Al-Ni-Polyester Abradable Seal for Turbomachine Corrosion
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Solution Overview
Problem
The existing abradable materials for axial turbomachines lack sufficient corrosion resistance and durability, which affects the efficiency and longevity of the seals in high-speed and varying temperature environments, particularly in aircraft compressors.
Innovation Solution
A composition for an abradable coating comprising mainly aluminum and nickel powders, with a filler such as polyester or hexagonal boron nitride, applied via plasma spraying to form a dense, impermeable barrier that enhances corrosion resistance and sealing performance, while maintaining the material's friability for rotor blade protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional abradable material composition (aluminum, silica, polyester) is used, then the material provides dynamic sealing and erodes upon rotor blade contact, but the corrosion resistance is insufficient for high-speed and varying temperature environments
Solution Approach 1:
The patent applies composite materials by combining aluminum powder (55-80% mass), nickel powder (20-45% mass), and filler (5-50% mass) to create an abradable coating with enhanced corrosion resistance. The nickel component specifically addresses the corrosion resistance deficiency while maintaining the abradable properties needed for dynamic sealing in high-speed turbomachine environments.
2Reliability
If the abradable material is made more resistant to corrosion, then the seal durability improves, but the material may lose its friability needed for rotor blade protection
Solution Approach 1:
The patent applies parameter changes by precisely controlling the mass percentages of aluminum (55-80%), nickel (20-45%), and filler (5-50%) to achieve the optimal balance between corrosion resistance and friability. The nickel content is limited to a specific range to provide sufficient corrosion protection while the aluminum and filler maintain the material's ability to erode protectively against rotor blades.
3Reliability
If the operating clearance between rotor blade tips and internal casing surface is reduced, then the sealing efficiency improves, but the risk of ingestion and pumping phenomena increases
Solution Approach 1:
The patent applies beforehand cushioning by creating a protective abradable coating layer on the internal casing surface that can erode to accommodate rotor blade tip clearance variations. This coating acts as a cushion that prevents direct metal-to-metal contact and reduces the harmful effects of ingestion and pumping phenomena while maintaining effective sealing.
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 solution significantly improves corrosion resistance and durability, ensuring effective sealing across a wide temperature range without premature degradation, reducing maintenance needs and maintaining rotor blade integrity.
Implementation Method 1
applied via plasma spraying to form a dense, impermeable barrier
Implementation Method 2
intended to cooperate by abrasion with a rotor element
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a composition for an abradable turbomachine seal, the composition comprising an aluminum base, nickel powder, and polyester powder. The invention also relates to an external casing (28) for a low-pressure axial turbomachine compressor with an abradable seal surrounding an annular row of rotor blades (24). The seal comprises a rounded support (34) covered with a layer of abradable material (38) having a metallic phase consisting mainly of aluminum and a smaller proportion of nickel. The abradable material further comprises between 25% and 55% of an additive, such as polyester, methyl methacrylate, hexagonal boron nitride, or calcium fluoride. The support (34) is segmented and forms an organic matrix composite external casing (28) for the compressor. The invention also proposes a method for producing an abradable seal by plasma spraying an Al-Ni-polyester powder.