MCrAlY Coating Rejuvenation via Aluminide Treatment
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Solution Overview
Problem
MCrAlY coatings in gas turbine components face depletion of β-phase material due to high temperatures, leading to oxidation and increased maintenance costs through stripping and re-coating, which can be brittle and inefficient.
Innovation Solution
An aluminide treatment process is applied to MCrAlY coatings to replenish β-phase material externally, using a slurry or gel containing NiAl and/or Ni2Al3, with techniques like soaking, spraying, or brushing, followed by heating to rejuvenate the coating without stripping, reducing maintenance duration and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stripping and re-coating methods are used to repair MCrAlY coatings, then oxidation resistance can be restored, but service time is extended and costs increase
Solution Approach 1:
The patent changes the chemical composition parameters of the coating by applying an aluminide treatment that increases aluminum content in the MCrAlY coating. This parameter change restores the β-phase material without requiring complete stripping and re-coating, thereby maintaining oxidation resistance while reducing maintenance time
Solution Approach 2:
The patent extracts only the depleted β-phase material from the coating for replacement, rather than removing the entire coating system. The aluminide treatment selectively replenishes aluminum in the affected regions, allowing partial repair that saves time compared to complete stripping and re-coating
2Reliability
If MCrAlY coatings are stripped and re-coated for repair, then oxidation resistance is restored, but repair costs increase
Solution Approach 1:
The patent uses a relatively simple aluminide treatment process with inexpensive aluminum-containing compounds to repair the coating, rather than requiring expensive proprietary re-coating systems. This approach provides cost-effective restoration of oxidation resistance
Solution Approach 2:
The patent performs preliminary preparation of the coating surface through controlled oxidation and aluminide treatment before final repair. This preliminary action creates a receptive surface that enhances the effectiveness of the repair treatment, reducing the need for expensive iterative repairs
3Reliability
If MCrAlY coatings are stripped and re-coated, then coating integrity is restored, but substrate alloys may be adversely affected
Solution Approach 1:
The patent converts the harmful effect of oxidized material on the coating surface into a beneficial preparation step. The controlled oxidation and subsequent aluminide treatment create a surface condition that enhances aluminum diffusion and β-phase formation, restoring coating integrity without harsh stripping that could damage the substrate
Solution Approach 2:
The patent introduces an intermediary aluminide treatment layer between the substrate and the oxidized coating material. This intermediary layer facilitates controlled aluminum diffusion and protects the substrate alloy from direct exposure to harsh stripping chemicals or processes
4Duration of action of stationary object
If aluminide coatings are applied to extend service life, then coating durability is improved, but the coatings may become brittle and produce craze-cracking
Solution Approach 1:
The patent applies aluminide treatment locally to depleted regions of the MCrAlY coating rather than uniformly throughout. This localized approach replenishes aluminum where needed to extend service life while maintaining the original ductile properties of non-treated regions, preventing overall brittleness
Solution Approach 2:
The patent applies partial aluminide treatment only to the extent necessary to restore β-phase material in depleted regions. This controlled partial action extends service life without excessive aluminum accumulation that would cause brittleness and craze-cracking throughout the entire coating
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 process rejuvenates MCrAlY coatings by forming outward β-phase material, extending service life, reducing costs, and maintaining oxidation and corrosion resistance without the drawbacks of traditional repair methods.
Implementation Method 1
applying an aluminide treatment onto the MCrAlY coating to form a treated MCrAlY coating, and outwardly forming β-phase material from the MCrAlY coating into the treatment
Implementation Method 2
followed by heating to rejuvenate the coating without stripping
Data Source
Figure 1
AI summary
A process (100) of treating a coated article (101) and a treated article (107) are disclosed. The process includes providing an article (101) having a MCrAlY coating (105), applying an aluminide treatment (117) onto the MCrAlY coating (105) to form a treated MCrAlY coating (115), and outwardly forming β-phase material (109) from the MCrAlY coating (105) into the treatment. The applying is selected from the group consisting of soaking, spraying, brushing, dipping, pouring, pack cementation, vapor deposition, and combinations thereof. The treated article (107) includes a substrate (103) and a treated MCrAlY coating (115) positioned on at least a portion of the substrate (103). The treated MCrAlY coating (115) includes a β-phase aluminide (109) in a spray-applied, brush-applied, pour-applied, dip-applied, pack cementapplied, vapor deposit-applied, or soaking-applied treatment.