No abstract

Electrical and thermal management in nanodevices by means of carbon nanotube is highly promising. One main challenge toward CNT-based nanoscale electrical and thermal management devices is the development of effective strategies for reducing the bundle-bundle interface resistance. Here we report a novel strategy, based on the densification of CNT bundles

Stacking thin graphene layers into three-dimensional (3D) microscopic structure named graphene nanoplatelets (GNPs) could render much lower-1-1 thermal conductivity (κ) compared with single-layer graphene with ultrahigh κ of around 5000 W•m •K. In this study, decorating GNP surface with nanoparticles (NPs) is proposed to be an effective approach to further push down the lower limit value of κ for GNPs. By introducing six metallic and non-metallic NPs, i.e., Au, Ag, Cu, Fe, Al O and SiO NPs onto the GNP surface, we experimentally corroborate that the κ values of 2 3 2-1-1 5 GNP stacking powders approaches to 0.07 W•m •K , which is 10 magnitudes lower than that of ideal 2D graphene materials. This remarkable reduction could be ascribed to the greatly limited sizes of ideal 2D lattice structure (~2 μm) together with random stacking arrangement and extra phonon scattering sites due to the introduction of heterogeneous NPs. Significantly, it is demonstrated that even distribution and small diameter of NPs are beneficial to thermal transport of stacking GNPs. The progress made so far could pave way to GNP materials with tunable thermal transport performance.

Droplet rebound dynamics on superhydrophobic surfaces has attracted much attention due to its importance in numerous technical applications, such as anti-icing and fluid transportation. It has been demonstrated that changing the macro-structure of the superhydrophobic surface could result in significant change in droplet morphology and hydrodynamics. Here we conduct both experimental and numerical studies of droplet impacting on a cone, and identify three different dynamic phases by changing the impacting conditions, i.e., the Weber number and the cone angle. The spreading and retracting dynamics are studied for each phase. Particularly, it is found that in Phase 3, where the droplet leaves the surface as a ring, the contact time is reduced by 54% compared with that of a flat surface. A theoretical model based on energy analysis is developed to get the rebound point in Phase 3, which agrees well with the simulation result. Besides, the effect of Weber number and cone angle on the contact time is explored.Finally, the phase diagram of the three phases distribution with We and cone angle is given, which can provide guidance to related applications.