Influence of different plasma spraying methods on the physical properties of YSZ coatings

Abstract

Yttria-stabilized zirconia (YSZ) coatings were deposited at various arc currents of atmospheric plasma spraying. Two different technological configurations were used to form YSZ coatings; in first case, the plasma torch moved along the coated surface, while in another case, the coatings were formed on rotating substrate surface placed in front of the plasma torch. The thermal tests of the YSZ coatings were performed at temperature of 800 °C for 10 min. The surface morphology, elemental composition, phase structure and microhardness of YSZ coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Vickers indentation, respectively. It was obtained that the increase of the arc current from 180 A to 240 A enhanced the oxidation of the surface of the YSZ coatings. The XRD results indicated that the as-sprayed coatings consisted of the tetragonal ZrO2 phase. The YSZ/substrate ratio increased steadily from 0.05 to 4.4 (before the thermal effect) with the increase of the current from 160 A to 240 A, when coatings were sprayed on the rotating substrates. However, neither the substrate position nor the thermal effect influences the phase structure of the YSZ coatings. The YSZ coatings sprayed on the rotating substrates were less porous, had lower amount of micro or macro cracks, demonstrated higher adhesion and better resistance to the thermal impact compared to the YSZ coatings deposited on the immobile substrates.