Methods have been developed for weakening and removing ceramic rods from a metal casting by means of polymorphic transformations in cristobalite and β-Ca2SiO4 during vibration in water containing surfactants without the use of aggressive and environmentally harmful reagents. The hot-bending strength (at 1050°C) of ceramic made from cristobalite was about 20 MPa while that of β-Ca2SiO4 at 1300°C was 18 – 24 MPa, which is adequate for use as a rod material. The use of carbamide formaldehyde resin with silicate sol as a binder for powders made from tridimite, mullite and zircon made it possible to weaken the rods, on cooling, as a result of polymorphism of cristobalite. The weakening and removal of the rods during vibration in water containing a surfactant was achieved with a polymorphic transformation from β-Ca2SiO4 into γ-Ca2SiO4 in mixes made from MgO, α-Al2O3, fused SiO2 and stabilized ZrO2.
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We wish to express our gratitude to Candidate of Technical Sciences T. N. Shestoperova for her enormous assistance in performing the experiments and analyzing the results.
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Translated from Steklo i Keramika, No. 4, pp. 26 – 31, April, 2012.
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Belyakov, A.V., Razumnova, I.V., Demonis, I.M. et al. Easily removed ceramic rods for casting gas-turbine engine blades using molding patterns. Glass Ceram 69, 125–129 (2012). https://doi.org/10.1007/s10717-012-9429-x
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DOI: https://doi.org/10.1007/s10717-012-9429-x