Microstructure, surface morphology, and mechanical properties of nanocrystalline TiN/amorphous Si 3 N 4 composite films synthesized by ion beam assisted deposition

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Nitrile-butadiene rubber (NBR) has been wildly applied in vibration controltechnology, it is usually mixed with organic small molecular modifiers and well vulcanized, which can greatly enhance the mechanical and damping properties of the material. This work aims to design the optimum blending ratio of hindered phenol A/B/NBR composite with the best damping property by means of molecular dynamics (MD) simulation, and investigate the mechanical performance from the molecular level. The shear deformation simulation is conducted on pure NBR models to study the impact of rubber crosslink degree (CD) on elasticity and plasticity of NBR. To research the damping mechanism of the material, detailed analyses of the micro molecular structure and reciprocating shear simulation are carried out on NBR composite models with different hindered phenol A/B ratio. The simulation results indicate a strong positive correlation between intermolecular H-bonds and loss factor 𝜼, and the NBR composite with hindered phenol A/B per hundred rubber (phr) 30/30 shows the best damping performance.

TiN ∕ TiB 2 nanomultilayers with different TiB2 layer thicknesses were deposited by the multitarget magnetron sputtering method. Studies show that because of the template effects of the cubic TiN layer, the normally amorphous TiB2 layer crystallizes into a compact hexagonal structure when its thickness is less than 2.9 nm. As a result, the multilayers form a c-TiN∕h-TiB2 coherent epitaxial structure with the orientation relationship of {111}TiN∕∕{0001}TiB2,⟨110⟩TiN∕∕⟨112¯0⟩TiB2. Correspondingly, the multilayers show a significant hardness enhancement with a maximum hardness of 46.9 GPa. Further increase in TiB2 layer thickness leads to the formation of amorphous TiB2 that blocks the coherent growth of the films, and thus the hardness of the multilayers decreases gradually.