Abstract No.:

Requirements on ceramic substrate properties for surface functionalization by thermal spraying

Filofteia-Laura Toma* / Fraunhofer Institute for Material and Beam Technology, Germany
Stefan Scheitz/ Technische Universit├Ąt Dresden, Germany
Lutz-Michael Berger/ Fraunhofer Institute IWS, Germany
Thomas Kuntze/ Fraunhofer Institute IWS, Germany
Sven Thiele/ Fraunhofer Institute IKTS, Germany
Christoph Lyphout/ University West, Sweden
Richard Trache/ University West, Sweden
Nicolaie Markocsan/ University West, Sweden

A key challenge in the realization of thermally sprayed coating solutions on ceramic substrates consists in the setting of an appropriate substrate roughness. The aim of the work deals with the evaluation of the sprayability of porous and dense Al2O3 ceramic substrates. Depending on their properties, the substrates were coated either directly or pre-treated with conventional sand blasting. As an alternative to sand blasting, the modification of the substrate surface by laser structuring (laser ablation) was also proposed. The laser structuring was performed using a pulsed solid-state diode laser at a wavelength of 355 nm. The coating was performed by APS and HVOF using Al2O3 as feedstock powder. Substrates with suitable porosity and mechanical strength could be directly sprayed. Pretreatment dense substrates by blasting led to damage and crack formation at the substrate / layer interface. With laser ablation method different laser structured substrate surfaces could be generated. In this type of pretreatment, the sprayed coatings showed an optimum bond to the substrate and could be sprayed in the required coating thicknesses.

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