Basic Knowledge of Ceamic Foundry Sand

What is Ceramic foundry Sand?

Ceramic foundry sand, which the scientific name of "fused ceramic sand for foundry", is calcined bauxite with aluminum oxide (Al 2O 3) as the main component, which is melted, blown and sieved to produce casting sand with different particle sizes.  


The grain size of casting pearl sand is generally 0.053-3.35mm. The mineral phases of the perlite sand are mainly corundum and mullite, as well as trace amorphous phase. The main chemical components of Ceramic foundry sand are Al2O3 (Al203) and SiO2 (SiO2). The fire resistance is generally ≥ 1800 ℃. It is a kind of nearly spherical, high strength and high hardness aluminum-silicon refractory. Pure pearl sand, the color of which is mostly black- brown.


With excellent physical and chemical properties, ceramic foundry sand has been rapidly promoted in casting production. Over the past two decades, casting manufacturers have obtained significant economic and environmental benefits, and are called by experts as "green casting new materials in the 21st century".



How is Ceramic foundry Sand produced?

The general process flow of production of ceramic foundry sand is as follows: add bauxite ore containing 65-80% Al2O3 into the arc furnace, melt the bauxite raw material into liquid by using the high temperature generated by arc discharge, apply air pressure of 70-85m/s to the liquid when the liquid flows out of the furnace, crush and cool the liquid raw material by strong wind, and obtain the shape of sphere or near-sphere under the action of liquid surface tension. Through sieving, different standard sizes of Ceramic foundry sand are obtained. Finally, sand is mixed according to the particle size distribution required by the customer, and qualified products are obtained through proper packaging.


What is the technological advantage of Ceramic foundry Sand?


a. Sub-spherical particles with smooth surface - small consumption of binder, less gas generation, good mobility, good filling property, and good collapsibility after pouring.


b. Low thermal expansion rate - the expansion rate of heated perlite sand is 1/5 of silicon sand and 1/2 of chromite sand. The produced casting has high dimensional accuracy, less ripple and crack defects and high finished product rate.


c. Good crushing resistance - Ceramic foundry sand material is dense, with high compressive strength, low crushing rate when reused, greatly improving the recycling rate of core sand, reducing the discharge of waste sand and beneficial to environmental protection.


d. High fire resistance - reduce sand adhesion.


e. Relatively small bulk density - the bulk density of Ceramic foundry sand is about 2g/cm3, which is less than 2.5-2.9g/cm3 of chromite sand. The produced sand core is lighter and easy to handle, which can reduce the use of core sand.


f. Good applicability to binder - the main component of Ceramic foundry sand is Al2O3, the pH is neutral, and acidic and basic material hardening binders can be used.


g. The price of ceramic foundry sand is relatively cheap - the price is about 1/3 of that of zirconium sand. Although much higher than silica sand, but if properly used, the comprehensive cost accounting is much higher.