Chromium-Aluminide Coatings via Pack Cementation Method on Inconel 718 Alloy and Fe-Cr-Ni SuperAlloy

Abstract

In this study, it is invastigated the low-temperature formation of chromium aluminide coatings on a CrNiFe-base superalloy and Inconel 718 by pack cementation process. A novel pack-aluminizing diffusion coating was applied at 800°C during 4 and 6 hours.The chrom-aluminising powder packs were prepared using aluminium and chromium powders as a source for depositing aluminium and chrominium, Al₂O₃ powder as an inert filler and ammonium chloride NH₄Cl as an activator. A scanning electron microscope (SEM) with energy dispersive X-ray spectrometer (EDS) and XRD were used to characterize the surface layers. SEM analysis revealed that coating layers were homogenous, compact and nonporous and there was a good bonding at the interface of the coating and matrix. Layer thickness variation was changed from 11,17 to 18,2 µm measured from the surface to the matrix. The hardness of the coating layer increased to 1000 HVN while the hardness of the matrix was 350 HVN with the increasing process time.

Keywords

• Low Tempeture pack Aluminising,Chromising,layer thickness

References

1. [1] I. Schoukens, I. Vandendael, J. De Strycker, A. A. Saleh, H. Terryn, and I. De Graeve, “Effect of surface composition and microstructure of aluminised steel on the formation of a titanium-based conversion layer,” Surface and Coatings Technology, vol. 235, pp. 628–636, Nov. 2013.
2. [2] Z. D. Xiang and P. K. Datta, “Relationship between pack chemistry and aluminide coating formation for low-temperature aluminisation of alloy steels,” Acta Materialia, vol. 54, pp. 4453–4463, 2006.
3. [3] R. Pillai et al., “Carbides in an aluminised single crystal superalloy: Tracing the source of carbon,” Surface and Coatings Technology, vol. 288, pp. 15–24, 2016.
4. [4] A. Erdogan, “Investigation of high temperature dry sliding behavior of borided H13 hot work tool steel with nanoboron powder,” Surface & Coatings Technology, 2018.
5. [5] M. Sabri, A. Erdogan, M. Öge, and A. Günen, “Dry sliding wear behavior of borided hot-work tool steel at elevated temperatures,” Surface & Coatings Technology, vol. 328, pp. 54–62, 2017.
6. [6] D. Chaliampalias et al., “The effect of Al and Cr additions on pack cementation zinc coatings,” Applied Surface Science, vol. 256, no. 11, pp. 3618–3623, Mar. 2010.
7. [7] Y. F. Yang, C. Y. Jiang, Z. B. Bao, S. L. Zhu, and F. H. Wang, “Effect of aluminisation characteristics on the microstructure of single phase β-(Ni,Pt)Al coating and the isothermal oxidation behaviour,” Corrosion Science, vol. 106, pp. 43–54, 2016.
8. [8] C. Houngninou, S. Chevalier, and J. . Larpin, “Synthesis and characterisation of pack cemented aluminide coatings on metals,” Applied Surface Science, vol. 236, no. 1–4, pp. 256–269, Sep. 2004.

9. [9] K. Nikolov, P. Kaestner, C. P. Klages, S. Puls, and B. Schuhmacher, “Low-pressure diffusion chromising of thin low-carbon steel sheet for improved surface and bulk properties,” Journal of Alloys and Compounds, vol. 692, pp. 101–107, 2017.
10. [10] F. J. Pérez, F. Pedraza, M. P. Hierro, M. C. Carpintero, and C. Gómez, “Chromising of stainless steels by the use of the CVD-FBR technology,” Surface and Coatings Technology, vol. 184, no. 1, pp. 47–54, 2004.
11. [11] X. J. Lu and Z. D. Xiang, “Formation of chromium nitride coatings on carbon steels by pack cementation process,” Surface and Coatings Technology, vol. 309, pp. 994–1000, Jan. 2017.
12. [12] Z. D. Xiang and P. K. Datta, “Pack aluminisation of low alloy steels at temperatures below 700 °C,” Surface and Coatings Technology, vol. 184, no. 1, pp. 108–115, Jun. 2004.