The pack aluminizing process is an advanced surface treatment method used in various industries, particularly aerospace, to deposit aluminium or aluminium-chrome alloy coatings on metallic surfaces. This process involves cement deposition under a controlled atmosphere (hydrogen or argon) followed by high-temperature diffusion to enhance the corrosion and high-temperature resistance of critical components such as turbomachine parts.

Applications

  •  Engine Components: Used for distributors, turbine blades, compressors, and injectors of turbomachinery, as well as other critical engine components where extending the life of parts in a corrosive environment is essential.
  • Maintenance and Repair: Required in maintenance procedures to restore worn parts and extend their lifecycle.
  • Performance Enhancement: Treated parts show significant improvement in performance under severe operating conditions.
Close-up of an operator removing metal components after a fluoride ion cleaning process, showing the surface residues and the clean finish of the parts after thermochemical treatment. Immersion of blades in cement for aluminizing

Operating Principles

  1. Preparation: Parts to be treated are carefully degreased and cleaned to remove any surface contaminants, ensuring optimal adhesion of the coating.
  2. Masking: Innovative masking solutions are applied to the parts to protect areas that do not require coating. This ensures that the deposition is limited to critical areas, avoiding overspill.
  3. Aluminizing: The prepared parts are then loaded into a thermochemical furnace where the atmosphere and pressure are strictly controlled. The parts in the furnace are heated to a high temperature (800°C – 1200°C) to promote the evaporation and diffusion of the cement.
  4. Aluminizing Reaction: The aluminium and/or chrome in the cement evaporates at high temperature and diffuses onto the metal surface, reacting with the base metal to form a protective coating. This coating also diffuses into the material, creating a diffusion zone enriched with aluminium and/or chrome.
  5. Subsequent Specimens and Destructive Testing: For each treated batch, specimens are included to ensure the quality of the treatment. Destructive testing and coating thickness and uniformity tests are conducted.
  6. Coloration Tests: Our laboratory conducts coloration tests to evaluate the quality and homogeneity of the coating, ensuring compliance with the required specifications.

Advantages of the Process

  • Corrosion Resistance: The coating forms an effective protective barrier against corrosive elements, thus extending the lifespan of components.
  • High-Temperature Resistance: Treated parts can withstand high-temperature and highly corrosive environments, increasing their durability and performance.
  • Adaptability to Complex Shapes: The treatment is particularly suitable for parts with complex geometries, ensuring complete and uniform coverage.
Vapor Phase Aluminizing
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Usage at Revima Engine Parts

At Revima Engine Parts, the pack aluminizing process (parts immersed in cement) is NADCAP certified. It is used for the production of new parts or high-precision repairs for major clients such as Pratt & Whitney and Safran Group.

We are manufacturers and proprietors of our aluminizing or chromaluminizing cements (Al, Al-Cr…). We deposit under hydrogen or argon and then diffuse. The typical coating can have a thickness between 30 and 100 microns. We are qualified by Pratt & Whitney Canada (CPW452 or PWA73 process), Safran (CCT00526, CCT00868/CCT00868), and GE (F50TF8).

We primarily apply this process to the following materials: MarM247, INCO738, INCO792, L605, Stel31, MarM509, Wi52, INCO713, IN100, MarM004, MarM002, C1023.

Additionally, the Revima design office is available to support its clients in developing technical specifications tailored to their needs, determining the most suitable coating process. We also offer our expertise to evaluate the feasibility of your projects and provide comprehensive advice and technical assistance.

Conclusion

The pack aluminizing process using thermochemical furnaces is an advanced and efficient technique for treating metallic surfaces in the aerospace industry.

It allows for the deposition of protective aluminium coatings, thereby increasing the heat and corrosion resistance of parts. By ensuring uniform coating on complex geometries and optimal diffusion into the material, pack aluminizing is essential for maintaining the high standards of quality and durability required in the aerospace sector, thereby ensuring the reliability and safety of treated components.

Contact us at

soa-customers@revima.com