Effect of Y2O3 Dispersion Method on the Microstructure Characteristic of Ni-Base Superalloy

An optimum route to fabricate the Ni-base superalloys with homogeneous dispersion of oxide nanoparticles is investigated. Two methods for developing a uniform dispersion of oxide nanopar-ticles are compared on the basis of the resulting microstructure. Microstructural analysis reveals that the calcined powder from polymeric additive solution with yttrium nitrate and polyvinyl alcohol represented more fine and uniform distribution of Ni, Y and O elements. The densified specimen by spark plasma sintering at 1000 °C using calcined powder exhibits fine microstructure with oxide nanoparticles compared with that using mechanically alloyed powder, presumably by the particle growth or agglomeration prevention from chelating reaction during the calcination step. The oxide particles in the sintered specimen is identified as Y–Al–O phase, formed by the reaction of Y2O3 with Al during calcination and sintering.

Fabrication of Nanoyttria by Method of Solution Combustion Synthesis

In the work the research on properties of an yttria nanopowder obtained by solution combustion synthesis (SCS) in terms of its application in ceramic technology is presented. In order to characterize the SCS reaction the decomposition of yttrium nitrate, glycine and their solution was investigated using differential thermal analysis coupled with FT-IR spectrometry of the gases emitted during the measurements. The product obtained in the SCS process was characterized in terms of its microstructure, particle size distribution and BET specific surface. Although the obtained powders showed nanoscaled structures, only after calcination at a temperature of 1100 °C nanosized particles were revealed. The calcined powder occurred in an agglomerated state (cumulants mean Zave = 1.3 µm). After milling particle size was successfully decreased to Zave = 0.28 µm. The deagglomerated powder was isostatically densified and tested for sintering ability. The obtained nanopowder showed very high sintering activity as the shrinkage onset was detected already at a temperature of about 1150 °C.

Microstructure and Phase Composition of Yttria-Stabilized Zirconia Nanofibers Prepared by High-Temperature Calcination of Electrospun Zirconium Acetylacetonate/Yttrium Nitrate/Polyacrylonitrile Fibers

For the first time, dense nanofibers of yttria-stabilized tetragonal zirconia with diameter of ca. 140 nm were prepared by calcination of electrospun zirconium acetylacetonate/yttrium nitrate/polyacrylonitrile fibers at 1100–1300 °C. Ceramic filaments were characterized by scanning electron microscopy, X-ray diffractometry, and nitrogen adsorption. With a rise in the calcination temperature from 1100 to 1300 °C, the fine-grain structure of the nanofibers transformed to coarse-grain ones with the grain size equal to the fiber diameter. It was revealed that fully tetragonal nanofibrous zirconia may be obtained at Y2O3 concentrations in the range of 2–3 mol% at all used calcination temperatures. The addition of 2–3 mol% yttria to zirconia inhibited ZrO2 grain growth, preventing nanofibers’ destruction at high calcination temperatures. Synthesized well-sintered, non-porous, yttria-stabilized tetragonal zirconia nanofibers can be considered as a promising material for composites’ reinforcement, including composites with ceramic matrix.

Production of zirconia-based ceramic fibers using viscose material

The paper focuses on the technology of producing ZrO2-Y2O3 ceramic fibers by impregnating twisted viscose yarns with zirconyl nitrate solutions with the addition of yttrium nitrate and subsequent heat treatment. We determined the effect of the impregnating solution concentration on the strength characteristics of the obtained ceramic fibers. As a result, we proposed a method for determining the tensile strength of discrete ceramic fibers

Green Synthesis and Morphology of Nano Yttria Mediated by Agaricus bisporus

Nano-yttrium oxide has been synthesized from yttrium nitrate hexahydrate by combustion of Agarics bisporus (mushroom) used as fuel. The precursor yttirium nitrate and fuel in acid medium are combusted in furnace at 400 ºC for 3 h yields yttria nanopowder. Morphology of the reaction products are characterized by SEM and TEM. Synthesized yttria nanoparticle are characterized by UV, FTIR, XRD and EDAX are discussed. The crystallite size obtained nano yttria particles are calculated by Scherer′s equation and compared with Williamson-Hall method.

EFFECTS OF YTTRIUM NITRATE ON MICROSTRUCTURE AND HIGH TEMPERATURE RESISTANCE OF ZrO2–Y2O3 CERAMIC COATINGS PREPARED BY A MODIFIED PEO PROCESS ON AN Al–12Si ALLOY

A ZrO2–Al2O3 ceramic coating and YSZ–Al2O3 coating were prepared on ZAlSil2Cu3Ni2 alloys by a modified plasma electrolytic oxidation (PEO) in zirconium salt solution. The microstructure, heat-insulating and high temperature oxidation properties were investigated by SEM, XRD and a fabricated heat insulation temperature testing device. The results showed that the surface of the YSZ–Al2O3 coating was composed of fine particles and had lower roughness. Yttrium partially stabilized the zirconia solid solution (Y[Formula: see text]Zr[Formula: see text]O[Formula: see text] which was formed in zirconium yttrium salt solution with a higher reaction temperature. The growth rate of the YSZ–Al2O3 coating was greater than the ZrO2–Al2O3 coating. Especially, the outward growth obviously improves. Furthermore, the heat insulation property of the coating enhances. The curves of the weight gains in the sample with YSZ–Al2O3 coating showed a logarithmic shape under the high temperature oxidation treatment of 400[Formula: see text]C. The weight gains of the sample with YSZ–Al2O3 coating were relatively lower than that of the as-coated sample. The ceramic layer had good high temperature stability.