Penetrant Techniques

Penetrant techniques can be used to highlight surface flaws such as open porosity and surface-breaking cracks for optical or radiographic inspection. The usefulness 

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Identification. If the notch left by incomplete penetration emerges at a visually accessible surface, visual examination, perhaps aided by magnetic-particle or liquid-penetrant techniques, may reveal the defect. Otherwise, ultrasonics, radiography, or eddy-current techniques may have to be used. 

There are two well-established experimental techniques for determining the distribution of pore radii. They are the mercury penetration technique and the desorption isotherm method. 

Gels for quantitating gel characteristics were prepared In screw capped centrifuge tubes (22 X 100 mm) by heating at 100 C for 15 min C14, l, l, ). Gel strength was determined by a penetration technique using the Instron fitted with a disk probe (6.0 ran diameter) (15.16). Instrumental texture profile analysis on gel sections (1.5 X 1,0 cm) was done on an Instron fitted with a... 

In many applications, powders come into contact with a liquid and we would like to quantify their wetting behavior. The usual way to do this is by the capillary rise method [233,234], In a capillary rise measurement the powder is pressed into a tube of typically 1 cm diameter (Fig. 7.7). This porous material is then treated as a bundle of thin capillaries with a certain effective radius [235-237], In order to measure this effective radius, first a completely wetting liquid is used. Either the speed of the liquid rise is measured (this technique is sometimes referred to as the capillary penetration technique [238]) or the pressure required to keep the liquid out of the porous material, is determined. This backpressure is equal to the... 

Two Co-Mo-alumina catalysts obtained from a commercial vendor as either marketed or special research samples were used in this study. The surface area and pore-size distributions (using the mercury penetration technique) were determined by an independent commercial laboratory. The catalyst properties are given in Table II. Note that the monodispersed (MD) and bidispersed (BD) catalysts have the same metallic composition and are chemically similar. 

Hiller, S., Bruce, D.M., and Jeronimidis, G. (1996). A micro-penetration technique for mechanical testing of plant cell walls. J. Texture Stud., 27, 559-587. 

Desai TR, et al. Determination of surface free energy of interactive dry powder liposome formulations using capillary penetration technique. Colloids Surf B Biointerfaces 22(2) 107-113, 2001. 

Where D is the depth of penetration, K is a constant, and is a faction often found to be between 0 and 1. Experiments conducted on IGA of Al-4% Cu using the foil penetration technique have indicated such a penetration law [86]. In these... 

More detailed information concerning the role, advantages, and limitations of the in-situ penetration techniques can be found in the works by Ladd et al. (1977), Mori (1981), Robertson and Campanella (1984), Robertson et al. (1988), Worth (1984), Jamiolkowski et al. (1985,1988), and Robertson (1986). Details of offshore in-situ testing are presented in Chapter 4. 

Two possible explanations for F being lower than X-Wc are O 1) the crystallinity is underestimated by the density method due to the assumption that the surface component has the same density as in the melt corrected for temperature, and 2) the surface fraction is underestimated by penetration techniques due to inability of the penetrant to reach all portions. Further work is necessary to determine which of these, if either, is correct. Infrared spectroscopy has been used to estimate the % crystallinity for TPBD36,38from the intensities of a crystalline band at 1335 cm and a related amorphous band at 1350 cm. However there is considerable band overlap and therefore these measurements are only considered to be semiquantitative. For TPBD the enthalpy of the crystal-crystal transition, Ahxr, was found to be proportional although not directly so to the specific volume, at least at low molecular weights (7x10 or smaller). 

While the new liquid is pumped into the drop through the inner tube, its bulk is pumped out via the outer tube. Due to the liquid flow, the drop volume is permanently mixed. In this way, the drop volume is completely exchanged when an amount of more than 250% of the drop volume has been pumped through. This experimental procedure has the only drawback that it is difficult to control the spread amount very accurately. On the other hand, it has quite a number of advantages when compared to other penetration techniques, in particular, the easy temperature control and the easy applicability to liquid/liquid interfaces. 

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