Transonic Flow Phenomena of the Cold Spray Deposition Process

Abstract

The cold spray deposition process is an emerging technology for coating surfaces. Micron-sized particles are accelerated and transported to substrates by means of supersonic free jets. Upon impacting the substrate, particles stick to the surface and form coatings. In contrast to well-known thermal spray processes particles are not melted throughout the whole process, hence the prefix cold. In the cold spray process a number of different transonic flow regimes are encountered. Phenomena characteristic of the various transonic regimes will be introduced and discussed making reference to results obtained at the pilot facility for cold spray of the German Aerospace Center.