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This paper studies the water nanojet ejection process using molecular dynamics simulation. The results show that nanoscale water droplets cannot separate from the nozzle plate surface when the nozzle aperture has a diameter of 27.5 Å or smaller. The maximum height of the produced water nanojet is reduced after reaching to its highest position when the jet does not separate from the plate surface. Separation phenomenon between the water nanojet and the nozzle plate surface is the most obvious with the 27.5-Å-diameter nozzle aperture for this simulation setup. In addition, initial findings on the characteristics of nanoscale water droplets (width and contact angle) impinging onto a fixed plate surface are revealed in preparation for future investigation.

There is a notable reduction in wear rate with and without current when carbon brushes are used as anode. Wear rates are minimum at the rotor speeds where surface waves on the wavy rotor passing beneath the brush cause resonance in brush-stiffness-rotor system. Surface waves on the rotor excite brush vibrations and thus reduce the wear rate without disconnecting the contact circuit.

The adhesion strength of the coated SiO2thin film to SUS304 stainless steel substrates with various surface treatment conditions is studied in this research. The surface of the SUS304 stainless steel substrate is first treated with 1000-W plasma and then a SiO2thin film is deposited onto the surface via radio-frequency magnetron sputtering. Scanning electron microscopy is employed to observe the surface and cross section of the coating and X-ray diffraction is used to analyze the crystallographic structure. Moreover, a nanoscratch test instrument was employed to examine the indentation, scratches, coating hardness, modulus of elasticity, coefficient of friction, and critical adhesion of the SiO2film and to obtain surface profiles. A comparison of the coating adhesion of the substrate surfaces with and without plasma treatment indicates that critical adhesion increases significantly after Ar/N2/O2plasma treatment. [ABSTRACT FROM AUTHOR]

Abstract: The surface characteristics of SUS304 stainless steel are investigated before and after surface modification by Ar/N2/O2 plasma under atmospheric pressure conditions. It was found that plasma treatment of a stainless steel plate has a significant effect on the wettability, contact angle, and free energy of the SUS304 surface. The contact angle and surface free energy were analyzed. The optimal surface modification parameters are a power of 1000W, a torch-to-sample distance of 80mm, a treatment time of 300s, and an oxygen content of 1.5wt%. Under these processing conditions, a contact angle of just 1.60° was obtained. The surface morphology, surface element composition, and surface roughness of the treated SUS304 specimens were examined using scanning electron microscopy (SEM), and atomic force microscopy (AFM), respectively. The results show that the optimal surface modification conditions lead to the formation of fine, uniformly distributed crystallites in the SUS304 microstructure. Moreover, compared to the untreated surface, the treated surface had a significantly lower carbon content and a more uniform distribution of surface peaks. [Copyright &y& Elsevier]