1. High thermal shock resistance-the material must not crack or peel off during preheating or contact with molten metal. The material should have a low coefficient of thermal expansion to minimize the transverse compressive stress when in the filter bowl.
\n2. Corrosion resistance: The filter material should not react significantly within the expected application range (time, temperature, alloy content), and must be kept from being wetted by molten aluminum and its common alloys.
\n3. Sufficient bending and compressive strength.
\n4. Production economy.
\n5. The used filter material must be safely handled and disposed of.
\n6. Low density or light weight, which is convenient for the operator of the casting pit.<\/p>\n
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The thermal expansion rate of the ceramic foam filter is in the range of 1.5-7.5\u00d710-6mm\/\u2103. Under normal conditions of use, the ceramic foam filter is proven to resist the chemical attack of molten aluminum alloy. The ceramic foam filter is light in weight and preferably has a density of about 0.25-0.40 g\/cc.<\/p>\n
Ceramic foam is a tough foam made from ceramics. Manufacturing techniques include impregnating open-cell polymer foams internally with ceramic slurry and then firing in a kiln, leaving only ceramic material. The foams may consist of several ceramic materials such as aluminum oxide, a common high-temperature ceramic, and gets insulating properties from the many tiny air-filled voids within the material.<\/p>\n