The role of silica sol in precision casting

The role of silica sol in precision casting

What is silica sol in precision casting? It is a colloid composed of 30% silica and 70% water. If the silica sol acts as a binder, 70% of the water must be evaporated. However, only by first bonding the silica sol coating and sand particles with this colloidal solution can the thickness and strength of the shell be formed layer by layer. Silicone sol has a characteristic that as viscosity increases, in fact, with the increase of silica content, silicone sol will produce gelation. These two are actually the principles of silica sol shell making. Today, precision casting manufacturer Tianyao Metal will talk to you about the role of silica sol in precision casting.

We know from the above description that silica sol is a colloidal solution of silica, where the solute is silica and the solvent is water. Due to the evaporation of water, the silica sol will become thicker, which means that the content of silica will increase, and the silica sol will have the risk of gelation. Therefore, the storage of silica sol is sealed and should be placed in a cool and dry place. Its storage temperature is 0-40 ℃. The same goes for silica sol, and the same goes for coatings made from silica sol. This is where the surface layer needs to be watered. The reason why the surface layer needs to be replenished with water is because the slurry of the surface layer is constantly stirred, and the temperature of the slurry will also increase, which will accelerate the evaporation of water. Therefore, there is the saying of replenishing water. The surface layer needs to be replenished with water, and the transition layer and back layer should not be replenished with water. In principle, it is necessary to replenish water. However, in reality, we often see a situation where water is rarely replenished. The reason is that the relative amount of transition layer and back layer materials is large, and they are replenished almost every day. Therefore, water replenishment is omitted.

Another thing is awakening, which is actually a very important process. The coating should be applied well and evenly, and the first thing to do is to wake up. As we mentioned earlier, the new mixture of the surface layer slurry must be stirred for more than 24 hours, and some additional materials must be stirred for more than 12 hours; The new slurry for the transition layer and back layer needs to be stirred for more than ten hours, and some additional materials need to be stirred for more than five hours. Not only do you need to know these data, but you also need to strictly follow the rules to ensure the quality of your shell making. In addition, never use reasons such as urgency or rush to deliver goods as a pretext for illegal operations, as it can only be a case of lifting one's hand and hitting one's own foot.

Someone may also ask, what should we do if we need to make a slight adjustment to the viscosity of the slurry? That can be done using silica sol and powder. The viscosity cannot be a fixed value, it must be a range, which is a well-known fact.

Precision machining