Parameters Evaluation of Bond-Coat Deposited by CO₂ Laser Beam for Aeronautical Turbine Blades

Abstract

The high temperature environments where aeronautical turbine blades are exposed makes mandatory the use of ceramic coatings. A bond coat comprised by a MCrAlY alloy (M=Co, Ni) is necessary to match the blade metallic substrate with the ceramic, also acting as a corrosion barrier. The laser treatment of metals and alloys is based in the surface local heating, followed by high cooling rates. The laser parameters such as scanning speed and laser power, plays an important role on the morphological, mechanical and chemical characteristics of the deposited material. In the present investigation, the NiCrAlY deposition was performed in stainless steel substrates with a CO2 laser beam. Different laser parameters of scanning speed and number of scanning cycles were implemented. The samples were characterized by optical microscopy and measurements of Vickers hardness. The results show that it is possible to achieve coatings with high hardness, free of pores or any pronounced defects, metallurgically bonded to the substrate.

Structural Characterization of Tungsten Carbide (Wc) Coatings Deposited on 4340 Steels by Co2 Laser Irradiation

“…This surface treatment works on the local heating of the material surface, by beam radiation absorption and its subsequent rapid cooling, promoting an efficient surface and coating blend. In this way, Teleginski et al (2016), Pita and Silva (2017) and Silva et al (2019) explained that some operation parameters, such as power density and laser beam displacement velocity affect the morphological, mechanical, and chemical characteristics of the deposited material, due to the high temperatures involved in this process. The laser beam dispersion radiance and its uniformity directly affects heat and time to meet the temperature target, contributing to materials dynamics.…”