Role of suspension preparation in the spray drying process to obtain nano/submicrostructured YSZ powders for atmospheric plasma spraying

Abstract

2014AbstractThermal barrier coatings were manufactured by atmospheric plasma spray process from YSZ powders. These powders were made by a reconstitutionprocess which consists in a spray-drying of suspensions followed by thermal treatment of the granules.Nano- and submicron-sized YSZ particles were used as starting material. Feeding well dispersed suspension to spray-drying chamber is thefirst key step in the reconstitution process. With this aim, concentrated, stable YSZ suspensions were obtained by means of the optimisation of thepreparation conditions. Then reconstituted granules were produced by spray-drying of the YSZ suspensions and the following thermal treatmentwhich was optimised.The reconstituted powders were then successfully deposited on austenitic stainless steel coupons by APS. The findings in this work proved thatthe reconstituted powders characteristics which in turn are related to the starting suspension properties affect the final coating microstructure interms of the amount of unmelted zones