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Thermophysical and microstructural studies on thermally sprayed chromium carbide coatings

: Thiele, Sven; Sempf, Kerstin; Berger, Lutz-Michael; Spatzier, Jörg

Deutscher Verband für Schweißen und Verwandte Verfahren e.V. -DVS-; The Thermal Spray Society -TSS-; International Institute of Welding -IIW-:
ITSC 2011, International Thermal Spray Conference & Exposition. CD-ROM : Abstracts; Including manuscripts on CD-ROM, of the conference in Hamburg on September 27 - 29, 2011 in the context of DVS Congress and DVS Expo
Düsseldorf: DVS Media, 2011 (DVS-Berichte 276)
ISBN: 3-87155-268-2
ISBN: 978-3-87155-268-7
ISSN: 0418-9639
International Thermal Spray Conference & Exposition (ITSC) <2011, Hamburg>
Deutscher Verband für Schweißen und Verwandte Verfahren (DVS Studentenkongress) <2011, Hamburg>
Conference Paper
Fraunhofer IWS ()
Fraunhofer IKTS ()
Wärmeleitfähigkeit; Chromcarbid; Hochtemperatur; Raumtemperatur; Wärmeausdehnungskoeffizient; spezifische Wärme; Hochgeschwindigkeitsspritzen (Sauerstoff); Phasenzusammensetzung; Mikrostruktur; thermische Eigenschaft; Erosionsbeständigkeit

Cr3C2-NiCr coatings are commonly used to provide abrasion and erosion wear resistance on the surface of components, in particular for corrosive and atmospheric high-temperature environments. For these classical and new applications the knowledge of the thermophysical properties is highly important. In the present work the dependence of the heat conductivity on temperature of two HVOF-sprayed Cr3C2-25NiCr-coatings prepared by a liquid-fuelled HVOF-process from two different feedstock powders from room temperature up to 700 °C was determined. Thermal diffusivities, density functions, specific heat capacities and coefficient of thermal expansion (CTE) were measured in order to compute the heat conductivity for the coatings. All measurements were performed twice (as-sprayed and after a first t hermal 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. Heat conductivities (average of the two coatings) ranging from about 11 W/(mK) at 50°C up to about 20 W/(mK) at 700°C were determined. Differences between the two coatings were clearly detectable. The heat conductivity of the Cr3C2-NiCr coatings is significantly lower than determined previously for a WC-17%Co coating.