General Electric Company

Ic Patterns, LLC

Fopat LLC

Robert Dzugan

Nipendra P Singh

Faurice D Neece

Richard M Harrington

Anil R Chaudhry

Travis Westendorf

Stephen Joseph Ferrigno

William R Young

Adrian M Ablett

Marc J Froning

Stephen J Lotz

Various techniques are provided for creating fugitive foam patterns for use in investment casting operations. In certain illustrative embodiments, a fugitive foam pattern is assembled from independently formed portions. A first section is formed in a mold. Once cured, a mating surface of the first section is exposed to the cavity of a second mold and the section is formed. The second section integrally adheres to the first section. The process is repeated as necessary. In alternative embodiments, a channel is created in a foam pattern using a temporary core that is removed without chemical leaching. The core material comprises water-soluble materials, acid-soluble materials, low-melting point materials, or a combination thereof. A pattern may also be created by inserting foam around a core that remains with the foam pattern.

Foam pattern techniques

A method of creating a foam pattern comprises mixing a polyol component and an isocyanate component to form a liquid mixture. The method further comprises placing a temporary core having a shape corresponding to a desired internal feature in a cavity of a mold and inserting the mixture into the cavity of the mold so that the mixture surrounds a portion of the temporary core. The method optionally further comprises using supporting pins made of foam to support the core in the mold cavity, with such pins becoming integral part of the pattern material simplifying subsequent processing. The method further comprises waiting for a predetermined time sufficient for a reaction from the mixture to form a foam pattern structure corresponding to the cavity of the mold, wherein the foam pattern structure encloses a portion of the temporary core and removing the temporary core from the pattern independent of chemical leaching.

Foam patterns

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Casting materials

A vacuum centrifugally cast combustion liner suitable for use in a gas turbine engine operating at temperatures ranging from ambient up to about 1700.degree. F. is provided. The combustion liner is formed by centrifugally vacuum casting a precipitation hardened nickel-based superalloy having controlled, low amounts of aluminum and titanium. The combustion liner is characterized by a homogeneous grain structure having enhanced strength and creep resistance particularly at elevated temperatures. In addition, the preferred elemental composition, particularly the relatively small amounts of aluminum and titanium, enhance the weldability and overall manufacturability of the combustion liner.

Method for forming a thin-walled combustion liner for use in a gas

A superalloy article is fabricated by casting a high melting temperature superalloy composition and then refurbishing the primary defects that are found in the surface of the cast piece. The article is refurbished by excising the primary defects and a surrounding portion of metal by grinding, filling the excised volume with metal of the same composition as the cast article by welding or a similar technique, smoothing the surface around any resulting filler metal defects, and applying a cladding powder to the surface from which the filler metal defects are removed. The cladding powder is applied by painting a binder onto the surface and then dusting cladding powder onto the binder before it has dried. The cladding powder is a mixture of particles of a high melting temperature superalloy and particles of a lower melting temperature metal. The article is heated to a preselected temperature, depending on the alloy, to melt and subsequently solidify the cladding powder. Finally, the article is hot isostatically pressed to achieve final closure of surface defects.

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Cincinnati, OH, United States of America

Robert Dzugan