Papers by Keyword: Wettability

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Authors: Gang Sun, Yan Fang
Abstract: The microstructure, hydrophobicity and chemical composition of the butterfly and locust wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter and a Fourier transform infrared spectrometer (FT-IR). The hydrophobicity models were established on the basis of the Cassie equation. The wetting mechanism was comparatively discussed from the perspective of biological coupling. The butterfly and the locust wing surfaces are composed of naturally hydrophobic materials, but exhibit different complex wettability. The butterfly wing surface is of low adhesion (sliding angle 1~3°) and superhydrophobicity (contact angle 151.6~156.9°), while the locust wing surface is of extremely high adhesion (sliding angle>180°) and superhydrophobicity (contact angle 155.8~157.3°). The complex wettability of the wing surfaces ascribes to the coupling effect of hydrophobic material and rough structure. The butterfly and locust wings can be used as bio-templates for design and preparation of biomimetic functional surface, intelligent interfacial material and no-loss microfluidic transport channels.
Authors: Fu Quan Song, Xiao Xing Chen
Abstract: With the development of Micro Electro Mechanism System, the linear slip boundary of liquid flow has been often used. In this paper, some flows in different wettability boundaries were researched by Non-Equilibrium Molecular Dynamics (NEMD) simulation, and the characteristics of the slip length were discussed. The results show that: when liquid flow on the hydrophobic boundary, the slip length decreases with the external force increasing and the shear rate increasing near boundaries, the width of channel and the external force are not independent variables of the slip length, and the shear rate and the surface wettability are independent variables of the slip length. The slip length can be reduced by increasing the driving force for liquid flow in a channel. Finally, a new power law model of the slip boundary of liquid flow was derived.
Authors: Ying Ying Li, Guan Cheng Jiang, Ling Li, Wei Xing Xu, Zhi Heng Zhao
Abstract: Aiming at the cutting bed settling problems in horizontal section during drilling process, a novel additive FGC for cuttings transport is applied. The experimental results show that the wettability was converted to amphiphobic and the cuttings preferentially attached to gas bubbles after FGC adsorption on the cuttings’ surface. The surface area of the cuttings is increased and the density of it is reduced, making cuttings more easily to be driven by liquid and settlement decrease. Tested by the horizontal simulation device, the cuttings transport effect is good and most of cuttings can be circulated to the outlet position by drilling fluid.
Authors: Zuo Sheng Lei, Xiao Xing Jin, Chao Yue Chen, Yun Bo Zhong, Zhong Ming Ren
Abstract: A mathematic model based on moving mesh Arbitrary Lagrange-Eulerian (ALE) is developed to solve incompressible fluid flow concerned with the free surface and wettability. A mercury sessile drop with different wetting angles is chosen to validate this method. Besides, two more extensive applications called electrowetting-on-dielectric (EWOD) and transferred drop are numerically simulated and compared with previous researchers work in order to demonstrate its efficiency.
Authors: Zhi Wei Niu, Ji Hua Huang, Hao Yang, Shu Hai Chen, Qi Wang, De Hua Li
Abstract: Based on the difficulty to accurately control temperature for torch brazing, the study is concerned with developing low-melting-point solders for brazing pure aluminum. For this purpose, Ge and Zn have been chosen to be added to Al-Si-based alloy. The melting characteristic, wetting property of solders with Al and mechanical property of the brazed joints were investigated. The results show that the addition of 10 wt. % germanium into the traditional Al-12Si (wt. %) filler metal causes its liquidus temperature to decrease by about 23 °C. An addition of 30 % zinc into such Al-Si-Ge ternary alloy will cause its liquidus temperature to drop further to 525 °C. The solders have good wettability with Al. With the increase of Zn content in the alloys, the spreading areas of solders exhibit nonlinear decrease, and there exist a very large value at the zinc content of 15%. When Al-Si-10Ge-30Zn solder was used to braze the pure aluminum, an optimized bonding strength of 116 MPa was achieved.
Authors: Feng Guo, Xun Jia Su, Gen Liang Hou, Zhao Hui Liu, Hai Peng Jia
Abstract: Superhydrophobic surfaces have been a hot topic during the last decade owing to their great potential in widely application. In this work, we report on a facile and low-cost two-step method to fabricate superhydrophobic surface on steel substrates. The as-obtained surface shows an interesting hierarchical structure composed of microscale flowerlike cluster and nanoscale particles, which is similar to that of a lotus leaf. After further modification with stearic acid, the resultant surface exhibits remarkable superhydrophobic properties. The water contact angle is as high as 155°. Moreover, the superhydrophobic properties are long-term stable.
Authors: Maral Rahimi, Peter Fojan, Leonid Gurevich, Alireza Afshari
Abstract: Aluminium alloys are the predominant materials in modern industries. Increased knowledge about the surface characteristics of bare aluminium can enhance the understanding about how to optimize the working conditions for the equipment involving aluminium parts. This work focusses on the properties of native surface of aluminium alloy 8011, which is the main construction material for the production of air-to-air heat exchanger fins. In this study, we address its water wettability, surface roughness and frost formation in different psychometric parameters. The contact angle measurements revealed that this aluminium alloy exhibits a relatively high contact angle of about 78 degree, i.e. is not wetted completely. AFM measurements revealed significant surface roughness of typical heat exchanger fins. The thickness of formed frost was studied in relation to the wettability, humidity and the cold surface temperature.
Authors: Ling Jia, Bei Qing Huang, Xian Fu Wei, Na Feng
Abstract: Water-based ink in low-energy surface wetting more difficult and hinder its application. In order to solve water ink in low-energy on the surface wettability problem, change the kind of cosolvent, kind and content of surfactants prepared ink. They were tested in low-energy CD the surface contact Angle to examine wettability of ink, test the surface tension, ink affecting wettability factors were analyzed. Results show that: in water-based ink add isopropyl alcohol, flow ping agent 432 and substrate wetting agent 245, can better improve its surface wettability in low-energy, and base material wetting agent 245 content about 1.25% wet effect is good.
Authors: Jong Min Kim, K.C. Yang, S.B. Lee, Seong Hyuk Lee, Young Eui Shin, Kyong Ho Chang, J.G. Han, Y.S. Eom, J.T. Moon, J.W. Baek, Jae Do Nam
Abstract: A novel electrically conductive adhesives (ECAs) with solder particle have been developed. The kinetics of the curing reaction were investigated using isothermal differential scanning calorimeter (DSC). The dynamic DSC scans were also conducted to investigate the temperature dependant curing degree. The temperature dependant viscosity characteristic of polymer was investigated using rheometer. The wetting characteristic of two solders on two kinds of metals were investigated using an optical microscope. It was found that developed resin material showed good fluxing capacity against Sn-Bi solder on Ni/Au and the wetting angles was about 24º.
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