Papers by Keyword: Hydrophilic Surface

Abstract: Non-equilibrium molecular dynamics simulations have been employed to study the explosive boiling phenomena of water over a hot copper plate. The molecular system was comprised of three sections: solid copper wall, liquid water, and water vapor. A few layers of the liquid water were placed on the solid Cu surface. The rest of the simulation box was filled with water vapor. Initially, the water molecules were equilibrated by using Berendsen thermostat at 298 K. Then heat was given to the copper plate at different temperatures so that explosive boiling occurs. After achieving the equilibrium by performing the previous two steps, the liquid water at 298 K is suddenly dropped on the hot plate. NVE ensemble was used in the simulation and the temperature of the copper plate was controlled to different temperatures with phantom atom thermostat. Four temperatures (400K, 500K, 650 K and 1000K) were taken to study the explosive boiling. The simulation results show that, the explosive boiling temperature of water on Cu plate is 500 K temperature. At this point, the energy flux was found 1.79x10⁸ J/m³ which is very promising with the experimental results. Moreover, if the temperature of the surface was increased the explosive boiling occurred at a faster rate. The simulation results also show that explosive boiling occurs earlier for the hydrophilic surface than hydrophobic surface as for the hydrophilic surface the water attracted the Cu plate more than the hydrophobic surface and so the amount of energy transfer is more for the hydrophilic surface.

Abstract: A series of tests was carried out on the hydrophilic surface that was made of a new hydrophilic anti-frosting paint with the character of restraining frost growth. Compared the result with prevenient hydrophilic paint, the new paint presented in this paper has better effect on retarding frost formation under low and high relative humidity environment and the thickness of the coat made by the new paint was only 0.06mm, that was only 20 percentage of film thickness of prevenient paint.

Abstract: Electrospun polyacrylonitrile (PAN) fabrics were prepared by electrospinning with 7%w/v concentration to dissolve in dimethylformamide (DMF) and spinning time 12 h. Radio frequency inductively couple plasma (RF-ICP) at 13.56 MHz were used to improve PAN fabrics surface by O2 gas in plasma treatment that became to hydrophilic properties of PAN fabrics surface. Physical properties were determined by scanning electron microscopy (SEM) and contact angle measurement which found that characterized on PAN fabrics surface after plasma treatment with increased treated time had been damaged on these fabrics surface which measured contact angle measurement with water were range 29.3 to 74.7. Chemical properties were analysed by fourier transform infrared spectroscopy (FTIR) that had been found peak intensities of aliphatic C-H band at 1450 and 2930 cm-1 and peak intensities of cyclic C=O bands at 1732 cm-1 and peak intensities of saturated nitriles at 2243 cm-1 and peak intensities of hydroxyl O-H band at 3600-3650 cm-1.

Abstract: The high reactivity of the free silicon surface and its consequence: the “omnipresent” native silicon dioxide hinders the interface engineering in many processing steps of IC technology on atomic level. Methods known to eliminate the native oxide need in most cases vacuum processing. They frequently deteriorate the atomic flatness of the silicon. Hydrogen passivation by a proper DHF (diluted HF) treatment removes the native silicon oxide without roughening the surface while simultaneously maintains a “quasi oxide free” surface in a neutral or vacuum ambient for short time. Under such circumstances the last thermal desorption peak of hydrogen is activated at around 480-500°C where the free silicon surface suddenly becomes extremely reactive. In this study we show that deuterium passivation is a promising technology. Due to the fact that deuterium adsorbs more strongly on Si surface than hydrogen even at room temperature, deuterium passivation does not need vacuum processing and it ensures a robust process flow.