Wear Resistant Airfoil Tip Metal Boride Coating
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Solution Overview
Problem
The existing methods for configuring airfoil tips and casing seals in gas turbine engines to minimize gas leakage are costly and time-consuming, particularly when reconditioning, and require abrasive materials like cubic boron nitride for wear resistance.
Innovation Solution
A wear-resistant coating comprising metal boride compounds, such as M3B4 (where M is titanium, vanadium, chromium, zirconium, niobium, molybdenum, tantalum, or tungsten, with a hardness of 1500 to 2500 HV 0.05 g, is applied to the airfoil tips and an abradable coating is applied to the seal members, with a thickness less than or equal to 254 micrometers, formed using boronizing processes like gaseous, liquid, or plasma-assisted chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If abrasive material such as cubic boron nitride is applied to airfoil tips, then wear resistance is improved, but manufacturing cost and time increase significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material from traditional cubic boron nitride to metal boride compounds (TiB2, ZrB2, HfB2, NbB2, TaB2, WB2, MoB2). This parameter change maintains the hard and wear-resistant properties while enabling more efficient application processes that reduce manufacturing time and cost.
Solution Approach 2:
The patent employs a coating that can be applied as a thinner layer compared to traditional abrasive materials, reducing the amount of material needed and the time required for application and curing. This approach treats the coating as a consumable layer that provides protection without requiring lengthy reconditioning cycles.
2Reliability
If thick coating is applied to airfoil tips, then wear resistance is improved, but gas leakage increases due to larger clearance
Solution Approach 1:
The patent changes the physical properties of the coating material to metal boride compounds that achieve superior wear resistance at much thinner thicknesses (0.001 to 0.006 inches) compared to traditional coatings. This parameter change in material composition allows the coating to provide adequate protection without creating excessive clearance that would lead to gas leakage.
Solution Approach 2:
The coating comprises metal boride compounds combined with metal powders (titanium, zirconium, hafnium, niobium, tantalum, tungsten, or molybdenum) in specific weight percentages. This composite material structure provides both wear resistance and dimensional stability, enabling thin coating application that minimizes clearance while maintaining protective properties.
3Reliability
If traditional abrasive coating process is used, then wear resistance is achieved, but manufacturing cost increases
Solution Approach 1:
The patent modifies the chemical composition parameters to use metal boride compounds that can be applied through more cost-effective processes. The coating formulation with specific metal powder combinations and boron content (15-30 weight %) enables reduced material costs and simplified application procedures compared to traditional cubic boron nitride coatings.
Solution Approach 2:
The coating system is designed to be applied in thin layers that provide adequate wear protection without requiring expensive traditional abrasive materials. The use of metal boride compounds with metal powders creates a cost-effective coating solution that reduces both material and application costs while maintaining protective performance.
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 provides superior wear resistance and cutting ability to the airfoil tips, reducing metal transfer during sliding contact and minimizing gas leakage, thereby enhancing engine efficiency and reducing reconditioning costs.
Implementation Method 1
formed using boronizing processes like gaseous, liquid, or plasma-assisted chemical vapor deposition
Implementation Method 2
formed using boronizing processes like gaseous, liquid, or plasma-assisted chemical vapor deposition
Implementation Method 3
The coating includes metal boride compounds... provides superior wear resistance and cutting ability
Data Source
Figure 1
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AI summary
A gas turbine engine includes an engine static structure extending circumferentially about an engine centerline axis; a compressor section, a combustor section, and a turbine section within the engine static structure. At least one of the compressor section and the turbine section includes at least one airfoil and at least one seal member adjacent to the at least one airfoil. A tip of the at least one airfoil is metal having a wear resistant coating and the at least one seal member is coated with an abradable coating. The wear resistant coating is formed as a layer in a base metal surface of the airfoil, has a thickness less than or equal to 10 mils (254 micrometers) and includes metal boride compounds.