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7263 |
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Friday, May 06, 2022, Hall K2 2:40 PM Process Diagnostics, Sensors & Controls |
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Importance of correct evaluation of in-flight particle state in thermal spray coating quality |
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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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In-flight particle state has been shown to have a crucial role in determining the properties of thermally sprayed coatings. Therefore, process control strategies have been suggested to keep the in-flight particle state constant in order to decrease the coating quality variability. Such strategies are already used to some extent in industrial applications, where the particle state is measured before starting a coating. Only if the measured particle state is inside the process window, does the coating commence. In this paper we show the importance of the evaluation procedure of the in-flight particle state on the measurement uncertainty of the evaluated particle state, which in turn limits the possibility of differentiating between various particle states, and thus also affects the process control. This paper demonstrates this on the example of atmospheric plasma spraying of yttria-stabilized zirconia (YSZ) using a commercially available sensor Accuraspray for measuring the ensemble particle temperatures and velocities as well as the intensity of the particle jet. It is concluded that the stabilization time of the particle jet might be different from what is practically considered, which leads to a trade off between the usefulness of such a diagnosis technique and its measurement uncertainty. |