Composite Rough Surfaces

This area of research is still at its beginning and many aspects are not resolved. This includes in particular the structure and conformation of polymers at an interface as well as the modification of polymer dynamics by the interface. We have given several examples of the potential of surface and interface analytical techniques. They provide information on surface roughness, surface composition, lateral structure, depth profiles, surface-induced order and interfacial mixing of polymers on a molecular and sometimes subnanometer scale. They thus offer a large variety of possible surface and interface studies which will help in the understanding of polymer structure and dynamics as it is modified by the influence... 

Trade-Name Manufactuter Production Method Elemental Ccomposition, weight % Approx. Maximum Producrioo Ibmp. "-Grain Size, nm ("-surface roughness) Surface composition Avg. Diam> tn Fibers Per Tow... 

TCO thin films can exhibit tremendous variability in transparency, microstructure (and surface roughness), surface composition, conductivity, chemical stability at high current densities (in OLEDs, OPVs, and chemical sensors), and in their chemical compatibihty with contacting organic layers. Variability is often noticeable from production batch to production batch and within batches of the same metal oxide material [34]. Surface pretreatment conditions have also been shown to dramatically impact the electrochemical, physical, and photophysical properties of metal oxide films [8, 9, 24, 26, 27, 35]. Modification... 

As long as the liquid actually wets the rough surface, a less contentious approach linking the roughness factor to the extent of contact would seem to be via the spreading coefficient as shown in Eq. 20 and summarised in Table 1. If air is trapped within pits by the liquid, a composite surface is produced. 

Cassie [39] extended Wenzel s treatment to composite surfaces. His treatment can be applied to a rough surface incompletely wetted by a liquid so that it consists of an area fraction f wetted and /2 unwetted surface. Then ... 

Welds on steelwork need special attention because of the different composition of weld metal and adjacent steelwork, the rough surface and spatter caused by welding and the presence of welding flux. The latter is often alkaline and destructive to many paints. It is necessary to clean thoroughly, preferably by reblasting for 25-50 mm each side of the weld, fare the rough metal and wash off residual flux. The cleaned surface should then be stripe coated with the primer used on the remainder of the surface. 

The simplest technique introduced by Young as early as 1805 [18] is the measurement of the contact angle as a measure of surface tension and surface energy [1,19, 20,21], In many cases this gives an indication of surface composition and can be used to observe changes in composition, structure and/or roughness at the surface during a particular surface treatment. A quantitative description or distinction between different parameters is hardly possible in most cases. 

Although it is, in principle, feasible to quantify LEIS results, the determination of absolute ion fractions is far from trivial. In LEIS experiments, the surface composition is therefore generally obtained in a relative measurement by comparison of signals of the element in the sample of interest with those of reference samples, assuming that the matrix does not have a significant role and that the surface roughness is similar. 

The release of non-Brownian particles (diameter s 5 pm) from surfaces has been studied. The influence of several variables such as flow rate, particle size and material, surface roughness, electrolyte composition, and particle surface charge has been considered. Experiments have been performed in a physically and chemically well-characterized system in which it has been observed that for certain particle sizes there exists a critical flow rate at which the particles are released from surfaces. This critical flow rate has been found to be a function of the particle size and composition. In addition, it has been determined that the solution pH and ionic strength has an effect on the release velocity. 

Various finishes can be achieved — gloss, satin (or egg-shell) or matt. This is accomplished by the addition of particles of size 1-5 pm of, for example, silica, china clay or the white pigment, TiCK The degree of mattness depends on various factors, such as particle size, surface treatment of the particles, rate of film formation, and the polymer composition, e.g., urethane/acrylate compared with epoxy/acrylate. The former requires smaller particles larger particles cannot be used as they create a rough surface. 

Sobolev et al)5111 conducted a series of analytical studies on droplet flattening, and solidification on a surface in thermal spray processes, and recently extended the analytical formulas for the flattening of homogeneous (single-phase) droplets to composite powder particles. Under the condition Re 1, the flattening ratios on smooth and rough surfaces are formulated as ... 

The morphology of alkaline-etched (100) and (110) silicon surfaces varies from rough surfaces that exhibit micron-sized pyramids or ridges [Sc5] to smooth orange peel-like surfaces, depending on the etchant composition and substrate doping density. Mirror-like surfaces can be obtained on (111) crystal planes. 

Thus, a rough estimate of the surface composition, at solution concentrations around the cmc of the surfactant mixture, should be possible provided that the cmc s of the single surfactants are known. 

Khuri-Yakub, B. T., Reinholdtsen, P., and Chou, C.-H. (1985). Acoustic imaging of subsurface defects in composites and samples with rough surfaces. IEEE 1985 Ultrasonics Symposium, pp. 746-9. IEEE, New York. [205]... 

It leads to more extreme surface compositions in WC stars, i.e. to smaller surface helium concentrations but higher C- and O-abundances, The surface helium mass fraction Y can be roughly estimated to be larger than a certain value, depending on the mass of the convective core Mcc Y > (Mwc — Mcc)/ Mwc VHe), where Mwc is the mass of the WC star, Mwc its average mass loss rate, and rne its He-burning lifetime. 

If correlations do exist for simple metals, predictions are much more difficult for composite materials. On the other hand, cathode activation has two aims (i) to replace active but expensive materials with cheaper ones, and (ii) to enhance the activity of cheaper materials so as to approach or even surpass that of the more expensive catalysts. In the case of pure metals there is little hope to find a new material satisfying the above requirements since in the volcano curve each metal has a fixed position which cannot be changed. Therefore, activation of pure metals can only be achieved by modifying its structure so as to enhance the surface area (which has nothing to do with electrocatalysis in a strict sense), and possibly to influence the mechanism and the energetic state of the intermediate in the wanted direction. This includes the preparation of rough surfaces but also of dispersed catalysts. Examples will be discussed later. 

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