Methods for repairing ceramic cores
a core and ceramic technology, applied in the field of casting processes and materials, can solve the problems of defective cores being disposed of rather than repaired, cracks and voids can occur in the core material, casting defects, etc., and achieve the effect of sufficient structural integrity and promoting adhesion of the repair mixtur
Inactive Publication Date: 2014-08-28
GENERAL ELECTRIC CO
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Benefits of technology
The invention allows for repairing defective ceramic cores that might be unsuitable for use in the casting process. By using a repair mixture that is similar in composition to the slurry used to form the ceramic core, the repaired core will have sufficient structural integrity to survive the casting process. Additionally, diluting the repair mixture with a binder / diluent can promote adhesion of the repair mixture to a ceramic core.
Problems solved by technology
When forming cores as described above, defects such as cracks and voids can occur within the core material.
Cores with defects generally cannot be used in the component casting process as the cores may break during casting, resulting in casting defects.
Commonly, defective cores are disposed of rather than repaired due to the difficulty in restoring the structural integrity of the cores, especially in regards to hollow cores.
Method used
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[0014]The present invention is generally applicable to processes for repairing cores formed with defects such as cracks. Although the processes hereinafter will be discussed in reference to cores comprising silica-containing materials, it is foreseeable and therefore within the scope of the invention that the processes could be performed on cores comprising other materials.
[0015]FIG. 1 represents a ceramic core 10 for use with a mold assembly (not shown) suitable for investment casting a hollow component (not shown), such as components used in gas turbine engines, including, but not limited to, turbine blades, nozzles, or other airfoil components, in accordance with one aspect of the invention. The core 10 is formed from a slurry comprising at least one refractory material suspended in a liquid vehicle. Suitable refractory materials include, but are not limited to, silica, zirconia, alumina, mullite, and / or the like. For example, the slurry may comprise a silica refractory powder, a...
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Abstract
A method is provided for repairing defects in a ceramic core adapted for use in a casting process. The ceramic core is formed from a slurry comprising at least one refractory powder material suspended in a liquid vehicle. The method includes forming a repair mixture comprising a liquid diluent and the at least one refractory powder material suspended in the liquid vehicle of the slurry. The repair mixture is applied to a region of the ceramic core that includes at least one defect and then the ceramic core is fired to burn off the liquid vehicle in the repair mixture and form a ceramic composition that closes the defect.
Description
BACKGROUND OF THE INVENTION[0001]The present invention generally relates to casting processes and materials. More particularly, this invention relates to cores and processes for repairing cores formed with defects such as cracks.[0002]Metal alloy materials can be formed into components by various casting techniques, a notable example being investment casting (lost wax) processes. Investment casting typically entails dipping a wax or plastic model or pattern of the desired component into a slurry comprising a binder and a refractory particulate material to form a slurry layer on the pattern. A common material for the binder is a silica-containing material, for example, colloidal silica. A stucco coating of a refractory particulate material is typically applied to the surface of the slurry layer, after which the slurry / stucco coating is dried. The preceding steps may be repeated any number of times to form a shell mold of suitable thickness around the wax pattern. The wax pattern can ...
Claims
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IPC IPC(8): B22C9/10
CPCB22C9/10B22C1/205
InventorYANG, XILEE, MARTIN KIN-FEIDECARR, SYLVIA MARIEMAURER, NORBERT OTTO
OwnerGENERAL ELECTRIC CO