Tomographic investigation of the injection conditionsin the case of suspension plasma spraying

In order to be able to feed feedstock with particle sizes in the nanometre range into the process, suspensions are being utilised for thermal spraying. However, if the suspension is injected radially, the material injection is significantly more complex than in conventional thermal spraying processes. This is caused by the two-phase nature of the suspension, by the resulting rheological and fluidmechanical properties of the suspension and by the interaction between these properties and the process parameters. The utilisation of tomography in order to investigate injection conditions in the case of suspension plasma spraying (SPS) is presented in this article. As is shown, injection conditions leading to improved coating properties can be found on the basis of tomographic measurements.