Brazed CoNiCrAlY Boron Sealing Component for Turbine Rings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing High Velocity Oxy Fuel (HVOF) technique for coating turbine ring components is difficult to implement, requires a sandblasted surface state for bonding, and is not suitable for repair due to the need for thorough machining and potential spalling or peeling of the coating, making it inefficient for both new manufacturing and repair processes.
Innovation Solution
A brazing method using a Cobalt-Nickel-Chrome-Aluminium-Yttrium (CoNiCrAlY) alloy with 0.5-5% boron is employed to coat superalloy bodies, allowing for a thicker scattering layer and improved bonding without the need for a sandblasted surface, enabling multiple repairs and replacing the HVOF deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HVOF technique is used to deposit coating on turbine ring body, then coating can be applied to protect against corrosion and oxidation, but the process is difficult to implement and requires sandblasted surface state for good bonding
Solution Approach 1:
The invention changes the surface preparation parameters from sandblasting to shot peening, which modifies the surface topology and mechanical properties differently. Shot peening creates a controlled roughness profile that enhances coating adhesion without requiring the extensive surface conditioning needed for HVOF, thereby simplifying the manufacturing process while maintaining reliable bonding.
Solution Approach 2:
The invention replaces the HVOF thermal spray system with a brazing process. Instead of using high-velocity particle deposition, the coating is applied through a metallurgical bonding process where the coating material is brazed to the substrate. This substitution eliminates the need for complex HVOF equipment and difficult surface preparation, making the process easier to implement while ensuring strong, reliable coating attachment.
2Reliability
If HVOF deposition is used on turbine ring, then coating can be applied, but thorough machining is required and traces of former deposition should not be left, making repair difficult
Solution Approach 1:
The invention changes the bonding mechanism from mechanical adhesion (HVOF) to metallurgical bonding (brazing). The brazed coating creates a diffusion bond with the substrate that is more tolerant of surface imperfections and previous coating traces. This allows repair processes to be simpler, as thorough machining to remove all traces of former deposition is not required, yet the coating integrity and reliability are maintained through the strong metallurgical bond.
3Quantity of substance
If HVOF technique is used for coating, then coating can be deposited, but equipment settings are difficult to achieve and surface state must be oxide free
Solution Approach 1:
The invention replaces the complex HVOF thermal spray equipment with a brazing process. The brazing operation uses standard metallurgical equipment and procedures that are more familiar and easier to control in manufacturing environments. The coating material is applied through brazing rather than high-velocity spray deposition, eliminating the need for difficult-to-achieve equipment settings and oxide-free surface requirements, while still achieving complete and uniform coating deposition.
4Reliability
If HVOF coating is applied to superalloy body, then sealing function is provided, but the coating and substrate must be replaced together, increasing cost
Solution Approach 1:
The invention segments the coating and substrate into separable components through the brazing process. The brazed coating can be removed and replaced independently from the expensive superalloy substrate. This segmentation allows the coating to be treated as a replaceable consumable component, while the valuable substrate is retained and reused. The sealing function is maintained through the new coating, but the overall cost is reduced by avoiding substrate replacement.
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 brazing method allows for more efficient and cost-effective production and repair of turbine ring components with improved coating durability and reduced machining requirements, overcoming the limitations of HVOF by providing a stronger, thicker coating that can withstand high temperatures and mechanical stress.
Implementation Method 1
the body made of superalloy and said new coating are brazed together so as to obtain said sealing component
Data Source
AI summary
A method for producing a sealing component has a body made of superalloy covered by a coating to be placed in contact with a gas turbine blade tip. Steps are carried out in which:a) the new coating is produced by moulding from an alloy of a cobalt-nickel-chromium-aluminium-yttrium (CoNiCrAlY) type further containing between 0.5 and 5% by mass (wt %) of boron, andb) the superalloy body and the new coating are brazed together in order to obtain the said sealing component.