Plasma-assisted reactive high-rate vapor deposition of yttria-stabilized zirconia using electron beam evaporation and spotless vacuum arc
Some applications in energy technology will require large-area and dense coatings of yttria-stabilized zirconia(YSZ)while high coating rate is demanded for economic reasons. A combination process of co-evaporation of yttriumandzirconiumby EB-PVD from a dual crucible, reactive processing procedure of introducing oxygen, and aspotless arc burning between zirconiumas cathode and yttriumas anode were investigated experimentally. TheYSZ layers were deposited at relatively high static coating rates (20 to 80 nm s−1) in comparison to other PVDprocesses. The cubic crystal structure that was identified by means of XRD corresponds to the YSZ phase withthe highest ionic conductivity and is therefore especially well-suited for use as a solid-state electrolyte.Pores were evidenced in the microstructure of the layers deposited at a coating rate of N50nms−1. Nevertheless,very dense YSZ layers could be obtained at a coating rate of 30nms−1 and a spotless arc current of 300 A. Specificleakage rates of YSZ layers on porous Ni/NiO-YSZ anode substrates measured using air are in the region of1 Pa m s−1. The investigations have shown that the intense plasma created with a spotless arc has a considerableinfluence on growth and microstructure of YSZ layers, even at high coating rates.