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Cyclic oxidation tests of sintered MCrAlY:Pt composites were carried out at temperatures of 1223 and 1273 K. Composite tablets were previously produced by spark plasma sintering. To assess an effect of platinum dispersed, microstructural characterisation was performed on the tablets before and after the cyclic oxidation treatment. Scanning electron microscopy analysis of the oxide layer showed that the presence of typical α-Al 2 O 3 and NiAl 2 O 4 spinel had structure columnar and equiaxial in both samples. Fine sintered microstructure and addition of Pt into the MCrAlY matrix enhanced the resistance of the material to cyclic oxidation.

The effect of the polyvinylpyrrolidone (PVP, MW = 130,000) molar content, PVP/Lu = 1, 2.5, 4 and 5; on the photoluminescent and structural properties of sol-gel derived Lu2O3:Eu3+, Bi3+ has been analyzed. Thin hybrid films were deposited by means of the dip-coating technique on silica quartz substrates. Films deposited at 700 °C presented a cubic structure, with non-preferential orientation, even with the presence of PVP. The photoluminescence (PL) spectrum and Comission Internationale de l’Éclairage (CIE) chromaticity diagram of films revealed a reddish Eu3+ emission at 612 nm (5D0 →7F2) with an excitation at 320 nm of the Bi ions (6s2→6s6p), showing a highly-effective energy transfer process form Bi3+ to Eu3+ luminescent centers. On the other hand, the color temperature of the samples is strongly dependent on the PVP content, as a consequence of the observed difference on the branching ratios of 5D0 →7FJ transitions of europium ions. Lifetime studies present two different behaviors for the thin films: A non-exponential nature for the lower PVP contents, and a simple exponential nature for the highest PVP one, showing that the PVP tends to promote a better dissolution of segregates and, therefore, increases the lifetime of the Eu3+ emission.

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This study compares the hot corrosion performance of yttria-stabilised zirconia (7YSZ), and 7YSZ + Gd 2 O 3 composite samples in the presence of molten mixture of Na 2 SO 4 + V 2 O 5 at 1150°C. For 7YSZ, the reaction between NaVO 3 and Y 2 O 3 produces YVO 4 and leads the transformation of tetragonal ZrO 2 to monoclinic ZrO 2 . A high-density in sintered 7YSZ + Gd 2 O 3 samples, led minor amounts of monoclinic ZrO 2 and tetragonal GdVO 4 as the hot corrosion products with only traceable amounts of YVO 4 , and a stable corroded layer was formed. Due to the synergic effect of doping of zirconia with Gd 2 O 3 , the 7YSZ + Gd 2 O 3 sample has a much better hot corrosion crack resistance than 7YSZ.