[nanoPost] Nanostructured metallic coatings with higher mechanical and corrosion resistance pro

University Italy

Prototype apparatus for cold gas dynamic spray deposition of powder which will produce nanostructured metallic coatings with higher mechanical and corrosion resistance properties than traditional structured coatings. The principle of the cold gas dynamic spray is based on the acceleration of the particles by a high velocity gas. The solid metallic particles are introduced into the high-pressure chamber of a converging-diverging de Laval type nozzle and are accelerated in a supersonic stream by a propellant gas. The particles reach velocities of 500 to 1500 m/s. With these conditions, when the metallic particles impact a solid surface its kinetic energy is sufficient to cause a plastic deformation and the strengthening of the particles which impact with the substrate by a process analogous to the explosive welding. Advantages of the cold gas dynamic spray method include the ability to produce of coatings with properties that are close to the original powder and/or substrate, the absence of severe thermal exposure and oxidation of the powder and substrate. This technique is very promising to develop nanostructured coatings starting from metallic nanosized particles or from metallic nanostructured powders.

Sonoelectrodeposition is a technique that combining the potential benefit of electrodeposition of metals with ultrasound. The coupling of ultrasound to an electrochemical system acts as a source of activation, influences greatly the mass transport to the electrode/solution interface, as well as assists in situ cleaning, and the production of highly reactive intermediate species. For example, using pulse sonoelectrochemistry zinc powders with nanometric dimensions were produced. These powders were about three times more reactive than the commercial one. This method is a possible process route to produce metallic nanoparticles for several uses, such as catalysts, coatings etc.