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Common silica sol casting method
Many people in the industry know about the silica sol, but before we introduce the silica sol casting, let's take a look.
I. Chinese Name: Silica Sol
Second, the English name: silica sol
Third, the definition: a stable dispersion of fine silica particles in water.
Silica gel is a colloidal solution, odorless, non-toxic, the molecular formula can be expressed as mSiO2nH2O.
1. Since the colloidal particles are fine (10-20nm), there is a considerable specific surface area, and the particles themselves are colorless and transparent without affecting the true color of the covering.
2. Viscosity is low, water can penetrate wherever it penetrates, so when mixed with other substances, the dispersibility and permeability are very good.
3. When the water of the silica sol evaporates, the colloidal particles are firmly attached to the surface of the object and silicon and oxygen are formed between the particles. This is a good adhesive.
1. Used as a binder for various refractory materials, with strong adhesion, high temperature resistance (1500-1600°C), etc.
2. It can be used in the paint industry to make the paint firm, and it can also resist dirt, dust, aging, fire and other functions.
3. For thin shell precision casting, can make shell type strength, casting finish high. Its shape is better than that of water glass, and instead of ethyl silicate, it can reduce costs and improve operating conditions.
4. The silica sol has a high specific surface area and can be used for catalyst manufacture and catalyst support.
5. It is used in the paper industry and can be used as cellophane release agent, photographic paper pretreatment agent, cement bag anti-slip agent, etc.
6. It is used as a sizing agent in the textile industry. It is used together with an oil agent to treat the spinnability of wool and rabbit hair, to reduce breakage, prevent flying, increase the yield, and increase economic efficiency.
7. Used as silicon steel sheet processing agent, picture tube dispersant, floor wax anti-sliding and so on.
Silica sol casting has the advantages of high dimensional accuracy, good surface quality, etc. It is a widely used, less advanced, non-cutting process. The adoption of silica sol casting method can save a lot of machine tool equipment and processing man-hours, and can also save metal raw materials. Silica sol casting is a widely used precision casting method in the field of precision casting. This precision casting method effectively reduces the cost and improves the competitiveness of precision casting companies. Casting is one of the most important steps in the casting of silica sols. What are the common casting methods for silica sol casting?
1. Crystallization under pressure
Put the shell in the pressure tank and cast it. After the end, immediately close the pressure tank and introduce high-pressure air or inert gas into the tank to make the casting solidify under pressure to increase the density of the casting.
2. Vacuum suction pouring
The shell is placed in a vacuum casting box and the gas in the cavity is sucked through the tiny holes in the shell so that the liquid metal can better fill the cavity, duplicate the shape of the cavity, improve casting accuracy, prevent blowholes, cast Inadequate defects. This method is more common abroad.
3. Directional crystallization
Some investment castings such as turbine blades, magnetic steels, etc., if their crystal structure is columnar crystals arranged in a certain direction, their working performance can be improved a lot, so investment casting oriented crystallization technology is rapidly developing. 4. Hot gravity casting
This is the most widely used form of casting, ie, the shell is free-flowing at high temperatures after it has been removed from the roaster.