| you are: Properties glin as raw materials for pottery
Feature of the clay test is ability to harden at drying on air. Durability of the dried up clay is caused by action van-der-vaalsovyh forces and cementation of grains of minerals by ions of impurity. Forces of capillary pressure pull together clay particles, interfering with them razedaniju thereof occurs air usadka. At saturation by water meniscuses disappear, action of capillary forces stops, particles freely move a lot of water, and clay razmokaet. http://www.anturage-mebel.ru/divany.php Автор: vova_piterskiy продам диван б/у (цену предлагайте).
Usadka is a reduction of the linear sizes and volume of a clay raw at its drying (air usadka) and roasting (fire usadka glin). Usadku express in percentage of the initial size of a product.
Air usadka occurs in the course of evaporation of water from a raw owing to reduction of a thickness of water covers round particles of clay, occurrence in a time of a raw of meniscuses and forces of the capillary pressure, aspiring to pull together particles. In the end of drying the role of the osmotic phenomena and the intermolecular attraction, strengthening air usadku increases. For various glin linear air usadka fluctuates from 2-3 to 10-12% depending on the maintenance of thin fractions. For reduction of shrinkable pressure to fat glinam add otoshchiteli. Surface-active substances (SDB, etc.) Entered into clay weight in number of 0,05-0,2%, improve wetting of particles of clay by water, allowing to reduce forming humidity and to lower air usadku. Other way of decrease in sensitivity glin to drying provides introduction in clay of 1-1,5% bitumen and degtevyh substances or an irrigation of a surface of the clay bar leaving a tape press by film-forming structure (for example, bitumen emulsiej).
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