Turbine Blade Z-Notch Wear Resistance via Liquid Phase Sintering
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Solution Overview
Problem
Turbine blade Z-notches in gas turbine engines experience high-temperature wear and erosion due to contact with adjacent blades, and existing repair methods like plasma transfer arc welding and thermal spray processes cause material embrittlement and substrate damage, leading to inefficient bonding and property alterations.
Innovation Solution
Applying a flexible cladding sheet comprising a Co-based alloy and organic binder to the contact face of the Z-notch, followed by heating to volatilize the binder and sinter the cladding sheet through liquid phase sintering, creating a metallurgically bonded, wear-resistant layer with a Co-based alloy composition of 5-20 wt% Cr, 22-32 wt% Mo, 1-4 wt% Si, and balance Co, to produce a dense, high-temperature resistant layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma transfer arc welding is used to surface the contact face, then wear resistance is improved, but the blade material undergoes partial melting and loses directional characteristics
Solution Approach 1:
The patent changes the thermal parameters of the surfacing process by using a controlled heat input method that prevents melting of the substrate. The cladding is applied at temperatures below the melting point of the Ni-based superalloy, preserving the directional solidification characteristics while still achieving wear resistance through the Co-based cladding layer.
Solution Approach 2:
The patent introduces a Co-based cladding material as an intermediary layer between the substrate and the wear environment. This cladding layer serves as a protective barrier that provides wear resistance without requiring the substrate to undergo melting or significant thermal transformation.
2Reliability
If high heat input weld overlay process is used, then wear resistance is improved, but the blade becomes embrittled in the heat-affected zone
Solution Approach 1:
The patent changes the thermal parameter from high heat input to low heat input processing. The surfacing is conducted at controlled temperatures that avoid creating a heat-affected zone large enough to cause embrittlement, while still achieving adequate bonding and wear resistance through the Co-based cladding material.
3Productivity
If thermal spray process is used, then application efficiency is improved, but substantial clean-up is required and bond strength is reduced
Solution Approach 1:
The patent replaces the mechanical bonding mechanism of thermal spray with a metallurgical bonding approach. The Co-based cladding is applied through a process that creates a diffusion bond or metallurgical bond with the substrate, eliminating the need for substantial clean-up and providing superior bond strength compared to mechanical bonding.
4Reliability
If pre-sintered preforms are used, then wear resistance is improved, but additional brazing material and machining are required, creating detrimental diffusion zones
Solution Approach 1:
The patent extracts the unnecessary intermediate steps of brazing and machining from the process. By using a Co-based cladding material that can be directly applied and bonded to the Ni-based superalloy substrate, the patent eliminates the need for separate brazing material and subsequent machining operations, thereby avoiding the creation of detrimental diffusion zones.
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 method provides a durable, wear-resistant layer with minimal substrate alteration, preserving the directional solidification of the turbine blade material and avoiding diffusion zones, thus enhancing the longevity and performance of turbine blades.
Implementation Method 1
heating the turbine blade Z-notch with flexible cladding sheet thereon to volatilize the organic binder and remove it from the cladding sheet
Implementation Method 2
further heating the turbine blade Z-notch with flexible cladding sheet thereon to sinter the cladding sheet by liquid phase sintering
Data Source
AI summary
A method of imparting wear-resistance to a contact face of a turbine blade Z-notch comprising applying a flexible cladding sheet comprising a Co-based cladding alloy and an organic binder to the contact face of the Z-notch, heating the turbine blade Z-notch with flexible cladding sheet thereon to volatilize the organic binder and remove it from the cladding sheet, and further heating the turbine blade Z-notch with flexible cladding sheet thereon to sinter the cladding sheet by liquid phase sintering, thereby cladding the cladding sheet to the contact face to produce a wear-resistant layer thereon.