Composite Core Casting for Complex Turbine Airfoil Passages
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Solution Overview
Problem
Conventional ceramic cores used in investment casting for gas turbine engine components are fragile and prone to warpage and fracture, leading to low casting yields and dimensional limitations, especially when creating complex internal passages.
Innovation Solution
A composite core is created using a combination of refractory metal and ceramic materials, where the refractory metal core is coated with ceramic layers to prevent oxidation and erosion, and the ceramic core is used to reinforce fragile sections, allowing for the creation of complex features and improved robustness during the casting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ceramic cores are used in investment casting, then the casting process can be performed, but the cores are fragile and prone to warpage and fracture leading to low casting yields
Solution Approach 1:
The patent applies composite materials by combining refractory metal (such as molybdenum, tungsten, or their alloys) with ceramic materials to create a composite core. The refractory metal provides strength and resistance to warpage, while the ceramic material provides refractory properties. This composite structure resolves the contradiction by achieving both high strength for reliability and appropriate ceramic characteristics for the casting process.
Solution Approach 2:
The patent changes the material parameters of the core by using refractory metals with high melting points and appropriate mechanical properties. The refractory metal core can be coated with ceramic layers to maintain refractory characteristics while benefiting from the metal's superior strength and ductility, thereby improving casting yield through parameter optimization.
2Device complexity
If conventional ceramic cores are used, then the process is simple, but dimensional limitations occur when creating complex internal passages
Solution Approach 1:
The composite refractory metal-ceramic core enables complex geometries by combining the formability and strength of metal with the refractory properties of ceramic. The refractory metal component can be more easily formed into complex shapes with internal passages, while ceramic coatings maintain the necessary thermal resistance, thus overcoming dimensional limitations.
3Object-affected harmful factors
If ceramic material is used for the core, then thermal resistance is provided, but oxidation and erosion protection is insufficient
Solution Approach 1:
The patent creates a composite core where refractory metal provides the base structure with inherent oxidation and erosion resistance, while ceramic coatings are applied to enhance thermal resistance. This combination achieves both protection mechanisms simultaneously, improving overall core durability and reliability in the harsh casting environment.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite core enhances the durability and thermal resistance of the casting process, enabling the production of complex internal passages with higher precision and increased yield, while reducing the risk of core failure and improving the mechanical properties of the superalloy components.
Implementation Method 1
the refractory metal core is coated with ceramic layers to prevent oxidation and erosion
Implementation Method 2
pouring a slurry material mixed with a binder into the flexible mold, and sintering the slurry material in an oxygen-free environment to form the composite core
Data Source
AI summary
A method of making a composite core includes forming first and second cores of refractory metal and ceramic material. Each of the first and second cores is formed with two layers of a material. The layers are bonded together to form a laminate master pattern, and a flexible mold is formed around the pattern. The pattern is removed from the flexible mold, and slurry material, either pulverulent refractory metal material or ceramic material, is poured into the flexible mold. The slurry material is sintered to form each core. The first core is used as an insert while making the second core to create a final composite core.