Turbine Blade Internal Passage Coating via CVD

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Solution Overview

Problem

Current methods for protecting gas turbine engine components from oxidation and hot corrosion, such as vapor phase aluminiding, are labor-intensive, costly, and risk chemical attack on internal passages, requiring lengthy and complex processes that increase manufacturing time and cost.

Innovation Solution

A method using Chemical Vapor Deposition (CVD) to deposit a diffusion aluminide coating on internal passages of turbine blades at lower temperatures, reducing the number of process steps and preventing metal coating buildup on exterior surfaces, thereby lowering production time and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vapor phase aluminiding is used to protect internal passages from oxidation and hot corrosion, then protection is achieved, but the process becomes labor-intensive and costly with increased manufacturing time

Engineering Contradiction:

Improveprotection from oxidation and hot corrosionVSAvoidmanufacturing time and cost

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the mechanical/chemical vapor phase aluminiding process with an electrochemical galvanizing process. Instead of using vapor phase diffusion at high temperatures, the invention uses electrochemical deposition to apply zinc or zinc-aluminum alloy coatings to internal passages, significantly reducing process time and labor requirements while maintaining protective functionality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental parameters of the coating process by transitioning from thermal diffusion (vapor phase aluminiding at 1800-2000°F) to electrochemical deposition (galvanizing at much lower temperatures). This parameter change enables faster processing, reduced energy consumption, and simplified manufacturing procedures while achieving the same protective effect

Inventive Principle:

Principle #35Parameter changes

2Reliability

If vapor phase aluminiding is applied to the entire blade, then internal passages are protected, but external surfaces require additional chemical stripping steps

Engineering Contradiction:

Improveprotection of internal passagesVSAvoidnumber of process steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies different coating treatments to different surfaces of the turbine blade. External surfaces receive controlled aluminide coating through vapor phase exposure, while internal passages receive galvanizing coating through electrochemical deposition. This local differentiation eliminates the need for chemical stripping steps and wax filling procedures required by uniform coating approaches

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating process is segmented into distinct treatments for external and internal surfaces. The external surface undergoes vapor phase aluminiding for oxidation resistance, while internal passages undergo separate galvanizing treatment for corrosion protection. This segmentation allows each surface to receive the most appropriate coating method without requiring subsequent removal or modification steps

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If high temperature vapor phase aluminiding is used, then coating is deposited, but process time and manufacturing cost increase

Engineering Contradiction:

Improvecoating depositionVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces the time-consuming thermal diffusion process with rapid electrochemical deposition. Instead of requiring extended exposure to high temperatures for coating formation, the galvanizing process deposits protective coatings much faster through electrochemical reactions, dramatically reducing manufacturing cycle time

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 CVD process effectively protects internal passages from oxidation and hot corrosion while minimizing external coating buildup, reducing manufacturing time and costs by operating at lower temperatures and simplifying the coating process.

Implementation Method 1

A method using Chemical Vapor Deposition (CVD) to deposit a diffusion aluminide coating on internal passages of turbine blades

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

Diffusion processes generally entail reacting the surface of a component with an aluminum-containing gas composition to form two distinct zones

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS7838070B2Method of coating gas turbine components

Publication Date: 2010.11.23 GENERAL ELECTRIC CO

AI summary

A method of forming a metal coating on surfaces of internal passages of a turbine blade includes, in an exemplary embodiment, the steps of positioning the turbine blade in a CVD chamber, coupling a reagent gas manifold to at least one internal passage inlet, and coating the surfaces of the at least one internal passage by a CVD process using metal coating reagent gases to form a metal coating on the surfaces of the at least one internal passage.