scholarly journals Wetting Behavior of the Ag-5CuO Brazing Alloy on ZTA Composite Ceramic with/without CuO Coating in Air

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 609
Author(s):  
Guangjie Feng ◽  
Manqin Liu ◽  
Yalei Liu ◽  
Zhouxin Jin ◽  
Yifeng Wang ◽  
...  
Keyword(s):  
Contact Angle ◽  
Triple Line ◽  
Composite Ceramic ◽  
Heating Process ◽  
Wetting Behavior ◽  
Subsequent Heating ◽  
Rich Liquid ◽  
Zirconia Toughened Alumina ◽  
Pure Al2o3

The wetting of Ag-5 wt.% CuO (Ag-5CuO) alloy on initial/CuO-coated zirconia toughened alumina (ZTA) composite ceramic in air was studied in detail. The results showed that the contact angle of the Ag-5CuO/ZTA system rapidly decreased from 81° at 970 °C to 45° at 990 °C during the heating process, however, moderate reductions in contact angle were observed in the subsequent heating and temperature holding stages. In comparison with the contact angle of pure Al2O3, an increment of about 4° of the stable contact angle of Ag-5CuO alloy on the heterogeneous ZTA was observed. The reaction between Al2O3 and CuO can reduce the damage of the CuO-rich liquid to ZrO2 in the ZTA substrate. Both oxygen and CuO were helpful in reducing the contact angle of Ag on ZTA and enhancing the bonding of the Ag/ZTA interface. The continuous CuO coating on ZTA and the monotectic liquid containing more CuO in the region near the triple line induced reductions of more than 40° and about 10° in the contact angle, respectively, between the initial and the CuO coating-improved wetting systems.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

The Pressure Drop and Dynamic Contact Angle of Motion of Triple-Lines in Hydrophobic Microchannels

2010 ◽  
Author(s):  
Dongin Yu ◽  
Chiwoong Choi ◽  
Moohwan Kim
Keyword(s):  
Contact Angle ◽  
Pressure Drop ◽  
Liquid Film ◽  
Dynamic Contact Angle ◽  
Triple Line ◽  
Dynamic Contact ◽  
Superficial Velocity ◽  
Channel Diameter ◽  
Fluid Property ◽  
Static Contact

At two-phase flow in microchannels, slug flow regime is different for wettability of surface. A slug in a hydrophilic microchannel has liquid film. However, a slug in a hydrophobic microchannel has no liquid film instead, the slug has triple-lines and makes higher pressure drop due to the motion of the triple-line. In previous researches, pressure drop of triple-line is depended of dynamic contact angle, channel diameter and fluid property. And, dynamic contact angle is depended of static contact angle, superficial velocity and fluid property. In order to understand the pressure drop of motion of triple-lines, pressure drop of slug with triple-lines in case of various diameters (0.546, 0.763, 1.018, 1.555, 2.075 mm), various fluids (D.I.water, D.I.water-1, 5, 10% ethanol mixture) and various superficial velocity (j = 0.01∼0.4 m/s) was measured. Dynamic contact angle was calculated from relation of the pressure drop of slug with triple-lines. Comparing with previous dynamic contact angle correlations, previous correlation underestimated dynamic contact angle in the region of this study. (10−4≤Ca≤10−3, 10−2≤We≤10−1, 68°≤θS≤110°)

Surface Topography Induced Ultrahydrophobic Behavior: Effect of Three-Phase Contact Line Topology

2006 ◽  
Author(s):  
Neeharika Anantharaju ◽  
Mahesh Panchagnula ◽  
Wayne Kimsey ◽  
Sudhakar Neti ◽  
Svetlana Tatic-Lucic
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Anomalous Behavior ◽  
Contact Angles ◽  
Wet Etching ◽  
Surface Geometry ◽  
Wetting Behavior ◽  
Void Fractions ◽  
Three Phase ◽  
Receding Contact

The wettability of silicon surface hydrophobized using silanization reagents was studied. The advancing and receding contact angles were measured with the captive needle approach. In this approach, a drop under study was held on the hydrophobized surface with a fine needle immersed in it. The asymptotic advancing and receding angles were obtained by incrementally increasing the volume added and removed, respectively, until no change in angles was observed. The values were compared with the previously published results. Further, the wetting behavior of water droplets on periodically structured hydrophobic surfaces was investigated. The surfaces were prepared with the wet etching process and contain posts and holes of different sizes and void fractions. The surface geometry brought up a scope to study the Wenzel (filling of surface grooves) and Cassie (non filling of the surface grooves) theories and effects of surface geometry and roughness on the contact angle. Experimental data point to an anomalous behavior where the data does not obey either Wenzel or Cassie type phenomenology. This behavior is explained by an understanding of the contact line topography. The effect of contact line topography on the contact angle was thus parametrically studied. It was also inferred that, the contact angle increased with the increase in void fraction. The observations may serve as guidelines in designing surfaces with the desired wetting behavior.

Synthesis of Al2O3/AlB12/Al Composite Ceramic Powders by Pulsed Nd:YAG Laser Igniting Method and a Study of their Mechanical Properties

2010 ◽  
Vol 26-28 ◽  
pp. 919-924
Author(s):  
Kai Jin Huang
Keyword(s):  
Fracture Toughness ◽  
Reaction Mechanism ◽  
Nd:Yag Laser ◽  
Bending Strength ◽  
Composite Ceramic ◽  
Composite Ceramics ◽  
Ceramic Powders ◽  
Pulsed Nd:Yag Laser ◽  
Al Composite ◽  
Pure Al2o3

Based on the combined toughening principle, pure Al2O3/AlB12/Al composite ceramic powders have been synthesized using pulsed Nd:YAG laser igniting method. This method starts from Al and B2O3 powder mixtures, after which Al2O3/AlB12/AlN composite ceramics were fabricated by hot-press sintering at 1600°C for 2h under the protection of a N2 atmosphere. XRD and SEM techniques were used to characterize the phases and morphologies of the powders and the ceramics. The bending strength and the fracture toughness of the ceramics were measured by the three-point bending method and the indentation fracture method, respectively. The results show that the pure Al2O3/AlB12/Al composite ceramic powders can be successfully synthesized by pulsed Nd:YAG laser igniting method because the adiabatic temperature of Al-B2O3 system is more than 1800K. Al2O3 and AlB12 phases were formed by the liquid-liquid reaction mechanism and the liquid-solid reaction mechanism, respectively. The bending strength and the fracture toughness of the Al2O3/AlB12/AlN composite ceramics were 525.86MPa and 5.68MPa.m1/2, respectively. These values are 50.25% and 42% greater than those of the pure Al2O3 ceramic (350MPa and 4MPa.m1/2) due to the reinforcing and toughening in-situ formation of small AlN particles.

Macroscopic Wetting Behavior and a Method for Measuring Contact Angles

1990 ◽  
Vol 112 (3) ◽  
pp. 289-295 ◽  
Author(s):  
K. Katoh ◽  
H. Fujita ◽  
H. Sasaki
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Liquid Surface ◽  
Contact Angles ◽  
Critical Height ◽  
Solid Cone ◽  
Wetting Behavior ◽  
Conventional View ◽  
The Subject ◽  
Thermodynamic Instability

Macroscopic wetting behavior is investigated theoretically from a thermodynamic viewpoint. The axisymmetric liquid meniscus formed under a conical solid surface is chosen as the subject of the theoretical analysis. Using the meniscus configuration obtained by the Laplace equation, the total free energy of the system is calculated. In the case of the half vertical angle of the cone φ = 90 deg (horizontal plate), the system shows thermodynamic instability when the meniscus attaches to the solid surface at the contact angle. This result, unlike the conventional view, agrees well with the practical wetting behavior observed in this study. On the other hand, when 0 deg < φ < 90 deg, the system shows thermodynamic stability at the contact angle. However, when the solid cone is held at a position higher than the critical height from a stationary liquid surface, the system becomes unstable. It is possible to measure the contact angle easily using this unstable phenomenon.

scholarly journals Amphiphobic Nanostructured Coatings for Industrial Applications

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 787 ◽  
Author(s):  
Federico Veronesi ◽  
Giulio Boveri ◽  
Mariarosa Raimondo
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Friction Reduction ◽  
Hybrid Coatings ◽  
Wetting Behavior ◽  
Wide Range ◽  
Solid Liquid

The search for surfaces with non-wetting behavior towards water and low-surface tension liquids affects a wide range of industries. Surface wetting is regulated by morphological and chemical features interacting with liquid phases under different ambient conditions. Most of the approaches to the fabrication of liquid-repellent surfaces are inspired by living organisms and require the fabrication of hierarchically organized structures, coupled with low surface energy chemical composition. This paper deals with the design of amphiphobic metals (AM) and alloys by deposition of nano-oxides suspensions in alcoholic or aqueous media, coupled with perfluorinated compounds and optional infused lubricant liquids resulting in, respectively, solid–liquid–air and solid–liquid–liquid working interfaces. Nanostructured organic/inorganic hybrid coatings with contact angles against water above 170°, contact angle with n-hexadecane (surface tension γ = 27 mN/m at 20 °C) in the 140–150° range and contact angle hysteresis lower than 5° have been produced. A full characterization of surface chemistry has been undertaken by X-ray photoelectron spectroscopy (XPS) analyses, while field-emission scanning electron microscope (FE-SEM) observations allowed the estimation of coatings thicknesses (300–400 nm) and their morphological features. The durability of fabricated amphiphobic surfaces was also assessed with a wide range of tests that showed their remarkable resistance to chemically aggressive environments, mechanical stresses and ultraviolet (UV) radiation. Moreover, this work analyzes the behavior of amphiphobic surfaces in terms of anti-soiling, snow-repellent and friction-reduction properties—all originated from their non-wetting behavior. The achieved results make AM materials viable solutions to be applied in different sectors answering several and pressing technical needs.

scholarly journals Comments on “An Essay on Contact Angle Measurements”: Determination of Surface Roughness and Modeling of the Wetting Behavior

2011 ◽  
Vol 8 (11) ◽  
pp. 998-1002 ◽  
Author(s):  
Antonia Terriza ◽  
Rafael Alvarez ◽  
Francisco Yubero ◽  
Ana Borras ◽  
Agustin R. González-Elipe
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Wetting Behavior ◽  
Angle Measurements ◽  
Contact Angle Measurements

Molecular dynamics study of wetting behavior of grafted thermo-responsive PNIPAAm brushes

Soft Matter ◽  
2016 ◽  
Vol 12 (12) ◽  
pp. 3093-3102 ◽  
Author(s):  
Debdip Bhandary ◽  
Zuzana Benková ◽  
M. Natália D. S. Cordeiro ◽  
Jayant K. Singh
Keyword(s):  
Molecular Dynamics ◽  
Contact Angle ◽  
Virial Coefficient ◽  
Excess Entropy ◽  
Second Virial Coefficient ◽  
Wetting Behavior

Left panel shows variation of contact angle with temperature along with snapshots of the droplets. Right panel shows variation of excess entropy, Sexcess (solid symbols), and second virial coefficient, B2 (open symbols), of polymer–water (blue squares) and water–water (red circles) pairs as a function of temperature.

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