Airfoil Casting With Refractory Metal Cores for Complex Cooling 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 fabricating intricate cooling passages.
Innovation Solution
The use of refractory metal cores formed through a tomo-lithographic process, which are stronger and more durable than ceramic cores, with a protective ceramic coating to prevent oxidation and erosion, and a method involving the creation of a computer model, digital slicing, and lamination of metal foils to achieve precise and robust core structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic cores are used in investment casting, then the process can form hollow components with cooling passages, but the cores are fragile and prone to warpage and fracture
Solution Approach 1:
The patent applies composite materials by combining refractory metal (such as molybdenum, tungsten, or their alloys) with ceramic coating materials. The refractory metal core provides structural strength and durability, while the ceramic coating provides thermal resistance and protection against oxidation. This composite structure resolves the contradiction between core strength and thermal resistance, enabling the core to withstand both mechanical stresses during casting and thermal environments without fracturing or warping.
2Productivity
If conventional ceramic cores are used, then casting can proceed, but casting yields are low due to core failure
Solution Approach 1:
The refractory metal-ceramic composite core structure significantly improves core stability during the casting process. The refractory metal provides high mechanical strength and ductility, preventing core failure under thermal and mechanical loads, while the ceramic coating maintains thermal resistance. This combination ensures core survival through the casting process, directly increasing casting yields by eliminating the primary cause of core failure.
Solution Approach 2:
The patent changes the material parameters of the core from conventional ceramic to refractory metal with ceramic coating. This parameter change transforms the core's mechanical properties (increasing strength and ductility) while maintaining or improving thermal properties. The refractory metal's higher toughness and resistance to thermal shock compared to conventional ceramics prevent core failure, thereby improving casting yields.
3Manufacturing precision
If ceramic cores are used, then cooling passages can be formed, but dimensional accuracy and tolerance are limited
Solution Approach 1:
The refractory metal-ceramic composite core enables better dimensional accuracy and tighter tolerances in complex geometries. The refractory metal's superior mechanical properties allow the core to maintain its precise shape during casting without warpage or deformation, even for intricate cooling passage configurations. The ceramic coating preserves the intended geometry while providing thermal protection, resulting in higher manufacturing precision for complex components.
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 refractory metal cores enable higher casting yields and improved dimensional accuracy, reducing the risk of core failure and enhancing the ability to produce complex geometries with tighter tolerances, thus improving the efficiency and reliability of gas turbine engine components.
Implementation Method 1
making a refractory metal core that defines an interior of the airfoil by a tomo-lithographic process
Implementation Method 2
with a protective ceramic coating to prevent oxidation and erosion
Data Source
AI summary
A method of making an airfoil includes making a refractory metal core that defines an interior of the airfoil by a tomo-lithographic process, making a mold that defines an exterior of the airfoil, inserting the refractory metal core into the mold, and pouring an airfoil material between the refractory metal core and the mold to cast the airfoil.