Abstract
One of the greatest obstacles for a wide distribution of thermal spraying techniques is the lack of online control over the spraying process. The thermally sprayed coatings are optimized by an empirical modification of the spraying parameters and the subsequent correlation of these parameters to the obtained coatings. Some intrinsic parameters, such as the fluctuations in twin wire arc spraying and wear in the atomization nozzle, are not adjustable. Even though they have an enormous impact on the obtained coating quality, they are often scientifically neglected for reasons of simplification. In this work, acoustic emission analysis is utilized to study the effect of uncontrollable parameters on acoustic signals. In order to enable an easy determination of the changes in the acoustic signals, the acoustic sensors were mounted on the spraying nozzle as well as on the substrate. At increased current, a lower acoustic emission is recorded. A correlation between uncontrollable parameters, the acoustic signals, and the obtained coating quality was observed. This research contributes to the online control of the spraying process.
