Abrasive Coating for Gas Turbine Blade Tip Sealing
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Solution Overview
Problem
High-temperature gas turbine engines face challenges in maintaining efficient operation due to leakage and wear issues between blade tips and shrouds, primarily caused by inadequate sealing, which can lead to reduced efficiency and potential component failure.
Innovation Solution
A method involving the formation of an abrasive coating system on gas turbine blade tips using directed energy deposition, followed by machining and etching to create a desired thickness profile and expose abrasive particles, which abrade an abradable layer to establish a precise seal, reducing leakage and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional sealing methods are used between blade tips and shrouds, then manufacturing is simpler, but leakage increases and sealing efficiency decreases
Solution Approach 1:
The abrasive coating is deposited on the blade tip before final assembly, allowing the sealing surface to be prepared in advance. The coating process includes preliminary deposition followed by controlled etching to expose abrasive particles, creating a ready-to-function sealing surface that will automatically form the desired seal upon contact with the abradable coating during engine operation
Solution Approach 2:
The invention changes the physical and chemical parameters of the sealing surface by depositing a metal matrix composite coating containing abrasive particles. The coating composition, particle distribution, and surface morphology are controlled through deposition parameters and subsequent etching processes, transforming the sealing surface from a smooth traditional surface to one with exposed abrasive particles that enhance sealing capability
2Reliability
If an abrasive coating with protruding particles is created, then sealing efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The coating process creates local variations in surface properties by controlling abrasive particle distribution and exposure. The etching process selectively removes metal matrix material to expose abrasive particles at specific locations, creating a surface where different regions have different functional characteristics - some areas have exposed particles for sealing, while other areas maintain the metal matrix structure for structural integrity
Solution Approach 2:
The etching process is controlled to remove only a portion of the metal matrix, exposing abrasive particles to the extent needed for effective sealing without completely removing the binding matrix. This partial action maintains the structural integrity of the coating while providing sufficient abrasive exposure to functionally resolve the sealing problem
3Duration of action of stationary object
If the abrasive coating is used, then wear resistance increases, but the complexity of the coating system increases
Solution Approach 1:
The sealing surface utilizes a composite material system consisting of a metal matrix (such as nickel-based superalloy) reinforced with dispersed abrasive particles (such as carbide, nitride, or oxide particles). This composite structure combines the ductility and bonding capability of the metal matrix with the hardness and wear resistance of the abrasive particles, creating a coating that simultaneously provides sealing function and wear protection
Solution Approach 2:
The abrasive coating system is designed to be self-forming during engine operation. When the coated blade tip contacts the abradable coating on the shroud, the abrasive particles automatically abrade the abradable material to form a precise seal, eliminating the need for complex external sealing mechanisms. The system uses the relative motion and contact pressure during normal operation to create and maintain the seal
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 enhances sealing efficiency, reduces leakage, and increases engine power by up to 5% by ensuring a continuous seal and minimizing wear between blade tips and shrouds, thereby improving the overall performance and longevity of the turbine engine.
Implementation Method 1
depositing the plurality of abrasive particles and the metal matrix on the substrate using directed energy deposition
Implementation Method 2
etching an outer surface of the machined abrasive coating to remove a portion of the metal matrix and form an etched metal matrix
Data Source
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AI summary
In some examples, a method for forming an abrasive coating (21) on a component (e.g., a turbine blade (16), turbine vane (16a), or knife rings (231, 232, 233)) of a gas turbine engine (11). The method may include forming an abrasive coating system on a substrate, the abrasive coating system including an abrasive coating (21) including a plurality of abrasive particles (68) in a metal matrix (69); machining the abrasive coating (21) on the substrate to define a machined abrasive coating having an abrasive coating thickness profile; and etching an outer surface of the machined abrasive coating to remove a portion of the metal matrix (69) and form an etched metal matrix such that the abrasive particles (68) protrude from the metal matrix (69).