scholarly journals Design, Fabrication, and Characterization of New Materials Based on Zirconia Doped with Mixed Rare Earth Oxides: Review and First Experimental Results

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 746 ◽  
Author(s):  
Adrian Mihail Motoc ◽  
Sorina Valsan ◽  
Anca Elena Slobozeanu ◽  
Mircea Corban ◽  
Daniele Valerini ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Extreme Environments ◽  
Chemical Properties ◽  
Electronic Configuration ◽  
Electron Beam Evaporation ◽  
Rare Earth Oxides ◽  
Added Value ◽  
High Price ◽  
Preliminary Results

Monazite is one of the most valuable natural resources for rare earth oxides (REOs) used as dopants with high added value in ceramic materials for extreme environments applications. The complexity of the separation process in individual REOs, due to their similar electronic configuration and physical–chemical properties, is reflected in products with high price and high environmental footprint. During last years, there was an increasing interest for using different mixtures of REOs as dopants for high temperature ceramics, in particular for ZrO2-based thermal barrier coatings (TBCs) used in aeronautics and energy co-generation. The use of mixed REOs may increase the working temperature of the TBCs due to the formation of tetragonal and cubic solid solutions with higher melting temperatures, avoiding grain size coarsening due to interface segregation, enhancing its ionic conductivity and sinterability. The thermal stability of the coatings may be further improved by using rare earth zirconates with perovskite or pyrochlore structures having no phase transitions before melting. Within this research framework, firstly we present a review analysis about results reported in the literature so far about the use of ZrO2 ceramics doped with mixed REOs for high temperature applications. Then, preliminary results about TBCs fabricated by electron beam evaporation starting from mixed REOs simulating the real composition as occurring in monazite source minerals are reported. This novel recipe for ZrO2-based TBCs, if optimized, may lead to better materials with lower costs and lower environmental impact, as a result of the elimination of REOs extraction and separation in individual lanthanides. Preliminary results on the compositional, microstructure, morphological, and thermal properties of the tested materials are reported.

Nano Crystallite ZrO2, La2O3 and CeO2: Synthesis, Characterization and their Properties

2013 ◽  
Vol 209 ◽  
pp. 212-215
Author(s):  
A.K. Patel ◽  
A.R. Umatt ◽  
B.S. Chakrabarty
Keyword(s):  
Rare Earth ◽  
Surface Area ◽  
Gas Adsorption ◽  
Chemical Properties ◽  
Rare Earth Oxide ◽  
Combustion Method ◽  
Rare Earth Oxides ◽  
Precipitation Method ◽  
Reaction Conditions ◽  
The Rare Earth

It is well known that a minor addition of rare earth oxides can provide a beneficial effect towards various catalytic reactions. Use of rare earth oxide in different applications could improve commercial productivity in an affordable way. Among the rare earth oxides, ZrO2, La2O3 and CeO2 are very interesting due to their various characteristics showing a large range of applications in organic reactions. The changes in the molecular properties of materials at the nano scale level greatly enhance their physical properties as well as chemical properties and activity. Due to the extremely small size of the particles, an increased surface area is provided to the reactant enabling more molecules to react at the same time, thereby speeding up the process. In this work, the enhancement in the catalytic activity of these nano structured rare earth oxides has been studied under different reaction conditions. Nano crystalline ZrO2, La2O3 and CeO2 samples were synthesized using precipitation method and optimum reaction conditions have been established; whereas the corresponding bulk samples were synthesized by combustion method. The identification of phase and crystalline size of synthesized oxides have been done by X-ray diffraction, the band gape of these three oxides in both the forms has been analyzed by UV absorbance and surface area has been determined by gas adsorption analysis (BET). Moreover their different properties and the activity of nano crystallite oxides have also been compared with their bulk counterparts. Even the activity of ZrO2 is also compared with the rare earth oxides La2O3 and CeO2.

Ein Beitrag zur Kristallchemie dreiwertiger Seltenerdoxide Zur Stabilisierung der monoklinen B-Form / About the Crystal Chemistry of Three-Valent Rare Earth Oxides The Stabilisation of the Monoclinic B-Modification

1977 ◽  
Vol 32 (5) ◽  
pp. 495-498 ◽  
Author(s):  
W. Muschick ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
High Temperature ◽  
Single Crystals ◽  
Rare Earth Oxides ◽  
Temperature Reaction ◽  
Crystal Data ◽  
X Ray ◽  
High Temperature Reaction ◽  
Type Crystal

Single crystals of 1—x Ho2O3 : xCaO (x = 0.07), CaHoO2.5 (A) and Ca0.5Ho1.5O2.75 (B) were prepared by high temperature reaction and investigated with X-ray single crystal data. It can be shown that small amounts of CaO stabilize the monoclinic B-Typ of rare earth oxides. Phase (A) and (B) cannot be seen as a stabilized B-type crystal because they have an new crystal structure with space groupC22h–P 21/m, a = 656.6, b = 356.7, c = 529.4 pm, β = 92.3°; a = 650.2, b = 352.4, c = 584.5, β = 92.3°.

Effects of Rare Earth Oxides on Microstructures and Properties of Magnesia Refractories

2008 ◽  
Vol 368-372 ◽  
pp. 1158-1160 ◽  
Author(s):  
Bao Guo Zhang ◽  
Zhou Fu Wang ◽  
Shao Wei Zhang ◽  
Xi Tang Wang ◽  
Zi Wei Xu
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Rare Earth ◽  
High Temperature ◽  
Mechanical Strength ◽  
Grain Boundaries ◽  
Bulk Density ◽  
Rare Earth Oxide ◽  
Rare Earth Oxides ◽  
Microstructure And Mechanical Properties

The effects of Y2O3, La2O3 and Nd2O3 on the sintering, microstructure and mechanical properties of magnesia refractories were investigated. Addition of rare earth oxide (ReO) to magnesia refractories increases the bulk density, decreases the porosity and improves the mechanical strength of the refractories. The improved sinterability was attributable to the vacancies generation associated with the solid-solution reactions between MgO and ReO. In the samples with ReO, rare earth silicate phases form at magnesia grain boundaries, providing additional bonding between magnesia grains and between magnesia grains and matrix. Consequently, the samples with ReO showed much higher high temperature strengths than those without ReO.

Manufacturing of stable hydrophobic surface on rare-earth oxides aluminium hybrid composite

2020 ◽  
pp. 095440892097910
Author(s):  
Vipin Kumar Sharma ◽  
Vinod Kumar ◽  
Ravinder Singh Joshi
Keyword(s):  
Contact Angle ◽  
Rare Earth ◽  
Hybrid Composites ◽  
Chemical Properties ◽  
Hydrophobic Surface ◽  
Water Repellency ◽  
Rare Earth Oxides ◽  
Nano Particles ◽  
Matrix Composites ◽  
Sic Reinforcement

Hydrophobic surfaces have shown promising applications in the field of energy, medicines, transportation and aerospace. Currently used materials including metals, alloys and metal matrix composites have shown hydrophilic behaviour and require some alternatives materials in order to make them hydrophobic. However, these alternatives materials go down in severe environmental conditions. Instead of alternative materials to be called as surface modifier, the addition of lanthanides series rare-earth-oxides (REOs) as reinforcement for class of aluminium hybrid composites is studied for their effect on hydrophobic properties. Wettability behavior analysis between the aluminium liquid matrix and Al2O3/SiC reinforcement can be improved by the addition of REOs. Results showed that the contact angle of composites with Al2O3/SiC reinforcement lies in the range of 87.94° to 98.52°. Whereas addition of 2.5 wt % REO raised the contact angle above 100.78°. The hybrid composites with REOs show better corrosion resistant properties due to better hydrophobicity. As REO ceramics have better mechanical, thermal and chemical properties as compared with polymer-based materials, they can be applied to the industrial conditions involving exposure to elevated temperature or abrasive wear without degradation of the water repelling properties. The water repellency of the aluminum based hybrid composites improved with the incorporation of rare earth nano-particles as per the Cassie-Baxter Model.

High-Temperature Jet Spray Reactor for the Preparation of Rare Earth Oxides by Pyrolysis: Computer Simulation

JOM ◽  
2014 ◽  
Vol 66 (9) ◽  
pp. 1647-1653 ◽  
Author(s):  
Qiu-yue Zhao ◽  
Chao Lv ◽  
Zi-mu Zhang ◽  
Zhi-he Dou ◽  
Ting-an Zhang ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Rare Earth ◽  
High Temperature ◽  
Rare Earth Oxides

Films of rare earth oxides formed by electron beam evaporation

1987 ◽  
Vol 154 (1-2) ◽  
pp. 101-108 ◽  
Author(s):  
R.O. Adams ◽  
A. Digiallonardo ◽  
C.W. Nordin
Keyword(s):  
Electron Beam ◽  
Rare Earth ◽  
Electron Beam Evaporation ◽  
Rare Earth Oxides
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