Study of the metallurgical bond between 316 steel substrates and NiCrAlY coating sprayed by HVOF and irradiated with a low power CO2 laser

Abstract

Coatings are used to promote the thermal protection of metal alloys. In the aeronautical industry, the coatings
used to protect the turbine blades are called Thermal Barrier Coatings (TBC). The use of NiCrAlY is an alternative
as a bonding layer in coatings for turbine blades and it is possible to increase its useful life. This
work aims to study the metallurgical bond between the 316-stainless steel substrate and the NiCrAlY coating
which was sprayed through the High-Velocity Oxygen-Fuel (HVOF) and after irradiated by a CO2 laser
beam with power of 125 W and speed of 50 mm/s. The samples were characterized by scanning electron microscopy
(SEM) and the semi-quantitative analysis energy dispersive spectroscopic (EDX) showed that the
chemical composition of the coating and the substrate have maintained its original stoichiometry. The line
scan analysis is a technique of the EDX to analyze the diffusion between the main chemical elements of 316
steel and NiCrAlY and X-ray diffraction by identifying the alumina AL2O3 phases on the sample surface and
the results showed the metallurgical bond between substrate and coating.
Keywords: HVOF, AISI 316 steel, coating, NiCrAlY, CO2 Laser.