Cold Spray Coating Technology: At ARCI

Cold Gas Dynamic Spraying (CGDS) or Cold Spray is a relatively new thermal spraying process in which powder particles (typically 1 to 50 mm in diameter) are accelerated to velocities of the order of 500 to 1000 m/s in a supersonic jet of high pressure gas. Upon striking a target surface, the powder particles undergo severe plastic deformation and form a coating on the target, which is built up layer by layer. It bears immense promise especially for retaining the microstructure present in the feedstock as it is not heated in the jet to the point where any significant chemical/microstructural changes are experienced. The presentation would provide an overview of the several aspects of cold spraying including particle diagnostics, microstructural characterization, property evaluation etc., as detailed below.

The talk would begin with modeling studies of gas particle transport phenomena for the flow through a De Laval nozzle along with particle diagnostics studies using high speed imaging systems. Results of modeling studies including validation studies, model sensitivity analysis, regression analysis etc., will be presented. The influence of process parameters and heat treatments on the properties of cold spayed coatings will be presented. The microstructural aspects of cold sprayed nanocrystalline coatings with specific reference to nanocrystalline copper alumina coatings along with the underlying mechanisms will also be presented.

The immense promise of cold sprayed coatings for applying cost effective corrosion resistant coatings (Zinc based alloys and stainless steel) will be shown along with a comparison with the coatings from conventional thermal spraying techniques. The presentation shall end with a discussion on the various methods to assess the quality of the cold spray coatings especially with regard to inter-splat bond strength.