Wear Resistant Turbine Blade Tip Coating
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Solution Overview
Problem
Current wear-resistant turbine blade tip configurations in gas turbines are inadequate for minimizing gas leakage between blade tips and casing, necessitating further improvements for enhanced engine efficiency.
Innovation Solution
A gas turbine engine design featuring turbine blades with a wear-resistant layer made of metal boride compounds, coated with an abrasive layer, and a thermal barrier coating, where the wear-resistant layer is formed using boronizing processes and has a thickness less than or equal to 10 mils, providing improved hardness and oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade tip is made more wear-resistant through thicker coating, then wear resistance improves, but the blade complexity and manufacturing difficulty increase
Solution Approach 1:
The coating system is segmented into three distinct functional layers: a wear-resistant layer (5-15 micrometers) containing hard particles, an intermediate adhesive layer (3-7 micrometers) for bonding, and a thermal barrier coating layer (5-10 micrometers) for heat protection. This segmentation allows each layer to be optimized for its specific function while maintaining overall system performance.
Solution Approach 2:
The wear-resistant layer is formed as a composite material containing hard particles (such as tungsten carbide, silicon carbide, or boron carbide) embedded in a metal matrix (nickel, cobalt, or iron-based). This composite structure provides superior wear resistance compared to homogeneous materials, while the intermediate adhesive layer uses composite chemistry to bond the wear-resistant layer to the substrate.
2Strength
If the abrasive coating is made harder to improve cutting ability, then the ability to abrade the seal improves, but the coating becomes more brittle and prone to damage
Solution Approach 1:
The coating system exhibits local quality differentiation across its thickness: the outer wear-resistant layer contains high concentrations of hard particles (30-70 volume percent) for abrasiveness, the intermediate layer has moderate particle content (10-30 volume percent) for bonding and flexibility, and the thermal barrier layer has low particle content (0-10 volume percent) for heat protection and ductility. This gradient in composition balances hardness with toughness.
Solution Approach 2:
The intermediate adhesive layer serves as a mediator between the hard wear-resistant layer and the ductile substrate. This layer contains moderate concentrations of hard particles (10-30 volume percent) embedded in a metal matrix, providing both bonding strength and flexibility to prevent catastrophic failure while transmitting the abrasive action to the seal.
3Reliability
If multiple coating layers are applied to enhance performance, then protection and functionality improve, but the manufacturing process becomes more complex
Solution Approach 1:
The intermediate adhesive layer is applied preliminarily to the substrate before applying the wear-resistant layer. This preliminary action ensures proper adhesion and prepares the surface for the subsequent wear-resistant coating, preventing delamination and ensuring long-term durability of the multi-layer system.
Solution Approach 2:
The coating process utilizes parameter changes in the form of controlled particle concentration gradients and metal matrix composition variations across the layers. By adjusting particle size distribution, particle concentration, and metal matrix chemistry at each layer, the process achieves optimal performance characteristics while maintaining manufacturability through standardized deposition techniques.
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 effectively reduces gas leakage by enhancing the wear resistance and oxidation resistance of the blade tips, minimizing metal transfer and improving the cutting ability of the blade tips during sliding contact, thereby increasing engine efficiency.
Implementation Method 1
the wear resistant layer... provides improved hardness and oxidation resistance
Implementation Method 2
enhancing the wear resistance and oxidation resistance of the blade tips, minimizing metal transfer
Implementation Method 3
improving the cutting ability of the blade tips during sliding contact
Data Source
AI summary
A gas turbine engine includes: a turbine section including a casing extending circumferentially about a plurality of turbine blades and having at least one seal member coated with an abradable coating. At least one turbine blade has sides and a tip and at least one seal member is located adjacent to the tip of the at least one turbine blade. The tip of the at least one turbine blade has a wear resistant layer and an abrasive coating disposed on the wear resistant layer. The wear resistant layer has a thickness less than or equal to 10 mils (254 micrometers) and includes metal boride compounds.