The surfaces of coatings, like the surfaces of bulk materials, have particular attributes which may differ from those of the material within the coating. For example, a chromium coating will generally have an oxide film at the surface. Similarly, as with a bulk material, a coating which has been subjected to a final mechanical treatment, such as polishing, may exhibit the effects of near-surface deformation. It is important to be aware of these localized variations in the nature of coatings, especially since this is where the immediate contact with the counter face occurs.
Effects such as wettability, adsorption and chemisorptions are controlled by the immediate surface, or more correctly the interface between the coating and its counter face – be that solid, liquid or gas. Equally important are the geometrical properties of surfaces and especially their topography. With coatings, the subject takes on a new significance, since the deposition method may sometimes significantly influence the surface topography. Some coating methods, such as electroplating, can smooth the surface. Other methods such as some thermal spraying techniques can lead to a roughening, while others may impart a specific and distinct type of topography, such as the faceted type exhibited by CVD diamond films.
Given this range of topographies it is particularly important to utilize appropriate surface roughness parameters when characterizing coated surfaces. Indeed, for certain types of coatings, such as those used in optical devices, it has been necessary to develop new techniques for the investigation of surface topography, even on an atomic scale, and these are referred to later.
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Sheth Group of Industries believes in providing quality services to our customers in right time and cost effective manner. They expertise in all types of surface preparation and thermal coating techniques and also provide shop and/or field services to both industries and large commercial customers in and out of India. SGI since 1980, specialize in all types of coatings and surface preparation.
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