| 摘要 |
1,156,721. Casting processes; moulds. UNITED AIRCRAFT CORP. 9 May, 1966 [27 May, 1965; 17 Feb., 1966], No. 20371/66. Heading B3F. [Also in Divisions B1, C7 and F1] A mould for casting turbine blades from a nickel based super-alloy by forming a single axially extending crystal having one of its axes less than 20 degrees from the longitudinal axis of the turbine blade, comprises an enlarged base portion 61 opening on to a water-cooled chill plate 22, a constricted passageway 63, a mould cavity 65 and a mouth 66. Random and columnar crystals form in the base portion 61, but a single crystal forms from the end of the passageway 63. A graphite susceptor 70 surrounds the mould and the casting operation may be carried out in a vacuum or in an inert, e.g. argon, atmosphere. Induction heating coils 72 are provided to maintain a temperature gradient away from the cooled chill plate 22 to ensure longitudinal solidification of the blade. The Specification contains a variety of material Specification of nickel base alloys suitable for single crystal forming in the mould, and the results of tests carried out on test samples. Heat treatment of the finished machined blade may be carried out and a sintered protective coating may be provided. The alloys described fall within the range containing, by weight, Cr 2-25%, Co 1-30%, Al 0-9%, Ti 0-6%, Mo and W 2-14%, Nb 0-3%, V 0-1À2%, the balance being nickel plus impurities. |
