Abradable Seal Manufacturing via Mold Preheating and Compaction
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Solution Overview
Problem
Existing abradable seals for turbomachines face challenges with adhesion to molds, leading to difficulties in demolding and limited mechanical strength, which affects the durability and corrosion resistance of the seals.
Innovation Solution
A method involving preheating a mold, filling it with a mixture of powdery materials including a filler and matrix, degassing, and compacting to solidify the mixture, with specific temperature and pressure controls to reduce adhesion and enhance mechanical strength and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mold is preheated to high temperature (at least 300°C, preferably 400°C or 500°C) for extended periods (at least 2 hours, preferably 3 hours), then the adhesion between the abradable seal and mold is reduced facilitating easier demolding, but the energy consumption and processing time increase
Solution Approach 1:
The mold is preheated before the abradable seal material is introduced, creating a temperature difference that prevents adhesion between the material and mold. This preliminary thermal preparation ensures easy demolding without requiring excessive heating duration, as the mold is already at optimal temperature when the material is placed inside.
2Strength
If the mixture is compacted at high pressure (10 MPa to 20 MPa, preferably at least 15 MPa) for extended periods (30 minutes to 90 minutes, preferably 60 minutes), then the mechanical strength and density of the abradable seal are improved, but the production cycle time increases
Solution Approach 1:
The compaction process employs periodic compression cycles with multiple phases: initial compression at 10-20 MPa, intermediate relaxation periods for degassing, and final compression stages. This periodic approach achieves high density and mechanical strength (15-20 MPa final pressure) while managing the total processing time through efficient cycling rather than continuous compression.
Solution Approach 2:
The compaction process utilizes temperature as a varying parameter, performing compaction at elevated temperatures (above room temperature, up to 500°C) to reduce material viscosity and improve flow characteristics. This allows achieving high density and mechanical strength with optimized pressure-time parameters, reducing the required compaction duration while maintaining quality.
3Reliability
If the abradable seal is produced with high filler content (55% to 80% aluminum, 20% to 45% nickel, 5% to 20% silicon) and low matrix content (5% to 50% by mass), then the abradability and corrosion resistance are improved, but the mechanical strength and structural integrity may be compromised
Solution Approach 1:
The abradable seal employs a composite material system with multiple fillers (aluminum 55-80%, nickel 20-45%, silicon 5-20%) dispersed in a polymer matrix (polyester, polyamide, or polyimide comprising 5-50% by mass). This composite structure combines the corrosion resistance and abradability of metallic fillers with the binding and structural properties of the polymer matrix, achieving both high reliability and structural integrity through synergistic material combination.
Solution Approach 2:
The material composition is optimized with different filler distributions: aluminum provides bulk volume and abradability, nickel enhances corrosion resistance at critical surfaces, and silicon improves mechanical properties. The matrix content (5-50% by mass) is carefully controlled to provide sufficient binding while maintaining high filler content for desired abradable properties, creating local quality variations that optimize both strength and corrosion resistance.
4Ease of manufacture
If the mold cavity is coated with aluminum foil during preheating, then the adhesion to the mold is reduced and demolding is facilitated, but an additional material and processing step are required
Solution Approach 1:
A release agent or coating layer is applied to the mold cavity surface before introducing the abradable seal material. This intermediary layer acts as a barrier between the material and mold, preventing adhesion and facilitating easy demolding. The coating may be applied as a spray, dip, or brush-on layer, creating a non-stick surface that simplifies the demolding process without requiring complex mold designs.
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 method results in a more durable and corrosion-resistant abradable seal with improved mechanical strength, facilitating easier demolding and enhanced performance in turbomachines, particularly in high-temperature and high-speed environments.
Implementation Method 1
preheating the mold
Implementation Method 2
the internal surface of the mold cavity intended to receive the mixture is covered with an aluminum foil
Implementation Method 3
compacting the mixture in the mold so as to solidify the mixture in the mold
Implementation Method 4
a pressure of 10 MPa to 20 MPa, or at least 15 MPa, is applied to the mixture
Implementation Method 5
the internal surface of the mold cavity intended to receive the mixture is covered with an aluminum foil
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
The invention provides a method for manufacturing an abradable seal for a turbomachine, such as a low-pressure compressor seal for a turbojet engine. The method comprises the following steps, carried out as follows: (a) preheating (100) a metal mold in a furnace; (b) filling (102) the hot mold with an aluminum-based powder mixture; (c) degassing (104) the mixture in the mold; (d) compacting (106) the mixture in the still-hot mold at room temperature, so as to solidify the mixture within the mold. The abradable seal is thus produced in angular segments forming tiles. The angular segments are then bonded into a composite housing of the turbomachine.