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7260 |
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Wednesday, May 04, 2022, Hall -2.32/33 11:30 AM Pre- & Post-Treatment |
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Analysis and comparison of online coating thickness measurements using two different sensing techniques |
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Majid Nabavi / Oerlikon Metco AG, Switzerland Uroš Hudomalj* / ETH Zürich University, Switzerland Ehsan Fallahi/ Oerlikon Metco, Switzerland Konrad Wegener/ ETH Zürich University, Switzerland Lukas Weiss/ Inspire AG, Switzerland |
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Coating thickness is one of the most important parameters of thermal spray coatings. Therefore, real-time thickness control has long been the goal of many research and practices. However, in order to be able to control the coating thickness, one must first be able to measure it online and with a sufficiently small uncertainty. Online measurement of coating thickness based on the differential distance measurement method has been demonstrated in the past to provide promising results. However, the measurement uncertainty of using the approach has not been sufficiently addressed. Moreover, there exist different sensing techniques for measuring the distance. This paper analyzes two approaches for online coating thickness measurements – using confocal distance sensors and length gauges. They are used in a standard turn-table setup for coating the samples while simultaneously measuring the thickness. The paper addresses the sources of their measurement uncertainties, showing that the contribution to the uncertainty of the setup is as important as the contribution of the sensors themselves. Moreover, the paper compares the two online approaches with a reference, destructive coating thickness measurement method. It shows that the surface roughness of the coating influences the thickness measurement. Pros and cons of both online approaches are discussed. |