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Monday, May 4, 2009 - 4:00 PM

Densification of Atmospheric Plasma Sprayed Wear Resistant Coatings

W. Tillmann, E. Vogli, B. Krebs, V. Franzen, Technische Universität Dortmund, Dortmund, Germany

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Deep drawing of high strength steels imposes high tribological requirements on forming tools. Thermal spraying is regarded as a promising technology to improve the tool’s performance and the service life of the forming tool, as long as ambitious demands of the coating process are matched. However, the surface quality especially on complex geometries does not fulfil the required targets. A novel approach to optimize thermally sprayed coatings is densification by rolling. This process shows a high potential to reduce surface roughness and enhance properties like porosity and hardness even on free formed surfaces.

In the present study metal matrix composite coatings were manufactured by atmospheric plasma spraying and the coatings were densified by a subsequent rolling procedure. Two level screening experiments by means of Design of Experiments (DoE) were done and main influencing parameters were found. Based on these results the process could systematically be improved.


Summary: This study deals with the manufacturing of dense and smooth hard material based coatings by atmospheric plasma spraying combined with a subsequent densification. Spattered and broken Cr3C2-NiCr powders with varying compositions were investigated. To identify the most relevant process parameters a statistical design of experiments was carried out. Two level screening experiments by means of the Placket-Burman method and a two level full factor factorial standard design have been conducted.