DotumChe;mso-bidi-font-family:Gulim" lang="EN-US">This presentation gives an overview concerning basic principles of Cold Spraying (CS) and Aerosol Deposition (AD) for making the methods suitable for applications. As powder spray techniques dealing with solid impacts, both methods result in coatings of high purity and unique properties, not attainable by other spray methods. The presentation summarizes current models and key parameters for both techniques to achieve and to improve bonding and coating qualities, and gives examples for applications in electronics, mechanical part repair and additive manufacturing.

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DotumChe;mso-bidi-font-family:Gulim" lang="EN-US">Cold Spraying deals with supersonic velocity (400  900 m/s) impacts of deformable metal powders in sizes typically between 15 and 50 µm, as attained by acceleration in an expanding, high pressure (10-50 bar) gas jet in a converging/diverging nozzle. With cold spraying, thick deposits of up to several centimeters can be build-up, applicable as additive manufacturing technique. Supported by modelling, reaching and exceeding the critical velocity, and thus influences on coating quality, are associated with the occurrence of adiabatic shear instabilities, means thermal softening over-compensating strain and strain rate hardening effects under severe, high strain rate plastic deformation at particle-particle interfaces.

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DotumChe;mso-bidi-font-family:Gulim" lang="EN-US">Aerosol deposition deals with high velocity impacts of ceramic particles in sizes of typically less than one micron and impact velocities of typically 100 to 500 m/s. For avoiding the interaction with the surrounding atmosphere and possible particle deceleration, the coating process has to be performed in vacuum. Small particles easily adopt the velocity of the gas stream, low pressures (typically < 1 bar) and straight nozzle outlets are sufficient to reach needed velocities for bonding. Coating formation is typically associated by a grain refinement as compared to the feedstock powder. By AD, coatings with some tens of microns in thickness be build up, so far bridging the gap between thin film technics and powder spraying.