Sessile drop technique

About: Sessile drop technique is a research topic. Over the lifetime, 2827 publications have been published within this topic receiving 68943 citations.

Substrate dependent drop deformation and wetting under high frequency vibration

Abstract: We explore the peculiar steady component of a sessile drop response to MHz order vibration, found to be dependent on its initial wettability. Placed on a vibrating hydrophobic substrate, the drop elongates vertically in the direction of the incident sound wave while remaining hydrophobic. In contrast, the drop is seen to spread on a slightly hydrophilic substrate. We elucidate this discrepancy by revealing the competing effects between the radiation pressure exerted at the bulk air/water interface and the acoustic streaming force on the contact line, revealing the critical role of the flow in the viscous boundary layer.

Dissolution of carbon from alumina-carbon mixtures into liquid iron: Influence of carbonaceous materials

Abstract: Due to their excellent thermal shock and wear resistance at high temperatures, alumina-carbon based refractories are used extensively in the steel industry. A clear understanding of factors affecting the dissolution of carbon from refractories is of crucial importance, as carbon depletion from the refractory can significantly deteriorate refractory performance and metal quality. Atomistic simulations on the alumina-graphite/liquid iron system have shown that nonwetting between alumina and liquid iron is an important factor inhibiting the penetration of liquid metal in the refractory matrix and limiting carbon dissolution. This study investigates the role played by the carbonaceous material in the dissolution of carbon from the refractory composite. Two carbonaceous materials, namely, petroleum coke and natural graphite, respectively, containing 0.35 and 5.26 pct ash, were used in this study. Substrates were prepared from mixtures of alumina and carbon over a wide concentration range. Using a sessile drop arrangement, carbon pickup by liquid iron from alumina-carbon mixtures was measured at 1550 °C and was compared with the carbon pickup from alumina-synthetic graphite mixtures. These studies were supplemented with wettability measurements and microscopic investigations on the interfacial region. For high alumina concentrations (>40 wt pct), carbon dissolution from refractory mixtures was found to be negligible for all carbonaceous materials under investigation. Significant differences however were observed at lower alumina concentrations. Carbon dissolution from alumina-petroleum coke mixtures was much lower than the corresponding dissolution from alumina synthetic graphite-mixtures and was attributed to poor wettability of petroleum coke with liquid iron, its structural disorder, and the presence of sulfur. Very high levels of carbon dissolution, however, were observed from alumina-natural graphite mixtures, with carbon pickup by liquid iron from mixtures with up to 30 wt pct alumina reaching saturation. A sharp reduction to near zero levels was observed in the 30 to 40 wt pct alumina range. Along with implications for commercial refractory applications, these results are discussed in terms of material characteristics, interactions between ash impurities and alumina, and formation of complexes in the interfacial region.

Sessile Droplets at a Solid/Elastomer Interface

Abstract: The spreading parameter S is the fundamental parameter controlling the stability of thin liquid films intercalated between a hydrophobic solid and a soft elastomer (Young modulus E): S = γSR − (γSL + γLR), where γSR, γSL, and γLR are respectively the solid/elastomer, solid/liquid, and liquid/elastomer interfacial tensions. We describe here a simple experimental method to determine S. We monitor by interferometry the profile of liquid droplets squeezed at the solid/elastomer interface. S is negative and the droplets do not spread. We find that (i) an intercalated droplet is a very flat semiellipsoid with a macroscopic contact angle of 90° and (ii) the radius R of the wet area scales like R ∝ H2/h0, where H is the thickness at the center and h0 = |S|/E is a characteristic length in the range of 100 A. From the shape analysis we extract h0 and as a consequence the spreading parameter S. This measurement was performed for different liquids sandwiched between a cross-linked silicone polymer and chemically mod...