Papers by Keyword: Rare Earth Oxide

Abstract: Fe-Ni-Cr alloy powders with CeO₂ were flame sprayed and fused on the surface of 1045 carbon steel substrate. The effect of CeO₂ on microstructure and tribological behavior of coatings were studied experimentally by means of scanning electron microscopy (SEM), field emission gun scanning electron microscopy (FEGSEM), energy dispersive spectroscopy (EDS) and wear tests. The results show that an adhered oxide debris layer was formed on the worn surface in friction which contributed to decreased wear. Wear rate of the material increased with the load, but dramatically decreased at first and then slightly decreased the sliding speed. The friction coefficient of the material decreased slightly with the load, but increased with sliding speed at first, and then tended to be a constant value. Wear mechanism of the coatings was oxidation wear and a large amount of counterpart material was transferred to the coatings, the RE oxide in the debris layer contributes to the improvement in wear resistance.

Abstract: Pure carbon, pure iron and single crystall silicon were firstly loaded into a pure graphite crucible to obtain a hypereutectic Fe-C melt by carburizing at high temperatures in this paper. The powder of oxide La₂O₃ and CeO₂ were added respectively to the melt under the same process conditions and cast iron samples were obtained. The graphite morphology of the samples was observed under optical microscope and SEM. Matrix of the samples were etched by electrolysis way. At last non-ferrous residue on the surface of cast iron samples was gathered, calcined,observed under SEI and BEI and analysed with EDS to find the trace of oxide La₂O₃ or CeO₂. The results showed that oxide La₂O₃ or CeO₂ was really added into the melt but the morphology of graphite did not change. The only effect of the oxides was making the amount of graphiteto increase slightly. All the results of this paper indicat that the oxide La₂O₃ or CeO₂ is possibly the base for graphite flake to precipitate but is not a sufficient condition for graphite to nodularize.

Abstract: Reflectance design and synthesis for Er₂O₃ single layer and Er₂O₃/TiO₂ double layer are made. The optimum reflectance and thickness are determined. The developed simulator can be used for the optimization of antireflecting coatings for optoelectronic devices to improve the power output parameters.

Abstract: Amorphous Al₂O₃ doped Er₂O₃ films were deposited on Si(001) substrates by radio frequency magnetron sputtering technique. Emission spectra exhibit a strong emission band around 410 nm and a series of emission band near 970, 980, 1018, 1042 and 1080nm. Ellipsometry measurements show that the refractive index of the ErAlO films in the region of 400～1000 nm is between 1.76-1.83. The reflectivity of the ErAlO on Si is much smaller than that of clean Si and pure Er₂O₃ films. All the results indicate that ErAlO could be a promising material for Si solar cells.

Abstract: Effects of rare-earth oxides addition (0.38~1.52 mol% of Sm2O3, Eu2O3 and Er2O3) on the property and microstructure of the hot-pressed (1300°C, 2h, 35 MPa) Al2O3 (12 wt %)/TiAl insitu composites have been investigated. The results show that the doping of rare-earth oxides has a positive effect on both mechanical properties and densities of Al2O3/TiAl composites. Densities enhanced with increasing of rare-earth oxides. The flexural strength and fracture toughness were higher than other samples when the rare-earth oxide content was 0.38 mol %. The matrix grains and Al2O3 particles were significantly refined, and Al2O3 particles evenly distributed in the matrix.

Abstract: Er2O3 films were deposited on Si(001) substrates by radio frequency magnetron technique. X-ray photoelectron spectroscopy, x-ray diffraction and atomic force microscopy show the Er2O3 films obtained are stoichiometric, amorphous, and uniform. The electronic structure is studied which shows a large energy gap value of the Er2O3 film, indicating Er2O3 film could be a promising antireflection coating for solar cells.

Abstract: Al doped Er2O3 films were deposited on Si(001) substrates by radio frequency magnetron technique. X-ray diffraction and atomic force microscopy show the Al doped Er2O3 films obtained are amorphous and uniform. The optical constants are studied which shows a proper value of refractive index and a lower reflectivity, indicating it could be a usefully material for solar cells.

Abstract: Fused quartz granule (d50=0.033mm) was used as raw material, Pr6O11, Sm2O3, Gd2O3, Dy2O3 and Ho2O3 were used as additives with dosage of 2% each. Fused quartz ceramic materials were fabricated in reduction atmosphere at 1300°C, 1400°C and 1500°C for 1h. Samples were examined apparent porosity, bending strength, thermal expansion rate (RT~1200°C), and analyzed by XRD and SEM. The results indicated that additives Pr6O11, Sm2O3 and Dy2O3 had a bit inhibiting effect on crystallization of fused quartz sintered at 1300°C and 1400°C, Ho2O3 and Gd2O3 had more inhibiting effect on crystallization in samples sintered at various temperatures, sample containing Ho2O3 had least thermal expansion rate. Pr6O11, Sm2O3 and Dy2O3 had few facilitating effect on sintering, Gd2O3 and Ho2O3 had more facilitating effect on sintering of fused quartz ceramic materials, samples with Gd2O3 and Ho2O3 had lower apparent porosity and higher bending strength and more compact microstructure. It can be deduced that Gd2O3 and Ho2O3 play the excellent role as the crystallization inhibitor to fused quartz materials.

Abstract: Y2O3 was added to β-type Ti-29Nb-13Ta-4.6Zr (TNTZ) in order to achieve excellent mechanical performance and low Young’s modulus. TNTZ specimens with 0.05%–1.0% Y are all found to be composed of a β phase. Young’s moduli of TNTZ with 0.05–1.0% Y are all maintained low, and are almost the same as that of TNTZ without Y2O3. The grain size of TNTZ with 0.05%–1.0% Y is smaller than that of TNTZ without Y2O3. Moreover, Y2O3 precipitates can prevent the texture movement, and this effect becomes more obvious with an increase in the Y concentration. The tensile strength of TNTZ is successfully improved by adding Y2O3. TNTZ specimens with 0.2% and 1.0% Y exhibit good balance between the tensile strength and the elongation.

Abstract: Synthesis plays an important role in the phase stabilization of unusual compounds. Of late, preparation of metastable compounds has gained a tremendous momentum due to unusual properties exhibited by them. In this article, we will discuss how by mere change in certain parameters of the reaction a metastable phase can be isolated using a soft chemical route. Surface energy induced stabilization are also observed wherein enhanced stability of the mixed oxides are observed in the nano-regime of the compound.