Mechanical stability of boron-based coatings grown on Incoloy 909 superalloy by thermochemical diffusion

ABSTRACT

Incoloy 909 superalloy was treated at 950°C to form coatings of different chemical composition by thermochemical diffusion. Packing of the samples in reactive powders lead to the formation of iron borides (Fe₂B and FeB) together with nickel boride, NiB, and nickel silicide, Ni₂Si, on the surface of the alloy depending on the exposure time. X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses suggest that growth of the coatings is controlled by diffusion of reactive species into the metal structure. Microabrasion wear resistance of the coated specimens was studied at 1 N load for a fixed sliding speed of 0.11 m s⁻¹ and it was compared against uncoated samples of the alloy. It was found that coating the alloy for 12 and 20 h increased the hardness of the alloy and therefore its wear resistance.

KEYWORDS:

• Boronising
• superalloy
• hardness
• wear resistance
• scanning electron microscopy
• X-ray diffraction
• abrasion
• coatings

Acknowledgements

The authors would like to thank Mexican Program for Lecturer Formation and Development (PRODEP) and Universidad Autónoma de Nuevo Leon (UANL) for the facilities provided to develop of this investigation.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Omar F. Alonso-Saavedra http://orcid.org/0000-0002-5890-0576

Rafael Colás http://orcid.org/0000-0001-6017-7244

Additional information

Funding

The authors would like to thank the Mexican National Council for Science and Technology (CONACYT) for the support of proyect 238232.