TiAl Alloy Surface Coating for Oxidation-Resistant Hot Forging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The TiAl alloy is prone to oxidation during hot forging, leading to the formation of a hard and brittle α-case layer that complicates processing and increases the risk of forging cracks, and the use of protective sheaths complicates the hot forging process and reduces workability.
Innovation Solution
A TiAl alloy member with a substrate coated in an Al layer containing Ti, forming an alumina film through diffusion coating, which prevents α-case formation and enhances workability by allowing high-speed forging in an air atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the TiAl alloy is hot-forged while being covered with the sheath to prevent oxidation, then oxidation resistance is improved, but device complexity and ease of operation deteriorate due to difficult welding work and sheath removal difficulties
Solution Approach 1:
The patent uses a disposable alumina coating layer applied to the TiAl alloy surface before hot forging. This coating serves as a temporary protective barrier during the hot forging process to prevent oxidation, then is removed or discarded after serving its purpose. This eliminates the need for complex sheath application and removal processes while maintaining oxidation protection during critical operations.
Solution Approach 2:
The alumina coating acts as an intermediary layer between the TiAl alloy and the oxidizing environment during hot forging. This mediator prevents direct contact between oxygen and the alloy surface, protecting against oxidation without requiring complex sheath structures or difficult welding operations.
2Ease of operation
If the TiAl alloy is hot-forged in the air atmosphere without protective sheath, then ease of operation is improved, but object-affected harmful factors worsen due to oxidation and α-case formation
Solution Approach 1:
The alumina coating is applied in advance to the TiAl alloy surface before hot forging begins. This preliminary protective layer is already in place when the alloy enters the hot forging process, preventing oxidation from the start without requiring complex protective sheaths or inert atmosphere equipment.
Solution Approach 2:
The alumina coating serves as a temporary, disposable protective layer that enables air atmosphere hot forging without complex equipment. After serving its oxidation protection function during hot forging, the coating is removed or discarded, allowing simple and economical processing.
3Reliability
If the TiAl alloy is hot-forged with protective sheath, then oxidation resistance is improved, but productivity deteriorates due to complicated work and sheath removal time
Solution Approach 1:
The alumina coating is a simple, disposable protective layer that eliminates the need for complex sheath application and removal operations. This dramatically reduces preparation time and increases hot forging productivity while maintaining adequate oxidation protection during the process.
Solution Approach 2:
The patent extracts only the essential protective function from the complex sheath system, using a simple alumina coating that provides oxidation protection without the cumbersome application and removal processes of traditional sheaths, thereby streamlining the entire hot forging workflow.
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 alumina film formed on the TiAl alloy surface effectively suppresses α-case formation, reducing the risk of forging cracks and improving workability by enabling high-speed forging at higher strain rates without the need for complex sheath removal processes.
Implementation Method 1
an Al layer formation step of forming an Al layer, containing Al as a main constituent and containing Ti, on a surface of the substrate by diffusion coating the substrate with Al
Implementation Method 2
an alumina film provided on a surface of the Al layer and made of alumina
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A TiAl alloy member (10) for hot forging includes a substrate (12) made of TiAl alloy, and an Al layer (14) formed on a surface of the substrate (12), the Al layer (14) containing Al as a main constituent and containing Ti.