Papers by Keyword: Y₂O₃

Abstract: This study presents a rapid method for synthesizing yttrium oxide nanoparticles (Y₂O₃-NPs) utilizing ethanol and yttrium oxide (Y₂O₃). The Y₂O₃-NPs were analyzed using Fourier transform infrared (FT-IR), ultraviolet spectroscopy (UV-Vis), atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction (XRD).The X-ray diffraction (XRD) analysis revealed that the Y₂O₃ exhibited a preferred alignment and possessed a cubic crystal structure with a (111) orientation. The Atomic Force Microscopy (AFM) findings indicated the presence of a nanoscale structure characterized by a spherical surface that exhibits excellent dispersibility. The granules were seen to have a consistent size ranging from 19 to 36 nanometers, and the surface had a roughness ranging from 38 to 78 nanometers. The aim of this paper was to examine the features of (Y₂O_3-NPs) with antifungal and antibacterial activities. Studies on Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella, Escherichia coli, and Candida have shown the effectiveness of NPs as an antibacterial and antifungal agent.

Abstract: A powder metallurgical process has been applied to synthesize the FeNiCr+Y₂O₃ oxide dispersion strengthened (ODS) alloys. The composition of the reinforcing Y₂O₃ added into matrix was varied from zero to 2.0 percent weight. Raw powders were carefully weighed with a four-digit balance. Y₂O₃ powder was pre-linked into Fe powder as the dominant element in the matrix by manually ground for half an hour. Ni and Cr powders were then mixed evenly for the next a half hour to obtain FeNiCr+Y₂O₃ precursor. Avoiding agglomeration and grain coarsening, the precursor was uniformly homogenized by milling for 20 hours. The precursors were then compressed at an isostatic pressure of 100 kN to 12 grams of pellets each. To prevent sample erosion during smelting with an electric arc furnace (EAF), crystal growing mechanism by conventional sintering was performed at 900 °C for 2 hours. This strengthens the bonds between precursors in forming ODS alloys. The samples were then melt-casted in the arc by 4 times flips. As a result, the neutron diffraction analysis and SEM-EDS strongly reveal the austenitic crystal structure and Y2O3 oxide successfully dispersed in the cast-alloy respectively. The microstructures with Y2O3 oxide spread uniformly overall the cast-alloy surfaces.

Abstract: This research study utilises Essential Macleod software to optimize beam splitter for efficient hybrid photovoltaic application. The spectral splitting was carried out by alternating multilayer coating designs having Na₃AlF₆ as low index material, Y₂O₃ as middle index material and TiO₂ as high index material. The wavelength range of optimized design was selected from 400 nm to 1000 nm with reference wavelength 510 nm at an incident angle of 45. The beam splitter model comprises 56 alternating layers based on the formula [LMHM]¹⁴. The Optimac refinement approach is used to enhance the modelled structure. Different built-in analysis techniques in the essential Macleod package are also used to analyze our design, like density, total absorptance and admittance diagram. It is concluded that the modelled beam splitter transmits about 90% light in the visible spectrum range and reflects 90% light in the infrared region, which is very useful for an application like solar cells and the thermoelectric generator.

Abstract: The effects of the alloying sequence and refining time on the inclusions in Fe–9Cr alloy reinforced with Y₂O₃ nanoparticles were investigated. The size and number of inclusions in the alloys were determined via optical microscopy, and their morphology and composition were determined via scanning electron microscopy. The Y₂O₃ mainly acted as a nucleating agent in the Si–Mn+Y₂O₃+Ti alloying process, promoting the precipitation of other oxides, which was beneficial for the formation of Y–Ti–O particles. In contrast, no Y–Ti inclusions were formed when the Si–Mn+Ti+Y₂O₃ alloying process was employed. In addition, the inclusions in the alloy tended to stabilize after refinement for 5–10 min. This study offers a general pathway for the manufacture of oxide dispersion strengthened steel via a smelting process.

Abstract: Excellent creep strength of the ODS steels is associated with an attractive interaction between dislocations and oxides. The aim of this study is to explore the Fe-Al-O and Fe-Al-Cr-Y-O systems with high oxygen content (up to 1.5 wt %) represented by alumina or yttria oxides (up to 5 vol. %) to identify the potentials of the new generation of ODS alloys. The basic material is prepared from Fe and 10 or 11 wt. % of Al. Theoretical models showed stability of Al oxides even above 1000°C, while practical results show coarsening with time at these temperatures. Stability of Y oxides is about 200°C higher, so there is a potential to have stable creep resistant alloy in range of 1000-1200°C.

Abstract: This study elucidates the effect of the percentage of Y₂O₃ on the microstructure and tribological performance of Ti-6Al-4V clad by SiC and Ni powder, using gas tungsten-arc welding (GTAW). The microhardness of the clad layer was measured using a Vickers hardness tester. The microstructure of the clad layer was analyzed using a scanning electron microscope (SEM) and an electron probe micro-analyzer (EPMA). X-ray diffraction (XRD) was used to determine the constituent phases of the clad layer. A pin-on-disk rotating tribometer was used to evaluate the wear resistance of the substrate and the clad layer. According to the experimental results, TiC and TiSi₂ reinforcing phases were formed in situ in the clad layer during cladding process. The microhardness of the clad layer was two to three times that of the substrate, and the wear loss of the clad layer was about 51.5%~14.7% of that of the substrate. The optimal amount of Y₂O₃ enhanced the formation of TiC and TiSi₂ and thus improved the microhardness of the clad layer. However, an amount of Y₂O₃ that over a critical value reduced the formation of reinforcing phases and degraded the mechanical properties of the clad layer.

Abstract: Mullite/10 wt. %h-BN composites with 5 wt. % Y₂O₃ additive were fabricated by pressureless sintering at different temperatures. The densification, phase composition, microstructure, mechanical and dielectric properties of the mullite/h-BN composites were investigated. With the addition of Y₂O₃, the sintering temperature of the mullite/h-BN composites declined, while the density, mechanical and dielectric properties all increased. The addition of Y₂O₃ promoted the formation of liquid phase at high temperature, which accelerated the densification. Besides, Y₂O₃ particles which were located at the grain boundaries inhibited the grain growth of mullite matrix. For the mullite/h-BN composites with Y₂O₃ additive, the appropriate sintering temperature was about 1600°C. The relative density, flexural strength, fracture toughness and dielectric constant of the Y₂O₃ doped mullite/h-BN composite sintered at 1600 °C reached 82%, 135 MPa, 2.3 MPa·m^1/2 and 4.9, respectively.

Abstract: Despite the impressive development in understanding transformation toughening, tailoring the toughness of zirconia toughened alumina (ZTA) ceramics remained a major challenge. In our research, a simple route based on the powders mixing process of ZTA powders with varying CeO₂ additions (0 - 10 wt.%) is developed to investigate this issue. The experimental results clearly reveal that the fracture toughness of ZTA ceramics can be tailored by mixing of ZTA starting powders.

Abstract: The phase evolution of yttrium iron garnet (YIG) during reaction 3Y₂O₃-5Fe₂O₃ was investigated by modifying Fe₂O₃ particle sizes (FPS). Five different sizes of Fe₂O₃, (d₅₀) are used to prepare YIG powder. Solid state reaction (SSR) was applied at 1200 °C in order to gain insight on the effect of FPS towards the YIG formation. Rietveld refinement method was used to quantify the amount of YIG yielded (%). Larger FPS (> 50 μm) initiates only 5Fe₂O₃ + 3Y₂O₃ à 3YFeO₃ + Fe₂O₃ + Y₃Fe₅O_12.. However, when the fine FPS (5 μm) is used, the reaction pathway was changed into 5Fe₂O₃ + 3Y₂O₃ à 6YFeO₃ + 2Fe₂O₃ à 2Y₃Fe₅O_12. These behaviors is explained that the smaller FPS consumed quickly to form YIG due to the smaller particle distance between Fe₂O₃ and Y₂O₃. This shall be leading to higher reaction rates (mass-transfer kinetics).

Abstract: cBN/SiAlON composites were prepared by spark plasma sintering (SPS) method using Si₃N₄, AlN, Al₂O₃, cBN and Y₂O₃ powders as raw materials. The sintering process is at the temperature of 1500°C holding for 5 min. Effect of the Y₂O₃ content on phase composition, microstructure, bulk density, hardness and fracture toughness of the cBN/SiAlON composite was investigated. The experimental results showed that when the Y₂O₃ content was 0.2 wt. % the bulk density and fracture toughness of the composite had the maximum values of 3.0 g/cm³ and K_IC = 5.7 MPa∙m^1/2, respectively. The cBN/SiAlON composite with 0.8 wt. % Y₂O₃ addition got the maximum hardness of 16.4 GPa.