Physical and FE-Simulation of Thermal Shock Behaviour of Refractory Ceramics
To characterize thermomechanical properties of refractory ceramics, physical simulation was carried out using the simulation and test centre Gleeble 3500. A new heating method based on the heat transfer from electrical heater into the specimens was developed to test non electrical conductive materials like alumina-mullite refractory ceramic. The graphite containing refractory ceramics were heated directly via electrical current. In addition, for enhanced understanding of damage and failure mechanisms under thermal shock loading, a combination of experimental testing and numerical simulation methods has been used. The thermal shock behaviour of the alumina (99,7 %) disk samples has been investigated by using a plasma test stand: the bottom of the ceramic disks were locally heated in the centre by plasma beam; during the heat treatment the temperature distribution at the top of the sample was recorded with a thermographic system. To characterise the thermal shock resistance, a thermomechanical simulation was subsequently carried out. It calculates the temperature and stress distribution within the ceramic disks. Beside reference material alumina (99,7 %), more refractory ceramics fabricated within other subprojects of SPP 1418, such as Ca-Aluminate/Alumina-Multilayer (Fraunhofer IKTS), Multilayer Laminates (WW3, FAU), Refractory Castables Containing Eutectic Aggregates (GHI, RWTH), have been investigated using this plasma test stand. By means of investigation and comparison of the damage mechanisms under thermal shock loading, refractory ceramics were approved, which exhibit better thermal shock resistance and are suitable for steel casting applications.