Modificación superficial por láser de recubrimientos protectores de Al sobre acero

Abstract

This Thesis research, having for title: Laser Surface Modification of Al Protective Coatings on Steel, is circumscribed to Materials Engineering, more specifically, to Surface Engineering. With this main idea, it has been taken as a reference a material system formed by a metallic coating on a steel (iron aluminides on P92 grade steel), with a wide usage in the conventional energies sector, with fossil fuels. Applying a laser treatment it is aimed to optimized the chemical and physical properties that provide coating's protective properties, thus making it more versatile and competitive compared to other protection alternatives. In a practical way, it has been studied material systems in which the protective layer of Fe aluminides had already been consolidated, as well as to obtain this layer by the processing of steel samples with an Al precoating. Considering both approaches it is allowed to value more precisely the reach and development of the laser treatment applied. Conventionally laser processing in surface engineering, focused on protective coatings, has suffered from significant deficiencies in the quality of the surface finish and the microstructure of the constitutive phases of the protective system. By modifying the use of the laser beam with respect to the usual procedures as cladding, remarkable advances could be expected. In this sense, two key experimental parameters have been considered: laser scanning velocity on the surface, and sample's displacement velocity, perpendicular to the scanning movement. In addition, the influence of the process atmosphere has been explored because of its key influence on the characteristics of the resulting coating...