Surface wicking

Figure 4 shows curves of F vs. (p for three surfaces when 6 is 45°. Curves 1 and 2 show minima (W-1, W-2) where predicted by WenzePs equation. Curve 3 has no minimum, but approaches -oo as approaches 0. This behavior implies surface wicking. The necessary condition for surface wicking is... 

Equation 21 says that when r is greater than 1.414, surface wicking can occur (for e = 45°). This is true for curve 3 but not for curves 1 and 2. 

It is not possible to obtain composite surfaces for 6 less than 90° for our model. (This is not true for all surfaces-for example, one composed of parallel fibers.) Accordingly, there is no drastic decrease in hysteresis in Figure 11 as is observed in Figure 10. On the other hand, when 6 is less than 90°, there is a surface roughness at which surface wicking tends to occur. This occurs when = 0. Whether or not wicking actually occurs depends on the vibrations in the drop and on the nature of the energy barriers. 

The Washburn model is consistent with recent studies by Rye and co-workers of liquid flow in V-shaped grooves [49] however, the experiments are unable to distinguish between this and more sophisticated models. Equation XIII-8 is also used in studies of wicking. Wicking is the measurement of the rate of capillary rise in a porous medium to determine the average pore radius [50], surface area [51] or contact angle [52]. 

A dynamic-FAB probe tip incorporating a screen and wick assembly at the target surface. 

Directed Oxidation of a Molten Metal. Directed oxidation of a molten metal or the Lanxide process (45,68,91) involves the reaction of a molten metal with a gaseous oxidant, eg, A1 with O2 in air, to form a porous three-dimensional oxide that grows outward from the metal/ceramic surface. The process proceeds via capillary action as the molten metal wicks into open pore channels in the oxide scale growth. Reinforced ceramic matrix composites can be formed by positioning inert filler materials, eg, fibers, whiskers, and/or particulates, in the path of the oxide scale growth. The resultant composite is comprised of both interconnected metal and ceramic. Typically 5—30 vol % metal remains after processing. The composite product maintains many of the desirable properties of a ceramic however, the presence of the metal serves to increase the fracture toughness of the composite. 

Other Considerations Autoignition can occur if combustible fluids are absorbed by wicking-type insulations. Chloride stress corrosion of austenitic stainless steel can occur when chlorides are concentrated on metal surfaces at or above approximately 60°C (140°F). The chlorides can come from sources other than the insulation. Some calcium sihcates are formulated to exceed the requirements of the MIL-I-24244A specification. Fire resistance of insulations varies widely. Calcium sihcate, cellular glass, glass fiber, and mineral wool are fire-resistant but do not perform equally under actual fire conditions. A steel jacket provides protection, but aluminum does not. 

Regardless of which, or which combination, of the above mechanisms is responsible for adhesion in a given case, intimate molecular contact between the adhesive and adherend is required. This means that the contact angle of the liquid adhesive against the adherend surface should be as low as possible, and preferably 0°. For the case of contact adhesion, this is immediately evident, but in cases where mechanical interlocking is the primary mechanism for adhesion it is also the case because the adhesive must first be able to flow or wick into the pores of the... 

The technology of kerosene burners is quite mature. The most popular kerosene heater is the perforated sleeve vaporizing burner or range burner (Figure 1). It consists of a pressed steel base with concentric, interconnected grooves and perforated metal sleeves, between which combustion takes place. Kerosene is maintained at a depth of about 1/4 inch in the grooves. As the base heats up, oil vaporizes from the surface, and the flame lights from asbestos wicks. Combustion air is induced by natural draft. The flame is blue, and the burner is essentially silent, odorless, and smokeless. 

There is no intermetallic compound formation and the electrodeposit behaves as a simple mixture of the two metals. It can be considered as basically a stable wick of tin through which zinc is fed to be consumed at a rate lower than its consumption from a wholly zinc surface. If the conditions are such that zinc is rapidly consumed, and no protective layer of corrosion products is formed, the coating may break down, but in mildly corrosive conditions some of the benefits of a zinc coating, without some of its disadvantages, are obtained. 

Wickes BT, Kim Y, Castner DG (2003) Denoising and multivariate analysis of time-of-flight SIMS images. Surface Interface Anal 35 640... 

Quantitative analytical treatments of the effects of mass transfer and reaction within a porous structure were apparently first carried out by Thiele (20) in the United States, Dam-kohler (21) in Germany, and Zeldovitch (22) in Russia, all working independently and reporting their results between 1937 and 1939. Since these early publications, a number of different research groups have extended and further developed the analysis. Of particular note are the efforts of Wheeler (23-24), Weisz (25-28), Wicke (29-32), and Aris (33-36). In recent years, several individuals have also extended the treatment to include enzymes immobilized in porous media or within permselective membranes. The important consequence of these analyses is the development of a technique that can be used to analyze quantitatively the factors that determine the effectiveness with which the surface area of a porous catalyst is used. For this purpose we define an effectiveness factor rj for a catalyst particle as... 

The prepared Ampholine gel is set up in the tank and thick filter paper strips are soaked with either the anodic or cathodic electrolyte and placed along the appropriate edge of the gel. The samples may be applied either to small filter paper squares laid on the surface of the gel or, for bulk preparative work, incorporated in the gel. The appropriate voltage is applied through terminals attached to the electrode wicks and after about 30 min can be switched off to permit the removal of the sample filter papers before continuing the separation. 

Mist explosions are, of course, dust explosions in which the particles happen to be liquid. Other less common types of detonation involving gaseous oxidants are reviewed in [37], These include wick explosions, foam explosions, and surface explosions. 

The cohesion of the matrix and reinforcements can be damaged, even in the bulk, by moisture or chemical surface attack. The fluids can propagate to some depth by absorption and wicking consequently it is important that a skin protects the reinforcements from direct contact with the external environment. 

For battery separators, regenerated cellulose is placed on the surface of nonwoven so that the nonwoven is available to promote the wicking of the electrolyte. The nonwovens should not allow the penetration of viscose into itself. Suitable nonwovens are made from polypropylene, poly(vinyl alcohol), and hardwood hemps. Regenerated cellulose films are commonly used in alkaline manganese cells, both primary and secondary, in NiCd industrial batteries, as well as in silver—zinc batteries. 

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