This paper describes the development of an online process control system for spraying thick thermal barrier coatings as part of a Brite Euram research project. In addition to the evaluation of the substrate temperature, a system for acoustic emission analysis for particle impact and for controlling crack propagation is developed. The procedure, the problems overcome, and the results obtained are described. Paper includes a German-language abstract.

During the coating of components like rolls the major parameters are easily to control. But this is not sufficient to guarantee and stable a high coating quality. Additionally non-controllable parameters, e. g. nozzle wear, influence the process mainly. For this purpose a new testing method is necessary. On base of the acoustic emission analysis a testing equipment was developed in order to control the spraying conditions. In this investigation acoustic emission is applied to anlyse the signals generated by the impact of the molten particels on the component surface. The analysis of the signals is carried out in combination with a new classification method. The results of controlling APS(Atmosperical Plasma Spraying)-process during the disposition of a Cr2O3- coating will be presented. Paper text in German.