Abstract No.:
2869

 Scheduled at:
Tuesday, September 27, 2011, Saal A 2:25 PM
Metals Processing 1


 Title:
Tribological behavior of novel suspension plasma sprayed coatings for hot extrusion tools

 Authors:
Martin Erne* / Leibniz Universität Hannover - Institut für Werkstoffkunde, Deutschland
Daniel Kolar / Institute of Materials Science, Leibniz Universität Hannover, Germany
Kai Möhwald/ Institute of Materials Science, Leibniz Universität Hannover, Germany
Friedrich-Wilhelm Bach/ Institute of Materials Science, Leibniz Universität Hannover, Germany

 Abstract:
Up to now no coating systems are marketable in the field of direct hot extrusion, which provide both surface protection of the parts being in contact to the billet (i.e. container and die), and a significant reduction of the frictional losses being induced by the billet passing along the container walls. To dispense the use of lubricants and to enhance the usable forming capacity of the process, the results of achieving suspension plasma sprayed coatings are presented, which show a reduction of their coefficient of friction under dry sliding conditions. To reach this goal a new approach was chosen to achieve the functional phase content in the coating by mixing of different oxide ceramics in the plasma using the high surface-to-volume ratio of the feedstock with primary particle sizes below 100 nm. By means of x-ray diffraction it could be proven, that the desired phases could be synthesized, but the contents in the coatings are quite low. Nevertheless the coatings showed a considerable lowering of their frictional coefficient in tribological testings below 0.1 against 100Cr6 in the region of the operation temperatures for the hot extrusion of aluminum alloys. Furthermore in miniature hot extrusion experiments a significant lowering of the required forming force could be recorded. Nevertheless the adhesion and cohesion of the coatings have to be optimized due to the high demands of the operation in the hot extrusion process. Beside those results the topics concerning the dispersion of nanosized feedstock and the mass flow controlled feeding and injection into a Sulzer Metco Triplex II and a GTV Delta gun are discussed. Furthermore the characteristics of both guns concerning the Suspension Plasma Spraying Process are outlined.

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