In terms of the development of artificial sand, it should be particularly mentioned that China has made very important independent innovation achievements in this area, and developed high aluminum "Fused ceramic sand". Fused ceramic sand has many excellent properties and is suitable for various casting alloys and various special casting processes, but its price is lower than that of zirconium sand and chromite sand.
The manufacturing method of fused ceramic sand is to select high-quality bauxite raw materials and melt them in an electric arc furnace. When the molten liquid flows out of the furnace, it is blown away with compressed air flow. After cooling, spherical or nearly spherical particles are obtained with smooth surface.
Characteristics of Fused ceramic sand
The particle shape of fused ceramic sand is spherical or nearly spherical, and its color is black brown. The particle size can be between 0.5 ~ 2.0 mm, which can be selected by the customer according to the process requirements.
The fire resistance of fused ceramic sand is above 1800 ℃. Its high temperature chemical stability is much better than that of silica sand. It can be used for cast steel, cast iron and various non-ferrous alloys.
Fused ceramic sand is an electrofusion-material with compact texture and better durability. The expansion rate of fused ceramic sand after heating is 1 / 5 of that of silica sand and 1 / 2 of that of chromite sand. As a molding material, it can effectively prevent the expansion defects of castings.
The price of fused ceramic sand is relatively cheap, about 1/3 of zirconium sand and 1/2 of chromite sand.
Application of Fused ceramic sand
The use of some pearl sand in molding sand and core sand can effectively prevent the expansion defects of castings. In recent years, some manufacturers of coated sand in China have added some Fused ceramic sand to the raw sand, which can make the shell mold and shell core have the properties of high temperature resistance, low expansion, easy collapse, high strength and low gas generation. For cores with particularly complex shapes, it can also solve the problem that sand shooting is not easy to compact.
For large and medium-sized steel castings, chromite surface sand is usually applied at the hot spot during molding to improve the surface quality of castings. Now, Fused ceramic sand can be used to replace chromite sand, which can not only improve the surface quality of castings, but also reduce production costs, and is also conducive to the regeneration and reuse of old sand.
If the foundry adopting lost foam casting process or V-method molding process replaces silica sand with fused ceramic sand, under the same compaction conditions, the compactness of sand filling is higher, and the dimensional accuracy and surface quality of castings will be significantly improved. More importantly, it can eliminate silicon dust in the production workshop and greatly improve the working environment.