Bone China forming 14

Bone China, atmospheric adsorption water refers to exist in the material within less than 8 ~ 4 mm diameter capillary, colloid particles in the surface and the water contained fiber leather wall, the adsorption, moisture penetration and structure in the physical and chemical state and material in combination with its vapor pressure produced by less than the vapor pressure of liquid water in the same temperature, so it is also called the physical chemical combined water, dry is more difficult to remove. Atmospheric adsorption water depends on the ambient air, The outside conditions) The temperature and relative humidity, increasing with the increase of air relative humidity. Bone China free water refers to exist in the wettability on the surface of the bone China material moisture content and pore water in the capillary and appropriate diameter greater than 8 ~ 4 mm of water. The combination between water and the material is very weak, is a mechanical mixture. Vapor pressure and liquid water produced by it in the same humidity when the vapor pressure of the same, so it is also called mechanical combined water, the combined water. Bone China easy to remove when dry. Drying process, the bone porcelain of vitro volume loss of approximately equal to eliminate free water volume, the free water and water shrinkage said. Bone China bone China began by free water on the surface of the billet surface moisture into atmospheric water adsorption state is called the critical moisture moisture content. In the critical state, the bone porcelain on the surface of the billet surface water vapor partial pressure by equal to less than the vapor pressure of liquid water in the same temperature. Critical moisture value is not fixed, it is because of bone China body surface moisture evaporation rate, bone, bone China porcelain blank thickness slab diffusion resistance changes in the body. Bone porcelain surface moisture evaporation rate large, thick bone porcelain body, inner diffusion resistance is big, the critical moisture value is high. Bone China bone porcelain body moisture content and surrounding air ( The outside conditions) Balance, namely bone porcelain billet surface on the surface of the water vapor partial pressure and ambient air vapor pressure equals the atmospheric absorption of water is called water balance. The humidity, the water contained bone porcelain body and saturated air balance, its moisture content is atmospheric adsorption water big value, more than the value is free water. Free water and atmospheric water adsorption equilibrium state as shown in figure 5 - 5. When the relative humidity of the air stays the same, atmospheric absorption of bone porcelain body moisture reduction with the rise of temperature. From the above analysis, the bone porcelain drying technology of processing object is free water. Rule out the process of free water bone porcelain body volume shrink; And eliminate atmospheric adsorption water, do not shrink, won't produce stress. Bone China porcelain bone dry moisture diffusion in the process of drying process is essentially the process of bone porcelain body moisture movement. Bone China body by internal diffusion and external diffusion rule out water. Spread out is bone porcelain body surface water evaporation, and through the steam membrane diffusion process to the world. Spread out on the surface of the bone China is the power of billet surface water vapor partial pressure of water vapor pressure and the surrounding medium. Within the internal moisture diffusion is bone porcelain body moved to the surface of the process, mainly by diffusion penetration and MAO fine reaction. Obey the law of diffusion of bone porcelain body body due to difference in temperature and moisture concentration difference of moisture movement led by wet heat conduction and conduction. — Tangshan bone porcelain hotel suits to be continued. 。 。 。 。 。