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7300 |
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Thursday, May 05, 2022, Hall -2.32/33 2:20 PM Electronics & Sensors |
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Influence of the process parameters on the electrical resistance of mullite coatings |
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Elisa Olesch* / RWTH Aachen University, Germany Kirsten Bobzin / Surface Engineering Institute , Germany Wolfgang Wietheger/ Surface Engineering Institute , Germany Elisa Burbaum/ Surface Engineering Institute , Germany Nazlim Bagcivan/ Schaeffler Technologies AG & Co. KG, Germany M. Öte/ Schaeffler Technologies AG & Co. KG, Germany Björn Müller/ Schaeffler Technologies AG & Co. KG, Germany Carsten Kunde/ Diamant Metallplastic GmbH, Germany Anna-Lena Elsner/ Diamant Metallplastic GmbH, Germany |
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Various alumina-based materials can be applicated to achieve different electrical insulation properties based on the variation of the material specific relative permittivity. Thermally sprayed mullite (Al2O3 SiO2) can form an amorphous content due to the high cooling rates of the process. The formation of amorphous content causes a change in the AC-resistance. The tendency to form amorphous areas can be influenced by the composition of the feedstock material or coating parameters. On the one hand, mullite coatings based on two different compositions are investigated. On the other hand, a parameter variation was used to achieve various particle temperatures during the process. The coatings are investigated via X-ray diffraction for phase formation, electron microscopy for coating structure and impedance spectroscopy for measuring the AC-resistance. Particle diagnostics is used to correlate the analytic results with the in-flight particle temperatures. A variation of the feedstock material as well as the parameters causes different amounts of amorphous contents. These changes can be qualitatively imaged in the phase spectrum. An increased amorphous phase content correlates with a decreased AC-resistance. In summary, mullite has promising insulation properties which can be modified by the feedstock material composition as well as the coating parameters. For future application mullite is a good candidate for increasing the electrical insulation properties in conditions under high electrical and mechanical demands. |