Soluble casting core for metal matrix composite components and method of producing thereof

Abstract

A process for manufacturing a soluble casting core for use in casting complex shaped metal matrix composite components. The soluble casting core is generated by a sequence of steps which provide a molten slurry mixture composed of an alkali metal salt such as sodium carbonate and a plurality of ceramic particulates such as magnesium oxide dispersed therein. After heating and mixing the slurry mixture is solidified in a mold pattern to form a casting core configured to generate a complex shaped component during a casting process. The soluble casting core is used for casting molten metal alloys therein, without failure of the casting surfaces and forming of a complex shaped metal matrix composite component. The soluble casting core is readily dissolved and separated from the soluble casting core by immersing the core mold in heated water and / or exposing to steam, without damage to the metal matrix composite component.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] Not Applicable. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to the inventors and / or the assignee of any royalties thereon. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to methods and materials for manufacture of casting cores utilized to form complex metal components. More specifically, the present invention relates to methods of manufacture of casting cores composed of soluble materials mixed with ceramic materials for casting complex metal components. [0005] 2. Description of the Related Art [0006] Conventional investment casting methods typically utilize casting cores composed of machined graphite or steel for manufacture of relatively non-complex shapes. Use of molds lacking the need for expensive and time-consuming...

AI Technical Summary

Benefits of technology

[0010] The process includes providing molten sodium carbonate to form the basic component of the slurry mixture in which a ceramic particulate material is dispersed evenly therein. One embodiment includes magnesium oxide particulates mixed throughout the molten sodium carbonate salt in a mixing ratio including about 1 part magnesium oxide mixed with about 3 parts molten sodium carbonate. Alternative ratios of magnesium oxide mixed with molten sodium carbonate are utilized to adjust the density of the casting core slurry and to adjust the CAE of the solidified casting core mold to approximate the CTE of the molten metal composite material selected to form the MMC component. The magnesium oxide particulates serve as heterogeneous nucleation agents within the molten sodium carbonate, and further serve to reduce the grain size of the sodium carbonate salt during solidification of the molten slurry mixture thereby resulting in a dense core mold when the molten sodium carbonate and magnesium oxide when solidified after being poured in a preheated mold pattern formed of metal such as stainless steel or graphite. The dense core mold formed is resistant to surface etching and mold failure upon contact with molten metal during pressure infiltration casting.

[0011] The process further includes the casting core slurry mixture being solidified in a preheated mold pattern thereby attaining a casting core mold having smooth surfaces impervious to molten metal during high temperature and pressure casting. Upon removal of the preheated mold pattern from the solidified casting core mold, the non-metal casting core mold is easily machined as needed in order to form exactly configured surfaces utilized as a complex shape mold during pressure infiltration casting with molten metals.

Problems solved by technology

(hereinafter, the '219 patent), use of graphite or steel molds are excessively expensive when the molds must be machined into complex or intricate shapes.

The '219 patent does not disclose use of a molten salt such as sodium carbonate mixed with ceramic particulates, which, when solidified into a casting core, is impermeable when subjected to molten metal and is readily dissolved after casting when exposed to non-corrosive solvents such as water for separating the casting core from a cast MMC component.

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