Composition of fire resistant coating for lost foam casting

The refractory coating for lost foam casting consists of refractory aggregate, carrier (solvent), suspending agent, binder and other additives.

① Refractory aggregate. It is the main component of the coating for lost foam casting. It has the functions of heat insulation, isolation, anti sand sticking and reducing the surface roughness of castings. In the EPC coating, its mass fraction is usually more than half, mainly including zircon powder, bauxite, talc powder, brown corundum powder, quartz powder, mullite powder, mica powder and other refractories. In general, different refractory materials are selected according to different materials of castings. In addition, the prevention of sand sticking and high permeability should be considered. The shape of particles determines that it is more conducive to improve the permeability, so in actual production, a certain number of particles with spherical shape are usually selected, which is more conducive to the discharge of gas after the sample model is gasified by high temperature molten metal solution.

② Carrier (solvent). The main components of casting coating carrier are ethanol and water. As far as the fire-resistant coating for lost foam casting is concerned, the hanging coating, gas generation, drying, price and other aspects should be considered. Water is often used as its carrier, commonly known as water-based coating. At the same time, the suspension and thixotropy of water-based coating are better, which is more convenient to adjust.

③ Binder. The binder in EPC refractory coating plays an important role in the strength and adhesion of EPC coating. It not only improves the strength and hanging property of the refractory coating, but also improves the suspension property. It also makes the mold coating have good adhesion, and does not react with the pattern.