Development of Aluminizing Coatings on Additively Manufactured Inco 939 Alloy by High-Temperature Low-Activity Process

Karabastık E. C., SARIOĞLU C.

Journal of Materials Engineering and Performance, 2025 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Basım Tarihi: 2025
  • Doi Numarası: 10.1007/s11665-025-11495-w
  • Dergi Adı: Journal of Materials Engineering and Performance
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, PASCAL, Aerospace Database, Applied Science & Technology Source, Aquatic Science & Fisheries Abstracts (ASFA), Chemical Abstracts Core, Communication Abstracts, Compendex, Computer & Applied Sciences, INSPEC, Metadex, Civil Engineering Abstracts
  • Anahtar Kelimeler: above the pack process, additive manufacturing, aluminizing, high temperature low activity (HTLA), Inco 939, platinum aluminizing, yttrium aluminizing
  • Marmara Üniversitesi Adresli: Evet

Özet

This study aims to establish a laboratory scale out of pack/above the pack diffusion coating system to produce sound aluminide coatings on addivitely manufactured (AM) Inco 939 substrates and incorporation of yttrium and platinum to the standard aluminide coatings. Since the introduction of additively manufactured parts into turbine engines has increased more recently and there are limited investigations about protective coatings upon these alloys, the coatings were produced on Inco 939 SLM (selective laser melting) samples. Successful plain aluminide coatings in terms of industrial coatings quality standards (growth type, total thickness, additive/IDZ ratio, at.% Al) have been produced in the laboratory conditions via out of pack/above the pack technique. The pack mixture is optimized as 20 wt.% Al-Cr-5 wt.%NH4Cl and balance Al2O3. The process temperature is fixed as 1100 °C during 4 hours and there is no post-heat treatment. After aluminization optimization trials, co-deposition of yttrium to the aluminide coatings has been achieved by 2 wt.% Y2O3 addition to the source powder mixture. The yttrium precipitates were detected in additive layer close to the interdiffusion zone (IDZ). Platinum aluminide coatings were produced by using previously Pt electroplated specimens, and double-phase platinum aluminide coatings were resulted. The effect of post-heat treatment after platinum plating so-called platinum diffusion treatment has been highlighted to eliminate continuous PtAl2 layer. To sum up, Inco 939 SLM samples have been successfully coated with standard aluminide, yttrium aluminide and state-of-the-art platinum aluminizing techniques and this fills the gap about optimization of diffusion coatings on additively manufactured alloys. Turbine engine designers/manufacturers may consider application of these AM 939 alloys with coatings to the hot section of prototype engines and receive valuable feedback from test campaigns.