MCrAlY Stripping technology

Efficient and Effective Chemical Stripping of MCrAlY, Aluminides and other Coatings

Chemical stripping is a process used to remove thermal spray coatings and surface treatments from turbine components. It involves immersing the parts in an optimized chemical solution that selectively dissolves or weakens the coating without causing damage to the substrate/component.

This selective removal method allows for the restoration of the component surface, extending the service life of high value gas turbine components.

What is Stripping?

Chemical stripping is a technique used to remove MCrAlY (Metal-Chromium-Aluminum-Yttrium) coatings and diffusive coatings from various metal substrates without causing damage to the base material.

These coatings, designed to resist oxidation and corrosion at elevated temperatures, are commonly applied to components in gas turbines, aircraft, and other industrial applications requiring high strength.

The chemical stripping process involves immersing the coated component in a chemical solution specifically formulated to dissolve the MCrAlY or diffusion layer, leaving the underlying metal substrate intact and ready for new coating applications.

How does the Stripping process work?

The MCrAlY stripping process begins with component preparation and immersion in a stripping solution containing strong acids, such as hydrochloric or sulfuric acid, combined with additives to optimize the efficiency of the chemical reaction. The solution selectively acts on the coating, dissolving metals and creating soluble complexes that are subsequently removed from the surface.

Process parameters, including:

  • Solution concentration,
  • Temperature,
  • Immersion time

are carefully calibrated to ensure uniform and precise removal of the coating without adversely affecting the metal substrate. Once the stripping process is complete, the component is rinsed to remove any residual chemicals and, if necessary, further treated to prepare it for recoating or repair.

Why MCrAlY Stripping is Essential?

The MCrAlY stripping process begins with component preparation and immersion in a stripping solution containing strong acids, such as hydrochloric or sulfuric acid, combined with additives to optimize the efficiency of the chemical reaction. The solution selectively acts on the coating, dissolving metals and creating soluble complexes that are then removed from the surface.

MCrAlY and diffusive coatings deteriorate over time due to extreme operating conditions, such as high temperatures, oxidation and mechanical stress. Chemical removal of these coatings is essential to restore component performance, allowing you to:

  1. Repair worn components: Removing the damaged coating and applying a new one extends the life of the components, reducing the need for replacement.
  2. Prepare the substrate for new coatings: A clean, residue-free surface is essential to ensure that new coatings adhere properly and provide maximum protection against wear and corrosion.
  3. Reduce maintenance costs: Chemical stripping is a cost-effective and less invasive option than mechanical methods, allowing components to be treated without compromising their form or integrity.

 

Stripping is used in:

Advantages of Stripping

The chemical stripping process offers several advantages over other coating removal techniques. Here are some of the key benefits:

  • Precise and controlled removal: Chemical stripping allows coatings to be removed uniformly and selectively, while fully preserving the integrity of the underlying metal substrate.
  • Minimized risk of damage: Unlike mechanical methods, chemical stripping does not pose a risk of abrasion, deformation or damage to the component.
  • Effective on complex geometries: This method can be applied to components with intricate geometries, allowing the coating to be removed even in difficult-to-reach areas.
  • Cost-effectiveness: Chemical stripping is a faster and less expensive process than mechanical techniques, reducing downtime and operating costs.
  • Compatible with different alloys: The process is safe and effective on various types of metal substrates, including high-performance alloys used in the aerospace and gas turbine industries.

MCrAlY Stripping Applications?

Chemical stripping of MCrAlY coatings is widely used in various industrial sectors to ensure the maintenance and reliability of components subjected to extreme operating conditions.

Key applications include:

  • Gas Turbines: Turbine components, such as blades and nozzles, require continuous protection against oxidation and corrosion at elevated temperatures. Stripping allows components to be regenerated without the need for costly replacements.
  • Aerospace: Jet engines and other aircraft components require ongoing maintenance. Stripping damaged coatings is a critical step in the regeneration and safe reuse of components.
  • Energy: Power generation facilities, especially those using gas turbines, benefit from stripping to optimize component performance, reducing maintenance costs and increasing operational efficiency.

MCrAlY Stripping Results

Flame Spray’s chemical stripping service guarantees:

  • Complete removal of the coating: ideal preparation for the subsequent application of new protective coatings.
  • Restoration of the original performance of the components, extending their useful life and reducing replacement costs.
    Preparation of surfaces for repair or subsequent coating, ensuring optimal adhesion and superior performance.

Trust Flame Spray for the MCrAlY Stripping service: an advanced, safe and effective solution to guarantee the regeneration of your critical industrial components, extending their life and maintaining high performance in extreme operating environments.

MCrAlY Service

Flame Spray offers an advanced MCrAlY Stripping service for the removal of high performance coatings from metal components, particularly used in gas turbines and high temperature applications.

This process is essential for the refurbishment, maintenance and restoration of critical components, ensuring they can be reused without compromising their structural integrity.

 

Results

  • Coating removal
  • Repair of Gas turbine components

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MCrAlY Stripping: Frequently Asked Questions (FAQ):

MCrAlY refers to a family of high-temperature corrosion-resistant coatings consisting of a mixture of metal elements, such as Nickel, Cobalt (M), Chromium (Cr), and Aluminium (Al), with Yttrium (Y) aiding in the formation of a stable oxide layer that is particularly important in providing protection against thermal cycling.

Aluminides are intermetallic compounds composed primarily of aluminum with other metallic elements, such as nickel, iron, or titanium. They are known for their high-temperature strength and oxidation resistance.

Chemical stripping is a process used to remove coatings, residues, or contaminants from a surface using chemical agents. It involves immersing the material in a stripping solution that dissolves the undesired layers.

Yes, MCrAlY coatings can be chemically stripped using suitable stripping agents. The choice of stripping solution depends on the specific composition of the coating and the desired stripping effectiveness.

Aluminides, particularly those with aluminum as the primary component, can be chemically stripped using appropriate stripping solutions. However, the selection of the stripping agent must be done carefully to avoid damaging the underlying substrate.

Common stripping agents for MCrAlY and aluminides include acidic solutions containing various chemicals, such as sulfuric acid, hydrochloric acid, nitric acid, or mixtures thereof. Alkaline solutions can also be used depending on the specific requirements.

Chemical stripping can be a selective process, depending on the choice of stripping agent and the materials involved. Different coatings and substrates may have varying susceptibilities to the stripping solution, requiring careful consideration to achieve the desired results.

Yes, alternative methods to chemical stripping include mechanical methods like abrasive blasting or thermal methods like plasma or laser ablation. These methods are often used when chemical stripping is not suitable or feasible.

Yes, safety precautions must be followed when performing chemical stripping. This includes wearing appropriate protective equipment like gloves, goggles, and a respirator. Adequate ventilation and adherence to the handling and disposal guidelines for the stripping agents are also crucial.

Chemical stripping, particularly for complex coatings like MCrAlY or aluminides, is often best performed by professionals with experience in handling hazardous chemicals and knowledge of the specific requirements for each material. It ensures safety, efficiency, and optimal results. Contact our Gas Turbine specialist for more information