h1

%0 Thesis
%A Olesch, Elisa
%T Methodik zur Bewertung und Entwicklung plasmagespritzter Schichten zur elektrischen Isolation
%V 81
%I RWTH Aachen University
%V Dissertation
%C Düren
%M RWTH-2024-11131
%@ 978-3-8440-9727-6
%B Schriftenreihe Oberflächentechnik
%P 1 Online-Ressource : Illustrationen
%D 2024
%Z Druckausgabe: 2024. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2025
%Z Dissertation, RWTH Aachen University, 2024
%X Rolling bearings in inverter-fed motors experience premature failure due to high electrical load despite existing protective measures. The application of Al<sub>2</sub>O<sub>3</sub> protective coatings using thermal spraying is already an established method for protecting bearings against current flow. The aim of this work is to improve the insulation protection coatings with alternative coating concepts. The coating development carried out is accompanied by a new methodological approach. Free-standing coatings and coated flat samples are examined using a newly designed impedance measurement setup. The impedance spectroscopy is validated and tested for the sample types mentioned. Plot simulations and fittings of impedance curves are carried out in order to achieve the goal of improved electrical insulation. In the final step, three selected newly developed composite coating systems are tested on bearing rings in a demonstrator. Using the methodology described and impedance spectroscopy, it was possible to show that mullite represents a significant improvement in electrical insulation compared to Al<sub>2</sub>O<sub>3</sub>. In particular, Al<sub>2</sub>O<sub>3</sub> reconditions more slowly when exposed to moisture from the environment. Mullite on the other hand is less affected by the surrounding humidity and therefore represents a fundamental advantage for the adressed application. The demonstrator was able to show that the newly developed coating composite consisting of mullite and a new type of sealant is a suitable alternative to the Al<sub>2</sub>O<sub>3</sub> reference for use as a protective coating against electrical current. Based on the demonstrator tests, it was possible to reduce the number of critical current density by about 50 
%F PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
%9 Dissertation / PhD ThesisBook
%R 10.2370/9783844098273
%U https://publications.rwth-aachen.de/record/997190