Easily removed ceramic rods for casting gas-turbine engine blades using molding patterns

• Published in: Glass and ceramics 2012-07, Vol.69 (3-4), p.125-129
• Main Authors: Belyakov, A. V., Razumnova, I. V., Demonis, I. M., Folomeikin, Yu. I.
• Format: Article
• Language: English
• Subjects: Aerospace engines; Ceramics; Characterization and Evaluation of Materials; Chemical tests and reagents; Chemistry and Materials Science; Composites; Cristobalite; Formaldehyde; Gas turbine engines; Gas-turbines; Glass; Materials Science; Metal castings industry; Natural Materials; Powders; Rods; Silicates; Surface active agents; Surfactants; Transformations; Vibration
• ISSN: 0361-7610; 1573-8515
• DOI: 10.1007/s10717-012-9429-x

Methods have been developed for weakening and removing ceramic rods from a metal casting by means of polymorphic transformations in cristobalite and β-Ca 2 SiO 4 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-Ca 2 SiO 4 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-Ca 2 SiO 4 into γ-Ca 2 SiO 4 in mixes made from MgO, α-Al 2 O 3 , fused SiO 2 and stabilized ZrO 2 .