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7365 |
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Thursday, May 05, 2022, Hall -2.32/33 1:40 PM Electronics & Sensors |
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Microstructure, oxidation behavior and electrical properties of the suspension sprayed ZnO-TiO2 coatings for heating elements applications |
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Oliver Kunze* / Technische Universität Dresden, Germany Filofteia-Laura Toma / Fraunhofer Institute for material and beam technology IWS, Germany Anja Meyer/ Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany Stefan Scheitz/ Fraunhofer Institute for material and beam technology IWS, Germany Annegret Potthoff/ Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Germany Christoph Leyens/ Technische Universität Dresden / Institute for material sciences, Germany |
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There is a widespread need in commercial and services sectors for controlled tempering and/or heating of devices, machines and system components. Thermally sprayed multilayer coating systems composed of ceramic electrically insulating and conductive layers can answer this need. Earlier developments usually made use of metallic (i.e. NiCr-based) and ceramic (i.e. TiOx) heating layers which have mostly a limited application temperature because their oxidation behavior. In this contribution suspension spraying was used to produce conductive heating layers in the ZnO-TiO2 coat-ing system. Unary suspension starting from a Zn2TiO4 raw powder and binary suspensions containing fine dispersed ZnO and TiO2 (anatase, rutile) raw feedstocks are used for suspension spraying. The microstruc-ture and phase composition of the suspension sprayed coatings are evaluated by SEM/EDX microscopy, X-Ray diffraction and XRF-analysis. In terms of suitability for electrical heating systems, DC-measurements are performed to evaluate the electrical resistivity. Thermal stability and oxidation behavior of the coatings during heating and thermo-cycling tests at temperature up to 600 °C are investigated. The influence of the suspension formulation, spray parameters and coating build-up on the electrothermal properties will be discussed. |