Enhancement of the corrosion properties of cold sprayed Ti-6Al-4V coatings on mild steel via silica sealer

The pore formation associated with the cold spray process requires the development of an economical sealer to enhance the corrosion resistance of Ti-6Al-4V coatings on a mild steel substrate. Herein, a sound method is developed to seal pores in the cold sprayed Ti-6Al-4V coatings with silica sealer. Potentiodynamic polarization tests in 3.5 wt% sodium chloride electrolyte were employed to investigate the corrosion resistance of cold sprayed Ti-6Al-4V coatings fabricated at two standoff distances (30 and 70 mm) before and after the sealing process. The polarization resistance of cold sprayed Ti-6Al-4V coatings significantly increased by >80% after the sealing process. The electrochemical responses of cold sprayed Ti-6Al-4V were dependant on sealing the pores with agglomerated silica nanoparticles as observed by scanning electron microscopy and energy-dispersive X-ray analysis. The increase in polarization resistance makes the sealer an effective treatment for cold sprayed Ti-6Al-4V coatings used in marine environments and other engineering applications. This sophisticated sealing process can reduce the deposition cost by reducing the thickness of Ti-6Al-4V coatings and increasing their lifetime on metal components.