Treated surfaces

Fig.5 Weibull two-parameters dividing. Exemple of results for grey cast iron with heat treated surfaces [5],...

The importance of the solid-liquid interface in a host of applications has led to extensive study over the past 50 years. Certainly, the study of the solid-liquid interface is no easier than that of the solid-gas interface, and all the complexities noted in Section VIM are present. The surface structural and spectroscopic techniques presented in Chapter VIII are not generally applicable to liquids (note, however. Ref. 1). There is, perforce, some retreat to phenomenology, empirical rules, and semiempirical models. The central importance of the Young equation is evident even in its modification to treat surface heterogeneity or roughness. ... 

Silanes can alter the critical surface tension of a substrate in a well-defined manner. Critical surface tension is associated with the wettabiUty or release qualities of a substrate. Liquids having a surface tension below the critical surface tension, y, of a substrate wet the surface. Critical surface tensions of a number of typical surfaces are compared to y of silane-treated surfaces in Table 2 (19). 

Critical surface tensions for silanes refer to treated surfaces. 

Purpose (i) To provide protection to the treated surfaces by sealing ... 

Once it is recognized that particles adhere to a substrate so strongly that cohesive fracture often results upon application of a detachment force and that the contact region is better describable as an interphase [ 18J rather than a sharp demarcation or interface, the concept of treating a particle as an entity that is totally distinct from the substrate vanishes. Rather, one begins to see the substrate-particle structure somewhat as a composite material. To paraphrase this concept, one could, in many instances, treat surface roughness (a.k.a. asperities) as particles appended to the surface of a substrate. These asperities control the adhesion between two macroscopic bodies. 

As of this time, no one has solved the problem of the effect of asperities on a curved surface nor has anyone addressed the issue of crystalline facets. Needless to say, the problem of asperities on an irregular surface has not been addressed. However, Fuller and Tabor [118] have proposed a model that addresses the effects of variations of asperity size on adhesion for the case of planar surfaces. Assuming elastic response to the adhesion-induced stresses, they treated surface roughness as a random series of asperities having a Gaussian height distribution (f> z) and standard deviation o. Accordingly,... 

Function of primers - Protect treated surface - Protect treated surface... 

For particularly difficult to adhere substrates such as metallized or fluorocarbon treated surfaces the same principles that are applied in freezer grade adhesives are used. For especially difficult situations, styrenic block copolymers are added to... 

Optimized grit blast/silane treatments can provide wedge test durability as good as PAA with failure entirely cohesive within the adhesive (Fig. 21) [89]. Maintaining the process parameters within acceptable tolerances is critical with the heat drying of the silane on the treated surface being the most sensitive process parameter. 

As with chemical etches, developing optimum conversion coatings requires assessment of the microstructure of the steel. Correlations have been found between the microstructure of the substrate material and the nature of the phosphate films formed. Aloru et al. demonstrated that the type of phosphate crystal formed varies with the orientation of the underlying steel crystal lattice [154]. Fig. 32 illustrates the different phosphate crystal morphologies that formed on two heat-treated surfaces. The fine flake structure formed on the tempered martensite surface promotes adhesion more effectively than the knobby protrusions formed on the cold-rolled steel. 

Vacuum Deposition-also vapor deposition or gas plating the deposition of metal coatings by means of precipitation (sometimes in vacuum) of metal vapor onto a treated surface. The vapor may be produced by thermal decomposition, cathode sputtering or evaporation of the molten metal in air or an inert gas. 

Similar to prepared metallographic samples, the injection molded samples were cut along the flow direction, smoothed, and polished in order to expose their internal surface. After proper etching, the treated surfaces of the flank cross-section were photographed using a polarized light optical microscopy. Based on the color differences between the TLCP and matrix, volume fraction and aspect ratio of the TLCP fibers were measured [23]. 

Some potable supplies are treated surface waters from rivers, etc. These originally derive from any of the above, but will also contain the products of human activities, which lead to increased mineral contents and possibly some undesirable materials such as detergents. 

A different concept is the idea of manufacturing at point of use rather than transporting materials. A simple and familiar example is the office water cooler. The majority that you see around use large bottles of water. These need to be transported and stored and the empty bottles recycled. More than 600 kT of bottled water were imported into the UK in 1999, creating a significant transport impact. The alternative is to chill and filter mains water on-site. The water needs to be filtered and purified to meet consumer perceptions and expectations. These systems use a mixture of purification techniques including advanced filters, UV-disinfection and silver-treated surfaces to give users the confidence they require. 

Fig. 2.3.11 Left the ingress of a hydrophobic silane coating into building sandstone. Right subsequent water ingress and pumping through a treated surface.

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