https://commons.ru.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:33435 direction perpendicular to the coating/ZIRLO interface. The corrosion testing at various temperatures from 400 to 900 ℃ for 30 minutes showed that the TiZrN coating oxidises slowly and retained its microstructure, composition and crystallinity up to 600 ℃. At higher temperatures above 600 ℃, the TiZrN layer completely oxidised to a non-protective TiZr-oxide layer and resulted in rapid corrosion of the underlying ZIRLO substrate. The rapid corrosion was not observed in the uncoated ZIRLO sample for all temperatures. The results of samples subjected to annealing treatment at 500 ℃ in an oxygen atmosphere at various times up to 24 hours revealed that the TiZrN layer oxidises faster than ZIRLO. This was confirmed by sub-cubic and sub-parabolic oxide growth kinetics observed in the uncoated ZIRLO which are slower than the parabolic kinetics of TiZrN coated samples. In all coated samples, the spallation was observed near the edges of the samples. The spallation was caused by rapid corrosion of the underlying ZIRLO substrate which resulted from the penetration of oxygen ions between the TiZrN coating and ZIRLO substrate along the edges of the samples. In pure steam for 30 days at 360 ℃, a complete loss of the TiZrN layer occurred but the results show that the coating might have delayed the corrosion of ZIRLO. In summary, corrosion resistance of nc-TiZrN coated ZIRLO was lower than that of uncoated ZIRLO. The study shows that the failure of TiZrN coatings leads to rapid corrosion of the underlying ZIRLO substrate which was not observed on the uncoated ZIRLO. It is not yet understood why the presence TiZrN coatings reduced the oxidation resistance of ZIRLO.]]> Wed 12 May 2021 22:53:06 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:70622 272 kh). The Fe/Cr and Fe/Mo ratios in overall carbides decreased from 5 and 10 (initial state) to 1 and 2 (>272 kh), respectively. The TKD analysis indicated that the relative phase proportion of M2C and M7C3 carbides, relative to the total extracted carbides, is positively correlated with service exposure. These microstructural features correlate with the creep life fraction consumed and could potentially be used as another indicator of the remnant creep life.]]> Tue 12 Dec 2023 15:05:41 SAST ]]>