CN-121978148-A - Method for revealing 6H-SiC reciprocating friction trans-scale damage mechanism

CN121978148ACN 121978148 ACN121978148 ACN 121978148ACN-121978148-A

Abstract

The invention discloses a method for revealing a 6H-SiC reciprocating friction trans-scale damage mechanism, which comprises the steps of firstly obtaining macroscopic friction and wear behavior data of 6H-SiC through a reciprocating friction experiment under a series of loads. And then, analyzing the abrasion surface by combining a scanning electron microscope and an energy spectrum, and observing a high-load abrasion section by utilizing a focused ion beam and a high-resolution transmission electron microscope, so as to directly reveal a trans-scale damage sequence of subsurface amorphization, nanocrystalline residue and microcrack expansion. Further, the origin of critical damage processes such as amorphization and dislocation activity are reproduced and explained from the atomic scale through molecular dynamics simulation. According to the method, through a macroscopic experiment, microscopic characterization and atomic simulation, a system reveals a damage evolution mechanism of 6H-SiC from an atomic scale to a microscopic scale under reciprocating friction, and a systematic analysis means is provided for deep understanding of tribological behaviors and development of targeted performance research.

Inventors

FANG RANRAN
DENG YONGYI
CHEN XIANG
SUN ZEYU
Yang Jiaojun
JIANG GE
ZHANG SHUHUAI
HU TAO

Assignees

重庆邮电大学

Dates

Publication Date: 20260505
Application Date: 20260127

Claims (10)

1. An analysis method for revealing a 6H-SiC reciprocating friction trans-scale damage mechanism is characterized by comprising the following steps: (1) Under the conditions of three different normal loads of low, medium and high, carrying out reciprocating friction experiments on a 6H-SiC ceramic sample, obtaining friction coefficient curves under each load and calculating the wear rate of the friction coefficient curves; (2) Carrying out morphology observation and element plane distribution analysis on the abrasion surface under each load by using a scanning electron microscope and an energy spectrometer, and analyzing the surface state and the abrasion mechanism; (3) Preparing a sample with a longitudinal section from the abrasion sample under the high load condition by adopting a focused ion beam technology; (4) Observing a subsurface region of the cross-section sample by using a high-resolution transmission electron microscope, and identifying and confirming damage characteristics of the subsurface by analyzing a high-resolution lattice image, a selected area electron diffraction spectrum and a fast Fourier transform spectrum, wherein the characteristics comprise an amorphized region of a crystal structure, nanoscale crystal residues in or at an amorphized region and micro cracks which are initiated and expanded from a high defect density region; (5) Constructing a 6H-SiC atomic model consistent with the experimental crystal orientation, simulating a nanometer scratching process under different indentation depths by adopting a molecular dynamics method, analyzing a deformation and damage mechanism from an atomic scale, and explaining the phenomenon observed in the step (4); (6) And (3) analyzing the corresponding relation among macroscopic friction and abrasion behaviors, surface states, subsurface damage sequences and atomic scale mechanisms under different loads by combining the results of the steps (1) to (5).
2. The analysis method for revealing a 6H-SiC reciprocating friction cross-scale damage mechanism according to claim 1, wherein in the step (1), the three different normal loads are 5N, 10N and 30N respectively, the stroke of the reciprocating friction experiment is 5mm, the frequency is 2 Hz, the total duration is 30 minutes, and the experimental environment is 23 ℃ at room temperature and 50% relative humidity.
3. The analysis method for revealing a 6H-SiC reciprocating friction trans-scale damage mechanism according to claim 2, wherein the dual component adopted in the complex friction experiment in the step (1) is a SiC ball with the diameter of 10 mm.
4. The method according to claim 1, wherein in the step (1), the 6H-SiC ceramic is a pressureless sintered material having a bulk density of 3.14 g/cm3, a microhardness of 25.70 GPa, a flexural strength of more than 400 MPa, an elastic modulus of 415 GPa, a thermal conductivity of 148W.m - ¹·K - 1, and a fracture toughness of more than 4.5 MPa.m1/2.
5. The method of claim 2, wherein the step (2) is characterized in that the abrasion surface morphology under each load is observed, the surface presents abrasive dust particles and peeling pits under a low load of 5N, a relatively continuous and flat compaction layer is formed on the surface under a load of 10N, the compaction layer presents a large-area fracture and peeling morphology with a large number of microcracks under a high load of 30N, and the main component of the compaction layer is oxygen-enriched silicon oxide.
6. The analysis method for revealing a 6H-SiC reciprocating friction cross-scale damage mechanism according to claim 1 is characterized in that in the step (4), a damage space sequence exists in the subsurface region, namely, an amorphous region with a completely disordered crystal structure is firstly formed in a high stress concentration region, nanocrystalline residues with the size of nanometer scale (2-10 nm) and still maintaining the crystal structure are distributed in the amorphous region, and microcracks are initiated from a high defect density region and spread towards the inside of a material along a grain boundary.
7. The method for analyzing the mechanism of 6H-SiC reciprocating friction cross-scale damage according to claim 1, wherein in the step (5), the 6H-SiC atomic model size is 246.13 A× 426.309 A× 181.177A, 1,843,200 atoms are added, and the surface is (0001) plane by adopting the ABCACB stacking sequence.
8. The method of claim 1 or 7, wherein the molecular dynamics simulation in step (5) uses LAMMPS software, the time step is 1 fs, the NPT system is adopted to relax 100 ps under 293K, and Tersoff potential functions are used to describe the interatomic interactions.
9. The method of claim 1, wherein the different indentation depths in step (5) comprise 10 a, 20 a and 30 a, the simulation process comprises three stages, namely an indentation stage, a reciprocating sliding stage and an unloading stage, the sliding speed is 50 m/s, the scratch length is 150 a, the number of reciprocating cycles is 10, and the method further comprises simulating a multi-cycle reciprocating sliding process, wherein the multi-cycle simulation comprises at least 5 cycles.
10. An analytical system for revealing a 6H-SiC reciprocating friction trans-scale damage mechanism, characterized in that the analytical method according to any one of claims 1 to 9 can be accomplished, comprising: (1) The macroscopic tribology behavior testing unit comprises a reciprocating friction and wear testing machine, a normal load loading module and a data acquisition system, and is used for executing a reciprocating friction experiment and recording a friction coefficient curve in real time; (2) The surface wear state characterization unit comprises a scanning electron microscope and energy spectrometer combined system and is used for performing wear surface morphology observation and element plane distribution analysis; (3) The subsurface damage preparation and observation unit comprises a focused ion beam system and a high-resolution transmission electron microscope and is used for preparing a section sample, observing subsurface and identifying damage characteristics; (4) The atomic scale mechanism simulation unit comprises a molecular dynamics simulation platform configured with Tersoff potential function parameters and LAMMPS software, and is used for constructing a 6H-SiC atomic model and executing single-time and multi-period nanometer scratch simulation under different indentation depths; (5) And the cross-scale correlation analysis platform is integrated with data processing and visualization software and is used for comprehensively analyzing output data of the macroscopic tribology behavior testing unit, the surface abrasion state characterization unit, the subsurface damage preparation and observation unit and the atomic scale mechanism simulation unit.

Description

Method for revealing 6H-SiC reciprocating friction trans-scale damage mechanism Technical Field The invention relates to the field of advanced ceramic material tribology performance research, in particular to a method for comprehensively utilizing macroscopic experiments, microstructure characterization and molecular dynamics simulation to systematically reveal damage evolution mechanisms from atomic scale to microscopic scale aiming at 6H-SiC (hexagonal silicon carbide) ceramic under the reciprocating friction condition, and providing guidance for wear performance regulation based on the knowledge of the mechanisms. Background Silicon carbide (SiC) is an ideal candidate for critical structural components under extreme conditions due to its excellent hardness, wear resistance, high thermal conductivity, low coefficient of thermal expansion, and excellent chemical stability. Among them, 6H-SiC, one of the most stable hexagonal polytypes, has demonstrated great potential for use in microelectromechanical systems (MEMS), aerospace bearings, advanced packaging, and high temperature electronics. However, in these applications, the components are often subjected to high frequency, high load reciprocating sliding contact, resulting in unavoidable frictional wear, which becomes a critical constraint affecting device accuracy, stability, and service life. Currently, research on friction and wear behaviors of SiC ceramics has been advanced to some extent. A great deal of experimental work discusses the rule of influence of factors such as load, speed, temperature, environmental medium, dual materials and the like on friction coefficient and wear rate. For example, it has been observed that increasing the load in a certain range may cause a decrease in friction coefficient, a non-monotonic change in wear rate, lubrication by the formation of an oxide film at high temperature, tribochemical reaction in an aqueous environment, and the like. These studies are mainly based on the measurement of macroscopic tribological parameters and the topographical observation of the worn surface (e.g. using scanning electron microscopy SEM), and lack of systematic, direct experimental observations and theoretical explanations for the dynamic evolution of the subsurface microstructure of the material during wear, the initiation and early expansion mechanisms of damage, in particular the correlation and sequence between different scale (atomic-nano-micron) damage modes. In recent years, molecular Dynamics (MD) simulation provides a powerful tool for studying the deformation and damage mechanisms of materials at the atomic/nano scale. Simulation work has revealed that SiC may undergo phase transitions, amorphization, dislocation nucleation, and motion during nanoindentation, scratching, and the like. However, the simulation research on the atomic scale is often disjointed from the macroscopic experimental phenomenon, and a set of analysis frameworks which deeply integrate microscopic mechanism, experimental observation and macroscopic performance cannot be formed, so that the evaluation and design of the wear resistance of the material lack solid theoretical guidance. Therefore, a systematic research method capable of penetrating macro, micro and atomic dimensions is urgently needed to deeply reveal the friction damage nature of 6H-SiC and provide scientific basis for realizing active design of the performance of the system. In view of this, the present application has been made. Disclosure of Invention The invention aims to solve the problems that the abrasion mechanism of the 6H-SiC ceramic is not clear and the system mechanism explanation and the correlation analysis are lacked under the working condition of high-load reciprocating friction. Based on the method, a comprehensive research method for systematically revealing the trans-scale damage evolution sequence and the association with macroscopic tribology behaviors is provided. According to the method, 6H-SiC is subjected to reciprocating friction experiments under different normal loads (such as 5N, 10N and 30N), microstructure characterization and atomic scale simulation are combined, the rule of the abrasion rate of the 6H-SiC along with the change of the load is systematically researched, and the damage characteristics of subsurface materials under different abrasion states are deeply analyzed. Experimental results show that under the condition of specific medium load (for example 10N), a continuous and compact SiO 2 lubricating film can be formed on the surface of the material, the friction coefficient and the wear rate reach low levels at the moment, the observation of a wear section by a high-resolution transmission electron microscope directly reveals a trans-scale damage sequence with a spatial sequence of 'atomic scale amorphization- & gt nanocrystalline residue- & gt microcrack expansion' in a damaged area for the first time, and further molecular dynamics simulation is