What is Fused Ceramic Sand?
Ceramic foundry sand, whose scientific name is "fused ceramic sand", is a kind of sand with different particle sizes made of calcined bauxite with aluminum oxide (Al2O3) as the main component through melting, injection and screening. The mineral phases of Fused Ceramic sand are mainly corundum and mullite, as well as a small amount of amorphous phase. The main chemical components of Fused Ceramic sand are aluminum oxide (Al203) and silicon dioxide (SiO2), and the refractoriness is greater than 1800℃. It is an approximate spherical, high strength and high hardness Al Si refractory. Pure pearl sand is mostly black brown. The particle size of Fused Ceramic sand for casting is generally between 0.053 ~ 3.35mm.
How is Fused Ceramic Sand Produced?
First of all, there should be the following equipment: electric arc furnace, air compressor, screening machine.
Secondly, Al2O3 65-85% bauxite ore should be prepared as raw material.
The specific steps are divided into three stages:
1. Add bauxite ore into the electric arc furnace and melt the bauxite raw material into liquid by using the high temperature generated by electric arc discharge;
2. When the liquid flows out of the furnace, apply 70-85m/s air pressure to it, use strong wind to crush and cool the liquid raw material, and under the action of liquid surface tension, obtain spherical or nearly spherical sand particles with smooth surface.
3. After screening, Fused Ceramic sand with different standard particle sizes is obtained. After * *, it is mixed according to the particle size distribution required by the customer, and properly packaged to obtain qualified products.
The most easily neglected excellent property of Fused Ceramic sand is its crushing resistance.
The casting raw sand is easy to be broken (particle refinement, particle shape change, etc.) in the process of mixing and grinding, molding, pouring, sand removal and recycling (especially mechanical regeneration), which leads to the decline of molding sand process performance. The common problems are that the increase of fine powder content leads to the decrease of core sand strength, the increase of binder dosage, the increase of gas generation, and the decrease of air permeability. In addition, the crushed and finer raw sand causes dust pollution in the production environment, and causes more consumption of raw sand after dust removal. Controlling the crushing rate of raw sand in the casting process, using raw sand with high particle strength and low crushing rate has attracted more and more attention of foundry workers, and has gradually become an important index in the selection of raw sand.
Precautions when purchasing Fused Ceramic sand
1. When choosing Fused Ceramic sand enterprises, foundry enterprises should pay attention to the comprehensive strength of suppliers, mainly the quality assurance ability and production capacity, as well as their geographical location, past performance and other factors.
2. According to different casting materials, the Al2O3 content of Fused Ceramic sand should be selected reasonably, and other chemical compositions should be controlled to meet the requirements of fire resistance and crushing resistance of castings.
3. The particle size composition and average fineness of Fused Ceramic sand should be selected according to the casting quality. Coarse sand with small average fineness value shall be selected for castings with large quality or thick section; Fine sand with high average fineness value can be selected for castings with small quality or thin wall.
4. For Fused Ceramic sand, a new concept of grain size and gradation should be formed
It is necessary to abandon the inherent concept formed when using silica sand in the past, and reasonably grade to meet the process requirements.