A method for rapidly assessing the density of thin film materials
By simulating the behavioral changes of thin film materials using molecular dynamics models and combining experimental property parameters, a mapping table and database were established, solving the problem of rapid and accurate thin film density assessment. This approach is suitable for the rapid assessment of industrial thin film materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-26
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies struggle to quickly and accurately assess the density of thin film materials, especially when the film is too thin. Measurement results are often affected by the substrate and the measuring equipment, and high-precision instruments are expensive, making them difficult to widely apply in industry.
Using molecular dynamics methods, a molecular dynamics model of thin film materials is constructed to simulate their behavior under different operating conditions. Combined with experimental property parameters, a mapping table is established and a database is built to quickly calculate the film density.
It enables rapid and accurate assessment of film density, reduces costs, simplifies the measurement process, is suitable for industrial production, and guides improvements in film preparation processes.
Smart Images
Figure CN115620822B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molecular dynamics technology, and in particular relates to a method for rapidly evaluating the density of thin film materials. Background Technology
[0002] Friction and wear are among the main causes of failure in industrial machine parts, affecting not only production safety but also resulting in significant waste of resources and energy. Industrially, a protective thin film is typically deposited on a substrate material. These films usually possess one of the following properties: high strength and hardness, low friction, wear resistance, and chemical inertness and corrosion resistance. Because the properties of these films are also related to the coating thickness, current technology cannot produce excessively thick films, otherwise their performance will be affected. Therefore, excessively thin films make it difficult to measure their properties experimentally. However, thin films are economical, significantly improve workpiece properties, and have excellent prospects. They have already been applied to machining tools, load-bearing components, and data recording hard drives. Engineers have developed films suitable for various working conditions by controlling the process. Therefore, there is an urgent need to develop reasonable methods to assess the properties of thin film materials in order to evaluate the quality of the preparation process and the success of the preparation.
[0003] Currently, the measurement of thin film material properties is generally affected by their size. Excessive thinness means that the results of mechanical property measurements often include the properties of the substrate and even the indenter probe. Ultra-high precision measuring instruments are expensive, susceptible to environmental interference, and unsuitable for industrial applications. To achieve a rapid assessment of thin film material density, molecular dynamics calculations are employed. Molecular dynamics can calculate various properties of thin film materials independently, thereby establishing relationships between different properties and inferring other material properties from one type of property. Experimentally, measuring thin film properties using Raman spectroscopy or nanoindentation is relatively simple. Using these measured properties to infer properties that are difficult to measure in thin film materials is time-saving, labor-saving, and cost-effective. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above and to provide a method for rapidly evaluating the density of thin film materials.
[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:
[0006] A method for rapidly evaluating the density of thin film materials, applicable to covalently bonded amorphous solid materials, includes the following steps:
[0007] Identify readily measurable property parameters that are related to the density of the thin film material to be evaluated;
[0008] Measure the real-time property parameters and corresponding real-time operating condition parameters of the thin film material to be evaluated;
[0009] A molecular dynamics model of the thin film material to be evaluated is constructed to simulate the behavioral changes of the thin film material with the real-time property parameter values under the real-time operating condition parameter values. The density of the molecular dynamics model under the behavioral changes is output as the real-time density parameter of the thin film material to be evaluated.
[0010] Preferably, before measuring the real-time property parameters and corresponding real-time operating condition parameters of the thin film material to be evaluated, a database construction step is also included:
[0011] A molecular dynamics model of the thin film material to be evaluated was constructed using LAMMPS. The molecular dynamics model was then used to simulate the behavioral changes of the thin film material under multiple different operating conditions and with multiple different property parameters, and the output of multiple different operating conditions, property parameters and corresponding density parameters was generated.
[0012] Construct multiple mapping tables for different operating condition parameters, property parameters, and density parameters, and store these multiple different operating condition parameters, property parameters, corresponding density parameters, and mapping tables in a database.
[0013] Preferably, a molecular dynamics model of the thin film material to be evaluated is constructed to simulate the behavioral changes of the thin film material with the real-time property parameters under the real-time operating condition parameter values, and the density of the molecular dynamics model under the behavioral changes is output as the real-time density parameter of the thin film material to be evaluated. This specifically includes the following steps:
[0014] The mapping table is retrieved from the database, and the database is queried to determine whether a density parameter value corresponding to the real-time operating condition parameter value and the real-time property parameter value exists.
[0015] If it exists, the corresponding density parameter value is returned as the real-time density parameter of the thin film material to be evaluated;
[0016] If not, reconstruct the molecular dynamics model of the thin film material to be evaluated, simulate the behavioral changes of the thin film material to be evaluated with the real-time property parameter values under the real-time operating condition parameter values, and output the density of the molecular dynamics model under the behavioral changes as the real-time density parameter of the thin film material to be evaluated.
[0017] Preferably, the property parameters include any one or more of Raman spectroscopy, nanoindentation, hardness, and scratch test parameters.
[0018] Preferably, the operating parameters include any one or more of the following: air temperature, air pressure, vapor pressure, and acoustic, optical, and magnetic fields.
[0019] Preferably, the property parameters are the steady-state model property parameters of the thin film material to be evaluated.
[0020] This invention calculates material properties based on interatomic interactions, simulates the characterization of thin film materials under different working conditions, calculates the material properties, compares the calculated measurable parameters with experimental measurements, and finally obtains the thin film density, which is difficult to measure experimentally.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] 1. The method of the present invention can start from simple measurement, quickly calculate the properties of thin film materials, evaluate the quality of its process, shorten the research and development cycle, obtain a large amount of data, realize the improvement of the preparation process of thin film materials, and also guide future production; through these measured properties, the property parameters of thin film materials that are difficult to measure can be inferred, with accurate results, saving time and effort, and saving costs.
[0023] 2. The method of the present invention relies on simulation calculation, which can consider a wide range of working conditions and is less expensive than the method of complete experimental testing.
[0024] 3. The method of the present invention can be applied to: calculating material properties based on interatomic interactions, simulating the characterization of thin film materials under different working conditions, calculating material properties, comparing the calculated measurable parameters of the material with experimental measurements, and finally obtaining the thin film density that is difficult to measure experimentally. No production and processing are required, and it is easy to obtain a large amount of data. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a schematic diagram of the test material structure in this invention;
[0027] Figure 2 The figure shows a model for calculating material properties using molecular dynamics simulation in the method of this invention. It is a diamond-like carbon model, where: 1. thin film material, 2. transition layer material, 3. substrate;
[0028] Figure 3 This is a flowchart of a method for rapidly evaluating the density of thin film materials according to the present invention. Detailed Implementation
[0029] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.
[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0031] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.
[0032] Example:
[0033] A method for rapidly assessing the density of thin film materials, such as Figure 3 As shown, it includes the following steps:
[0034] 1. Establish a material property database
[0035] A molecular dynamics model of the thin film material to be evaluated was established using LAMMPS, such as... Figure 1 The image shows a diamond-like carbon simulation model. During the database establishment phase, it is necessary to consider the influence of operating conditions such as temperature, air pressure, vapor pressure, and acoustic, electrical, and magnetic fields on the material behavior. In addition to external influences, the calculation also needs to consider the changes in measured properties after changes in the intrinsic properties of the material. A rich database of material properties should be established to facilitate subsequent comparison with experiments and to evaluate the actual measured material properties.
[0036] The establishment of a material property database includes the following steps:
[0037] (1) A molecular dynamics model of the thin film material to be evaluated is constructed using LAMMPS, including the basic settings of the simulation box, system size, atomic types and selection and allocation of simulation potential functions; the model is generally generated by melt quenching and saved for subsequent property calculations.
[0038] (2) The properties of amorphous thin film materials are closely related to their density, and therefore the two can be correlated. Taking diamond-like carbon (DLC) films as an example, their tensile strength, Young's modulus, nanoindentation force-displacement curves, and their structure (atomic sp) are correlated. 3 (Related to hybridization content).
[0039] (3) For the constitutive characteristics of materials, the molecular dynamics simulation code LAMMPS provides the fixdeform command to apply tensile or compressive deformation or shear deformation to the material. At the same time, it can calculate and output stress-strain curves, thereby calculating the mechanical properties of the material under specific working conditions (such as temperature and strain rate, which can also be set in the simulation).
[0040] (4) Regarding material structural characteristics, such as sp 3Hybridity is calculated in LAMMPS using the code computecoord / atom, which specifies the cutoff parameter for the corresponding atom pair to determine the coordination number of the atom.
[0041] (5) Nanoindentation simulation of thin film materials: First, a diamond indenter is generated at a certain distance above the thin film using commands such as `lattice` and `createatoms`. It is then defined using `region` and `group` and set as a rigid body using the `fixrigid / nve` command. After relaxing the system, the indenter is lowered at a certain speed, primarily in displacement mode. The resistance experienced by the indenter is recorded. After reaching the maximum displacement, it is held still for a period of time before returning at the same speed until it is completely removed from the thin film. Simultaneously, changes in the film's microstructure are recorded. LAMMPS also provides methods for calculating other properties of thin films, which will not be elaborated here.
[0042] (6) Statistical calculation results, test the properties of thin film materials under multiple different working conditions, and establish a database, wherein the database stores multiple different working condition parameters, property parameters, corresponding density parameters and the mapping table.
[0043] 2. Experimental measurement of material properties
[0044] like Figure 2 As shown, the thickness of the thin film material 1 is generally about 1 micrometer. There may be a transition layer 2 between it and the substrate 3. The main components of the transition layer 2 are generally a gradient mixture of elements from the thin film and the substrate, with a thickness of 5-6 micrometers. The thickness of the substrate 3 is much larger than that of the two layers of thin film material 1 and transition layer 2. The influence of the substrate can be well eliminated by Raman spectroscopy and nanoindentation test, and the property parameters of the thin film can be measured. The measured property parameters can be compared with the molecular dynamics simulation database established in step 1.
[0045] 3. Calculation and comparison of corresponding working conditions
[0046] If a density parameter corresponding to the property parameters measured under experimental conditions exists in the database, the density parameter is taken as the density of the thin film. If it does not exist, a new molecular dynamics model is established based on the experimental conditions to simulate the behavior and changes of the thin film material under those conditions. Similar properties, such as Raman curves, are compared, and the simulated thin film density under those experimental conditions is taken as the density of the thin film.
[0047] Based on the experimental conditions, a new molecular dynamics model was established to simulate the behavior and changes of the thin film material under the experimental conditions. Comparison with similar properties, such as Raman curves, was made, and the simulated thin film density under these conditions was taken as the actual density of the thin film. Specifically:
[0048] (1) In the experiment, it is relatively easy to measure the structural characteristics of thin film materials and conduct nanoindentation and scratch tests. Taking diamond-like carbon thin film as an example, its structural properties are measured by Raman spectroscopy, its hybridization ratio is determined, and the corresponding molecular dynamics model is selected for nanoindentation testing.
[0049] (2) In the nanoindentation simulation, the planar direction is first set as a periodic boundary, and the box size in the indentation direction is expanded to allow for the placement of the indenter. Diamond indenters are generated using commands such as `lattice` and `createatoms`, defined using `region` and `group`, and set as rigid bodies using the `fixrigid / nve` command. The film is set from top to bottom as a Newtonian layer, a isothermal layer, and a rigid layer to ensure it has a deformation region, a heat dissipation region, and the ability to simulate the actual film scale. The `pair_style` command is used to set the tersoff potential function, referring to the LAMMPS manual for details. The isothermal layer temperature is recalibrated using the temperature scaling method `temp / rescale` to relax the system, and the diamond indenter is pressed down at a certain speed. The `compute` command is used to calculate the coordination number, stress, and other properties of the atoms. The calculated data is output using `dump` and `print`, with `dump_modify` controlling the output format and accuracy. The `velocity` command is used to set the pressing speed of the diamond indenter. The simulation is primarily in displacement mode; after the indenter reaches its maximum displacement, it is held still for a period of time and then returns at the same speed until it completely leaves the film. Finally, the output data is processed to obtain the simulated structure.
[0050] (3) Compare the structure with the experimental results to verify the accuracy of the simulation. If the correspondence is good, the density of the selected simulated material can be approximated as the density of the experimental material.
[0051] Inferring difficult-to-measure properties of thin film materials using these measured properties yields accurate results, saves time and effort, and reduces costs.
Claims
1. A method for rapidly evaluating the density of thin film materials, applicable to amorphous solid materials formed by covalent bonds, characterized in that, Includes the following steps: Identify readily measurable property parameters that are related to the density of the thin film material to be evaluated; Measure the real-time property parameters and corresponding real-time operating condition parameters of the thin film material to be evaluated; A molecular dynamics model of the thin film material to be evaluated is constructed to simulate the behavior changes of the thin film material to be evaluated with the real-time property parameter values under the real-time operating condition parameter values. The density of the molecular dynamics model under the behavior change is output as the real-time density parameter of the thin film material to be evaluated. Before measuring the real-time property parameters and corresponding real-time operating condition parameters of the thin film material to be evaluated, a database construction step is also included: A molecular dynamics model of the thin film material to be evaluated was constructed using LAMMPS. The molecular dynamics model was then used to simulate the behavioral changes of the thin film material under multiple different operating conditions and with multiple different property parameters, and the output of multiple different operating conditions, property parameters and corresponding density parameters was generated. Construct a mapping table of multiple different working condition parameters, property parameters and density parameters, and store the multiple different working condition parameters, property parameters, corresponding density parameters and the mapping table in a database; A molecular dynamics model of the thin film material to be evaluated is constructed to simulate the behavioral changes of the thin film material with the real-time property parameters under the real-time operating condition parameter values. The density of the molecular dynamics model under the behavioral changes is output as the real-time density parameter of the thin film material to be evaluated. The specific steps include: The mapping table is retrieved from the database, and the database is queried to determine whether a density parameter value exists that corresponds to the real-time operating condition parameter value and the real-time property parameter value. If it exists, the corresponding density parameter value is returned as the real-time density parameter of the thin film material to be evaluated; If not, reconstruct the molecular dynamics model of the thin film material to be evaluated, simulate the behavioral changes of the thin film material to be evaluated with the real-time property parameter values under the real-time operating condition parameter values, and output the density of the molecular dynamics model under the behavioral changes as the real-time density parameter of the thin film material to be evaluated.
2. The method according to claim 1, characterized in that, The property parameters include any one or more of the following: Raman spectroscopy, nanoindentation, hardness, and scratch test parameters.
3. The method according to claim 1, characterized in that, The operating parameters include any one or more of the following: air temperature, air pressure, vapor pressure, and acoustic, electrical, and magnetic fields.
4. The method according to claim 1, characterized in that, The property parameters are the steady-state model property parameters of the thin film material to be evaluated.