SAND FOR MAKING CASTING CERAMIC CORES Russian patent published in 2006 - IPC B22C1/00 

FIELD: foundry, possibly manufacture of articles of refractory alloys, mainly blades of gas turbine engines.

SUBSTANCE: sand contains as main component solid-solution powder on base of melt SiO₂ including 5 - 30% of Cr₂O₃ and(or) Al₂ O₃ and sintering additive. Components are taken at next relation, mass %: SiO₂ base components, 75.0 - 99.5; sintering additive, 0.5 - 25.0. Said additive contains powder of sialon,_{La2 O3 and(or) LaB6 . Sintering additive contains as sialon one of solid solution compound formed in system Si-Al-O-N. Mainly are used systems on base of silicon oxynitride with formula Si2x AlxO1+xN2-x where x = 0 - 0.2; on base of silicon nitride with formula Si6-zAlz Oz N 8-z where z = 0 - 4.2; on base of polytypoids of aluminum nitrides with formula Alm SiO2 Nm where m = 4,5,6,8. Such sand provides increased (up to 14 - 26 MPa) bending strength of cores, lowered (to 0.1 - 0.8%) casting shrinkage, lowered depth of interaction with alloy of kind given in description of invention till 0.03 - 0.05 mm.}

EFFECT: improved ecology and sanitary demands of process.

2 cl, 3 tbl