Homogenization of coating properties in atmospheric plasma spraying - technical objectives and first results of a DFG funded research group

摘要

The disadvantage of plasma torches using conventional single cathode techniques is the occurrence of azimuthal and axial instabilities inside the plasma torch. This causes electrical power fluctuations which result in inhomogeneities of the plasma jet enthalpy and with that an uneven plasma particle interaction. Hence, variations in particle properties occur and consequently an uneven coating quality is produced. Using the triple-cathode technique these electrical power fluctuations were successfully reduced, resulting in a stationary plasma flow. Thus this technique appears to offer the potential to homogenize coating properties. Similar results have been shown for plasma torches with triple anode arrangements. The goal of this research group is to homogenize properties of plasma sprayed coatings using of 3-cathode and 3-anode technologies based on numerical simulations. The approach used is to subdivide the complete APS process into the areas plasma torch, free jet as well as coating formation and characteristics. By simulation of the individual areas and combination with experimental results the corresponding process parameters will be obtained for the desired coating properties.