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.

Processing of Al–SiCp Metal Matrix Composites by Pressureless Infiltration of SiCp Preforms

Abstract: An optimum method for producing Al-SiCp metal matrix composites was developed by determining the optimum conditions for wetting SiC by aluminum and the optimum parameters for pressureless infiltration of SiCp preforms The quantitative effect of magnesium and silicon additions to aluminum, free silicon on the SiC substrate, nitrogen gas in the atmosphere, and process temperature on the wetting characteristics of SiC by aluminum alloys was investigated using the sessile drop technique The contribution of each of these parameters and their interactions, in terms of a relative power, to the contact angle, surface tension, and driving force for wetting were determined In addition, an optimized process for enhanced wetting was suggested and validated The optimum conditions for wetting SiC by aluminum that were arrived at were used to infiltrate SiCp preforms and the mechanical properties of the resulting metal matrix composites were measured The effect of SiC particle size, infiltration time, preform height, vol% SiC in the preform, and Si coating on the SiC particles on the pressureless infiltration of SiCp compacts with aluminum was investigated and quantified The contribution of each of these parameters and their interactions to the retained porosity in the composite, the modulus of elasticity, and the modulus of rupture were determined Under optimum infiltration conditions, metal matrix composites with less than 3% porosity, over 200 GPa modulus of elasticity, and about 300 MPa modulus of rupture were routinely produced

Influence of surface morphology on the wettability of cluster-assembled carbon films

Abstract: We have evaluated the surface energy and characterized the wettability of cluster-assembled carbon films deposited on polyethylene, Si and Al substrates by a sessile-drop method using water and glycerol. The effective surface energy of nanostructured carbon is of the order of 30 mJ/m2 as calculated using the Fowkes approach. The advancing contact angle (66–83°) is found to increase with surface roughness, i.e. the surface becomes more hydrophobic as the roughness increases. This behavior is ascribed to gas trapping in pores of the film with a self-affine surface. It is argued that the wettability of nanostructured carbon and other cluster-assembled coatings can be tuned simply by controlling the surface topography, through a suitable control of the deposition parameters, such as the cluster size distribution.

Time dependence of contact angle and its relation to repellency persistence in hydrophobized sand.

Abstract: Soil water repellency is a transient soil property varying with soil–water contact time. The purpose of the present study was to determine the time dependence of the sessile drop contact angle and its relation to repellency persistence estimated using the water drop penetration time (WDPT) test with hydrophobized sand. The contact angle decreased exponentially and almost reached apparent equilibrium after 20 min of soil–water contact time. Time dependence of the contact angle can mainly be attributed to the adsorption of water molecules onto low-energy hydrophobic organic matter surfaces. Contact angles initially greater than 90° decreased to less than 90° within about 40 s. However, the WDPT of these samples was longer than 3600 s. The WDPT responded to the initial contact angle, but not to the contact angle decreased with soil–water contact time. This was considered to be caused by differences in the surface free energy between the surface and the lower layers. Repellency persistence, or the WD...