Contact angle of mercury

The contact angle of mercury, like that of other liquids, depends not only... 

The measured contact angle of mercury on various samples can range from 112 to 170° [39], but for most applications the average value of 140° is used. It should be noted, however, that the accuracy of the pore radii measurement is limited by the accuracy of the contact-angle measurement [40]. Contact angles can readily be measured on flat surfaces or compacts of powders [6], and the measurement of contact angles with powder systems has also been reported [41]. 

Different methods have been developed to determine the contact angle of mercury on a solid material [8]. The static angle method uses an optical microscope combined with a goniometer to quantify the non-wetting behavior of a... 

The contact angle of mercury on the various materials was measured using two different methods. Prior to the pellet preparation, the samples were milled to obtain a particle size < 10 pm. 

From mercury penetration the surface area is determined knowing the surface tension and contact angle of mercury and the total volume of penetrated mercury. Measurements agree with the BET measurements below surface areas of 100 m /g. 

A value of 140 °C was used for the contact angle of mercury on the solid (0), and the surface tension of mercury (7) was taken as 0.485 N/m. These values correspond to an effective working range for the instrument of 150 pm to 1.7 nm in pore radius. The samples were outgassed at room temperature to a pressure of 50 mtorr (7 Pa) immediately prior to analysis to facilitate filling the penetrometers with mercury. All data were fully corrected for mercury compression with calibrated penetrometers. 

If the contact angle of mercury on evacuated, baked-out glass is as high as 70°, then A si is of the order of 150 dynes per cm. and a lower value of 6 would correspond to a value of even larger than that ... 

A value of 140°C was used for the contact angle of mercury on the solid (0), and the siuface tension of mercury (y) was taken as 0.485 N/m. These values correspond to an... 

In Equation (6.12), C2 = -1 /( cos a) is a constant that is related to the surface tension (/> and the cosine of the contact angle of mercury at the mercury-solid interface a. This area is interpreted as the one that would be measured by spheres of radius r. The total surface area of an adsorbent S is the sum of the surface area of the sample-mercury interphase at the beginning of the intrusion process So and the inner pore surface S. If So is neglected, then [7, 8]... 

The contact angle of mercury with polymeric materials is often 141.3° and the surface tension at the mercuiy/air interface is 0.48 N/m. Hence eq. IV. 2 reduces to... 

The contact angle of mercury on glass is about 120° (cosd = —0.5). What is the significance of the -0.5 for the cos 9 in terms of the capillary method of determining surface tension. 

Since it was difficult to measure the contact angles of mercury directly, some of the results have been obtained by the sessile drop method. 

In mercury intrusion porosimetry, mercury surroimds the sample and application of differential pressure on mercury forces it into the pores. Mercury does not wet hydrophilic and hydrophobic pores and cannot enter these pores spontaneously owing to a small contact angle. Application of pressure on mercury can force it into the pores. The measured intrusion volume is equal to the pore volume and the differential intrusion pressure is related to pore diameter as given in Equation 8.43, where o and 0 are the surface tension and contact angle of mercury, respectively. Mercury porosimetry is valuable in determining the pore structure of the catalyst layer, especially for gas diffusion electrodes, where the distribution of gas and liquid phase pores is essential for the optimization of performance. 

The surface tension of mercury at 20°C is equal to 0.4355 N m. The density of mCTcury is equal to 13.56 g cm. The contact angle of mercury against glass is 180°. Find the capillary depression (distance of the meniscus below the liquid surface) for mercury in a glass capillary tube of radius 0.35 mm at 20°C. 

Figure 2.4 Contact angles of mercury/solid substrate systems viewed in the scanning electron microscope [108]. (a) Hg/Zn, (b) energy-dispersive, characteristic mercury X-ray map of (a), (c) Hg/Pd, (d) Hg/Zr.

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