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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 The Activation Of The Coating Improves The Quality Of The Coating

Silica sol 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,Silica Sol Casting since the sixties of last century was introduced into the investment casting, the shell of the technology But the published literature [1] is mostly on the shell process and process parameters of the control and the choice of refractories and other aspects of the discussion, and the investment casting process shell micro Structural analysis has not yet seen the relevant reports.

From the perspective of colloid chemistry,Silica Sol Casting the change of the internal microstructure of the shell in the process of silica sol casting is discussed. In order to provide some effective theoretical guidance for the optimization of the shell technology.

2. Introduction to professional terms

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. Now as follows:

2.1 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). There is a clear physical interface between the colloidal particles and the dispersion medium, so the colloidal system is a two-phase or multi- Uneven dispersion system.

2.2 sol

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

Preparation is generally first dispersed in the disperser, and then grinding equipment grinding. For the annual consumption of 100t the following enterprises, 2 to 3 kilowatts of the disperser can be. The impeller has two kinds of blades and discs. The blade-type mixing force is large, can make the material up and down, but the speed will cause a little higher material splash, disc-shaped leaves up and down the staggered distribution of the material has a strong shear effect can be smooth high-speed rotation,Silica Sol Casting Well, productivity is also high, equipment can be made. Impeller speed can be used more than 200cm / min is appropriate. For the production requirements of enterprises is not high, can also choose a small ball mill, drum diameter of 0.5-0.8mm or so, speed 100 r / min or so. Paint in the ball mill grinding, in addition to good dispersion effect, but also make the aggregate broken, play a role in the activation of the coating to improve the quality of the coating. Ball mill than the colloid mill effect is good, polished by the ball mill coating not only high coating strength, and leveling and brushing and other process performance are better, milling time more than 4h.

Water-based paint mixing process is generally bentonite, CMC and water placed in a disperser to stir into the slurry and then add refractory continuous stirring, and then add adhesives,Silica Sol Casting surfactants and other additives. Bentonite and CMC pre-soak, the effect will be better. Alcohol-based paint such as the use of lithium-based bentonite as a suspending agent should be pre-issued with water for more than 24h, phenolic resin and PVB and so on first with alcohol soak, and then added to the disperser mixed. We have also taken the soaked phenolic resin and lithium bentonite mixed into a premix long-term preservation, when used in proportion to join the other mix together into a coating. The law is very suitable for small businesses.

According to the production of castings to choose the coating method of coating. For a single, small batch production of the appearance, should use brush. For larger castings can be used for flow coating. The viscosity of the coating should be smaller, and has a good coating performance; batch and shape complex patterns using dip coating and flow coating, thin wall easy to use the appearance of the spray method. Several methods can be used in combination. The coating must be uniformly covered with a mold surface, without defects, excessive flow or mixed bubbles. Coating thickness is generally 0.5-2.5mm, according to casting shape, thickness, complexity, alloy type,Silica Sol Casting gate static pressure head height and other factors to determine.

Generally need to apply 1-3 times, each coating must be dry, such as dry after the coating cracks, should reduce the proportion of paint, bentonite into the amount of appropriate increase in the amount of binder. The coating is dried and is typically recycled in the oven by hot air (below 60 ° C). Drying time 3-10h. Can also be used to dry, infrared or microwave drying.

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Address: No.238, Qiushe Road, Qiushe Industrial Park, Tongli Town, Wujiang District, Suzhou City, Jiangsu, 215200, P.R.China
Tel: +86-512-633758+86-608