Temperature measurement challenges and limitations for in-flight particles in suspension plasma spraying

Suspension plasma spraying (SPS) acquires a significant interest from the industry. The deposited coatings using this technique were proved to have unique microstructural features compared to those built by conventional plasma spraying techniques. In order to optimize this process, in-flight particle diagnostics is considered a very useful tool that helps to control various spraying parameters and permits better coating reproducibility. In that context, the temperature of in-flight particles is one of the most important key elements that helps to optimize and control the SPS process. However, the limitations and challenges associated with this process have a significant effect on the accuracy of two-color pyrometric techniques used to measure the in-flight particle temperature. In this work, the influence of several nonthermal radiation sources on the particle temperature measurement is studied. The plasma radiation scattered by in-flight particles was found to have no significant influence on temperature measurement. Moreover, the detection of the two-color signals at two different locations was found to induce a significant error on temperature measurement. Finally, the plasma radiation surrounding the in-flight particles was identified as the main source of error on the temperature measurement of in-flight particles.Peer reviewed: YesNRC publication: Ye