Effect of laser scanning speed on the morphological properties of CO2 laser modified, wire-arc sprayed aluminum bronze coatings, deposited on AISI-304 stainless steel

Abstract

Herein, the effect of laser-scanning speeds on the morphological properties of CO₂ laser-modified, wire-arc sprayed aluminum-bronze coating was investigated. Firstly, the aluminum-bronze coating was deposited on AISI–304 stainless steel by wire-arc spray method. The surface of the deposited coating was then modified, using CO₂ laser remelting process under various scanning speeds, ranging from 100–500 mm/min. Scanning electron microscopy revealed that the CO₂ laser treatment melted the aluminum bronze coating and the substrate beneath. This melting resulted in a stable, homogeneous alloy of coating and substrate. At CO₂ laser scanning speed of 100 mm/min, the coating was deeply diffused into the substrate and formed a coating of 696 µm thickness, composed of an alloy coating and substrate. With the increase in CO₂ laser scanning speed, a gradual reduction in the thickness of the diffused coating was observed. A maximum of 61% reduction in the diffused coating was observed at CO₂ laser scanning speed of 500 mm/min. SEM energy dispersive spectroscopy (EDS) validated the diffusion of aluminum bronze coating into the substrate by exhibiting 36.31 wt% Fe, 38.1 wt% Cu, and 2.82 wt% Al in the newly formed coating. With an increase in CO₂ laser scanning speed, the percentage of Fe was reduced whereas the percentage of Cu was increased in alloyed coatings. A maximum of 18% reduction in Fe percentage and 28% improvement in Cu percentage were achieved at the highest scanning speed of 500 mm/min, compared to 100 mm/min scanning speed.