Abstract No.:
2638

 Scheduled at:
Tuesday, September 27, 2011, Saal A 2:50 PM
Metals Processing 1


 Title:
Properties of low-pressure cold sprayed coatings for repairing of casting defects

 Authors:
Heli Koivuluoto / Tampere University of Technology, Finland
Mikko Kylmälahti / Tampere University of Technology, Department of Materials Science, Finland
Petri Vuoristo*/ Tampere University of Technology, Department of Materials Science, Finland

 Abstract:
Low-pressure cold spraying (LPCS) is a coating technique, where a portable cold spray system, e.g., DYMET 304K system is used to prepare technical coatings. Usually, compressed air is used as a process gas. The LPCS process is an appropriate method for spraying of metallic-ceramic composite powder materials, e.g., Cu, Ni, Zn, Al with additions of Al2O3 particles in the powder blends. The main functions of the hard ceramic particles are cleaning the nozzle, activating the sprayed surface and hammering the coating structure. This method has advantages for example in the field of repairing and restoration applications. For that, repairing casting defects and voids is one interesting application of the process. For these purposes, zinc-based composite materials are recommended for restoration and repairing of corrosion and mechanical damages. In this study, Zn+Al+Al2O3, Zn+Cu+Al2O3 and Zn+Ni+Al2O3 composite materials were investigated. Zinc and aluminum give corrosion resistance whereas copper and nickel can provide more mechanical resistance. Coating properties, such as microstructures, open-cell potential behavior and mechanical properties (hardness and adhesion strength) were investigated. The coatings have relatively dense coating structures and for corrosion resistance, zinc gives a cathodic protection for other materials in these composite coatings. Furthermore, mechanical properties are sufficient due to the relatively high hardness and adhesion to the Fe52 base material. These coatings have high potential in their use as repair materials for macroscopic casting defects.

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