ALSTOM K4-Injector-Block – Advanced HVOF-spraying for future applications

HVOF spraying has established itself in the last decade as a very cost competitive method, replacing more and more VPS/LPPS for the application of typical high temperature protective metallic coatings on IGT hot gas path components. In order to further improve this technology, ALSTOM recently developed a new design of 4-injector-block for the K2-gun. This advanced design does not only significantly optimize the energy consumption and spraying time, but also enables the future application of new complex metallic coatings.

A CFD simulation of the K2-gun was performed in order to identify the optimization potential. Based on the outcome, an improved prototype was manufactured, validated and successfully introduced into manufacturing. Target of the study was also to investigate in detail the impact of the hardware modification on parameters like spray spot geometry, deposition efficiency, fuel consumption and the corresponding coating quality (porosity, bonding etc.), which shall be discussed within this paper.