Impact of high temperature on the compression behavior of carbon-bonded alumina filters with functionalized coatings

Abstract Carbon-bonded alumina is currently applied in metal casting processes due to its excellent thermomechanical performance. Used as ceramic foam filters in steel casting, the surface composition of such material is essential for trapping primary and secondary inclusions in liquid steel, where functionalized coatings are proven to enhance the filtration efficiency considerably. In this paper, compression tests on uncoated and coated Al2O3–C foam filters are performed at high temperatures under argon atmosphere. The macrostructure of the prepared filters before the high temperature compression tests and the microstructure afterwards are examined by computer tomography and scanning electron microscopy, respectively. High temperature compression strength of the studied filters generally exceeds cold crushing strength values thanks to plastification processes. The applied coatings have positive impact on the filter strength. The observed high scatter of the compression strength can be attributed to the inhomogeneity of strut thickness, distribution of the oxide and non-oxide materials within the struts as well as coating thickness.