Insight into the Mechanisms of Nitride Films with Excellent Hardness and Lubricating Performance: A Review.

Transition metal nitride (TMN) films with excellent hardness and lubricating performance are versatile low dimension materials, which are widely used in various fields including industries, transportation, aerospace, and so on. This paper introduces one film design strategy and provides a review of the mechanisms for strengthening and lubricating nitride films. The design strategy refers to two aspects which determine the structures, the performance, the components, and the chemical constitutions of nitride films The strengthening mechanisms of nitride films are then illuminated in detail, including the solid solution effect, the grain size effect, the secondary phase effect, the stress or stress field effect, the template effect, and the valence electron concentration effect.

Investigation into fresh air delivery performance with vortex ring.

An air supply mode based on vortex ring structures was proposed to deliver fresh air for good indoor air quality. This study focused on the influence of air supply parameters, including formation time (T*), supply air velocity (U), and supply air temperature difference (ΔT), on the fresh air delivery performance of an air vortex ring using numerical simulations. The cross-sectional average mass fraction of fresh air (C) was proposed to evaluate the fresh air delivery performance of the air vortex ring supply.