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Molecular Dynamics Simulations of the Interfacial Structures in ZrB2/SiC Composite

Author: LuoXiaoGuang
Tutor: LiJinPing
School: Harbin Institute of Technology
Course: Materials Science
Keywords: First-principles Molecular Dynamics Zirconium diboride ZrB2 Silicon carbide (SiC) Interface
CLC: TB33
Type: Master's thesis
Year: 2007
Downloads: 404
Quote: 2
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Abstract


Using first-principles pseudopotential plane-wave method based on density functional theory to calculate the the ZrB 2 of the lattice constant, electronic structure, elastic properties of anisotropic parameters and the Debye temperature. The use of molecular mechanics method ZrB 2 , the typical surface of the beta-SiC surface, the establishment of the ZrB 2 / beta-SiC, the nine possible interface model. By molecular dynamics simulation based on 9 kinds of interface models from the sintering temperature to room temperature process interface structure evolution calculated ideal adhesive power of the interface, a combination of a variety of interface features. The results show that the the ZrB 2 of the lattice parameters, the calculated results and the experimental parameters of the electronic structure and the literature is quite consistent, the ZrB 2 has a covalent bond, ionic bond and metal bond mixed bonding characteristics, B 2 the p-Zr4d track electronic hybridization between the role of the main causes of its pseudo-bandgap explained the ZrB 2 has the physical nature of the high melting point and good conductivity. By default the copes system total and fitting the Birch-Murnaghan equation of state has been the ZrB 2 of the the ideal stiffness matrix, obtained ZrB 2 polycrystalline bulk modulus amount of 238GPa modulus of elasticity of 525GPa shear modulus 231GPa, Poisson's ratio is 0.13, calculated results and the experimental values ??are in good agreement. The ZrB 2 of the crystal structure of the layer stacking, but the calculation result is displayed and its anisotropy is not obvious. Using elastic constants the ZrB 2 of the Debye temperature of 927K, and the measured 910K more in line with. Based on molecular field was calculated the ZrB 2 , the typical surface of the beta-SiC surface, the results display the lattice bonding complexity of the relationship and the rough force field parameters, the ZrB 2 undulating surface; beta-SiC surface energy difference between the smaller, in line with a beta-SiC surface diversity of experimental results. Molecular dynamics simulations to calculate the temperature-dependent evolution the ZrB 2 , β-SiC low energy surfaces composed of nine kinds of interface structure. The simulation results show that the main factors for the interface position distribution constitute the interface atomic layer structural stability, atomic radius, electronegativity difference as well as between the atoms. Interface ideal adhesive power calculations show that, W ZrB 2 (0001) / / β-SiC (001) gt; W ZrB 2 < / sub> (0001) / / β-SiC (110) gt; W ZrB 2 (1120) / / β-SiC (001) (W ZrB 2 (1120) / / β-SiC (110) ), the interface deformation rate showed an opposite variation, because the interface is ideal for bonding power depends on the average interface bond strength and interface relaxation deformation of two factors. Observation literature in ZRB is 2 / SiC composite interface HRTEM images found in the actual material simulation interface model.

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