Papers by Keyword: Rare Earth Oxide

Abstract: This topic is based on the research and development of inorganic silver-loaded antibacterial materials with good antibacterial activity, and the preparation of silver-loaded calcium carbonate inorganic nano-antibacterial agents by redox reaction. At the same time, the mixed rare earth oxide was added to the ceramic glaze containing silver nano antibacterial agent, and the nano antibacterial building sanitary ceramics were prepared by firing at 1180 °C in an oxidizing atmosphere. This experiment investigated the effect of adding mixed rare earth oxides on the quality and properties of glaze. Experiments show that the new glaze has stronger antibacterial effect than the nano antibacterial glaze without mixed rare earth oxide, and the glaze quality is good. After adding 0.5 wt% of mixed rare earth oxide, the whiteness, abrasion resistance, hardness and thermal shock resistance of the glaze were significantly improved.This topic is based on the research and development of inorganic silver-loaded antibacterial materials with good antibacterial activity, and the preparation of silver-loaded calcium carbonate inorganic nano-antibacterial agents by redox reaction. At the same time, the mixed rare earth oxide was added to the ceramic glaze containing silver nano antibacterial agent, and the nano antibacterial building sanitary ceramics were prepared by firing at 1180 °C in an oxidizing atmosphere. This experiment investigated the effect of adding mixed rare earth oxides on the quality and properties of glaze. Experiments show that the new glaze has stronger antibacterial effect than the nano antibacterial glaze without mixed rare earth oxide, and the glaze quality is good. After adding 0.5 wt% of mixed rare earth oxide, the whiteness, abrasion resistance, hardness and thermal shock resistance of the glaze were significantly improved.

Abstract: The welding performance of E3, Er-W, La-W1and La-W2 was investigated in this paper. The erosion, morphological stability, U-I curve at high temperature and heavy current were studied by direct current straight polarity tungsten inert gas (DCSP TIG) welding. The morphology of erosion on the electrode surface was explored by scanning electron microscopy. The results suggest that when the welding current I₀ = 250 A,after loading 1h the mass loss of Er-W electrode was bigger than other electrodes and the tip size change of Er-W electrode was larger than others. While the mass loss of La-W1 was least and the tip size of La-W1 was relatively stable. The metallographic structure of the electrode tips showed that the recrystallized grain size of La-W1 was much smaller than others,which showed that metal rhenium can refine recrystallized grains of material and improve the electron emission performance. As a result, La-W1 electrode had superiority in welding performance.

Abstract: The oxidation behavior of Ni-based superalloy GH586 which is treated by pack-cementation aluminizing was investigated. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure of aluminide coatings and the surface morphologies of the oxide scales. Results show that the main phase of the aluminide coatings was NiAl. The aluminide coating can be formed at lower temperature due to the addition of rare earth oxide in the mixture powders. The thickness of aluminide coating at 900°C was about 110μm, and another aluminide coating with rare earth oxide Y2O3 at 800°C was about 38μm. The oxidation kinetics of aluminized specimens approximately followed a parabolic oxidation law at 1000°C. The morphology of the oxidation scales was primarily θ-Al2O3 with minor α-Al2O3. The scales of the coatings with rare earth oxide Y2O3 after oxidation was more dense.

Abstract: Effect of rare earth oxides (Y, Nd, Gd, Ho, Yb, Er, Pr, Dy, La, Ce) on the temperature characteristics of BaTiO3(BT)-Nb2O5-ZnO ceramics was investigated. It was found that, according to the effect on the dielectric constant peaks at 40°C and 127°C of BT ceramics, the doping rare earth oxides can be divided into three categories. The different doping effects of rare earth oxides on the temperature capacitance variation of BT ceramics can be explained by the change of the volume fraction of grain core and grain shell in the core-shell structure. BT ceramics sintered at 1140°C in air have the following properties: ε25°C>3300, tanδ≤1.0%, ρ≥1012 Ω•cm and ΔC/C(-55 to +125°C)≤±10%.

Abstract: The microstructures and fatigue properties of the TNTZ added with Y or Y₂O₃ have been investigated. The results indicate that TNTZ added with Y or Y₂O₃ are all found to be composed of β phase and the small amount of Y₂O₃. The grain size of TNTZ added with Y or Y₂O₃ is smaller than that of TNTZ. The Young’s modulus of TNTZ added with Y or Y₂O₃ are maintained at a low level, and Young’s modulus of TNTZ added with Y is smaller than that of TNTZ added with Y₂O₃. The mechanical properties are both improved by adding Y or Y₂O₃, while the tensile strength of TNTZ added with Y₂O₃ is slightly higher than that added with Y. The high cycle fatigue limit of the alloys added with Y or Y₂O₃ are similar, while the low cycle fatigue strength of TNTZ added with Y is higher than that added with Y₂O₃. The improvement in fatigue properties ascribes to the microstructure refinement and the pining effect of Y₂O₃ particles. On the other hand, Y elements form Y₂O₃ with the Oxygen elements in the matrix, thus lead to the weakening of the Oxygen solution effect.

Abstract: In order to develop new electrical contact materials with better properties, small amounts of rare earth (RE) oxides were selected as additions into AgSnO2-based composites. The effects of different RE oxide additions with different content in the matrix on the microstructure of AgSnO2, were investigated. In general, the resulting RE oxide-doped materials are found to have better performances than their original ones. Results indicate that the newly developed AgSnO2/La2O3 materials in this paper are leading candidates for environmentally friendly electrical devices and RE oxides would play an important role in improving performance of AgSnO2.

Abstract: Rare earth oxides are commonly employed as dopants or coatings to improve the development and adherence of alumina scales. However, for practical applications, doping is difficult to control and the use of coatings is preferred. Nevertheless the thickness of such coatings is relatively limited for long term exposures at high temperatures and thicker coatings are hence required. With this in mind, the cathodic electrodeposition technique has been investigated in this work. The results show that deposits of about 20 µm RE_xOOH_y coatings can be obtained on a Ni superalloy in 20 min. The applied current density and time significantly influence the microstructure, thickness, crystallite size and number of oxygen vacancies of the coatings. Their needle-like microstructure is indicative of non negligible amounts of rare earth hydroxides. However, the hydroxide peaks overlap with the oxide peaks in the X-ray diffraction (XRD) patterns. XRD also suggests that the coatings are either amorphous or of nanocrystalline nature, as supported by Raman spectroscopy. Their multicracked morphology is related to the shear stresses between the coating and the substrate, hydrogen bubbling and mostly by drying of the coatings in air. The number of cracks is increased after a heat treatment which also allows full crystallization of the RE_xO_y coating and pre-oxidation (α-Al₂O₃) of the superalloy. The combined effect of both oxides results in an improved oxidation resistance of the Ni-base superalloy at 1100°C in air.

Abstract: The sintering behavior and lattice parameters of β-sialon were investigated by varying temperature, z values and the amounts of sintering additive composed of Y₂O₃. The experimental results indicated that the z value of β-sialon decreases with the sintering temperature increases. The sinterability of the β-sialon declined with the z values increase . As the sintering temperature rise the phenomenon of anti-densification was occurred when the amount of additive was 7wt%.

Abstract: Amorphous Al2O3 and Er2O3 alloyed films were deposited on Si(001) substrates by radio frequency magnetron sputtering technique. Ellipsometry measurements show that the weighted average reflectivity in the wavelength between 400 and 1000 nm for the ErAlO is 2.25%. Emission spectra exhibit a strong emission band around 410 nm and a series of emission band near 970 and 1019 nm. All the results indicate that ErAlO could be a promising material for Si solar cells.

Abstract: This paper reports the influence of sintering additives (RE2O3, Al2O3RE2O3, RE = Yb, Y and Gd, 13 vol%) and mixing effect of 30 nm SiC powder with 800 nm SiC powder on phases of grain boundaries, grain size of SiC, fracture toughness and strength of SiC hot-pressed at 1950°C under 39 MPa of applied pressure. Rare earth ions were uniformly adsorbed on negatively charged SiC particles with 150 nm Al2O3 particles in aqueous suspensions at pH 5. A rapid densification of SiC with one component RE2O3 occurred above 1700°C when a liquid of SiO2 (formed on SiC particles)RE2O3 system was formed. The Al2O3RE2O3 additives lowered a liquid formation temperature to 14001500°C and enhanced the densification rate of SiC. An increased solubility of 30 nm SiC in a liquid during dissolution-precipitation process provided an amorphous phase of SiCSiO2Al2O3RE2O3 system at grain boundaries and suppressed the grain growth of SiC. The fracture toughness of dense SiC was dominated by the grain boundary thickness controlled by grain size of SiC and amount of oxide additives. Mixing of 30 nm SiC with 800 nm SiC improved greatly the strength of SiC with two component oxides and the mean flexural strengths reached 740810 MPa.