Hydrothermal Synthesis of Yttria-Stabilized Zirconia Nanocrystals with Controlled Yttria Content

The aim of the paper was to discuss different effects, such as, among others, agglomeration of selected nanoparticles, particularly those from zirconia, on the tribological behavior of lubricants. The explanation of the difference between the concepts of ‘aggregation’ and ‘agglomeration’ for ZrO2 nanoparticles is included. The factors that influence such an agglomeration are considered. Classification and thickeners of grease, the role of additives therein, and characteristics of the lithium grease with and without ZrO2 additive are discussed in the paper. The role of nanoparticles, including those from ZrO2 utilized as additives to lubricants, particularly to the lithium grease, is also discussed. The methods of preparation of ZrO2 nanoparticles are described in the paper. The agglomeration of ZrO2 nanoparticles and methods to prevent it and the lubrication mechanism of the lithium nanogrease and its tribological evaluation are also discussed. Sample preparation and a ball-on disc tester for investigating of spinning friction are described. The effect of ZrO2 nanoparticles agglomeration on the frictional properties of the lithium grease is shown. The addition of 1 wt.% ZrO2 nanoparticles to pure lithium grease can decrease the friction coefficient to 50%. On the other hand, the agglomeration of ZrO2 nanoparticles in the lithium grease can increase twice the friction coefficient relative to that for the pure grease.

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“…Nano-sized yttria doped zirconia can be synthesized by co-precipitation [55] or hydrothermal route [114,127,[129][130][131].…”

Section: Methods Of Preparation Of Zro 2 Nanoparticlesmentioning

confidence: 99%

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Rylski

Siczek

2020

Lubricants

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“…All the tested 5-component equiatomic systems have been synthesized via hydrothermal treatment at low temperature (120 • C), aiming to obtain non-agglomerated and easily sinterable powders. The benefits of this synthesis method on powders' quality is well known [18,19], even in the case of ESOs [10].…”

Section: Introductionmentioning

confidence: 99%

Entropy-Stabilized Oxides owning Fluorite Structure obtained by Hydrothermal Treatment

et al. 2020

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Entropy-Stabilized Oxides (ESO) is a modern class of multicomponent advanced ceramic materials with attractive functional properties. Through a five-component oxide formulation, the configurational entropy is used to drive the phase stabilization over a reversible solid-state transformation from a multiphase to a single-phase state. In this paper, a new transition metal/rare earth entropy-stabilized oxide, with composition Ce0.2Zr0.2Y0.2Gd0.2La0.2O2−δ, was found after several investigations on alternative candidate systems. X-Ray Diffraction (XRD) analyses of calcined powders pointed out different behavior as a function of the composition and a single-phase fluorite structure was obtained after a specific thermal treatment at 1500 °C. Powders presented the absence of agglomeration, so that the sintered specimen exhibited sufficient densification with a small porosity, uniformly distributed in the sample.

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“…Hydrothermal treatment is a well-known method for synthesizing nanosized functional ceramic materials with tunable morphology; some of its most relevant applications are in the synthesis of zirconia-based ceramics [15,16,17], ceria-based ceramics [18,19], perovskite-type structure RECrO 3 [20], and titania-based ceramics [21] etc. In several previous studies [18,22,23], we showed that hydrothermal treatment at 120 °C of products obtained by mixing rare-earth nitrate solution with ammonium carbonate solution caused the formation of carbonate-based crystalline phases with substantial differences in terms of composition, crystal structure, and powder morphology, as a function of the nature of the rare-earth used, the molar ratio between carbonate anions and rare-earth cations (this parameter is indicated by “R” in the following), and of the duration of the hydrothermal treatment.…”

Section: Introductionmentioning

confidence: 99%

New Insights in the Hydrothermal Synthesis of Rare-Earth Carbonates

et al. 2019

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The rare-earth carbonates represent a class of materials with great research interest owing to their intrinsic properties and because they can be used as template materials for the formation of other rare earth phases, particularly of rare-earth oxides. However, most of the literature is focused on the synthesis and characterization of hydroxycarbonates. Conversely, in the present study we have synthesized both rare-earth carbonates—with the chemical formula RE2(CO3)3·2-3H2O, in which RE represents a generic rare-earth element, and a tengerite-type structure with a peculiar morphology—and rare-earth hydroxycarbonates with the chemical formula RECO3OH, by hydrothermal treatment at low temperature (120 °C), using metal nitrates and ammonium carbonates as raw materials, and without using any additive or template. We found that the nature of the rare-earth used plays a crucial role in relation to the formed phases, as predicted by the contraction law of lanthanides. In particular, the hydrothermal synthesis of rare-earth carbonates with a tengerite-type structure was obtained for the lanthanides from neodymium to erbium. A possible explanation of the different behaviors of lighter and heavier rare-earths is given.

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Hydrothermal Synthesis of Yttria-Stabilized Zirconia Nanocrystals with Controlled Yttria Content

Cited by 28 publications

References 31 publications

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

The Effect of Addition of Nanoparticles, Especially ZrO2-Based, on Tribological Behavior of Lubricants

Entropy-Stabilized Oxides owning Fluorite Structure obtained by Hydrothermal Treatment

New Insights in the Hydrothermal Synthesis of Rare-Earth Carbonates

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