Nickel Phosphorous Coating with Columnar Microstructure for Fatigue Resistance
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Solution Overview
Problem
Conventional nickel phosphorous coatings for gas turbine engine components, deposited using electroless plating, exhibit high internal stresses and fatigue debit due to laminar grain structures, limiting their use due to reduced service life and increased cracking risk.
Innovation Solution
A nickel phosphorous coating with a columnar microstructure is applied using electroless plating followed by heat treatment, which reduces internal stress and enhances ductility, providing improved fatigue and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroless plating is used to deposit nickel phosphorous coating, then the coating provides corrosion resistance and mechanical protection, but the laminar grain structure causes high internal stresses and fatigue debit
Solution Approach 1:
The patent applies heat treatment to change the microstructure of the nickel phosphorous coating from laminar to columnar grain structure. This parameter change in the coating's internal structure reduces internal stresses and improves fatigue resistance while maintaining corrosion resistance properties.
Solution Approach 2:
The patent creates a composite structure by combining nickel phosphorous alloy with a specific columnar grain microstructure. This composite microstructure integrates the corrosion resistance of nickel phosphorous with the mechanical strength benefits of columnar grain orientation, resolving the contradiction between corrosion protection and fatigue resistance.
2Ease of manufacture
If conventional laminar grain structure coating is applied, then the coating process is straightforward, but the coating exhibits high internal stresses and increased cracking risk
Solution Approach 1:
The patent performs heat treatment as a preliminary action after electroless plating to transform the coating's microstructure before the component enters service. This preliminary heat treatment eliminates the harmful laminar structure and prevents future cracking, extending service life while keeping the original coating process simple.
Solution Approach 2:
The heat treatment process changes the physical parameters of the coating, specifically transforming the grain structure from laminar to columnar. This parameter change reduces internal stresses and eliminates cracking risks without complicating the overall manufacturing process.
3Temperature
If nickel phosphorous coating is used for thermal protection, then the component gains thermal stability, but the laminar structure limits ductility and increases cracking risk
Solution Approach 1:
The heat treatment changes the microstructural parameters of the nickel phosphorous coating, transforming it from a laminar to a columnar grain structure. This parameter change simultaneously improves ductility and maintains thermal stability, allowing the coating to better withstand thermal cycling without cracking.
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 columnar microstructure coating achieves lower internal stress and higher ductility compared to laminar coatings, improving fatigue debit and wear resistance, thus extending the service life and mechanical protection of gas turbine engine components.
Implementation Method 1
electroplating nickel phosphorous onto the surface of an article to form a coating
Implementation Method 2
heat treating the coated article after the electroplating. After the heat treating the nickel phosphorous has a columnar microstructure
Data Source
AI summary
An article for a gas turbine engine according to an exemplary embodiment of this disclosure, among other possible things includes a substrate and a nickel phosphorous coating disposed on the substrate. The nickel phosphorus coating has a columnar microstructure. A method of applying a coating to an article for a gas turbine engine is also disclosed.