculated using the Voigt-Reuss-Hill method, the optical properties were calculated using the density functional perturbation theory, and the expansion coefficient and Debye temperature were calculated using the Debye-Grüneisen model. The Debye temperature is a key parameter reflecting the stiffness and thermal properties of the material and is defined as:

[0053]

[0054] In the formula, θ D is the Debye temperature, h is the Planck constant, N A is the Avogadro constant, k Bis the Boltzmann constant, n is the total number of atoms in the supercell, M is the molar mass, ρ is the theoretical mass density, and v m is the average speed of sound;

[0055] The average speed of sound is calculated as:

[0056]

[0057] Among them, v t is the transverse speed of sound;

[0058]

[0059]

[0060] Where B is the bulk modulus and G is the shear modulus;

[0061] Through evaluation, the final high entropy ceramic laser protective coating is determined, such as Figure 2-3 As shown, (Hf x Nb 0.2 Ti 0.2 Zr 0.2 Ta 0.4-x )C,x∈(0,0.4).

[0062] Therefore, the high-entropy ceramic laser protective coating and its design method of the present invention can accurately predict and adjust the microstructure of the material to meet specific mechanical performance indicators by constructing a multi-element molar ratio model, accurately generating a K-point grid, comprehensively optimizing the structure, and evaluating comprehensive characteristics, thereby achieving the optimization of the laser protective coating scheme, ensuring the practicability and reliability of the material, and guiding the optimization of the design of high-entropy ceramic laser protective coatings in practical applications.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A high entropy ceramic laser protective coating, characterized in that: The chemical formula of high entropy ceramic protective coating is (Hf x Nb 0.2 Ti 0.2 Zr 0.2 Ta 0.4-x )C,x∈(0,0.4).

2. A design method for a high entropy ceramic laser protective coating as claimed in claim 1, characterized in that: The following steps are involved: S1. Use a special quasi-random structure method to construct a crystal model of high entropy ceramic protective coating with different element molar ratios; S2, using the Monkhorst-Pack scheme to generate multiple groups of K-point grids for the crystal models with different element molar ratios constructed in S1, and determine the optimal K-point grid; S3, using the optimal K-point grid to configure density functional theory calculation parameters, using density functional theory to perform geometric optimization on the crystal model structure of different element molar ratios, and determine the crystal model structure of the lowest energy state; S4. Determine the stability of the crystal model structure obtained in S3, calculate the elastic properties, optical properties, and high thermodynamic properties of the crystal model structure respectively, and determine the final high-entropy ceramic laser protective coating.

3. The design method of a high entropy ceramic laser protective coating according to claim 2, characterized in that: In S1, the element composition of the high entropy ceramic protective coating is first determined to be Hf, Nb, Ti, Zr, and Ta, different molar ratio combinations are set for the element composition, and then a crystal model is constructed.

4. The design method of a high entropy ceramic laser protective coating according to claim 2, characterized in that: In S3, the lattice constant and total energy of the crystal model structure in the lowest energy state are recorded, and the formation enthalpy and mixing enthalpy are calculated.

5. The design method of a high entropy ceramic laser protective coating according to claim 4, characterized in that: In S3, the formation enthalpy is defined as: ΔH f =(And tot -∑N i AND i ) / ∑N i ; In the formula, ΔH f is the enthalpy of formation, E tot is the total energy, N i is the number of atoms in the cell, E i is the monatomic energy of element i in a stable elementary crystal structure.

6. The design method of a high entropy ceramic laser protective coating according to claim 4, characterized in that: In S3, the mixing enthalpy is defined as: In the formula, ΔH mix is the mixing enthalpy, E tot is the total energy, is the number of individual metal carbides, is the energy of a single metal carbide.

7. The design method of a high entropy ceramic laser protective coating according to claim 2, characterized in that: In S4, the condition for judging stability is whether the enthalpy of formation and the enthalpy of mixing are less than 0. If both the enthalpy of formation and the enthalpy of mixing are less than 0, the stability is good. If both the formation enthalpy and the mixing enthalpy are greater than 0, the stability is poor and step S3 is performed again.

8. The design method of a high entropy ceramic laser protective coating according to claim 2, characterized in that: In S4, the elastic properties are calculated by the Voigt-Reuss-Hill method, the optical properties are calculated by the density functional perturbation theory method, and the high thermodynamic properties are calculated by the Debye-Grüneisen model, and the high thermodynamic properties include the expansion coefficient and the Debye temperature.

9. The design method of a high entropy ceramic laser protective coating according to claim 8, characterized in that: The Debye temperature is defined as: Where D D is the Debye temperature, h is the Planck constant, N A is the Avogadro constant, k B is the Boltzmann constant, n is the total number of atoms in the supercell, M is the molar mass, ρ is the theoretical mass density, and v m is the average speed of sound; The average speed of sound is calculated as: Among them, v t is the transverse speed of sound, v l is the longitudinal speed of sound.

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