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This study aims to analyze the nano-grinding behavior of silicon wafer workpieces with nanoscale roughness by molecular dynamics simulations. The nano-grinding process of silicon wafer workpieces with varying root-mean-square roughness under different grinding depths is simulated, considering synchronous rotation and translation of the diamond abrasive. The material removal mechanism, thermodynamic properties and mechanical responses are revealed. The findings demonstrate that the material removal in the nano-grinding process can be influenced by surface roughness and grinding depth, leading to its classification into compression, ploughing and cutting regimes. Moreover, reducing the grinding depth and surface roughness also reduces temperature, von Mises stress and grinding force, thus mitigating surface damage to silicon wafer workpieces. However, a minimal initial root-mean-square roughness may result in reduced surface smoothness of silicon wafer workpieces after a single grinding. [ABSTRACT FROM AUTHOR]

This work attempts to investigate contact between two self-affine fractal surfaces with one being of a rigid solid and other of a FCC deformable body. A normal contact model between two self-affine fractal surfaces at the nanoscale is established. Effects of surface morphology on contact force, atomic structure, dislocation with normal displacement are investigated by simulating the contact process of self-affine surfaces. Results show that the normal force for rougher surfaces at initial contact yields the larger negative extremum due to effects of surface morphology on interatomic repulsion and attraction. Furthermore, the atomic structure change proportion varies monotonically with normal displacement whereas effects of surface morphology can be approximately ignored. However, the phase transition generated by too large atomic slip leads to a non-monotonic variation between total dislocation lines length and normal displacement. Differences in contact ratio-separation dependence between the classical micro-asperity model and the established model are compared. [ABSTRACT FROM AUTHOR]

In this study, the effects of the surface structure of electrospun polyvinylidene fluoride (PVDF) nanoweb on surface wettability were analyzed. The conditions of the surface structure representing the lotus and petal effects were derived, and the difference in the dynamic behavior of the water droplets on the surfaces was investigated. To this end, a PVDF nanoweb was fabricated by electrospinning various concentrations of PVDF solutions. The nanoscale roughness was adjusted by varying the CF4 plasma etching time. It was seen that when the concentration of the electrospun PVDF solution was 15 or 20 wt%, a hierarchical structure of microbeads and nanofibers was formed. In the 20 wt% nanoweb, droplets formed an apparent contact angle of 149.5 ± 2.2°, and the petal effect was observed in which the droplets were pinned on the surface and did not roll off even when the nanoweb was tilted by 180°. As a result of introducing fine nanostructures with CF4 plasma etching on the 20 wt% nanoweb, the apparent contact angle increased to 162.8–164.4°, and the shedding angle decreased to 5.3–8.1°, showing a wetting transition to the lotus effect, regardless of the plasma etching time. In addition, the lotus effect was observed when 15 wt% nanoweb was treated with CF4 plasma etching for more than 10 min. We confirmed that the lotus effect was exhibited when the three-phase contact line of the PVDF nanoweb/water/air was discontinuous, and the contact area between the surface and the water droplets was reduced with increased air pockets at this interface, which led to a decrease in the adhesive force and the impact of negative pressure. [ABSTRACT FROM AUTHOR]

In this work, we present a novel methodology for incorporating the effect of fibre surface morphology on liquid water transport in polymer electrolyte membrane fuel cell gas diffusion layers (GDLs). Roughness features presented on the surface of the fibre are analysed using atomic force microscopy and are found to significantly impact the capillary pressure of liquid water pathways propagating through the GDL. A threshold capillary pressure was defined as the largest capillary pressure exhibited by the liquid water phase during the invasion of the throat. The threshold capillary pressures observed in the presence of roughness features are significantly greater than those in the absence of roughness features. Two-dimensional circumferential roughness models in cylindrical and converging-diverging throats are established, and an interfacial meniscus advancing algorithm is presented to determine the resulting threshold capillary pressures required for liquid water penetration. Revised Young-Laplace equations, which are particularly useful for pore network modeling, are suggested for calculating threshold capillary pressures that account for the effect of the roughness of throats with intrinsic contact angles greater than 90∘. [ABSTRACT FROM AUTHOR]

We present the first experimental study for enhancement of PtSi Schottky detectors using photonic crystal (PC) structures. PCs can be used for simultaneous reduction of reflection and increase of absorption. The 2-D PCs are fabricated by interference lithography and reactive ion etching. In PC with 4.2-μm depth, the average responsivity is enhanced by a factor of ~7 with respect to regular detectors. We show that the light absorption enhancement is not sufficient to explain efficiency enhancement. The extra enhancement may be due to nanoscale roughness on the PC walls that affect the carrier collection efficiency and cutoff wavelength. [ABSTRACT FROM PUBLISHER]

Atomic force microscopy is used as a vital tool in understanding the fundamental mechanisms of particulate processes in dry, humid and aqueous systems. Adhesion forces in both dry and humid systems were studied between surfaces of varying roughness, taking into account the capillary forces at high humidity conditions. Colloidal stability in aqueous systems due to non-DLVO forces and steric effects of surfactant aggregates formed on particle surfaces at varying pH and ionic strength conditions were investigated. The force–distance curves obtained by atomic force microscopy were used to determine the mechanical and thermodynamic properties of the self-assembled surfactant structures formed on the surface. Besides determining the repulsive force barrier provided by the surfactant aggregates in dispersion of slurries, the frictional interactions between surfactant adsorbed surfaces were measured using lateral force microscopy, providing valuable insights into the role of dispersants acting as lubricants. The range of interaction forces that can be explored using the Atomic Force Microscopy (AFM) can be utilized to predict, optimize and design a variety of industrially relevant processes such as chemical mechanical polishing (CMP), powder flow and handling and nano-dispersions, just to name a few. [ABSTRACT FROM AUTHOR]