Characterization of Mechanical and Physical Properties of Silica Aerogels Using Molecular Dynamics Simulation
Silica aerogels are nanoporous ultralight materials with extreme materials properties: the highest specific surface area of any material; slowest speed of sound through any solid material; excellent thermal insulators. Using molecular dynamics and the Tersoff potential, re-parameterized to simulate silicon dioxide, we have modeled the porous structures of silica aerogels. Our study shows that this potential is more suitable for modeling thermal properties in amorphous silica than the widely-used BKS potential. Increasing densities of aerogel samples are generated using an expanding and quenching process. Analysis of the fractal dimensions indicates a good fit with previous theoretical and experimental results. Each samples thermal conductivity is determined using reverse non-equilibrium molecular dynamics. Results indicate that the power-law fit of our data reflects the power-law exponent found in experimental studies. The results are also of the same order of magnitude as experimental bulk aerogel, but they are consistently higher. Analysis of the pore size distribution shows, firstly, that such a disparity is due to limited pore sizes represented in a finite nano-sized system, and secondly, that increasing system length scales leads to corresponding increases in the pore sizes that can be represented. Furthermore, we attempt to determine the mechanical properties, such as Youngs modulus of aerogel by using the same potential. We can conclude from all these results that our model is very suitable for modeling the mechanical and physical properties of bulk silica aerogel, and that an appropriate system length scale can be chosen to suit the pore size regime of interest.
molecular dynamics silica aerogel nanoporous ultralight materials
Jingjie Yeo Jincheng Lei Zishun Liu Teng Yong Ng
School of Mechanical and Aerospace Engineering,Nanyang Technological University,50 Nanyang Avenue,63 International Centre for Applied Mechanics,State Key Laboratory for Strength and Vibration of Mechan
国际会议
北京
英文
1-7
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）