Comparison of microstructure and chemical durability of Ce0.9Gd0.1PO4 ceramics prepared by hot-press and pressureless sintering

Zhao, Xiaofeng; Teng, Yan; Yang, Hang; Huang, Yi; Ma, Jiyan

doi:10.1016/j.ceramint.2015.05.051

Cited by 19 publications

(7 citation statements)

References 41 publications

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“…Hot-press sintering offers several advantages over conventional methods, primarily the very low temperature required for densi cation. 14,21,22) When the hot-pressed sintering entered the sintering stage (at suf ciently high temperature), the assistance in high compressive stress led to effective plastic deformation and compaction results, but the coarsening phenomenon easily resulted in the lower hardness of the 1400 C-sintered specimens. Thus, it is reasonable to speculate that the minor difference in the hardness resulted from the relative density, SPS and grain size effects.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Chang

Huang³

2017

Mater. Trans.

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The aim of this work is to nd the optimal sintering parameters of Cr-31.2 mass% Ti alloys and simultaneously investigate the effects of the TiCr 2 Laves phases. In this study, Cr-31.2 mass% Ti alloys are fabricated by vacuum hot-press sintering. Different compositions of submicron titanium (760 nm) powders are added to micron chromium (4.66 μm) powders. The experiments utilize various hot-press sintering temperatures (1250, 1300, 1350 and 1400 C) with the pressure maintained at 20 MPa for 1 h, respectively. The experimental results show the optimal parameters of the hot-press sintered Cr-31.2 mass% Ti alloys to be 1400 C at 20 MPa for 1 h. The relative density reaches 99.96% and the hardness and TRS (transverse rupture strength) reach 81.93 HRA and 475.73 MPa, respectively. In addition, the increase in temperature of the hot-press sintering is effectively decreased the Cr 3 Ti 3 O and slightly enhanced TiCr 2 phases, which will lead to the better mechanical properties. Signi cantly, the optimal hot-press sintered Cr-31.2 mass% Ti alloys possess a dense microstructure, excellent mechanical property and good electrical conductivity value (1.51 × 10 4 S·cm

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Section: Resultsmentioning

confidence: 99%

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Chang

Huang³

2017

Mater. Trans.

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“…The dissolution experiments of La 0.666 Nd 0.167 Sm 0.167 PO 4 monazite ceramics were performed at 363 K in pH = 5, 7, and 9 solutions to assess the chemical stability of ceramics in geological environment and to gain a general understanding of lanthanides leaching activity. Previous studies reveal that the weak leaching resistance of monazite ceramics has been found in different leachates at initial 7 days owing to surface defect caused by mechanical polishing, 32 and that the stable state corresponding to dissolution–diffusion phenomenon has been established after 21 days with an LR value of ∼10 −6 –10 −5 g/m 2 in pH = 5 solution 35 . It should be noted that the updated leachates in previous studies were not digested with strong acid prior to ion concentration measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies reveal that the weak leaching resistance of monazite ceramics has been found in different leachates at initial 7 days owing to surface defect caused by mechanical polishing, 32 and that the stable state corresponding to dissolution-diffusion phenomenon has been established after 21 days with an LR value of ∼10 −6 -10 −5 g/m 2 in pH = 5 solution. 35 It should be noted that the updated leachates in previous studies were not digested with strong acid prior to ion concentration measurements. Figure 7A presents the evolution of the normalized elemental leach rates (LR) of Ln elements (Ln = La, Nd, and Sm) in pH = 5 solutions pretreated with strong HCl acid.…”

Section: Monazite Ceramicsmentioning

confidence: 99%

Response of Nd³⁺ and Sm³⁺ precipitating into rhabdophane and the leaching mechanism of associated monazite ceramics

Zhao

Teng

et al. 2022

J Am Ceram Soc.

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Rhabdophane has been considered an important permeable reactive barrier to isolate groundwater radionuclides, and evaluating its precipitation response to different species of radionuclide in acid solutions is critical. In this work, the effects of pH values on the precipitation behavior of Nd3+ and Sm3+ into La‐rhabdophane are systematically investigated. Some specific issues such as ions removal, precipitation reaction kinetics, and crystal growth affected ions incorporation are discussed in detail, along with uncovering the veil of the Ln (La, Nd, and Sm) leaching mechanism of associated La0.666Nd0.167Sm0.167PO4 monazite ceramic based on dissolution experiments and density functional theory. The results reveal that Nd3+ and Sm3+ can be removed more than 98% in pH = 1 solution within 12 h, whereas uneven precipitation process to form unexpected stoichiometric ratio of rhabdophane has been observed in 30–50 nm short crystal. Grain growth effects based on spark plasma sintering can contribute to homogenize the materials composition with obtaining La0.666Nd0.167Sm0.167PO4 monazite ceramics. Furthermore, the binding energy of Ln–O in (1 0 0) surface of monazite plays an important role in controlling the leaching stability of Ln3+, associated with the leaching activities are energetically favorable in the order of La > Nd > Sm for La0.666Nd0.167Sm0.167PO4 monazite.

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“…23. Monazite [12,16,17,18,87,89,140,141,231,235,244,293,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359], Figure 23.…”

Section: Crystalline Ceramic Phasementioning

confidence: 99%

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

2019

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Crystalline ceramics are intensively investigated as effective materials in various nuclear energy applications, such as inert matrix and accident tolerant fuels and nuclear waste immobilization. This paper presents an analysis of the current status of work in this field of material sciences. We have considered inorganic materials characterized by different structures, including simple oxides with fluorite structure, complex oxides (pyrochlore, murataite, zirconolite, perovskite, hollandite, garnet, crichtonite, freudenbergite, and P-pollucite), simple silicates (zircon/thorite/coffinite, titanite (sphen), britholite), framework silicates (zeolite, pollucite, nepheline /leucite, sodalite, cancrinite, micas structures), phosphates (monazite, xenotime, apatite, kosnarite (NZP), langbeinite, thorium phosphate diphosphate, struvite, meta-ankoleite), and aluminates with a magnetoplumbite structure. These materials can contain in their composition various cations in different combinations and ratios: Li–Cs, Tl, Ag, Be–Ba, Pb, Mn, Co, Ni, Cu, Cd, B, Al, Fe, Ga, Sc, Cr, V, Sb, Nb, Ta, La, Ce, rare-earth elements (REEs), Si, Ti, Zr, Hf, Sn, Bi, Nb, Th, U, Np, Pu, Am and Cm. They can be prepared in the form of powders, including nano-powders, as well as in form of monolith (bulk) ceramics. To produce ceramics, cold pressing and sintering (frittage), hot pressing, hot isostatic pressing and spark plasma sintering (SPS) can be used. The SPS method is now considered as one of most promising in applications with actual radioactive substances, enabling a densification of up to 98–99.9% to be achieved in a few minutes. Characteristics of the structures obtained (e.g., syngony, unit cell parameters, drawings) are described based upon an analysis of 462 publications.

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Comparison of microstructure and chemical durability of Ce0.9Gd0.1PO4 ceramics prepared by hot-press and pressureless sintering

Cited by 19 publications

References 41 publications

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Response of Nd³⁺ and Sm³⁺ precipitating into rhabdophane and the leaching mechanism of associated monazite ceramics

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

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Comparison of microstructure and chemical durability of Ce0.9Gd0.1PO4 ceramics prepared by hot-press and pressureless sintering

Cited by 19 publications

References 41 publications

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Investigation of Vacuum Hot-Press Sintering Temperatures on the Sintered Characteristics of Cr-31.2 mass% Ti Alloys

Response of Nd3+ and Sm3+ precipitating into rhabdophane and the leaching mechanism of associated monazite ceramics

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

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Product

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Response of Nd³⁺ and Sm³⁺ precipitating into rhabdophane and the leaching mechanism of associated monazite ceramics