Engineered thermal spray coatings for bridge repair and reclamation

A research project at the Center for Thermal Spray Research (CTSR) of Stony Brook University investigated a metal restoration process in which powdered steel materials were deposited onto a prepared reclamation area through high velocity thermal spray processes. The goal was to use the high velocity to create impact fusion between the sprayed material and the parent substrate and impart compressive stresses to the coating and the interface. Another goal was to add overlay active metal coatings onto the spray-reclaimed surface so that underlying metallic layers were galvanically protected from future corrosion. A significant advantage of this strategy was the ability to tune the HVOF process to limit the extent of thermal load during the restoration process. Another advantage was that the high velocity process led to excellent bonding of the fill material with the parent steel, while peening effects induced compressive stresses onto parent and overlayed surfaces resulting in enhanced damage tolerance and fatigue resistance.