Abstract No.:	2220
Scheduled at:	Monday, May 03, 2010, Olivia Room 4:40 PM Paper and Printing
Title:	Cold spraying of Zn and Zn-alloy coatings for print applications
Authors:	Koichiro Onizawa* / Helmut-Schmidt-University Hamburg, Germany Jens Jansen / Helmut-Schmidt University, Germany Matthias Schulze/ Helmut-Schmidt University, Germany Frank Gärtner/ Helmut-Schmidt University, Germany Thomas Klassen/ Helmut-Schmidt University, Germany
Abstract:	Printing high number of copies is performed on the basis of engraving techniques. As state-of-the-art, requested depressions are produced by laser engraving, where the material is vaporized using an intense laser pulse. Zinc is ideally suited for laser evaporation due to a favourable combination of low evaporation temperature, low evaporation enthalpy, poor heat conductivity, and good absorption coefficient for the laser wavelength. Cold spraying can supply dense and defect free coatings and is intended to replace the time-consuming galvanic coating process. Furthermore, cold spray is also suited for Zn-based alloy. This opens opportunities for producing harder and more wear resistant coatings, which may allow for the production of larger numbers of copies without compromising quality. The contribution presents recent results on cold spraying of Zn, Zn-Al and Zn-Mg alloy powders. By careful tuning alloy compositions and spray conditions, dense coatings can be produced that are up to four times harder than pure bulk Zn, thus meeting the requirements for print applications. These new developments open opportunities for producing harder and more wear resistant coatings, which may allow for the production of larger numbers of copies without compromising quality.

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