Influence of plasma spraying parameters on properties of thermal barrier coatings

The aim of the present study is to investigate the influence of plasma spay deposition parameters on various properties of two standard thermal barrier coating (TBC) systems deposited on the steel substrate. Two TBC systems were investigated: NiCr–Al–Co–Y₂O₃/ZrO₂–Y₂O₃ and NiCr–Al–Co–Y₂O₃/ZrO₂–CeO₂–Y₂O₃. Powders were deposited by atmospheric plasma spraying (APS) with two variable parameters. The first variable was substrate temperature (21–23 and 160–180°C), and the second variable was transverse speed of the spraying gun (250 and 500 mm s⁻¹), i.e. coating thickness per one pass of the spraying gun. The quality assessments of TBC systems were made on the base of their microstructure, microhardness, tensile bond strength and thermal cyclic behaviour (thermal insulation properties and thermal cycling fatigue). Analysis of the results showed great influence of plasma spray deposition parameters on the quality of obtained TBCs.