Homogeneous Coating Paste for Turbine Internal Surfaces
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Solution Overview
Problem
Current methods for protecting the internal surfaces of gas turbine components, such as those in cooling passages, are costly, time-consuming, and produce discontinuous or high-maintenance coatings, failing to adequately address the unique environmental challenges of hot corrosion and erosion within these small, inaccessible passages.
Innovation Solution
A homogenous paste comprising Co2Al9, a halide activator, and an organic binder with an inert filler, applied through injection and curing, followed by heat treatment to form a stable diffusion aluminide coating, which is designed to provide a long-lasting, uniform, and cost-effective protective layer on both internal and external surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pack cementation is used to coat internal surfaces, then adequate coating protection is achieved, but the process becomes costly and time consuming
Solution Approach 1:
The invention changes the chemical composition parameters of the coating paste by incorporating specific halide activators (AlF3, NH4Cl, NH4Br, NH4I) in controlled amounts (0.1-5.0 wt%) alongside aluminum powder and inert fillers. This parameter modification enables the paste to form a uniform diffusion aluminide coating through simple heating treatment, achieving reliable protection without the complexity and time consumption of pack cementation processes
2Ease of manufacture
If slurry coating is used, then coating application is simplified, but discontinuous coating with saw-toothed surface structures is produced
Solution Approach 1:
The invention creates a composite coating paste material combining aluminum powder (5-50 wt%), inert filler (45-90 wt%), and halide activator (0.1-5.0 wt%). This composite formulation ensures uniform distribution of coating materials and promotes homogeneous diffusion during heating, producing continuous, smooth coatings without the saw-toothed defects characteristic of conventional slurry coatings
3Manufacturing precision
If vapor phase coating is used, then good coating quality is achieved, but system complexity and maintenance requirements increase
Solution Approach 1:
The invention extracts and eliminates the complex vapor phase delivery system, humidity control mechanisms, and specialized tooling required by conventional vapor phase coating. Instead, it uses a simple paste formulation that can be applied by conventional means and cured through standard heating treatment, achieving good coating quality without the associated system complexity and maintenance burden
4Reliability
If conventional coating methods are used on internal surfaces, then coating is achieved, but the coating does not last as long as external surface coatings
Solution Approach 1:
The invention modifies the chemical parameters of the coating paste by incorporating halide activators that promote deep diffusion of aluminum into the substrate during heating treatment. This creates a thick, uniform diffusion aluminide layer with superior adhesion and corrosion resistance, enabling the internal surface coating to last longer than conventional coatings and match or exceed the service life of external surface coatings
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 achieves a durable, continuous aluminide coating with controlled thickness and microstructure, enhancing the protection against hot corrosion and erosion while reducing costs and maintenance, and ensuring the coating lasts longer than conventional methods.
Implementation Method 1
diffusion aluminide coating
Data Source
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AI summary
The subject invention is directed to diffusion aluminide coatings, and more particularly, to a homogenous paste for applying a diffusion aluminide coating to a selected surface of a turbine component and to a method of applying a diffusion aluminide coating to a selected surface of a turbine component.