Abstract: A vaporizable refractory coated pattern assembly is formed having a sprue connected to a plurality of thin wall patterns of articles to be cast. The pattern assembly is supported in a refractory particulate media in an open bottom container that is evacuated to subambient pressure and rotated in a manner to distribute particulates to regions of the refractory coated patterns not yet directly contacted by particulates. The pattern assembly is comprised of relatively dense foam plastic pattern material that imparts increased strength to the thin wall patterns. The sprue includes a vent passage that communicates to a particulate media to vent pattern decomposition vapors thereto in a manner that enables faster replacement of the pattern assembly in the media, despite the use of the relatively dense pattern material.

Abstract: A titanium aluminide alloy and tooling made therefrom for use in contact with molten aluminum and its alloys where the titanium aluminide alloy includes a rare earth element in an effective amount to prolong resistance to attack of the alloy and tooling by the molten aluminum and its alloys.

Abstract: Tooling for handling molten or hot solid aluminum and its alloys wherein the tooling is made of a passivated titanium aluminide (TiAl) intermetallic compound having a thin passivating surface oxide film formed in-situ thereon by contact with an oxygen-bearing atmosphere at elevated temperature. The surface oxide film passivates and renders the tooling non-wetted by and non-reactive with molten aluminum and its alloys and non-bonded to hot solid aluminum and its alloys.

Abstract: Fold defects are reduced or eliminated in lost foam castings by contacting a destructible polymeric pattern surface proximate to which deleterious fold defects comprising unbonded seams are prone to form in the solidifying molten metal with a material that reduces or eliminates fold defects in the casting proximate the pattern surface. The material can comprise a silicone layer that is anti-sticking relative to a gas permeable refractory layer on the pattern or foundry sand directly contacting the pattern surface depending on casting configuration. The pattern is cleaned prior to contact with the material. Lower melt casting temperatures can be used with concomitant improvements in casting microstructure (e.g. finer dendritic arm spacing) and mechanical properties.

Abstract: Method and apparatus for melting reactive metallic materials, such as for example titanium base alloys and other reactive alloys, by selective and sequential induction heating of a plurality of solid alloy charge components segregated in a refractory melting vessel in a manner to effect rapid top-to-bottom melting that avoids harmful reaction of the melt with refractory melting vessel material and contamination of the melt.

Abstract: Method and apparatus for directional solidification (e.g columnar grain or single crystal casting) of a melt involves refractory particulates, such as SiC particles, provided about at least one article molding cavity region of a casting mold wherein the particulates are heated to an elevated temperature above a melt casting temperature. The article molding cavity region of the casting mold is heated from an initial preheat temperature to an elevated casting temperature by heat from the particulates prior to communication of the article molding cavity to a chill member. For single crystal casting, a radiation transparent crystal selector member is disposed in a mold grain nucleation and growth cavity located between the article molding cavity and the chill member to select a single crystal for propagation in the article molding cavity region. A melt permeable, thermal insulation member may be disposed between the mold grain nucleation and growth cavity region and the chill member.

Abstract: Method and apparatus for densifying an article wherein the article is disposed in a first molten salt pressure transmission medium in a container. The first medium is heated to a first elevated densifying temperature. The container is disposed in a second molten salt pressure transmission medium at a second temperature lower than the first temperature. The first medium and the second medium are communicated so that pressure applied to the second medium is transmitted to the first medium. Pressure is applied to the lower temperature second medium sufficient to densify the article disposed in the first higher temperature medium. Following densification of the article, the container is removed from the second medium. The method and apparatus are especially useful for closing internal porosity of metallic and intermetallic castings.

Abstract: A method for the countergravity casting of a melt involves placing a refractory mold in a vacuum chamber defined within a casting box where the mold may be optionally surrounded by support particulates in the vacuum chamber. The mold includes a mold cavity and a serpentine melt inlet passage formed by nested refractory members below the mold cavity and in melt flow communication therewith. The serpentine melt inlet passage is communicated with a fill tube extending from the casting chamber toward an underlying source of melt. The mold/chamber and the source are relatively moved to engage the fill tube and the source. A differential pressure is applied between the mold cavity and the source to urge the melt upwardly through the fill tube and serpentine melt inlet passage into the mold cavity. The mold/chamber and the source are then relatively moved to disengage the fill tube and the source after the mold cavity is filled with the melt.

Abstract: The present invention involves a method and apparatus for making an intermetallic casting (e.g. a titanium, nickel, iron, etc. aluminide casting) wherein a charge of a solid first metal protected from air as required is disposed in a vessel, and a charge of a second metal that reacts exothermically with the first metal is melted in another vessel. The molten second metal is introduced to the vessel containing the charge of the first metal so as to contact the first metal. The first and second metals are heated in the vessel to exothermically react them and form a melt for gravity or countergravity casting into a mold. The exothermic reaction between the first and second metals releases substantial heat that reduces the time needed to obtain a melt ready for casting into a mold. In particular, the exothermic reaction between the first and second metals, in effect, reduces the residence time of the intermetallic melt in the vessel.

Abstract: Apparatus and method for countergravity casting a melt employs a particulate mass disposed in a container about a mold having a mold cavity, an ingate passage communicated to the mold cavity for supplying the melt to the mold cavity, and a separate, preformed riser-forming member connected to the mold so as to communicate to an isolated and/or enlarged region of the mold cavity needing additional melt supply during solidification in the mold. The mold ingate passage and a source of the melt are communicated to conduct the melt through the ingate passage to the mold cavity to fill the mold cavity with the melt and form a riser of melt in the particulate mass. The riser of melt provides a source of additional melt for supply, as necessary, to the isolated and/or enlarged region during solidification of the melt in the mold cavity to accommodate melt shrinkage thereat.

Abstract: A casting mold includes an ingate for engaging an underlying source of the melt, an upstanding alloyant-containing reaction chamber having an upper region communicated to the ingate, and an exit gate communicating a lower region of the reaction chamber to a mold cavity. The mold and the source of a melt are relatively moved to engage the ingate and the source. A sufficient relative vacuum is applied to the mold cavity to draw the melt from the source upwardly through the ingate and into the reaction chamber where the melt reacts with alloyant therein. The melt is drawn upwardly to leave at least a portion of the volume of the mold cavity unfilled with melt and to provide a sufficient volume of melt in the reaction chamber to fill the unfilled volume of the mold cavity after disengagement of the mold and the source.

Abstract: Method and apparatus for the differential pressure, countergravity casting of molten metal in shortened cycle times into a casting mold having an inlet passage-forming collar that provides a dam to reduce runout of the melt from the mold during tilting of the mold from the casting position to an inverted solidification position.

Abstract: An expendable pattern of an article to be cast comprises a meltable material that expands upon heating (e.g., a wax pattern). The pattern is invested with particulate mold material to form a thin, layered shell having a wall thickness not exceeding about 0.12 inch. The thin shell wall thickness unexpectedly reduces damage and distortion to the shell during removal of the pattern therefrom by steam autoclaving. After firing, the thin gas permeable shell mold is surrounded by a refractory particulate support media in a vacuum housing. The vacuum housing is then evacuated to evacuate the mold cavity defined by the thin shell and concurrently a pressure is applied to the support media so as to compress the support media about the thin shell to support the shell against casting stresses when molten metal is countergravity cast into the evacuated mold cavity.

Abstract: A method and apparatus for countergravity casting of molten metal with exclusion of air in a gas-pervious mold sealed in an evacuable chamber having a free end of a fill pipe for the mold cavities projecting therefrom. The fill pipe is moved relative to an enclosed crucible containing the molten metal under an air-free atmosphere of inert gas to project the fill pipe free end into the crucible enclosure to a position below the molten metal so that evacuation of the chamber produces filling of the mold. Entry of air into the crucible enclosure is prevented by maintaining the surface of the molten metal and the ambient atmosphere a sufficient distance apart prior to insertion of the fill pipe to prevent circulating air currents from drawing air down to the metal or by blocking entry into the crucible enclosure. Entry of air can be further prevented by maintaining a sufficient pressure of inert gas in the crucible enclosure and by sealing the upper portion of the fill pipe between the chamber and the mold.

Abstract: A method for the differential pressure, countergravity casting of molten metal includes applying a differential pressure to urge molten metal through a constricted inlet passage into a mold cavity of a mold from an underlying molten metal pool, withdrawing the mold from the pool after the mold cavity is filled with the molten metal, holding the molten metal in the mold by combined differential pressure/molten metal surface tension holding action until the molten metal solidifies in the constricted inlet passage of the withdrawn mold or until the mold can be inverted. The differential pressure can be released after the metal solidifies in the inlet passage or after the mold is inverted to allow the molten metal to solidify under ambient pressure.

Abstract: A vacuum countergravity casting apparatus includes a vacuum chamber having a thermally conductive peripheral wall and a gas permeable mold sealed to the lower end of the peripheral wall by an elastomeric sealing gasket engaged therebetween. The peripheral wall is cooled at a location above and remote from the sealing gasket and an underlying molten metal pool when the mold is immersed in the pool during casting to maintain, by thermal conduction through the peripheral wall, the sealing gasket at a temperature to reduce thermal degradation thereof during casting; e.g., at a temperature below the gasket's thermal degradation temperature. Reduced thermal degradation of the sealing gasket during casting prolongs its useful life in casting successive molds.

Abstract: In an apparatus for vacuum countergravity casting of molten metal, a gas permeable, self-supporting mold is supported in an inverted casting position in an open bottom container with a particulate bed compacted about the mold. The mold may comprise a mold stack having a plurality of mold members stacked side-by side to form a plurality of mold cavities therebetween. The particulate bed may comprise loose, unbonded particulate compacted in-situ about the mold to support the mold stack in the container and press the mold members sealingly together before, during and after filling with molten metal.

Abstract: A countergravity casting process involves holding an inherently unstable mass of particulate mold material in an open bottom container around a destructible pattern therein by exerting external fluid pressure, such as atmospheric pressure, on a bottom side of the particulate mass in excess of internal pressure in the container. The container and an underlying molten metal pool are relatively moved to place the bottom side of the particulate mass in the pool. Molten metal is drawn through an ingate to the pattern to destroy and replace the pattern in the particulate mass. When the container and pool are relatively moved to extract the bottom side from the pool after casting, the particulate mold material is held in the container around the metal replacing the pattern by the external/internal pressure differential between the bottom side of the particulate mass and interior of the container.

Abstract: A vacuum countergravity casting apparatus includes a vacuum chamber and a gas permeable mold sealingly mounted in the mouth of the chamber and comprising a gas permeable upper mold member and a lower mold member held in sealing engagement at a mold parting plane without glue. To this end, the upper mold member includes an exterior mold surface confronted by the vacuum chamber and a plurality of vacuum passages extending between the exterior mold surface and a bottom parting surface thereof to expose an effective area of the lower mold member to subambient pressure in the chamber sufficient to urge the lower mold member into sealing engagement with the upper mold member at the mold parting plane. The vacuum chamber includes a mold-engaging stop member for engaging the upper mold member and limiting movement of the upper mold member inwardly of the vacuum chamber away from the lower mold member as the latter is urged into sealing engagement therewith.

Abstract: Apparatus for vacuum countergravity casting includes a gas permeable upper mold member and a lower mold member engaged to the upper mold member. A gas impermeable member includes a central portion overlying the upper surface of the upper mold member and in contact therewith at a plurality of spaced apart contact regions disposed across the horizontal dimension of the upper surface and further includes a peripheral portion in sealed relation substantially about the upper mold member. Reduced pressure is applied between the gas impermeable member and the upper mold member to draw molten metal into mold cavities therein when the lower mold member is placed in a molten metal pool. Simultaneously, ambient pressure, such as atmospheric pressure, above the gas impermeable member is transmitted by the contact regions to the upper mold member in opposition to ambient pressure transmitted to the lower mold member to substantially reduce bending stresses in the mold.