Induction Brazing TiAl Vane Sealing Fins with Hard Particles
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Solution Overview
Problem
Existing methods for armoring TiAl vanes in turbomachines, particularly sealing fins, face challenges due to high temperature requirements that exceed the material's tolerance, leading to altered component properties and costly, time-consuming masking processes, with issues related to adhesive properties and geometric complexities.
Innovation Solution
The method employs induction brazing with a mixture of hard materials and Ti-based or Ni-based braze materials, applied as preforms, tapes, or pastes, which are inductively heated to low local areas, reducing temperature stress and using a controlled cooling process to secure the hard material bond with the TiAl base material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If plasma spraying is used to apply armoring, then temperature stress on TiAl material can be kept low, but time-consuming masking devices are required and adhesive properties are poor
Solution Approach 1:
The patent extracts and removes the masking step entirely from the process by using induction brazing, which inherently provides localized heating only where the armoring is applied. This eliminates the time-consuming masking operation while maintaining low temperature stress on the TiAl substrate.
Solution Approach 2:
The patent introduces a braze material as an intermediary between the hard material particles and the TiAl substrate. This braze layer provides excellent adhesive bonding properties that resolve the poor adhesion issue of plasma-sprayed coatings, while the induction heating process maintains temperature control.
2Temperature
If plasma spraying is used to apply armoring, then temperature stress on TiAl material can be kept low, but adhesive properties are poor requiring nickel intermediate layers
Solution Approach 1:
The patent uses a specifically designed braze material as an intermediary layer between the hard material particles and the TiAl substrate. This braze layer provides superior adhesive bonding compared to nickel intermediate layers, eliminating the need for additional nickel layers and avoiding the formation of brittle nickel-titanium phases.
Solution Approach 2:
The patent creates a composite structure consisting of hard material particles embedded in a braze material matrix, which is then bonded to the TiAl substrate. This composite approach provides both the wear resistance of hard materials and the adhesive bonding capabilities of the braze material, resolving the adhesion issue while maintaining temperature control.
3Temperature
If kinetic cold gas spraying is used to apply armoring, then temperature stress can be kept low, but time-consuming masking is still required
Solution Approach 1:
The patent replaces the mechanical spraying process with induction brazing, which uses electromagnetic induction for localized heating. This substitution eliminates the need for masking because the induction heating can be precisely targeted to only the areas where armoring is applied, maintaining low temperature stress while eliminating masking time.
Solution Approach 2:
The patent extracts and removes the masking step from the process by using induction brazing, which inherently provides localized heating only where the armoring is applied. This eliminates the time-consuming masking operation while maintaining low temperature stress on the TiAl substrate.
4Reliability
If high temperature armoring is applied to TiAl vanes, then wear resistance is improved, but component properties are altered due to temperature stress
Solution Approach 1:
The patent applies armoring only to the specific local areas of the TiAl vane that require wear protection, such as sealing fins and leading edges. The induction brazing process heats only these localized areas to the brazing temperature, while the rest of the component remains at ambient temperature, thus preserving the component properties of the bulk TiAl material.
Solution Approach 2:
The patent changes the temperature parameter from high-temperature processes (that would alter component properties) to controlled induction brazing temperatures (below 1100°C) that maintain component properties. The brief exposure time at elevated temperature further minimizes any potential changes to the TiAl matrix structure.
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
This approach allows for efficient armoring of TiAl vanes with reduced temperature stress, maintaining component properties and improving wear resistance without the formation of brittle phases, while simplifying the coating process for complex geometries like sealing fins.
Implementation Method 1
the brazing preform and the end region of the sealing fin on which the brazing preform is disposed are inductively heated
Implementation Method 2
a brazing preform, which is sintered of a mixture of at least one hard material and one braze material, is arranged on a TiAl vane in order to be brazed by means of an inductive heating process
Implementation Method 3
When the brazing temperature has been reached, the braze material is fused and forms an adhesive bond with the hard-material particles and the base material
Data Source
AI summary
A method for armoring TiAl vanes of turbomachines is disclosed. A TiAl vane is provided onto which a mixture of at least one hard material and at least one braze material is applied so that subsequently the mixture can be brazed on the TiAl vane by an inductive heating process. A TiAl vane for a turbomachine, in particular for an aircraft engine, is also disclosed. The TiAl vane includes a TiAl main part and an armor which consists of a mixture of hard materials and braze material.