Wettability tests

Dynamic Wilhelmy wettability tests on single component systems, such as hexadecane/water/glass, can be done quickly in open beakers. 

Column (11) refers to the non-wettability test using the air-flow technique. 

Wettability Index (W), (based on the U.S. Bureau of Mines wettability test), in which the forced (pressure) imbibition of water is compared to forced imbibition of oil via capillary pressure curves. The wettability index varies from -oo for complete oil-wetting, to zero for neutral, to +°° for complete water-wetting. For practical purposes, W usually varies between about -1.5 and +1.0. 

U.S. Bureau of Mines Wettability Test See Wettability Index. 

Wettability Index A measure of wettability based on the U.S. Bureau of Mines wettability test in which the wettability index (W) is determined as the logarithm of the ratio of areas under the capillary pressure curves for both increasing and decreasing saturation of the wetting phase. Complete oil-wetting occurs for W = —oo (in practice about —1.5), and complete water-wetting occurs for W = oo (in practice about 1.0). Another wettability index is derived from the Amott-Harvey test. See also reference 8, Amott Test, Wettability. 

C-C/Cu-Clad-Mo Joints The microstructure of the composite/braze interface (Fig. I) reveals braze infiltration of the inter-fiber regions to several hundred micrometer distance in 5 min. This is consistent with the sessile-drop wettability test results [10] on Cu-Ti/porous C in which the sessile drop volume continuously decreased due to the reactive infiltration of open porosity in graphite, and sessile drops of high Ti content (e.g., Cu-28Ti) rapidly and completely disappeared into the graphite substrate. The reaction of carbon with Ti in the braze forms the wettable compound titanium carbide which facilitates self-infiltration and sound bonding. 

Wettability tests. Surface wettability may be readily assessed simply but subjectively by measurement of the contact angle. If the surface is clean, it is readily wetted and a drop of water will spread out rather than remain as a discrete droplet. This method cannot really be used to detect small variations in quality, but rather the gross effects. It does not lend itself to use on very rough or porous surfaces such as concrete. 

Test liquids used for the so-called DuPont wettability test... 

You cannot use a wettability test to determine if a surface has been sufficiently processed to remove all the contamination because the contaminant will become as wettable as the plasma treated polymer because the lack of cross-linking will make it easier to treat. 

Wettability of solids can also be directly determined from microscopic observations of the immersion or repulsion of the solids by an advancing liquid front at room temperature. The simplicity of the microscopic wettability test allows the use of any non-volatile liquid, such as produced water, deionized water, and oils. As well, the effect of additives such as... 

Microscopic wettability tests performed at CAN MET have demonstrated that solids from oil sands plants (froth, middlings, and tailings) prepared by solvent extraction to remove bitumen and water (Dean Stark) analysis were all oil wetted. It is known, however, that the bulk of the oil sands solids are in fact water wet. Since solvent extraction is the common method for preparation of oil field solids, it raises some questions about the utility of wettability tests on extracted solids using the conventional methods mentioned earlier. 

Figure 8. Microscopic wettability test showing the waterfront before it contacts the particles. The approaching waterfront is the dcirli arc at the left of the field of view.

Amott-Harvey. The wettability test devised by Amott [13] and its modification, the Amott-Harvey Relative Displacement Index (RDI) [14] are the most common quantitative measures of wettability employed for porous media by the oil industry. It relies on measurements of the saturation changes produced by spontaneous imbibition for both water. 

Several properties of the filler are important to the compounder (374). Properties that are frequently reported by fumed silica manufacturers include surface area, the acidity of the filler, nitrogen adsorption, oil absorption, and particle size distribution (375,376). Adsorption techniques provide a measure of the surface area of the filler, whereas oil absorption is an indication of the structure of the filler (377). Measurement of the silanol concentration is critical, and some techniques that are commonly used in the industry to estimate this parameter include methyl red absorption and methanol wettability tests (367,368,373). Other techniques to characterize fillers include weight loss, various spectroscopies, such as diffuse reflectance infrared spectroscopy (DRIFT), inverse gas chromatography (IGC), and photoacoustic IR, NMR, Raman, and surface forces apparatus (372,378-385). 

Demand absorbency plate test method can be converted into a 2D radial dynamic wicking measurement method when the liquid is introduced from a point source into the nonwoven fabric (also known as the point source demand wettability test). One example of this method is the Gravimetric Absorbency Testing System (GATS) system mentioned in Section 6.3.4.4, when a point source liquid introduction cell was used. 

Contrary to the strip test to measure the amount of hquid wicking into an in-plane of nonwoven fabric, the demand absorbency test (also referred to as the demand wettability test or the transverse wicking plate test) measures the hquid wicking into the nonwoven fabric driven by the capUlary pressure in the direction of fabric thinness.In demand absorbency tests, the hquid wUI only enter into the fabric when the sample demands it. These tests involve contacting the dry sample with a hquid in such a way that absorption occurs under a zero or shghtly negative hydrostatic head. No standards for this test method are currently available. 

The surface condition of substrates before bonding depend on the production lot, the shelf condition, and the storage period. Even if the surface is degreased with solvents or chemicals before bonding, it is not necessarily suitable for adhesion. As a method to evaluate the adhesion adequateness easily, wettability tests can be applied using standard liquids commercially... 

Critical Surface Tensions. Much wettability testing owes its basis to Zis-man and his critical surface tension of wetting (24,25). The contact angles of varions hquids (often a homologous series of hydrocarbons) on the surface are determined and the contact angles are plotted versus the surface tensions of the liquids (see Fig. 16). The plot is extrapolated to cos 6=1, that is, 0 = 0°, which represents the point where the liquid would just spontaneously spread if applied as a drop. This point defines the critical surface tension, As long as the... 

Condensable contamination in the ambient can be detected by adhesion and wettability tests on clean surfaces, by collection on an IR window followed by IR analysis, or by the change of resistivity of some heated oxides (sensors). 

Vianco, P. Rejent, J. Capillary flow solder wettability test. Proceedings of NEPCON West, Norwalk, CT, Reed Exhibition, Reed Exhibition Norwalk, CT, 1996 174-182 pp. 

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