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High-temperature thermal fatigue causes the failure of thermal barrier coating (TBC) systems. This paper addresses the development of thick TBCs, focusing on the microstructure and the porosity of the yttria partially stabilized zirconia (YPSZ) coating, regarding its resistance to thermal fatigue. Thick TBCs, with different porosity levels, were produced by means of a CoNiCrAlY bond coat and YPSZ top coat, both had been sprayed by air plasma spray. The thermal fatigue resistance of new TBC systems and the evolution of the coatings before and after thermal cycling was then evaluated. The limit of thermal fatigue resistance increases depending on the amount of porosity in the top coat. Raman analysis shows that the compressive in-plane stress increases in the TBC systems after thermal cycling, nevertheless the increasing rate has a trend which is contrary to the porosity level of top coat.

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Tin sulfides present electrical and optical properties, which give them high potential use in opto-electronic devices and photoconductive cells, i.e. photovoltaic applications. In this paper we report an electrochemical study of a tin solution, carried out by cyclic and stripping voltammetry. These techniques allow to establish the presence of surface limited processes and, hence, to define the experimental conditions for the Underpotential Deposition of Sn on Ag(111) previously covered by a S monolayer. Moreover, we studied the growth of the first layers of tin sulfides.