Process for making cores used in investment casting
AssigneeUnited Technologies Corporation
InventorsEdward P. Renaud, Edward C. Wingfield, Wallace W. Bowley
Life of this patent
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Abstract
Casting cores particularly useful in the investment casting industry are described. The cores are characterized by the presence of hollow ceramic particles, which facilitate the removal of the core from the casting they are used to form. In a preferred embodiment of the invention, the core is characterized by solid and hollow ceramic particles sintered to each other to form a core matrix, and such particles have the same composition. In an even further preferred embodiment, high temperature stable fibers are distributed uniformly throughout the matrix.
Claims8
In a process for making a ceramic core for use in investment casting, comprising mixing solid ceramic particles to form a core mixture, molding the mixture to form a core shape, and heating the core shape to sinter the particles and make a core, the improvement which comprises substituting hollow ceramic particles for between 30 and 70 percent, by volume, of the solid ceramic particles, wherein the core is characterized by solid ceramic particles sintered to each other and to the hollow ceramic particles.
In a method for making a casting core containing about 1.5 to about 6.5 weight percent high temperature stable fibers within a sintered ceramic matrix by firing a mixture containing said fibers and solid ceramic particles, the improvement which comprises substituting hollow ceramic particles for a portion of said solid ceramic particles.
A ceramic shell mold comprising a sintered ceramic core within the mold, said mold and sintered core defining a mold cavity for receiving molten metal, wherein the core comprises about 1.5-6.5 weight percent high temperature stable fibers within a matrix of sintered solid and hollow ceramic particles.
Dependencies are inferred from the claim text.