Study Of Molecular Dynamics Of Al₂O₃/TiC Composite Ceramic Tool Interface

Ceramic cutting tool has the characteristics of high hardness,good wear resistance and excellent thermal stability.The development of ceramic cutting tool is far-reaching significance to machinery manufacturing and equipment research.Throughout the development of ceramic cutting tool,composite ceramic cutting tool has become the focus of scholars at home and abroad.During the sintering preparation of composite ceramic materials,there are different degrees of interface interaction between the enhanced phase and matrix phases in the system,so the interface bonding strength is the main factor affecting the composite effect.In order to further research the influence of interface structure on the macroscopic mechanical property,simple experiments can not reveal the interaction effect of interfaces between interfaces from the atomic level.Only by deepening the research level to the structural characteristics of the interface and comprehensively considering the stability and interaction of the interface,can we have a deeper understanding of the relationship between the material interface and macro mechanical properties.Therefore,it is very necessary to research the interface structure and microscopic mechanism of composite ceramic cutting tool materials.This topic researches the interface of Al₂O₃/TiC complex phase ceramic cutting tool material.Considers the interface geometric characteristics,interface structure,interface stability and other factors,and focuses on the interface binding strength,interface bonding mechanism and interface mechanical properties.The purpose is to analyze the interface stability mechanism and failure mechanism of materials from the perspective of atoms and electrons,and find the optimal sintering temperature of ceramics through molecular dynamics simulation,so as to provide theoretical guidance for the preparation of Al₂O₃/TiC ceramic cutting tools.Thus,the interface research can be raised to atomic scale by means of computer simulation to solve the defect that traditional experiments can only stay at the interface observation.Using the method based on the first principle of density functional theory,the surface energy of several low exponential surfaces of Al₂O₃and TiC was calculated,and the exponential surface with low surface energy was selected for interface modeling.The interface models of three different atomic terminals of Al₂O₃(001)and TiC(100)surface were constructed to analyze the binding energy and electronic structure of the three models and reveal the interface stability mechanism.The results showed that Al₂O₃(001)crystal face and TiC(100)crystal face were the most stable.By comparing the binding energy of three different terminal models,it was conclud that the single layer O atom terminal had the highest binding energy of0.349 J/m~2,and the system structure was the most stable.Combined with the Griffith fracture strength theory,it was find that the system had the strongest ability to resist crack growth.The analysis of the electronic structure showed that the interface bonding effect of the single layer O atom model was the best,and the enhanced covalency of the atomic bonding at the interface was beneficial to improve the interface stability.Through the molecular dynamics methods based on first principles,the tensile stress strain and shear stress strain of the ideal interface of Al₂O₃(001)/TiC(100)composite ceramic cutting tool were calculated to explore the interface mechanical properties and interface failure mechanism of composite materials at the micro scale.The mechanical properties and failure mechanism of the interface are explored by molecular dynamics based on first principle.It was found that when the stress variable reached 12%,the maximum tensile stress was 11.83 GPa,and when the stress variable reached-10%,the maximum shear stress was 9.37 GPa.By studying the atomic motion and charge distribution of Al₂O₃(001)/TiC(100),the material failure was related to the atomic position and bonding change after applying strain.The molecular dynamics method based on Newtonian mechanics was used to explore the optimal sintering temperature of Al₂O₃/TiC composite ceramic cutting tool interface model,and finded the optimal sintering temperature to guide the sintering preparation of Al₂O₃/TiC ceramic cutting tools.The influence of the sintering temperature on the material interface was explored,and the interface stability and atomic migration of the ceramic cutting tool material at different sintering temperature were analyzed.The results showed that when the temperature reaches 1900K,the maximum interfacial binding energy was 5.66 J/m~2,the system was the most stable.Through experiments,it was found that the performance of Al₂O₃/TiC ceramic cutting tool material was the best when 1900K was used as the sintering temperature.Its bending strength was 687 MPa,hardness was 18.44 GPa and fracture toughness was7.32 MPa/m~2.