Abstract No.:
2961

 Scheduled at:
Tuesday, September 27, 2011, Saal B2.2 3:15 PM
Tribological Coatings 1


 Title:
Thermophysical and microstructural studies on thermally sprayed chromium carbide coatings

 Authors:
Sven Thiele* / Fraunhofer Institute for Ceramic Technologies and Systems, Germany
Lutz-Michael Berger/ Fraunhofer Institute for Material and Beam Technology, Germany
Jörg Spatzier/ Fraunhofer Institute for Material and Beam Technology, Germany

 Abstract:
Cr3C2-NiCr is widely used as standard composition for hardmetal coatings due to the high oxidation and corrosion resistance. Moreover, because of their lower density in comparison to WC-based compositions chromium carbide based coatings are attractive for rolling contact fatigue (RCF) applications. It can be also stated that the standard commercially available feedstock powder compositions, which have been on the market for long time, are not optimized for the preparation of coatings by thermal spraying for use under RCF conditions. The development of improved feedstock material requires in addition to optimization the coating structures the use of modelling processes. To obtain reliable data of thermal spray coatings for modelling in the present work thermophysical data of HVOF-sprayed Cr3C2-25NiCr - coatings from two different feedstock powders from room temperature up to 700 °C were determined. Thermal diffusivities, density functions, specific heat capacities and technical expansion coefficients in the specified temperature range were measured in order to compute the heat conductivity for the coatings. All measurements were performed twice (as-sprayed and after a first thermal cycle) in order to take into account the structural and compositional changes. XRD and FESEM studies were performed in order to characterize the phase compositions and microstructures in the as-sprayed and heat-treated states.

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