The inner surface of porous or granular solids is a dimensional parameter that is used in various scientific and technical disciplines. It encompasses all of the surfaces it contains , including those that are between grains and within pores. The actual measured variable of the inner surface is the specific surface .
In contrast to this, the outer surface is the surface that can be seen directly from the outside, i.e. that which would be obtained when the material system was packaged.
All porous ( sponge or foam-like ) materials as well as heaps (such as powder and debris ) are pervaded by numerous cavities. Since all chemical reactions essentially depend on how large their area of attack is compared to the volume, the inner surface is of great importance. For example, fine iron filings are highly flammable ( pyrophoric ), while larger pieces of iron are not. The weathering stability of a rock is also largely determined by its size and the number of cracks. There are similar effects with numerous purely physical phenomena, such as capillary action and moisture storage , thermal insulation , light reflection and others.
The specific surface area (of English. Surface ) is a surface measurement determined.
The mass -related specific surface
The volume -related specific surface
indicates the surface area A (in m 2 ) of a cubic meter of a material (unit ).
The smallest specific surface (for a given volume) has the sphere:
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