Abstract No.:
2499

 Scheduled at:
Wednesday, September 28, 2011, Saal A 2:25 PM
New Processes 2


 Title:
HVOF K2 vs. cold gas spraying

 Authors:
Alexander Schwenk / GTV Verschleiss-Schutz GmbH, Germany
Andreas Wank* / GTV Verschleiss Schutz, Germany

 Abstract:
A conventional GTV K2 kerosene fuel HVOF spraying system has been modified with the aim to achieve process conditions comparable to cold gas spraying concerning the average particle velocities and surface temperatures in the spray distance. The employed measurements include the use of expansion nozzles that have been optimized for supersonic conditions up to a Mach number of 2.5, the use of combustion chambers with reduced critical diameters that provide increased combustion chamber pressures up to 1600 kPa and the injection of the coolant medium water into the combustion chamber.
Copper powders with different size fractions and oxygen content are sprayed with the novel HVOF technology. Coatings are analysed concerning their microstructure, oxygen content and electrical conductivity. In-flight particle velocities and surface temperatures are determined by the GTV NIR Sensor. Results are compared with those obtained for cold gas spraying using identical powders. The new HVOF technology permits the production of copper coatings that show similar levels of porosity, oxygen content and electrical conductivity like cold gas sprayed coatings.
Also aluminium powder has been sprayed successfully with the novel technology. In-flight particle velocities can be almost as high as in modern cold gas spraying systems. Coatings are analysed and show a microstructure comparable to cold gas sprayed coatings.
The paper discusses economical aspects comparing cold gas spraying with the novel HVOF technology.


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