Cold spraying
While experimenting with the particle erosion of the target, which was exposed to a two-phase high-velocity flow of fine powder in a wind tunnel, scientists observed accidental rapid formation of coatings.
Main influential factors are: Cold spray parameters are selected with respect to the desired coating characteristics and economic considerations.
Being a cold process, the initial physical and chemical particle properties are retained and the heating of the substrate is minimal, resulting in cold-worked microstructure of coatings where no melting and solidification happen.
Other advantages are:[13] The jet obtained is a high-density particle beam due to the small size of the nozzle (10–15 mm2) and the short stand-off distance (25 mm).
For instance, it is difficult to spray hard and brittle materials because, in this case, mechanical adhesion through plastic deformation could be not as effective as it is for ductile particles.
CS can generally be used to produce coatings of a wide variety of metals, alloys, and metal-based composites, including those materials that have an exceptionally high melting temperatures (e.g. tantalum, niobium, superalloys).
Metal (nickel alloys) particles travel in a blend of nitrogen and helium gas and gradually stack up on the damaged part to recreate the desired surface.
This means that metals are not affected by heat-related distortion, and parts do not need to be manufactured in an inert gas or vacuum sealed environment, allowing the creation of much larger structures.
The world's largest and fastest metal 3D printer has a build envelope of 9×3×1.5 m and utilizes gas dynamic cold spray.
Manufacturing with cold spray technology provides advantages such as the ability to create shapes with no shape or size constraints, more efficient buy-to-fly ratio when compared to machining, and capable of fusing dissimilar metals to create hybrid metal parts – materials such as titanium alloys, copper, zinc, stainless steel, aluminium, nickel, even hastelloy and inconel can be sprayed together.
