HVOF Suspension Spraying of Alumina-based Coatings

In this study, various alumina-based suspensions were prepared by changing powder size (from 2 micron up to 15 micron) and solvent composition (water based, alcohol based, and mixtures of the both solvents in different mixing ratios). Using these suspensions, dense alumina-based coatings were deposited using DJ 2600 HVOF system (Sulzer Metco) with a modified nozzle. Effects of suspension characteristics (powder size and solvent composition) as well as HVOF process parameters (fuel amount, stand-off distance, suspension feedrate, etc) on the coating properties were evaluated, and based on these results, proper conditions in preparing alumina-based suspensions for HVOF spraying is discussed in the present work.