The Benefit of an On-Line Diagnostic System for the Optimization of Plasma Spray Devices and Parameters

Abstract

Abstract The coating characteristics of plasma sprayed layers are strongly related to the spray parameters and the gun design which also determine the state of the sprayed powder particles upon impact. On-line optical measurements of particle velocity and temperature can be used for the optimization of the spray parameters as they provide information of both, characteristic of the coating as well as process stability and performance of the plasma process. With the DPV-2000 diagnostic system the correlation between particle and coating characteristics have been investigated, especially for the new Triplex technology. Differences observed in the distribution of the particle properties between the Triplex and F4 gun are due to different standard spray parameters and correlated to the inherent difference of the operation principle of both plasma guns. The typical three fold symmetry of the Triplex plasma and powder injection is observed within the particle distribution pattern which also depends on the type of powder and spray parameter used. With the help of DPV-2000 measurements it is also possible to demonstrate the excellent process stability of the Triplex gun and to define and adjust parameter windows for different applications in order to obtain the desired range of coating properties. The advantages of the DPV-2000 diagnostic should also contribute to an enhanced basic understanding of new spray processes such as the LPPS Thin Film technology. Experiments have been performed to prove the feasibility of particle diagnostics under these special spray conditions. First results are presented.