Numerical Simulation And Failure Mechanism Study For The Indium Sealing Interface Of He-Ne Laser Gyro

As a kind of inertial guidance device,He-Ne laser gyro is widely used in the fields of modern aviation,navigation,spaceflight and other national defense fields.The hot press sealing between electrode and resonant cavity is one of the core technology in the production of He-Ne laser gyro,the failure of the sealing interface will directly cause the change of the discharge environment in resonant cavity,and reduce the life of the product.Numerical simulation was taken for the Al/In interface of cathode and Cu/In interface of anode based on the first-principles and molecular dynamics theories.The atomic diffusion and yield failure process of Al(001)/In(001)interface were studied and the failure mechanism of the interface was analyzed to provide theoretical guidance for the further optimization of indium sealing technology between electrode and resonant cavity.The main contents of this dissertation are as follows:1)The ideal crystal structures of Al,Cu and In were optimized based on the firstprinciples calculations.It was show that the Al(111),Cu(111)and In(001)surface was most stable by calculating the surface energy,analyzing the relaxation states and taking further study on the distribution of DOS of the five low index surfaces.2)The initial models of Al(111)/In(001)and Cu(111)/In(001)interface were constructed with the stable surfaces.It was shown that the ideal Cu(111)/In(001)interface was more stable than Al(111)/In(001)interface,and the tensile strength of Cu(111)/In(001)interface was higher by comparing the interface energies,adsorption energies and dissociation energies of the two interfaces and analyzing the atomic relaxation state near the two interfaces.The results showed that the DOS of Al/In and Cu/In interfaces overlapped in a certain energy range.The charge density and charge density difference diagrams showed that the covalent bonds were formed between the atoms at the interfaces,and the charge transfer process of Cu(111)/In(001)interface was more frequent.3)The variation rules of the tensile strength of Cu(111)/In(001)and Al(111)/In(001)interfaces under different temperatures and pressures were studied by using the classical molecular dynamics methods based on the 2NN-MEAM potential.The calculation results showed that the optimum process parameters of cathode sealing and anode sealing are 463 K,4MPa and 423 K,5MPa,and the tensile strength of Cu(111)/In(001)interface was higher than that of Al(111)/In(001)interface under same temperature and pressure.4)The atomic diffusion process and tensile failure process of Al(001)/In(001)interface were analyzed.The results showed that the interface failure of Al(001)/In(001)interface was caused by the defects in the interface layer and the indium layer,and the gas permeation channel was further formed which resulting in the change of the vacuum environment in the resonant cavity.