Countergravity Casting Apparatus and Desulfurization Methods
AssigneeRtx Corporation
InventorsJohn J. Marcin, Jr., Alan D. Cetel, Mario P. Bochiechio, Reade R. Clemens
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Abstract
An apparatus for countergravity casting a metallic material, has: a crucible for holding melted metallic material; a casting chamber for containing a mold; a fill tube capable of extending into the crucible to communicate melted metallic material to the casting chamber; and a gas source coupled to a headspace of the melting vessel to allow the gas source to pressurize the headspace to establish a pressure differential to force the melted metallic material upwardly through said fill tube into the mold. Extraneous sulfur is prevented from entering the molten metal from the mold by solidifying metal in the fill tube.
Claims14
A method for using an apparatus for countergravity casting a metallic material, the apparatus comprising:
- a melting vessel;
- a casting chamber containing a mold;
- a fill tube capable of extending into the melting vessel to communicate melted metallic material to the casting chamber;
- and
- a gas source coupled a headspace of the melting vessel to allow the gas source to pressurize said headspace to establish a pressure differential to force the melted metallic material upwardly through said fill tube into said mold,
- the method comprising:
- melting a nickel-based superalloy in the melting vessel;
- disposing the mold under subambient pressure on a mold base with the fill tube extending through an opening in said base;
- relatively moving said melting vessel and said base to immerse an opening of said fill tube in the melted nickel-based superalloy in said melting vessel and to engage said melting vessel and said base with seal means therebetween such that a sealed gas pressurizable space is formed between the melted nickel-based superalloy and said base;
- gas pressurizing said space to establish a pressure differential on the melted nickel-based superalloy to force it upwardly through said fill tube into said casting mold, the melted nickel-based superalloy passing through the filter which filters the sulfur-containing particles;
- and
- a step for preventing sulfur pick-up by the melted nickel-based superalloy in the melting vessel from the material of the mold.
The method of claim 8 wherein:
- the solidifying acts to prevent sulfur pickup by the nickel-based superalloy in the melting vessel from mold material.
The method of claim 8 further comprising:
- releasing the pressure differential;
- removing the mold and the fill tube;
- and
- replacing the removed mold and fill tube with a new mold and fill tube.
The method of claim 8 wherein:
- the fill tube comprises a ceramic filter.
The method of claim 8 wherein:
- at least one of the crucible, fill tube, and mold has at least a surface layer of a sulfur-gettering material of greater sulfur-gettering ability than alumina and zirconia.
Dependencies are inferred from the claim text.