Diffusion Coating Slurry for Smooth Substrates

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Solution Overview

Problem

Existing coating methods for components with limited access or smooth surfaces, such as honeycomb shapes, often result in incomplete or non-uniform coatings due to the coating material sliding without adhering, leading to increased costs and inefficiencies, especially when multiple applications are required to achieve desired thickness.

Innovation Solution

A slurry composition comprising between 10% and 40% metal powder, 10% to 15% activator, 10% to 20% polyethylene oxide, 10% to 20% thickener, up to 30% ceramic, and up to 25% binder, applied to the substrate, dried, baked, and cured to form a diffusion coating with improved adhesion and uniformity, reducing the need for post-heat treatment and enhancing coating coverage and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple applications of coating material are used to achieve desired thickness, then coating coverage is improved, but coating process cost and time increase

Engineering Contradiction:
Improvecoating coverageVSAvoidcoating process efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The invention changes the chemical composition parameters of the coating slurry by incorporating specific activators (ammonium chloride, ammonium fluoride, or zinc chloride) in controlled amounts (1-15% by weight). These chemical parameter changes enable the coating material to react with and adhere to smooth surfaces, allowing complete coverage in a single application rather than requiring multiple coats, thus improving both coverage and process efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite coating slurry system combining metal powder (15-40% by weight) with specific chemical activators and binding agents. This composite formulation enables the coating material to simultaneously achieve proper flow characteristics for application and strong adhesion to smooth surfaces, eliminating the need for multiple applications and improving overall coating process productivity

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If additional metal powder is added to increase coating thickness, then coating thickness is improved, but coating material cost increases

Engineering Contradiction:
Improvecoating thicknessVSAvoidcoating material cost
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The invention changes the chemical reactivity parameters by introducing activators (ammonium chloride, ammonium fluoride, or zinc chloride) that enhance the bonding efficiency of the metal powder to the substrate. This allows achieving the desired coating thickness with optimal metal powder content (15-40% by weight) rather than using excessive amounts, thereby controlling material costs while maintaining precise coating thickness control

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If coating material is applied to smooth surfaces, then coating application is simplified, but coating adhesion deteriorates causing incomplete coatings

Engineering Contradiction:
Improvecoating application simplicityVSAvoidcoating adhesion
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention introduces chemical activators (ammonium chloride, ammonium fluoride, or zinc chloride) as intermediaries between the coating material and the smooth substrate surface. These activators chemically interact with both the substrate and the metal powder, creating strong adhesion bonds that enable reliable coating attachment to smooth surfaces while maintaining simple application procedures

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention modifies the chemical composition parameters of the coating slurry by incorporating specific activators and binding agents in optimized proportions. These parameter changes transform the coating material's interaction characteristics with smooth surfaces, enabling both easy application and strong adhesion simultaneously, thus resolving the contradiction between operational simplicity and coating reliability

Inventive Principle:
Principle #35Parameter changes

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 provides a more uniform and efficient coating process for smooth and honeycomb-shaped surfaces, reducing costs and increasing coverage, while achieving a uniform thickness without the need for additional post-heat treatment, thereby improving the overall coating process efficiency and reducing costs.

Implementation Method 1

The curing of the slurry coating over the substrate transfers metal elements of the metal powder in the slurry to the substrate to form a coating on the substrate

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

between 10% and 20% thickener

Methodology Applied
Scientific EffectViscosity:

Implementation Method 3

between 10% and 20% polyethylene oxide

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 4

between 10% and 15% activator

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentEP2886677B1A slurry and a coating method
Publication Date: 2019.03.20 GENERAL ELECTRIC CO
  • EP2886677B1 patent drawingFigure 1
  • EP2886677B1 patent drawingFigure 2
  • EP2886677B1 patent drawingFigure 3~4

AI summary

A slurry and a coating method are provided. The slurry includes, by weight, between 10% and 40% metal powder, between 10% and 15% activator, between 10% and 20% adhesive, between 10% and 20% thickener, up to 30% ceramic, and up to 25% binder. The coating method includes providing a slurry including, by weight, between 10% and 40% metal powder, between 10% and 15% activator, between 10% and 20% adhesive, between 10% and 20% thickener, up to 30% ceramic, and up to 25% organic polymer binder, providing a substrate, applying the slurry over a surface of the substrate to form a slurry coating, drying the slurry coating over the substrate, baking the substrate and the slurry coating, and curing the slurry coating over the substrate. The curing the slurry coating over the substrate transfers metal elements of the metal powder in the slurry to the substrate to form a coating on the substrate.