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    Add: No.238, Qiushe Road, Qiushe Industrial Park, Tongli Town, Wujiang District, Suzhou City, Jiangsu, 215200, P.R.China

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Silica Sol Casting Forming A Very Critical And Important Part Of The Process

Silica Sol Casting is a high quality water-based binder commonly used in investment casting. Because of its shell does not require chemical hardening, high temperature strength, high temperature resistance to deformation ability, easy to dubbed high-quality liquid than the high-quality paint, since the sixties of last century was introduced after the investment casting, shelling technology But the published literature [1] is mostly on the shell process and process parameters control and the choice of refractory materials and other aspects of the discussion, while the investment casting process shell micro Structural analysis has not yet seen the relevant reports.

Some technical terms in the field of chemistry and casting the understanding of the field is not the same, for the convenience of discussion, we unified the use of colloidal chemistry to understand the terminology, and the use of narrow understanding. The briefing is as follows:

Colloid

First colloid is not a special substance, nor is the nature of matter, but the existence of a special state of material. The colloidal system is characterized by a certain size of the dispersed phase particles (the diameter of the dispersed phase particles is 1 to 100 nm), and there is a significant physical interface between the colloidal particles and the dispersion medium. Therefore, the colloidal system is a two-phase or multi- Uneven dispersion system.

Sol

From the definition of colloids, colloidal systems can be formed in dispersed media in different states as long as the particle sizes of the dispersed phases of different aggregates are between 1 and 100 nm. In addition to the dispersed phase and dispersion medium are gas and can not form colloidal system, the remaining eight kinds of dispersion system can form a colloid system. When the dispersion medium is solid,Silica Sol Casting it is called solid sol; when the dispersion medium is gas, it is called aerosol, and the colloidal dispersion system with liquid dispersion is called liquid sol or sol.

Gel

Also known as jelly. The colloidal particles in the sol can be connected to each other under certain conditions to form a space network structure, the structure of the gap filled with liquid as a dispersion medium, regardless of the amount of liquid, this will lose the liquidity of the dispersion system called gel. Fresh gel called wet gel,Silica Sol Casting when the liquid in the gel all lost also known as the gel, is the dry gel, the structure of the dry gel inside the filling is full of gas.

Gels are filled with water when the liquid is called water.

Gel has a certain geometric shape, with a solid mechanical properties, such as strength, elasticity and yield value. But from the internal structure, it is different from the usual solid, which consists of solid-liquid two-phase composition, but also has some properties of the liquid,Silica Sol Casting such as ions in the fresh hydrogel diffusion rate close to the diffusion rate in aqueous solution The This shows that the fresh hydrogel, the dispersed phase and dispersion medium are continuous phase, which is the structural characteristics of the gel

Capillary phenomenon

The continuous dispersed phase forms the solid skeleton of the gel, and the continuous dispersion medium forms the fluid portion of the gel, forming the particle size of the colloid so that the gel has a microstructure of the capillary. Capillary phenomenon refers to the liquid inside the fine tubular object, due to the adhesion between the liquid and the wall and the liquid itself,Silica Sol Casting the difference between the cohesion in the vertical tube within the rise or fall phenomenon, and the role of these two forces is the capillary force The role.

The gel structure of fresh gel is filled with liquid dispersion medium. With the progress of gel drying, the gel will change from liquid-solid two-phase to liquid-solid three-phase, and the final liquid phase will be replaced by gas phase and become dry gel The The permeability of the visible shell is determined by the microstructure of the capillaries of the gel. It is also seen that the drying process is a very critical and important link in the gel formation process and that factors related to the gel drying rate will ultimately affect the gel capillary Of the microstructure.


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Tel: +86-512-633758+86-608
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