A laser-based technique for the coating of mild steel with a vitreous enamel

Marked changes in the wettability characteristics of EN8 mild steel were observed after high-power diode laser (HPDL) surface treatment of the metal. The morphological, microstructural and wetting characteristics of the steel were determined using optical microscopy, scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS) and wetting experiments by the sessile drop technique. Improvements in the wetting action of the mild steel after HPDL surface treatment were identified as being the result of: HPDL-induced melting of the mild steel surface, which brought aabout a reduction of the surface roughness; and a small increase in the polar component of the surface energy and an increase in the surface O'2 content of the mild steel resulting from HPDL treatment. This work has demonstrated that the use of HPDL radiation to alter the wetting characteristics of mild steel in order to facilitate improved enamelling is a real possibility.