Production and Characterisation of Metastable Al2O3-TiO2 Coatings Obtained by APS plus Quench

It is well known that microstructure evolution during rapid solidification depends on the rate between undercooling and solidification velocity. Microstructural evolution in a non-equilibrium solidification process depends critically on the melt undercooling and growth (solidification) velocities of competing phases. One way of obtaining metastable structures is by Thermal Spray Technology. Metastable coatings can be produced starting from microstructured powders through Atmospheric Plasma Spray (APS) technique, followed by a quenching route. The initial powders are melted during the spraying and deposited over a substrate that is quenched with nitrogen feeders, producing metastable coatings. The obtained coatings were characterized using XRD, SEM, FESEM and TEM in the Thermal Spray Centre (CPT) of the University of Barcelona. The properties of such coatings were studied by hardness, obtaining promising results.