Thermal decomposition of zirconium hydroxide

Sato, Taichi; Ozawa, Fusaji; Nakamura, Takato; Watanabe, Hiroshi; Ikoma, Shuji

doi:10.1016/0040-6031(79)87110-5

Cited by 27 publications

(15 citation statements)

References 10 publications

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“…13 were identified as tetragonal zirconia (t-ZrO 2 ), quasi-amorphous zirconia and several spinel-like aluminas. These findings are consistent with several earlier reports 14–17 .…”

Section: Introductionsupporting

confidence: 94%

The new nano-enabled phase map of ZrO2-Al2O3

Koltsov

Kimmel

Stelmakh

et al. 2019

Sci Rep

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Rapid development of nanotechnology often requires verification of existing phase diagrams, which were suitable for bulk materials. This work presents a new phase map (phase diagram) for Al 2 O 3 -ZrO 2 crystalline powders including the role of the nanoscale particles. Al 2 O 3 -ZrO 2 composites are relevant for industry for applications demanding high hardness. The nanopowders were manufactured via co-precipitation process followed by microwave hydrothermal synthesis (MHS) at 270 °C, drying at room temperature and annealing in the temperature range 300–1500 °C. The phase composition was investigated using X-ray diffraction (XRD) and Rietveld refinement analysis. The grain size and size distribution were calculated using Rietveld refinement analysis and using transmission electron microscopy (TEM). A particular feature of the composites was the nanoisolation, separation of different phases on a nanoscale. This feature limited grain growth during annealing and permitted the phase diagram for a nano-enabled system to be determined, which turned out to be different from that of conventional composites. In particular, considerable solubility of Al 3+ in ZrO 2 was found for temperatures less than 1000 °C.

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“…13 were identified as tetragonal zirconia (t-ZrO 2 ), quasi-amorphous zirconia and several spinel-like aluminas. These findings are consistent with several earlier reports 14–17 .…”

Section: Introductionsupporting

confidence: 94%

The new nano-enabled phase map of ZrO2-Al2O3

Koltsov

Kimmel

Stelmakh

et al. 2019

Sci Rep

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“…This indicates that the prepared zirconium particles were amorphous. 21,22 Above 873 K, the tetragonal metastable phase changes to the monoclinic one. Crystallization into tetragonal (metastable) ZrO 2 appeared at 691 K (Figs.…”

Section: Resultsmentioning

confidence: 99%

“…Amorphous precipitates usually transform into the metastable tetragonal phase upon thermal treatment, then into a mixture of tetragonal and monoclinic phases and finally into the monoclinic phase. 22 The calculated crystallite diameters of the ZrO 2 samples (treated at 673, 873, 1073 and 1273 K) are plotted against calcination temperatures in Fig. 4 and 5).…”

Section: Resultsmentioning

confidence: 99%

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The influence of chemical and thermal treatment on the point of zero charge of hydrous zirconium oxide

2013

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Two zirconia samples were prepared by precipitation from aqueous zirconium oxychloride and zirconil sulphate solutions with potassium hydroxide. The prepared zirconia samples were amorphous. The pHpzc values of zirconia samples, determined from NaCl and NaNO3 solutions, were 6.6 ± 0.1 and 6.9 ± 0.1, respectively. After prolonged hydration of zirconia in doubly distilled water, pHpzc decreased to 4.7 ± 0.3. Crystallization into tetragonal (metastable) + monoclinic zirconia appeared at 691 K. Above 873 K, tetragonal metastable phase changes to monoclinic one. It was shown that crystallite sizes of zirconia treated at 673 - 1273 K increased from 9.5 nm to 40.5 nm, respectively. The increase in temperature from 385 K to 1070 K increased the pHpzc of zirconia samples from 6.6 to 9.0, respectively. [Projekat Ministarstva nauke Republike Srbije, br. 45012

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“…The char formation process is elaborated in Figure 12 . The decomposition reaction of MH proceeded from the edge of the plate or cracks in the interface towards the center of the crystal [ 49 ]. The acetic acid generated by decarboxylation of vinyl acetate groups in EVA matrix was more likely to interact with MH and lead to the formation of spherical MgO particles [ 50 ].…”

Section: Resultsmentioning

confidence: 99%

Enhanced Flame Retardancy in Ethylene–Vinyl Acetate Copolymer/Magnesium Hydroxide/Polycarbosilane Blends

Zhang

Wang

et al. 2021

Polymers

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A polymer ceramic precursor material—polycarbosilane (PCS)—was used as a synergistic additive with magnesium hydroxide (MH) in flame-retardant ethylene–vinyl acetate copolymer (EVA) composites via the melt-blending method. The flame-retardant properties of EVA/MH/PCS were evaluated by the limiting oxygen index (LOI) and a cone calorimeter (CONE). The results revealed a dramatic synergistic effect between PCS and MH, showing a 114% increase in the LOI value and a 46% decrease in the peak heat release rate (pHRR) with the addition of 2 wt.% PCS to the EVA/MH composite. Further study of the residual char by scanning electron microscopy (SEM) proved that a cohesive and compact char formed due to the ceramization of PCS and close packing of spherical magnesium oxide particles. Thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG–FTIR) and pyrolysis–gas chromatography coupled with mass spectrometry (Py–GC/MS) were applied to investigate the flame-retardant mechanism of EVA/MH/PCS. The synergistic effect between PCS and MH exerted an impact on the thermal degradation products of EVA/MH/PCS, and acetic products were inhibited in the gas phase.

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Thermal decomposition of zirconium hydroxide

Cited by 27 publications

References 10 publications

The new nano-enabled phase map of ZrO2-Al2O3

The new nano-enabled phase map of ZrO2-Al2O3

The influence of chemical and thermal treatment on the point of zero charge of hydrous zirconium oxide

Enhanced Flame Retardancy in Ethylene–Vinyl Acetate Copolymer/Magnesium Hydroxide/Polycarbosilane Blends

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