Preparation and characterization of highly amorphous HVOF stainless steel coatings

A partially amorphous FeCrMoWBCSi powder has been HVOF sprayed in order to produce highly amorphous coatings. The extinction or retention of crystalline phases due to the spraying process is discussed. Amorphicity in coatings is associated with a high melting degree. The latter is attained by a high particle temperature and sufficient residence time in the flame. Coating properties, such as porosity, microhardness and adhesion strength are evaluated. The lowest coating porosity corresponds to the most amorphous coating. The least crystalline coating presents the highest corrosion resistance in 3.5% NaCl.