Surface Layer


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surface layer

[′sər·fəs ‚lā·ər]
(meteorology)

Surface Layer

 

a thin layer substance near the contact surface of two phases, bodies, or mediums whose characteristics differ from those of the substances in the bulk phases. The characteristics typical of surface layers result from the accumulation of excess free energy in these layers and from the layers’ structure and composition. Surface layers at the boundary between condensed phases are often called interphase layers.

The thickness of surface layers depends on the difference in the densities of the phases, on the intensity and type of the intermolecular interactions in the boundary zone, and on the temperature, pressure, chemical potentials, and other thermodynamic parameters of the system. The surface layer is sometimes no thicker than a monomolecular layer, and at other times reaches dozens and hundreds of molecular diameters in thickness. Thus, the surface layers of liquids close to the critical temperature for combining may have a thickness of 1,000 Å (100 nanometers) and more. Surface layers formed by molecules or ions of an adsorbed substance are called adsorption layers. The composition and properties of surface layers become particularly altered upon adsorption of surfactants.

Adsorptive, chemisorptive, or chemical action on the surface layer of a solid may lead to its lyophilization or lyophobization, may reduce its strength, or may improve its mechanical properties. The state of the surface layer of various construction and radiotechnological materials strongly affects their operational and technical characteristics. Many types of surface phenomena are related to the properties of surface layers.

L. A. SHITS

References in periodicals archive ?
Once they sink beneath the lighter Bay of Bengal surface layer, they can be changed in the subsurface only by forces that would vigorously mix them.
Sinkholes are formed after the surface layer sinks due to an empty space underneath it.
Grinding is mainly used as the technology for surface treatment before the deposition process because residual pressure stresses are initiated in the surface layer of the cutting tool, which is better for prolonging the life of the cutting tool.[1-2] This paper presents some of the results from a study to assess the suitability of surface treatment of cemented carbide by laser and to determine how this surface treatment affects the adhesion and tribological properties of the deposited PVD film.
As shown in Figure 1, from the bottom to the top, the ACCDDPS structure is composed of the natural soil foundation, the cushion (as appropriate), the compacted basement, the original surface layer, and the covered layer.
Influence of the Concrete Surface Layer Thickness on Launch Effects.
To analyze the foam morphology (cell density, cell size distribution, surface layer thickness), magnified images of thin cuts of the samples were processed by using digital imaging software (ImageJ, National Institute of Mental Health, Bethesda, Maryland).
The mechanical characteristics including the deflection of concrete pavement surface layer, the strain distribution at the bottom of slab, and the plastic damage cracking under dynamic impact load are studied.
The tire has, inside in the tire radial direction of the crown portion, at least one spiral belt layer having a width narrower than the width of the tread portion; at the shoulder portion of the tread portion, an inner layer rubber having a smaller modulus at 300% elongation at room temperature than that of a surface layer rubber is arranged; the inner layer rubber extends to a buttress portion; and the range of the ratio of the moduli between the inner layer rubber and the surface layer rubber is from 0.3 to 0.9.
Each component of EVARREST--a Oxidized Regenerated Cellulose (ORC) underlying layer, nonwoven polyglactin 910 fibers needle-punched into the underlying ORC layer to provide increased surface area and mechanical strength and a surface layer of lyophilized human fibrinogen and human thrombin--plays an active role in the hemostasis process.
An insert made of Tepex dynalite 104-RG601 is used as the surface layer.
The beds comprised two layers of mussels: a basal layer attached to the rock and a surface layer attached to the basal layer.
In this study, the enhanced resonance search (ERS) method was used to determine the thickness and stiffness of the asphalt surface layer by using PiScanner.

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