Synthesis of RE3+ (RE = Ho, Tb, Pr)-Doped Alumina Ceramic Coatings by Plasma Electrolytic Oxidation of Aluminum: Investigation of Photocatalytic Performance

The corrosion mechanism of the low carbon low alloy steel with Al2O3 particles and rare Earth (RE) oxide particles was compared in a simulated marine environment. It is shown that when the Al2O3-containing particles are introduced, the number density of nonmetallic particles of the steel increases twice, and the average particle size decreases from approximately 2.4 μm to 1.4 μm. With the introduction of Al2O3-containing particles, the amount of pitting corrosion increases. Furthermore, pitting corrosion occurs more uniformly owing to the fineness of the Al2O3 particles, thereby leading to smaller, shallower pits after the Al2O3 particles are shed. Hence, the corrosion performance of the steel with Al2O3 particles is significantly improved than that of the steel without Al2O3 particles. By adding RE oxide particles into steel, the nonmetallic particles in steel are refined but not as effectively as that achieved by adding the Al2O3-containing particles. Different from Al2O3 particles, Cu is obviously enriched in the location of RE oxide particles at the initial corrosion stage, which makes the steel exhibit the best corrosion resistance. Cu enrichment is attributed to the mobile Cu present in the rust layer and to the micro acid region formed around the RE oxide particles.

Enhanced plasma nitriding assisted by combining hollow cathode discharge with rare earth oxide particles for iron-based metals

Potency of (doped) rare earth oxide particles and their constituent metals to inhibit algal growth and induce direct toxic effects

Review of effect of oxygen on room temperature ductility of titanium and titanium alloys

Effect of rare earth oxides on the morphology of carbides in hardfacing metal of high chromium cast iron

Most existing soil loss data are spatially‐averaged, though various tracing techniques have been used for obtaining spatially‐distributed data. Spatially‐distributed soil erosion data are needed for validating physically‐based erosion prediction models and for better understanding soil erosion dynamics. The objectives of this study were to evaluate the feasibility of using rare earth element (REE) oxides directly as tracers for soil erosion studies by examining their binding ability with soil materials, and also to test a quick acid‐extraction procedure. Five REE oxide powders were directly mixed with a Miami silt loam soil (fine‐loamy, mixed, mesic Typic Hapludalfs) and then leached with deionized water in a soil box to evaluate the mobility of REEs. Following leaching, soil samples were sectioned in 25‐mm increments and analyzed for REEs. The REE‐tagged soil was wet sieved to obtain REE concentrations in each aggregate size group. A simple acid‐leaching method was used to extract REEs from all soil samples. The extracts were analyzed by Inductively Coupled Plasma‐Mass Spectrometry (ICP‐MS) techniques. The data indicated that the maximum coefficient of variation of the proposed procedure was <10% for all REEs. The REE oxides were uniformly incorporated into soil aggregates of different sizes (>53 μm) and were bound with silt‐size particles. This finding shows that the direct use of REE oxides is feasible, which should be superior to other REE‐tagged particulate tracers because it eliminates the need of tagging exotic particles with REEs. Also, direct mixing of a trace amount of REEs does not substantially alter physicochemical properties of soil particles and aggregates. This work has shown that REE oxides have a great potential for tracing soil erosion and aggregation.

Role of rare earth oxide particles on the oxidation behaviour of silicon carbide coated 2.5D carbon fibre preforms

The effect of trace amounts of rare earth additions on the microstructure and properties were studied for the Sn-58Bi and Sn-58Bi-Ag solder alloys. At the same time, the intermetallic compounds (IMCs) in the solder alloys and intermetallic layer (IML) thickness at the solder/Cu substrate interface were investigated, both as-reflowed and after high-temperature aging. The results indicate that adding trace amounts of rare earth (RE) elements has little influence on the melting temperature and microhardness of the solders investigated, but adding RE elements improves the wettability and shear strength of the Sn-58Bi and Sn-58Bi-Ag solder alloys. In addition, it was found that the addition of RE elements not only refines the microstructure and size of the IMC particles, but also decreases the IML thickness and shear strength of the Sn-58Bi solder joint after high-temperature aging. Adding trace amounts of RE elements is superior to adding trace amounts of Ag for improving the properties of the Sn-58Bi solder. The reason may be related to the modification of the microstructure of the solder alloys due to the addition of trace amounts of RE elements.

In this study, the effects of trace addition of rare earth elements on the oxidation behavior of Sn-3Ag-0.5Cu-4Ti active solder were investigated in air at 200 and 250 °C. Addition of a trace amount of rare earth elements into active solder resulted in decreasing the oxidation rate of the solder at 200 °C. The oxidation rate increased with increasing the amount of rare earth elements in the solders. The active solder containing 0.05 wt.% rare earth elements showed the best oxidation resistance. After oxidation in air at 250 °C under the solder melting condition for 1008 hours, a less than 1.5 μm thick TiO oxide layer formed on solder. Doping concentration more than 0.2 wt.% rare earth elements, the oxidation rate increased significantly with the amount of the rare earth elements. After an exposure time of 1008 hours in air at 250 °C, the oxide layer formed on the 0.5 wt.% rare earth elements containing active solder was 6 times the thickness of the 0.05 wt.% rare earth elements containing solder.

Plasma electrolytic oxidation (PEO) of aluminum in electrolytes containing CeO2 and Eu2O3 powders in various concentrations was used for creating Al2O3 coatings doped with Ce3+ and Eu2+ ions. Phase and chemical composition, surface morphology, photoluminescence (PL) properties and energy transfer from Ce3+ to Eu2+ were investigated. When excited by middle ultraviolet radiation, Al2O3:Ce3+/Eu2+ coatings exhibited intense and broad emission PL bands in the ultraviolet/visible spectral range, attributed to the characteristic electric dipole 4f05d1→4f1 transition of Ce3+ (centered at about 345 nm) and 4f65d1→4f7 transition of Eu2+ (centered at about 405 and 500 nm). Due to the overlap between the PL emission of Al2O3:Ce3+ and the PL excitation of Al2O3:Eu2+, energy transfer from Ce3+ sensitizer to the Eu2+ activator occurs. The energy transfer is identified as an electric dipole–dipole interaction. The critical distance between Eu2+ and Ce3+ ions in Al2O3 was estimated to be 8.6 Å by the spectral overlap method.

This article presents the influence of surface additions of nanocrystalline rare earth (RE) oxides CeO2, La2O3, and CeO2 ? La2O3 on the isothermal oxidation behavior of Fe20Cr and Fe20Cr5Al at 1000 C. Thermo- gravimetric studies revealed parabolic kinetics in all cases and the scale thickness on specimen surfaces varied with the nature of RE oxide. The oxidation resistance of spec- imens coated with two RE oxides was significantly higher than those coated with either one of the two oxides. The marked increase in the oxidation resistance of the alloys coated with two RE oxides is due to optimization of RE ion radius and RE oxide grain size/shape.

Effects of RE oxide on the microstructure of hardfacing metal of the large gear

ABSTRACTThe melting properties and viscosity of CaO–SiO2–MnO–La2O3–CeO2 slags, with mass ratios of 0.97 and 1.05 between CaO and SiO2, were measured using the hot stage microscopy method and rotating cylinder method, respectively. In addition, the dephosphorisation kinetics of rare earth (RE) oxides containing slags was studied. For increasing mass contents of the RE oxides, La2O3 and CeO2 (0, 3, 6, 9, and 12 wt.%), in the slag, the melting temperature initially decreases and then increases. Minimum values appeared for mass contents of 6 wt.%. RE oxide concentrations below 9 wt.% are beneficial to the decrease in viscosity, which increases significantly with the mass fraction of RE oxides in molten slags with a basicity of 1.05. In slags with a basicity of 0.97, the RE oxides favour the decrease in viscosity, which does not change noticeably as their mass fraction is increased above 6 wt.%. Finally, it was found that the rate-limiting step of the dephosphorisation process is the diffusion of phosphorus.

Toxicokinetics of rare earth element oxides administered intravenously to rats

The present work reports on the spectroscopic and rheological properties of un-exposed and gamma (γ-) irradiated rare earth (RE) oxide nanoparticle-based ferrofluids (FFs). The FFs were produced by dispersing surfactant coated terbium (Tb3+)-doped gadolinium oxide (Gd2O3) nanoparticles in the ethanol medium and later on they were subjected to energetic γ-irradiation (1.25 MeV) at select doses (97 Gy and 2.635 kGy). The synthesized RE oxide nanoparticles were of ∼7 nm size and having a cubic crystal structure, as predicted from transmission electron microscopy and x-ray diffraction studies. Fourier transformed infra-red (FT-IR) spectra showed an adequate blue shift of the Gd-O vibrational stretching mode from a wavenumber value of ∼558 cm−1, for the un-irradiated sample to a value of ∼540 cm−1 corresponding to the irradiated sample (2.635 kGy). In contrast, photoluminescence spectra have revealed modification of defect states along with Tb3+ assisted radiative transitions. The rheology measurements have illustrated unusual shear thinning behavior of the FFs, with an apparently improved power index (s) value from 0.34 to 0.50, obtained for increasing γ-dose cases. The variation of the decay parameter with irradiation dose, as predicted from the nature of apparent viscosity curves, is attributed to the defect formation, role of impurity ions (Tb3+), and weakening of inter nanoparticle bonding. The unusual properties of the novel RE oxide based FFs may find scope in sealing and shielding elements in the radiation environment including accelerator and other related zones.