METHOD OF CASTING OF PRECISION CASTINGS OF PARTS Russian patent published in 1997 - IPC

FIELD: production of precision castings by investment casting with structure formation by high rate of oriented crystallization. SUBSTANCE: the offered method includes manufacture of molds by application of layers of ceramic coating with use of filler in form of refractory suspension of micropowders of white synthetic corundum, aluminum powder in the amount of 7% of filler mass, and graining material is used in form of polishing grain of white synthetic corundum. Prepared molds are filled with metal, single-crystal or oriented structure is formed by high-rate oriented crystallization. In micropowders and polishing grain of white synthetic corundum used for manufacture of molds, more low permissible level is established of low-melting impurities SiO₂ and K₂O+Na₂O in micropowders, wt. %: SiO₂≅ 0.03; K₂O+Na₂O ≅ 0.08; in polishing grain, wt.%: SiO₂≅ 0.03; K₂O+Na₂O ≅ 0.06. Permissible level of iron oxides content in micropowders is increased up to 0.07%; in polishing grain, it is at the same level. Molds are manufactured with precision guaranteeing products needing no machining. High level of thermomechanical properties of mold material allows reduction of mold wall thickness, improvement of conditions of formation of structure of castings and increase of casting yield by structure. EFFECT: higher efficiency. 2 tbl