Dynamics And Morphology Of Cracks In Silicon Nitride Films: A Molecular Dynamics Study On Parallel Computers

1995 ◽  
Vol 409 ◽  
Author(s):  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Priya Vashishta

AbstractMultiresolution molecular dynamics approach on parallel computers has been used to investigate fracture in ceramic materials. In microporous silica, critical behavior at fracture is analyzed in terms of pore percolation and kinetic roughening of fracture surfaces. Crack propagation in amorphous silicon nitride films is investigated, and a correlation between the speed of crack propagation and the morphology of fracture surfaces is observed. In crystalline silicon nitride films, temperature-assisted void formation in front of a crack tip slows down crack propagation.

1995 ◽  
Vol 408 ◽  
Author(s):  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Priya Vashishta

AbstractMultiresolution molecular dynamics approach on parallel computers has been used to investigate fracture in ceramic materials. In microporous silica, critical behavior at fracture is analyzed in terms of pore percolation and kinetic roughening of fracture surfaces. Crack propagation in amorphous silicon nitride films is investigated, and a correlation between the speed of crack propagation and the morphology of fracture surfaces is observed. In crystalline silicon nitride films, temperature-assisted void formation in front of a crack tip slows down crack propagation.


1996 ◽  
Vol 457 ◽  
Author(s):  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Andrey Omeltchenko ◽  
Kenji Tsuruta ◽  
Priya Vashishta

ABSTRACTNew multiscale algorithms and a load-balancing scheme are combined for molecular-dynamics simulations of nanocluster-assembled ceramics on parallel computers. Million-atom simulations of the dynamic fracture in nanophase silicon nitride reveal anisotropie self-affine structures and crossover phenomena associated with fracture surfaces.


Author(s):  
Longqiu Li ◽  
Shufeng Wang ◽  
Andrey Ovcharenko ◽  
Wuyi Wang

Silicon nitride films were attracting extensive research interest in the past few decades as hard disk protective coating, especially the beta-silicon nitride (β-Si3N4) films and amorphous silicon nitride (SiNx) films, which have high hardness, chemical durability and low friction coefficient properties against wear, corrosion and reducing the friction resistance, respectively. Considerable efforts have been made in studying silicon nitride. However, it’s difficult to determine its nano-tribological properties experimentally since the results were affected by a lot of contact and environment conditions. The molecular dynamics (MD) simulation method is employed in this work. A rigid diamond sphere modeled as a spherical tip are sliding over a layered silicon nitride film substrate, respectively, to investigate the tribological properties of silicon nitride films. The effect of the relative sliding velocity and sliding direction, the normal force and the thickness of crystalline silicon nitride films on the friction coefficient of silicon nitride films were investigated.


2003 ◽  
Vol 805 ◽  
Author(s):  
Frohmut Rösch ◽  
Christoph Rudhart ◽  
Peter Gumbsch ◽  
Hans-Rainer Trebin

ABSTRACTThe propagation of mode I cracks in a three-dimensional icosahedral model quasicrystal has been studied by molecular dynamics techniques. In particular, the dependence on the plane structure and the influence of clusters have been investigated. Crack propagation was simulated in planes perpendicular to five-, two- and pseudo-twofold axes of the binary icosahedral model.Brittle fracture without any crack tip plasticity is observed. The fracture surfaces turn out to be rough on the scale of the clusters. These are not strictly circumvented, but to some extent cut by the dynamic crack. However, compared to the flat seed cracks the clusters are intersected less frequently. Thus the roughness of the crack surfaces can be attributed to the clusters, whereas the constant average heights of the fracture surfaces reflect the plane structure of the quasicrystal. Furthermore a distinct anisotropy with respect to the in-plane propagation direction is found.


1990 ◽  
Vol 201 ◽  
Author(s):  
E. P. Donovan ◽  
C. A. Carosella ◽  
K. S. Grabowski ◽  
W. D. Coleman

AbstractSilicon nitride films (Si1−x,.Nx) have been deposited on silicon by simultaneous evaporation of silicon and bombardment of nitrogen ions. Films approximately 1 μm thick were deposited in an ambient nitrogen pressure of 50 μTorr. The substrate temperature (TSUB) ranged from nominally room temperature to 950° C for films with X between 0 and 0.6. Nitrogen atom fraction, X, was measured with Rutherford backscattering spectrometry (RBS). Refractive index was measured with near-IR reflection spectroscopy. Differences in film structure were measured by FT1R on the Si-N bond bending absorption mode, and by x-ray diffraction (XRD). X was found to depend upon the incident flux ratio of energetic nitrogen atoms to vapor silicon, and upon TSUB. Refractive index depends upon X and TSUB. XRD found evidence of the presence of amorphous structure, poly-crystalline silicon and (101) oriented β-Si3N4 depending on X and TSUB. The Si-N absorption signal increases with X and shows some structure at high TSUB.


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