Ceramic foam filters are a high-performance porous ceramic material widely used in the foundry industry to filter impurities (such as oxides, slag, bubbles, etc.) in molten metals, thereby improving the quality of castings, reducing defects and improving mechanical properties. As a professional manufacturer of ceramic foam filters, SF-Foundry uses advanced organic foam impregnation technology to produce high-quality silicon carbide (SiC), aluminum oxide (Al₂O₃) and zirconium oxide (ZrO₂) ceramic foam filters to meet the filtration needs of different metals (such as cast iron, cast steel, aluminum alloy, etc.).
This article will introduce the production process, key quality control points and application characteristics of different materials of ceramic foam filters in detail to help customers better understand our products and provide reliable filtration solutions for foundry companies.
What are the function of ceramic foam filters
Ceramic foam filters have a three-dimensional mesh open-pore structure. Their high porosity (usually 70%-90%) and uniform pore size distribution enable them to efficiently intercept tiny impurities in molten metals. Its main functions include:
Remove inclusions: filter non-metallic impurities (such as SiO₂, Al₂O₃ particles), reduce casting pores and slag inclusion defects.
Stabilize metal flow: reduce turbulence, make the molten metal fill the mold smoothly, and improve the surface finish of the casting.
Improve mechanical properties: reduce internal defects, improve key performance indicators such as tensile strength and fatigue life of castings.
SF-Foundry’s foam ceramic filter provides a variety of material options according to the pouring temperature of different metals:
- Silicon carbide (SiC) filter: temperature resistance of 1500°C, suitable for cast iron, ductile iron and some molten steel filtration.
- Alumina (Al₂O₃) filter: temperature resistance of 1200°C, mainly used for low melting point metals such as aluminum alloys and copper alloys.
- Zirconia (ZrO₂) filter: temperature resistance of 1700°C, suitable for precision casting of high temperature alloy steel, stainless steel, etc.
Production process of foam ceramic filters
SF-Foundry uses organic foam impregnation method to produce foam ceramic filters. This process is mature and stable, and can accurately control porosity and mechanical properties. The following is a detailed production process:
Raw material preparation
Ceramic powder: Select high-purity silicon carbide, alumina or zirconium oxide powder according to product requirements to ensure chemical stability and high-temperature performance.
Binder: Use silica sol, aluminum sol or organic resin as the bonding system to enhance the strength of the green body.
Additives: Including dispersants (to prevent particle agglomeration), rheology regulators (to optimize slurry fluidity) and sintering aids (such as MgO, Y₂O₃, to promote high-temperature densification).
Slurry preparation
Mix the ceramic powder, binder and additives in proportion and ball-mill them into a uniform slurry. The viscosity of the slurry needs to be precisely controlled to ensure the smooth progress of the subsequent impregnation process.
Organic foam impregnation
Template selection: Polyurethane (PU) sponge is used as the template. Its open-pore structure determines the porosity of the final filter (usually 10-30PPI, i.e., pores per inch).
Impregnation process: The PU sponge is immersed in the ceramic slurry, and the excess slurry is removed by extrusion or centrifugation to ensure that the slurry is evenly coated on the surface of the foam skeleton.
Drying and debinding
Drying: Slowly dry at 60-120°C to avoid cracking.
Debinding: Burn the organic foam template at 300-600°C to form a porous ceramic body.
High-temperature sintering
Set the sintering temperature according to different materials:
Silicon carbide filter: 1400-1600°C (atmosphere protection to prevent oxidation).
Alumina filter: 1500-1650°C.
Zirconium oxide filter: 1600-1800°C.
After sintering, the ceramic skeleton forms a stable three-dimensional network structure with excellent thermal shock resistance and mechanical strength.
Quality inspection
Porosity test: Archimedes drainage method or micro CT scanning is used.
Compressive strength test: Ensure that the filter can withstand the impact of molten metal.
High temperature stability test: Simulate the actual casting environment to verify the heat resistance.
SF-Foundry’s production advantages
Advanced production equipment
Automated slurry stirring and impregnation system is used to ensure batch consistency.
High temperature sintering furnace is equipped with intelligent temperature control system to avoid over-burning or under-burning.
Strict quality standards
Each batch of products is tested for compressive strength, air permeability and pore size distribution.
Comply with ISO 9001 quality management system and provide third-party test reports.
Customized service
Supports customization of different sizes (50×50mm to 300×300mm), shapes (round, square, special-shaped) and pore sizes (5-30PPI).
Special coatings (such as anti-oxidation coatings) can be developed according to customer needs.
Application cases of foam ceramic filters
Case 1: Production of automotive cast iron parts
After a well-known automotive parts manufacturer adopted SF-Foundry silicon carbide filters, the slag inclusion defects of castings were reduced by 50% and the mold life was extended by 15%.
Case 2: Aluminum alloy wheel casting
Customer feedback showed that after using alumina filters, the fluidity of molten metal improved and the yield rate increased from 92% to 97%.
Future development trends
As the demand for high-purity metals in the foundry industry grows, foam ceramic filters will develop in the following directions:
Higher porosity: Improve filtration efficiency and reduce flow resistance.
Nano-coating technology: Enhance anti-corrosion performance and extend service life.
Intelligent production: Combine AI to optimize process parameters and improve product consistency.
Conclusion
As a professional foam ceramic filter manufacturer, SF-Foundry is committed to providing high-performance and high-reliability filtration solutions. Our products are widely used in automotive, aerospace, energy equipment and other fields to help customers improve casting quality and reduce production costs.
For more technical details or customized requirements, please contact SF-Foundry team:
📧 Email: info@sf-foundry.com
📞 Phone: +8613785803358