Papers by Keyword: Adhesion Force

Abstract: Three different methods were used to obtain nature-inspired superhydrophobic surfaces on aluminum alloys: short-term treatment with boiling water, HF/HCl and HNO₃/HCl concentrated solution etching. Afterwards a thin octadecylsilane film was deposited on all pre-treated surfaces. The surface morphology analysis showed that each method allow to obtain a specific dual nano/micro-structure. The corresponding water contact angles ranged from 160° to nearly 180°. The adhesion force between the water droplets and superhydrophobic surfaces were evaluated. The specimen etched with HF/HCl acid mixture solution showed the lowest adhesion. However, the boiling water treatment sample was characterized by the highest adhesion. Furthermore, the relationship between hydrophobic behavior and surface morphology was discussed compressively. In addition, the electrochemical measurements show that the different superhydrophobic surfaces have an excellent anti-corrosion performance evidencing promising results suitable to obtain large-scale nature-inspired superhydrophobic surfaces for several industrial applications.

Abstract: Compaction of granular raw materials is a crucial process in modern heavy industries. Extreme operating conditions such as high temperatures, high loads and high press rotational velocities are applied in applications such as hot briquetting processes. For fast and smooth removal from the mold, the adhesion forces are a crucial parameter. To set up a model test for investigations of the adhesive behavior of several release agents under application-oriented harsh operating conditions an available forming tribometer was adapted. Special release agents to reduce adhesive wear and improve the release properties are considered. Surfaces and wear tracks of test samples were characterized by means of optical microscopy, 3D-topographical evaluation as well as SEM analysis. The benefit of the release agents on the subjacent microstructure was evaluated on cross-sections of tribo-stressed areas. Resulting adhesion forces could be well distinguished for all release agents and significant improvements to uncoated operating conditions were achieved. It was proven that the developed test instrumentation is suited to characterize the performance of release agents. The obtained results strongly indicate a significant decrease of severe surface deteriorations when suitable release agents are applied.

Abstract: In order to study the effects of composition ratio of silver paste and the sintering process on the properties of the silver film after sintering, the effects of different ratios of silver powders, glass powders and organic carrier in silver paste and different sintering temperatures and sintering time on the adhesion force and square resistance of the silver film were studied. The morphology of the sintered silver film was observed by SEM. The results showed that the silver film sintered at 760°C for 6 seconds had better properties after sintering when the ratio of silver powders, glass powders and organic carrier in silver paste was 80:5:15 and the silver powders was composed of spherical silver powders and flake silver powders at the ratio of 94:6. The adhesion force and square resistance of the silver film were 8.25 N and 3.47mΩ /□, respectively.

Abstract: Take-up roll is a key component employed in amorphous ribbon production line. The roll should supply enough adhesion fore to take up the flying ribbon with a high speed. In this paper, a novel magnetic take-up roll (MTUR) is proposed. Optimize the structure parameters with a finite element method to obtain enough and stable magnetic adhesion force (MAF). The different simulation models are established to calculate the performances of the MTUR. A prototype of the MTUR was manufactured and tested. Experiments prove that the optimal MTUR can generate MAF to overcome the resistant force that amorphous ribbon suffering in take-up process in certain air gap range

Abstract: Size plays an important role in sizing. The sort of size is various, and its various performance indicators are not comprehensive, so it brings very great difficulty to sizing workers. Through a large number of experiments, LX-6, PAM, SFB, LM, FY five kinds of solid poly-acrylic acid size of various performances had been tested, contrasted and analyzed. Meanwhile, the film-forming ability, and the adhesion of pure cotton roving and polyester-cotton roving were tested. Moreover, we did experiments on polyester cotton yarns, which were sized with these five kinds of size, and the sized yarn hairiness reduction rate, moisture regain, enhancement rate, reduction rate and other performance indicators had been tested, contrasted and analyzed. Results provide reference for the use of these five kinds of size.

Abstract: We present an experimental study of the interactions of negative and positive model particles and their influence on the surface elasticity of biomimetic pulmonary surfactant. In this purpose we have measured the adhesion force between negative (G) and positive (GS) particles and supported lipid bilayer by Atomic Force Spectroscopy. In addition, the modification in surface elasticity of lipid monolayer under quasistatic compression when interacting with negative and positive particles was investigated on a Langmuir trough. We found that, positive particles interact poorly with biomimetic pulmonary surfactant, therefore no modifications in surface elasticity were observed. Conversely, negative charged particles interact strongly with the biomimetic pulmonary surfactant, decreasing the surface elasticity. The results are directly relevant for understanding the interactions and the effects of particulate matter on pulmonary structures which could lead to pulmonary surfactant inhibition or deficiency causing severe respiratory distress or pathologies.

Abstract: The changes of the tip geometry due to the tip wear can completely alter the variation of the adhesion force dependence on the humidity. In this paper, we propose a simple method to calculate the width of tip wear using the adhesion force at inflection point of the experimental adhesion force versus humidity curves. Theoretical results show that the turning point of the adhesion versus humidity curve is closely correlated with the width of the worn tip, which can be precise calculated. The validity of the proposed method is proved by the agreement of our calculate results and the existing experimental data.

Abstract: A new axial friction set up for high speed friction was successfully developed and tested at the Extrusion Research and Development Center of TU Berlin. The friction behavior between the Aluminium alloy EN-AW 6060 and the hot-working steel 1.2344 at 300 °C and 400 °C was studied. The experiments were carried out with a relative friction speed from 0.1 to 50 mm/s, and a normalized contact/normal pressure of σ_n/k_f ~ 0 and 1.5. The friction stress curves were depicted and compared with the Tresca friction model. A similar tendency between them was found, however all the theoretical results were around 15 and 30 % higher than the experimental results. In general, higher friction forces were found at 300 °C. Moreover, the effect of normal stress on the friction stress could be studied. By increasing the normalized normal stress from 0 to 1.5 k_f the friction stress increases around 30 % at 300 °C and 10 % at 400 °C. A strong adhesion effect was observed especially at 400 °C, which represents around the 90 % of the total friction stress. The friction results can be reproduced using a friction factor of m= 0.85 at 300 °C and m= 0.7 at 400 °C.

Abstract: Like lotus leaf and rose petal, the canna leaf also has excellent super hydrophobicity.The purpose of this paper is to systematically study the super hydrophilicity of canna leaf. Using SEM to observe the morphology of the canna leaf, and analytical balance to measure the adhensive force between water droplet and the leaf . This paper shows that the first type of the canna leaf which has co-exsitence of the nanocrumb and micro-scale convex cells has the high contact angle and low contact angle hysteresis similar to lotus leaf. The another type on the leaf has high contact angle but high adhesion in a certain extent like the rose petal effect, whose microstructure unitarily simple has the micro convex cells, do not distributed anything of nanoscale.

Abstract: This study evaluates the role of antistripping agents to resist moisture-induced damage in asphalt binders. A total of five different types of antistripping agents are used. Plastomer and elastomer modified asphalt binders are used to modify the original base binder. Functionalized and non-functionalized AFM tips are used to determine adhesion in asphalt. With-CH₃ tip, lime is found to be the most effective to protect moisture damage in asphalt binder as the adhesion loss is almost zero. The statistical tests show the Pearson values are very close to-1 that indicates a good correlation among the variables. Also the p-values are well below the prescribed value of 0.2% that indicates the test results to be significant from the statistical point of view.