Cold gas spraying

HSU/Alexander List

In cold gas spraying, a feedstock powder is accelerated by a heated gas stream and shot onto a workpiece. Powder particles hit the substrate at supersonic speed and deposit on the surface to produce coatings or bulk parts. During the coating deposition, the spray material does not melt. Thus, material can be build-up without any undesired influences by oxidation or metastable phase formation during solidification, retaining the properties of the respective powder. Under ideal conditions, deposits reach mechanical strengths similar to those of respective bulk materials. The process can be carried out fully automated.
The major advantage of cold gas spraying concerns the high deposition rates, which can range up to 14 kg per hour. Depending on application, typical deposit thickness can be adjusted between 0.1 millimeters in case of functional coatings, up to several centimeters for processing full size parts. By high deposition rates and geometrical constraints, processing geometric details is limited to a resolution of some millimeters.
Besides commercial metals and metal alloys, it is also possible to process unconventional materials by cold gas spraying, as for instance amorphous metals.