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Technical Ceramics

Fiber-reinforced oxide ceramics as an innovative approach in foundry work

The Gießela project: Saving up to 10 tons of aluminum annually, minimizing energy losses, and significantly improving product quality in the aluminum foundry—these are the promises made by O-CMCs.

New materials for increased efficiency in foundries

Various tools made of steel, cast iron, or ceramic are used in aluminum foundries. Metallic tools require ceramic coatings, which must be renewed regularly, resulting in additional costs and effort. Ceramic tools, on the other hand, can be used without coatings. These are used to manufacture products such as riser pipes, dosing pipes, sprue bushings, structural ceramics for investment casting, and thermocouple protection tubes. However, conventional ceramics tend to exhibit brittle fracture behavior. This behavior causes the ceramics to fail catastrophically when subjected to excessive mechanical stress, such as an impact or shock. In addition, premature solidification and adhesion of liquid aluminum are not uncommon. 

Oxidic fiber-reinforced ceramics (O-CMCs) could be a promising alternative for the future. They consist of a porous ceramic matrix reinforced with fibers made of oxide ceramics, which gives them a high damage tolerance. Unlike conventional ceramics, O-CMCs can be used to produce thin-walled components (< 2 mm). In addition, they are not wetted by molten aluminum.

Ongoing innovation process

Over the next three years, the Gießela project will develop an innovative manufacturing process for O-CMC foundry aids. The use of optimized processes from textile technology and infiltration technologies is intended to create sustainable and user-friendly products with increased durability. The combination of a near-net-shape three-dimensional textile preform with a novel infiltration technology will result in products that are superior to conventional foundry aids in terms of thermal insulation, corrosion resistance, and mechanical strength.

Efficiency, sustainability and worker welfare

Due to the poor wetting of molten aluminum on the O-CMCs, an estimated 10 tons of usable aluminum per year could be saved from disposal at the project partner's site. In conjunction with significantly lower heat losses compared to conventional steel or cast iron products, the project creates added value in terms of energy and resource efficiency, sustainability, and worker well-being. A significant reduction in impurities in the aluminum melt due to alloying elements from metallic additives would also significantly improve the quality of foundry products and reduce scrap rates.

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