Mobile Metal Manufacturing Technologies For Repair And Retrofit of Infrastructure Systems

Structural steels found in bridges and railways are damaged over time due to loading and the environmental conditions in which they operate. VRC Metal Systems, LLC in collaboration with research partners at Northeastern University propose to develop novel protective/repair coating materials that can be applied to bridges and railways by using the cold gas spray (CS) technology to improve the wear and corrosion resistance of the existing materials and enable spot repair of cracks and corrosion areas. The top candidate for this cold spray coating is nickel–chromium carbide (Ni-CrC), an extremely high strength, nanostructured metal matrix composite (MMC). Other candidate materials that have shown promise include Stellite 6, 316L, 410 and 420 stainless steel. In general, cold sprayed coatings have crack-retarding compressive residual stresses and a high concentration of dislocation-trapping twin boundaries. The materials can be independently deposited in atmosphere at economic rates up to 200 cm3/hr requiring no special jigs or fixturing to apply (i.e. hand application) and can be applied at low temperatures compared to existing welding practices for repair and augmentation applications. The proposed work will develop a lower cost repair solution for railways and bridges