Abstract
Open cell ceramic foam filters are utilized to reduce non-metallic inclusions during casting of metals and therefore to enhance the quality of cast parts. A new generation of multifunctional filters made of carbon bonded alumina (Al2O3-C) has been developed within the scope of the collaborative research center CRC 920 [1]. The assessment of the resistance against high thermal and mechanical loads requires a mechanical characterization of the ceramic filter material. The mechanical properties show a distinctive size dependency, that’s why the specimen dimensions should be similar to the strut size of the real filter structures. The tensile fracture behavior is investigated by means of the Small Punch Test (SPT) using miniaturized disk-shaped specimens. During the mechanical tests a load-displacement curve is measured until failure occurs and a fracture stress is calculated from the experimental results. An estimation about the failure probability by means of Weibull statistics is performed because of the large scatter of the strength of the material. Furthermore, a modified version of the SPT, the so called Ball On Three Balls Test (B3B), is applied and compared to the SPT. In a final step numerical simulations of the B3B tests are performed by means of the finite element method to identify fracture mechanical material parameters like the fracture toughness.
Published Version
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