Compressor Blade Erosion Resistance via Aluminum Diffusion Zone
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Solution Overview
Problem
Compressor blades in gas turbines face increased erosion and corrosion due to wet compression, with existing anti-corrosion coatings like Sicoat 8610 providing inadequate protection against erosion, leading to flaking and exposure of the blade substrate.
Innovation Solution
A compressor blade with a metal alloy substrate coated with a hard material such as TiN, TiAlN, or CrN, combined with an aluminum diffusion zone that reacts to form aluminum oxide when the coating flakes off, preventing corrosion and further erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard material coating is applied to the blade substrate, then erosion and corrosion resistance is improved, but the coating may flake off locally leading to under-corrosion
Solution Approach 1:
An aluminum diffusion zone is created in the blade substrate before applying the hard material coating. This preliminary action ensures that aluminum is already present in the substrate surface, so when the coating flakes off, aluminum oxide can immediately form to protect the exposed substrate from under-corrosion.
Solution Approach 2:
The aluminum diffusion zone acts as an intermediary layer between the blade substrate and the hard material coating. It provides a controlled aluminum source that reacts to form protective aluminum oxide at the interface, preventing direct corrosion of the substrate when the coating deteriorates.
2Productivity
If water is added to compressed air for wet compression, then gas turbine efficiency increases due to cooling effect and mass flow increase, but erosion and corrosion on compressor blades increases
Solution Approach 1:
The compressor blade uses a composite structure combining the blade substrate with an aluminum diffusion zone and a hard material coating. This composite material system provides both the mechanical strength of the substrate and the erosion/corrosion resistance needed to withstand wet compression conditions.
Solution Approach 2:
The aluminum content in the diffusion zone is controlled within specific ranges (0.05-0.2 percent by weight, preferably 0.075-0.15 percent by weight) to optimize the balance between corrosion protection and material properties, enabling the blade to withstand wet compression while maintaining structural integrity.
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 aluminum diffusion zone provides long-lasting corrosion protection, extending the service life of the compressor blade by preventing under-corrosion and erosion, with the hard coating offering high resistance to both erosion and corrosion loads.
Implementation Method 1
the aluminum contained in this aluminum diffusion layer reacts when the hard material coating flakes off to form aluminum oxide, which protects the metal alloy of the blade substrate from corrosion
Implementation Method 2
an aluminum diffusion zone on a surface of the blade substrate
Data Source
Figure 1
Figure 2
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AI summary
The invention relates to a compressor blade (1) for a gas turbine (100). The compressor blade (1) has a blade substrate (2) that consists of a metal alloy and has an aluminum diffusion zone (3) on a surface of the blade substrate (2). In addition, the compressor blade (1) has a hard material coating (4) provided on the surface of the blade substrate (2). Other aspects of the invention relate to a compressor (105) that has such a compressor blade (1) and a method of producing such a compressor blade (1).