Rare Earth Oxide Y2O3 Research Articles

High-temperature tribological performance of Y2O3-Doped Cu-Zn self-lubricating composite by SPS

The rare earth oxide Y2O3 exhibits excellent wear resistance and stability in engineering applications. Copper-zinc-based wear-resistant composites with varying Y2O3 contents were prepared using spark plasma sintering. Their mechanical tribological properties were studied over a wide temperature range from room temperature to 300 °C. The results indicated that the composites have good densification, and uniformly distributed matrix components. Adding an appropriate amount of Y2O3 can significantly refine the grain and improve the matrix's mechanical and tribological properties. In the above temperature range, the friction coefficient and wear rate appear the lowest values when the concentration is 1 %, and the wear mechanism changes from abrasive wear to adhesive wear with the increase of temperature.

Rare earth oxide Y2O3 modified g-C3N4 for efficient photocatalytic hydrogen production: photocatalytic performance and electron transfer channels

This work used a one-step calcination process to prepare g-C3N4 composites with varying Y2O3 loading. XRD, TEM, and XPS verified the structure and morphology of the composite photocatalyst, and its photoelectrochemical and hydrogen production performance were studied. According to the experimental results, it is found that the composite structure between Y2O3 and g-C3N4 effectively suppresses the photoelectron–hole complex and enhances the photocatalytic hydrogen production properties of g-C3N4. Under the irradiation of a 300 W xenon lamp, YCN-3 had superior photocatalytic hydrogen generation performance, achieving a rate of 1079.61 μmol g−1 h−1, which was 2.3 times greater than that of g-C3N4 in its unmodified state. After three consecutive photocatalytic operations, satisfactory stability and reusability were obtained. Finally, the possibility of a mechanism for the photocatalytic charge transfer pathway is discussed, which provides an effective way for g-C3N4 photocatalytic hydrogen production.

Effect of Y2O3 addition on the organization and tribological properties of Ni60A/Cr3C2 composite coatings obtained by laser-cladding

This study aims to enhance the surface toughness and overall performance of arc-shaped nail teeth, which are vital components of presowing film-recovery machinery. Laser cladding technology was employed to deposit Ni60A/Cr3C2 composite coatings with the rare-earth oxide Y2O3 onto 60Si2Mn steel surfaces. The effects of different amounts of Y2O3 on the wear resistance of Ni60A/Cr3C2 composite coatings were evaluated. Scanning electron microscopy (SEM), X-ray diffraction, X-ray photoelectron spectroscopy, and 3D morphological analysis were used to investigate the microstructure, microhardness, elemental distribution, and tribological properties of the coatings. The ideal amount of Y2O3 to add to the mixtures to enhance the wear resistance was determined. The results showed that the coating containing 1.5% Y2O3 and Ni60A/Cr3C2 composite powder exhibited superior overall performance. Coatings with different amounts of added Y2O3 exhibited similar phase compositions, mainly consisting of γ-Ni-based, Ni2Si, M7C3 (M = Cr, Mn), and M23C6-strengthened phases. SEM analysis revealed that the coating with 1.5% Y2O3 exhibited excellent metallurgical bonding with the substrate. In addition, the coating exhibited finer grains, increased density, a more uniform distribution of coating elements, and a microhardness of 990 HV. Fewer grooves and smoother abrasions were observed after the wear test. The wear amount and depth were 14 × 10−4 g and 8.97 μm, which were 22.2% and 55.4% lower than the coating without added Y2O3, respectively. The tribological behavior indicated that adding the appropriate amount of Y2O3 facilitated the grain boundary consolidation while enhancing the adhesive properties of the oxide film, thereby increasing the wear resistance of the coating.

Effect of co-doped additives on microstructure and mechanical properties of microwave-sintered WC-10Co cemented carbide tool materials

Microwave sintering is an energy-efficient technology of preparing materials. High-performance WC-10Co cemented carbide tool materials were fabricated by microwave sintering. The effects of co-doped additives of metal carbide Cr3C2, VC, Mo2C and rare earth oxide Y2O3 on microstructure and mechanical properties of WC-10Co tool materials were studied. Compared to the existing cemented carbides with single inhibitor or pure metal carbide, the microwave-sintered cemented carbide with co-doped rare earth elements and metal carbides had more excellent mechanical properties. The co-doped additives showed evident effect on grain growth inhibition. The WC-10Co-0.3Cr3C2-0.3VC-0.3Mo2C sintered at 1400 ℃ with the holding time of 10 min showed the best mechanical properties. Its grain size, relative density, Vickers hardness (HV30), fracture toughness and flexural strength were 0.26 ± 0.04 µm, 98.2 ± 0.5%, 19.6 ± 0.2 GPa, 16.9 ± 1.0 MPa·m1/2 and 1888.5 ± 153.1 MPa, respectively.

Effects of tailoring microstructure on short-term creep behavior of high Nb containing TiAl alloys under various stress levels

In this work, the short-term creep behaviors of high Nb containing TiAl alloys with different microstructure characteristics at 800 °C under a wide range of stresses of 150–350 MPa were investigated in detail. In order to tailor microstructure of high Nb containing TiAl alloys, composition design strategies were applied, including the change of Al content and the introduction of non-metallic element C and rare-earth oxide Y2O3. Microstructure analysis shows that increasing Al content from 43 at.% to 46 at.% will not only change the phase constitution by changing the solidification behavior, but also affect the existence form of element C, that is, in the form of dissolved carbon atoms in low-Al alloy and Ti2AlC precipitate in high-Al alloy. Creep results confirm that both increasing Al content and introducing C and Y2O3 can effectively reduce the steady-state creep rate and enhance the creep resistance, but the latter has a more significant effect. In addition, the creep behavior of high Nb containing TiAl alloys strongly depends on the stress level, and corresponding creep deformation mechanism changes from grain boundary/lamellar interface sliding under low stress to dislocation motion under high stress. Meanwhile, the correlation between the critical stress value on creep mechanism transition and the alloy composition/microstructure was clarified.

Microstructure and element distribution characteristics of Y2O3 modulated WC reinforced coating on Invar alloys by laser cladding

As an essential material of aviation composite forming mold, Invar alloys will produce defects such as wear and crack during long-term service. In this paper, the rare earth oxide Y2O3 was added into the WC reinforced composite coating to improve the surface properties of Invar alloy. The microstructural evolution, element distribution and microhardness of composite coating were investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Vickers hardness tests. The mean area and proportion of regular cellular crystals were quantitatively measured. The effect of Y2O3 on the distribution of the W element in the coating is revealed. Results indicate that the addition of Y2O3 significantly increases the thickness of the coating and improves the melting efficiency. Furthermore, cellular dendritic crystals tend to transform into regular cellular crystals with higher Y2O3 amounts. The proportion of regular cellular crystals reaches up to 30.0% when the mass fraction of Y2O3 is 5%. The W and Y elements tend to converge at crystals boundaries. Meanwhile, the microhardness gradient of the cladding layer (CL) decreases with Y2O3.

Effect of rare earth oxide on microstructure and high temperature oxidation properties of laser cladding coatings on 5CrNiMo die steel substrate

In situ multiple ceramic reinforced Fe-based composite coatings with Y2O3 were fabricated on 5CrNiMo die steel by laser cladding processing. The influence of rare earth oxide Y2O3 on the microstructure and high temperature oxidation properties of cladding coating was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS) and high-temperature oxidation resistance test. The results showed that ceramic particles and microstructure of coatings can be fined by rare earth oxide Y2O3. Volume fraction of ceramics increased with the increase of Y2O3. The high temperature oxidation resistance of the coatings was improved by Y2O3. As well as, the cumulative oxidation mass of cladding coating with 2 wt% Y2O3 decreased by one-third of the coating without addition of Y2O3. A dense layer was formed on the coating with Y2O3, preventing the coating from being oxidized.

Recrystallization kinetics of 50% hot-rolled 2% Y2O3 dispersed tungsten

Tungsten is considered as the most promising material for the divertor of fusion reactors and the plasma-facing first wall due to its excellent properties. With the growing demand for higher and better mechanical properties, the addition of rare earth oxides Y2O3 was selected as a dispersion strengthener to enhance the tungsten. The recrystallization behavior of yttria oxide dispersion strengthened tungsten plate hot-rolled to a medium plastic strain by 50% thickness reduction was investigated by isothermal annealing under the temperature range from 1250 to 1350 °C. Degradation of mechanical properties caused by recovery and recrystallization during annealing were quantified by Vickers hardness measurement. The entire recovery and recrystallization process were described nicely by serval classical models. The introduction of Y2O3 particles into tungsten retards the recrystallization process compared to that of pure tungsten.

Effect of Y2O3 addition on the microstructure and properties of Ni60 additives by micro-plasma cladding

In this study, the effect of rare earth oxide Y2O3 dispersion particles on the wear resistance and high temperature oxidation performance of Ni60 cladding layer, prepared by micro-plasma cladding, were investigated in detail for the purpose of the additive manufacturing and repair. The results shown that the addition of rare earth oxide Y2O3 reduced the conductivity and thermal conductivity of the nickel-based powder, changing the surface tension of the nickel-based powder after melting and improving the wettability of the molten pool metal, which directly affected the weldability and molding parameters of the cladding layer. When the content of Y2O3 is 1%, the cladding layer was well formed, and the microstructure was mainly composed of cell dendrites and needle-like structures. Moreover, the addition of Y2O3 also changed the thermodynamic conditions of the nucleation growth of the cladding layer, reducing the size of the hard phase such as boron chromium compound, carbon chromium compound, and increasing the distribution concentration. When the Y2O3 content is less than or equal to 1%, the dispersion distribution of Y2O3 refined the microstructure of the cladding layer, decreasing the size of the precipitated phase. The dispersion strengthening enhanced the hardness of the cladding layer and improved wear resistance. The wear mechanism of Ni60 cladding layer was adhesive wear and minute abrasive wear. At 700 °C high temperature oxidation experiment, the oxidation kinetic curve was parabolic, and the cladding layer finally forming a continuous composite oxide film (Cr2O3, YCrO4, NiCrO3, FeCr2O4, SiO2). The presence of rare earth oxide Y2O3 reduced growth rate of oxide film and improved the high temperature oxidation resistance of the cladding layer.

Effects of rare earth oxide Y2O3 on microstructure and mechanical properties of proeutectoid ferrite/granular bainitic coating

Abstract

Effect of Y<sub>2</sub>O<sub>3</sub> on Microstructure and Oxidation Behavior of Aluminide Coating on Ni-Based Superalloy

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.

Effect of Y2 O3 on microstructural characteristics and wear resistance of cobalt-based composite coatings produced on TA15 titanium alloy surface by laser cladding

The effects of Y2O3 on the microstructure, phase composition of the coatings, microhardness and wear resistance of cobalt-based composite coatings prepared by laser cladding were investigated. The TA15 titanium alloy was selected as substrate which the cobalt-based composite powder with different content of Y2O3 was cladded on. The microstructure of the coatings was observed by scanning electron microscope (SEM) and metallurgical microscope. The phase structure of the coatings was determined by X-ray diffraction (XRD), and the microhardness and wear resistance of the coatings were measured by hardness tester and wear testing machine. The results show that the rare earth oxide Y2O3 can refine and purify the microstructure of the coatings, reduce the porosities and cracks and improve compactness of the coatings. Moreover the addition of Y2O3 improves the microhardness of the coatings and reduces the friction coefficient, thus improving the wear property of the coatings. And the wear resistance of the coating with Y2O3 has improved about 50 times; the highest value of microhardness in the coating is HV1181.1. And 0.8 wt% content of Y2O3 in the coating is the best choice for improving the microhardness and wear resistance of the coating. It is feasible to improve the microstructure and tribological properties of laser cladding coatings by adding of Y2O3. Copyright © 2014 John Wiley & Sons, Ltd.

Y<sub>2</sub>O<sub>3</sub>对半钢轧辊激光熔覆层的影响

在半钢轧辊表面激光熔覆的合金粉末中添加1.0 wt%含量的稀土氧化物Y2O3，产生了显著的固熔强化和弥散强化作用，熔覆组织高度细化，产生显著的晶粒细化和强韧性作用，且碳化物的弥散和均匀分布可以有效地阻止晶粒长大，避免热影响区片状马氏体的急剧增加，从而有效的防止裂纹的产生。可以在很大程度上提高半钢轧辊的耐磨性、硬度、抗冷热疲劳强度等各项性能，取得了良好的使用效果。When adding 1.0 wt% rare earth oxide Y2O3 to laser cladding alloy powder on the surface of semi- steel rolls, it made a significant effect on solid fusion strengthening and dispersion strengthening, the microstructure of cladding layer was highly refined, and had a significant role in grain refine-ment and toughness. In addition, the dispersion of carbide and its uniform distribution could pre-vent grain growth effectively, avoided the dramatical increasing of lamellar martensite in the heat affected zone, thus prevented the generation of cracks effectively. It largely improved the semi- steel rolls wear resistance, hardness, resistance to cold and hot fatigue strength, so it obtained good using effect.

Improving Photoelectrical Performance of a Dye Sensitized Solar Cell by Doping Rare-earth Oxide Y2O3:(Eu3+, Gd3+)

Y2O3:(Eu3+,Gd3+) is introduced into a dye-sensitized solar cell. As a luminescence medium, Y2O3:(Eu3+,Gd3+) improves light harvest via conversion luminescence process and increases photocurrent; as a p-type dopant, Y2O3:(Eu3+,Gd3+) elevates photovoltage. The cell's light-to-electric energy conversion efficiency enhances 18.6% compared to the cell without Y2O3:(Eu3+,Gd3+) doping.

Effects of Rare Earth Oxides on the Microstructure and the Mechanical Properties of High-Purity Alumina Ceramics Sintered at Low Temperature

High-purity alumina ceramics were prepared by sintering at low temperature, using rare earth oxide Y2O3 and Tm2O3 as sintering aids. Adding the mixture of Y2O3 and Tm2O3 in the alumina powders can effectively improve the sintering ability and mechanical properties. The mixture, Y2O3+Tm2O3, can restrain the grains growth, fine the grain size, make the grain uniform and finally help to form compact structure. The transgranular fracture was the main fracture mode. It was found the relative density of alumina ceramics with 0.3wt% Y2O3 and Tm2O3, sintered at 1620°C for 3hrs, can be over 99.2% and the strength, toughness and microhardness reach 533.1MPa, 4.9MPa⋅m1/2 and 17.2GPa, respectively.

Origin of diffuse electron scattering in yttria-cubicstabilized zirconia single crystals with 24–32 mol% yttria

Abstract Transmission electron microscopy (TEM) of yttria (Y2O3)-cubic-stabilized zirconia with an yttria content between 24 and 32 mol% reveals diffuse electron scattering. Analysis of the diffuse intensity maxima in electron diffraction patterns recorded with the incident electron beam along (112)c or (110)c zone axes suggests that they originate from incipient microdomains of the δ phase', a superstructure with the composition Zr3Y4O12. A compound with this composition has been observed before, however, for Y2O3 concentrations substantially higher (40 mol% or greater) than in our case. The microdomains are probably platelets and must have a diameter of less than 10 nm, rendering them hard to detect in TEM images. Apart from the δ phase, we have considered two other superstructures to explain the experimental observations, the pyrochlore type phase Zr2Y2O7 and the structure of the C-type rare-earth oxide Y2O3. However, our data allow us to rule out these superstructures as the main source of diffuse electron scattering.

Effect of radiation on the characteristics of MIS structures containing rare-earth oxides

The results of experimental studies of the effect of γ-irradiation on the electrical properties of MIS structures containing the rare-earth oxides Y2O3, Dy2O3, Tb2O3, Gd2O3, and Lu2O3 are reported. The static characteristics (current-voltage, capacitance-voltage) and dynamic characteristics (transient characteristics, diagrams of oscillatory regimes) of the structures before and after irradiation with doses D=104–106 rad are examined. It is found that the irradiation dose D=106 rad does not produce any substantial degradation of the characteristics of the structures. The radiation-induced changes observed in the experimental samples are consistent with existing data for MIS structures with SiO2 as the insulator.