Papers by Keyword: Wetting

Abstract: Due to lack of previous study on applying polymer additives in road base construction, this research presents experimental results on the improvement of long-term road base performance by the addition of carboxylated styrene–butadiene emulsion (Rovene^® 4045) and Portland cement. The specimens stabilized with Portland cement (0–6%) and Rovene^® 4045 (5–10%) and then subjected to different stress sequences to study the wetting and drying (WD) and wheel tracking (WT) tests on the 7-day-cured specimens. Results of tests conducted to assess the specimens’ resistance to WD cycling showed that the addition of a 4% Portland cement–7% Rovene^® 4045 mixture resulted in reductions of 86.99% in water absorption, volume changes of 88.55%, and weight changes of 92.84% relative to a sample with only 4% cement after 12 WD cycles. The permanent strain behaviour of the samples was assessed by the WT test. The results of WT test showed that the permanent deformation characteristics of the mixture were considerably improved by utilization of Rovene® 4045 modification, which resulted in reductions of 218.9% at 25 ^oC, and 356.8% at 50 ^oC in permanent strain of the mixture respectively. Therefore, this research nominates a new polymer additive having outstanding engineering properties and environmental friendly.

Abstract: This paper studied the growth morphology of the cells on the nanostructured surfaces of the bio-electrodes implanted in human patients. A transition model of the cells on those surfaces, which is the W model or C-B model, was deduced according to the effect of the microstructures on the wetting characteristics and the solid-liquid contact angle models of the microstructured surface. According to the contact angle formula of the model of the droplet on the solid surface, the formula was derived to describe the morphology of the ells on the nanostructured surface. The results of the experiments showed the impact of nanostructured to the morphology of the cells. The changes of the cell morphology on the smooth surface and the nanostructured surface showed that the cell morphology was affected by the nanostructures of solid surface, and the growth shape of cell was different when the sizes were different.

Abstract: The effect of substrate cleaning using ultrasonic cleaner on tungsten carbide was investigated. The surface energy of the substrate was measured using two liquids with dominant polar and dominant dispersion components which were distilled water (DI) and methylene iodide. Owens-Wendt method was carried out to calculate the surface energy of the substrate. The result showed that the cleaning process using solvent B (alkaline, DI, acid, DI, DI, alcohol) for 20 minutes without the wiping process led to the highest surface energy of 126.3399 dyne/cm with the polar component of 80.538 dyne/cm. Findings from this research suggested that type of solvent, cleaning time, and interactions among solvent type, cleaning time, and wiping process significantly influenced surface energy of the substrate.

Abstract: Porous ultra low constant materials (ULK) for isolation within the interconnect system of integrated circuits are a promising approach to reduce crosstalk and RC-delays due to shrinking feature sizes [1]. Due to their porosity and the integration of carbon rich species like methyl groups into the Si-O-Si backbone of currently fabricated PECVD SiCOH dielectrics those materials are highly sensible towards plasma processing, e.g. dry etching or resist stripping [2]. Metal hard mask approaches, e.g. using TiN hard masks are widely used to prevent the resist stripping plasma directly attacking the low-k material [3]. To reduce further plasma damage like carbon depletion and formation of polar silanol groups the development of less aggressive etching processes is in the focus of research and development activities. Nevertheless dry etching will attack the sidewalls and cause a material degradation. That is why repair processes, mainly based on silylation, are considered to follow the patterning step to reintegrate carbon rich species and to recover the dielectric’s properties [3]. Subsequently to dry etching and repairing the dielectric the wet chemical plasma etch residue removal process is performed. Besides material compatibility and effectiveness in residue removal the wetting behavior of the applied cleaning solutions towards the surface which has to be cleaned is crucial, especially looking on wetting issues like the incomplete wetting of very small via holes or pattern collapse. In this study we investigate in which way different silylation based repair processing regimes are affecting the wettability of the dielectric by water based cleaning solutions using contact angle based surface energy calculations.

Abstract: Recent studies have shown that even inherently hydrophilic surfaces (θ < 90 ̊) can become hydrophobic as a consequence of nanopatterning (1-4). This creates an issue in semiconductor manufacturing as aqueous chemistries (e.g. dilute HF solutions) are preferred to organic chemistries for their lower cost of ownership and greener environmental profile.

Abstract: Keeping the water-repellent stability of superhydrophobic surface is necessary in application. Based on the total reflection of Cassie interface and vacuum technique, the superhydrophobic stability of the lotus leaf and an artificial material was investigated. The results show that during the Cassie-Wenzel transition, primary wetting transition occurs at a certain pressure that in accordance with theoretical prediction. However, when the air film is entrapped between microstructures, stability of water-repellency was greatly enhanced, and part of the wetting transition can be recovered when the pressure was released. Due to the micro-and nanoscale hierarchical structures, the lotus leaf shows better water-repellent stability and dewetting property than the artificial superhydrophobic surface when the hydrostatic pressure was applied and released.

Abstract: In this thesis we provide the electrodeposition technology by means of monolayer templates for fabricating regularly hexagonal array of copper surface, predict the wetting transformation in theory. We report the result that original hydrophilic copper surface may turn to be hydrophobic surface by this kind of structurization. The apparent contact angle would convert from less thanto more than.

Abstract: ZnO with different morphologies were formed on Zn foils immersed in various concentrations of CuSO4 solutions. Then the specimens were heated at temperature of 200~600°C in air for 3h. The morphologies of as-prepared specimens were characterized by a scanning electron microscope (SEM). Water wetting angles on the specimens were measured. The results indicate that the morphologies of ZnO on the Zn foils relate to the CuSO4 concentration of in solutions. The morphologies on the specimens with dual-scale (nanoand micro) structure have higher wetting angles than those with flat structure. The water wetting angles can reduce with the increase in annealing temperatures of immersed specimens. The water wetting angles increase with keeping immersed specimens at room temperatures. The change of the wetting angle is explained by absorption of organic carbon on specimen surface and the geometric structure of the surface.

Abstract: Wetting behaviors of pure nickel and nickel-based alloys on sintered silicon carbide ceramics and their interfacial microstructures were investigated in this presentation. The nickel-based alloys were mainly the commercial nickel-molybdenum-chromium products. The wetting and spreading properties were observed by a real-time thermal optical measurement system under flowing argon-5%hydrogen atmosphere. As temperature increased, the pure nickel cylinder sample had few changes before 1356°C except for the thermal expansion in size and changed to liquid drop-shape when the temperature reached 1366°C. The contact angle was about 90^o. And nickel could not contact sintered silicon carbide ceramics well. However, the introduction of molybdenum and/or chromium in the pure nickel was good for the wetting properties of pure nickel on sintered silicon carbide ceramics. The contact angles of nickel-based alloys (B-1, C-1 and C-2) on sintered silicon carbide ceramics after holding 15min at 1400°C were 25^o, 12.5^o, 11.5^o, respectively. And they hardly reduced as temperature increased. The SEM images indicated that the interfacial microstructures of B-1 and C-1 on sintered silicon carbide ceramic substrates were uniform and the dissolved interface near silicon carbide ceramics indicated that they had a good bonding. At the same time, the reciprocal diffusion was clear in the intermediate layer. Besides that, the introduction of chromium was supposed to reduce the diffusion rate of molybdenum from the alloy to the ceramic substrate.

Abstract: The influences of different replacement levels of rice husk ash (RHA) blended cement concrete subjected to 5% Na₂SO₄ solution via wetting-drying cycles was evaluated in this study. RHA was used as a Portland cement Type I replacement at the levels of 0%, 10%, 20, 30%, and 40% by weight of binder. The water-to-binder ratio was 0.49 to produce concrete having target strength of 40 MPa at 28 days. The performance of RHA blended cement concrete on compressive strength, reduction in strength and loss of weight was monitored for up to 6 months. The results of the compressive strength test have been shown that use of RHA in blended cement has a significant influence on sulfate concentration. When increasing the replacement level of RHA, the strength of concrete also increases in comparison to OPC concrete (except RHA40) even exposed to 5% Na₂SO₄ solution. On the other hand, the reduction in strength and weight loss of specimens increased with increase in the exposure time. Generally, it can be said that the incorporation of rice husk ash as cement replacement significantly improved the resistance to sulfate penetration of concrete. Finally, RHA cement replacement in concrete mixed provided better resistance to sodium sulfate attack up to 6-month exposure.