This paper deals with the morphology, constitutive phases and fine microstructures of some EBPVD processed yttria partially stabilized zirconia thermal barrier coatings. This study has been performed by X-ray diffraction and scanning and transmission electron microscopy. It was shown that the coatings studied were constituted of a single metastable tetragonal t' phase, as expected if one refers...

Sintering behavior with and without external stress was investigated using undoped and doped (1500 ppm yttria) sub-micron a-alumina powders. The yttria doped alumina showed anomalous behavior with grain size around 0.9 pm, a second peak in densification rate during free sintering and a stagnation followed by a steep increase in flow stress during sinter forging. These were thought to correspond...

Yttria-stabilized hafnia (YSH) films of 90 nm thickness have been produced using sputter-deposition by varying the growth temperature (T(s)) from room-temperature (RT) to 400 °C. The effect of T(s) on the structure, morphology, and thermal conductivity of YSH films has been investigated. Structural studies indicate that YSH films crystallize in the cubic phase. The lattice constant decreases fr...

Two types of hot-pressed silicon nitride, one having an amorphous grain-boundary phase (6 wt% yttria, 3 wt% alumina) and the other having a predominantly crystalline grain-boundary phase (8 wt% yttria, 1 wt% alumina), were tested on a split Hopkinson pressure bar with a momentum trap, such that, in each test, the sample was subjected to a single predefined stress pulse and then recovered withou...

Upon the isothermal oxidation of an ODS FeAl Grade 3 intermetallic alloy, a structured oxide scale is developed between 800 and 950o C. TEM studies have revealed a three-layered structure with a top nanoequiaxed alumina, a central alumina and a bottom Fe-Al spinel. At these temperatures, aluminium outward diffusion does not seem to be suppressed neither by the spinel sub-layer nor by the yttria...

Impregnation and deposition-precipitation syntheses have been used to obtain Y2O3/SiO2 samples. In the deposition method, the urea causes the precipitation of yttrium hydroxide, which leads to the formation of yttria nanocrystalline particles in the final composites. Delaying the silica addition up to the visible muddying of the solution, a relevant formation of yttria nanocrystalline particles...

The Yttria stabilized Zirconia (YSZ) is a standard electrolyte for solid oxide fuel cells (SOFCs), which are potential candidates for next generation portable and mobile power sources. YSZ electrolyte thin films having a cubic single phase allow reducing the SOFC operating temperature without diminishing the electrochemical power density. Films of 8 mol% Yttria stabilized Zirconia (8YSZ) and fi...

An aqueous ceramic precursor solution was sprayed axially into an oxy-acetylene flame to produce yttria-stabilized zirconia ceramic deposits. Temperature and velocity fields of the oxy-acetylene flame were characterized by chemiluminescence and particle image velocimetry. Deposit samples were extracted from the flame at several downstream locations to study deposit evolution. The deposit phase ...