Effect of process factors on properties of high dispersion spherical α-Al2O3 particles prepared by hydrothermal method

Xiang, Hairu; Wang, Zhiyuan; Yin, Qiang; Wang, Lei; Zhang, Liwei; Wang, Hailong; Xu, Hongliang; Zhang, Rui; Lu, Hongxia

doi:10.1016/j.ceramint.2019.07.215

Cited by 17 publications

(6 citation statements)

References 29 publications

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“…Other physical properties of the ceramic plate are also listed in Table 3, and by comparing with the micron spherical α-Al 2 O 3 particles studied by our group previously, 35 the ceramic sintered by spherical α-Al 2 O 3 nanoparticles in this paper have better properties in all aspects. As the properties of ceramics are not the focus of this paper, only a comparison of sintering properties of the resulting nano spherical α-Al 2 O 3 powders and another type of alumina powders under the same sintering conditions is investigated in this paper as a way to demonstrate the superiority of spherical α-Al 2 O 3 nanoparticles.…”

Section: Properties Of Ceramicmentioning

confidence: 53%

“…Our previous studies have shown that the ratio of SO 4 2− /NO 3 − has a great influence on the morphology and dispersion of precursors, 34 so Al 2 (SO 4 ) 3 ·18H 2 O and Al(NO 3 ) 3 ·9H 2 O with specific molar ratios were used as aluminum sources in this paper. The preparation process of precursors by microwave hydrothermal technique refers to our previous reports for preparing micron‐sized spherical alumina 35 . First, Al 2 (SO 4 ) 3 ·18H 2 O and Al(NO 3 ) 3 ·9H 2 O in a molar ratio of 1:8 were dissolved in deionized water to prepare the aluminum source solution, keeping the total concentration of Al 3+ in the solution at 0.01 mol/L.…”

Section: Methodsmentioning

confidence: 99%

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Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Wang

Mai

et al. 2022

J Am Ceram Soc.

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Due to their special appearance, spherical α‐Al2O3 nanoparticles play an important role for obtaining high‐performance structural and functional ceramics. However, there are still problems such as easily agglomerates to form worm‐like structures at high temperatures and difficult availability of spherical nanoparticles. In this study, spherical α‐Al2O3 nanoparticles with high dispersion were prepared by a combination of a microwave hydrothermal method and an addition of nano‐Al particles as seeds. First, spherical amorphous alumina precursors were synthesized by the microwave hydrothermal method at 100°C for 30 min using Al2(SO4)3·18H2O, Al(NO3)3·9H2O, and urea, as raw materials, and then spherical α‐Al2O3 nanoparticles with a diameter of about 66 nm were acquired after calcined the precursor at 1050°C for 90 min by adding nano‐Al seeds, which reduced the calcination temperature by 50°C and holding time by 30 min compared to that without seeds. Kinetic analysis shows that 5 wt.% nano‐Al seeds can reduce the activation energy of crystalline transition of γ‐Al2O3 to α‐Al2O3 from 516.51 to 474.37 kJ/mol. Moreover, the microscopic mechanism of nano‐Al particles as seeds was investigated. The characterizations of sintering properties show that spherical α‐Al2O3 nanoparticles facilitate the acquisition of uniform microstructure for resulting ceramic and the fracture modes include both intergranular and transgranular fractures.

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Section: Properties Of Ceramicmentioning

confidence: 53%

Section: Methodsmentioning

confidence: 99%

Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Wang

Mai

et al. 2022

J Am Ceram Soc.

Self Cite

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“…And there exist two weak peaks respectively around 1000 and 1200 cm −1 , which could be explained as asymmetric stretching TO mode and LO mode of Si–O bond of SiO 2 36 . Also, the peak at 671 cm −1 can be assigned to the stretching vibrations of Al–O, exhibiting the generation of Al 2 O 3 37 . Besides, the peak appearing around 2200 cm −1 might be attributed to the C≡N bond, owing to the formation of organic groups during the preparation process caused by N‐doping 38 .…”

Section: Resultsmentioning

confidence: 93%

Fabrication of novel silicon carbide‐based nanomaterials with unique hydrophobicity and microwave absorption property

Zhong

Zhang

Wang

et al. 2020

Int J Applied Ceramic Tech

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With the rapid development of modern electronic information technology, the issues caused by electromagnetic interference (EMI) are becoming more and more serious in the field of civilian. The EMI can not only hinder the normal functions of electronic devices, but also contribute to negative impact on the health of human beings and wildlife. 1,2 In addition, in the military applications, electromagnetic (EM) microwave can be used to detect aircrafts, which might expose the location information of these facilities, thus horribly threatening their survival. 3 Therefore, there is an urgent demand in both civil and military fields for high-performance MA materials that can efficiently absorb EM waves. The ideal MA materials should not only possess remarkable MA capacity over a wide frequency range, but also require some other special properties, such as light weight, thin thickness, good environment stability, etc. 4,5 To exploit the ideal MA materials

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“…The smaller the grain size of the precursor, the lower the phase transition temperature from θ‐ to α‐phase transition, and the easier the sublattice reconstruction. Xiang et al 30 . conducted experiments that revealed a suboptimal product morphology when using just a solo aluminum sulfate as the aluminum source.…”

Section: Introductionmentioning

confidence: 99%

“…The smaller the grain size of the precursor, the lower the phase transition temperature from θ-to α-phase transition, and the easier the sublattice reconstruction. Xiang et al 30 conducted experiments that revealed a suboptimal product morphology when using just a solo aluminum sulfate as the aluminum source. However, by adding a small amount of aluminum nitrate, they were able to achieve a better dispersion and ultimately reduce αphase transition temperature to 1100 • C. Additionally, Wu et al 31,32 employed aluminum sulfate co-hydrothermally with either aluminum nitrate or aluminum chloride to create boehmite that transitioned from an irregular to spherical morphology.…”

Section: Introductionmentioning

confidence: 99%

The effect of different anions on the crystallization course of α‐Al₂O₃ powder in hydrothermal method

Zhang,

Ouyang,

Zhou

et al. 2023

Int J Applied Ceramic Tech

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Abstractα‐Al2O3 powder with excellent sintering properties plays an irreplaceable role in advanced ceramics. However, the preparation of α‐Al2O3 at low temperature still remains a grand challenge. Herein, aluminum sulfate, aluminum nitrate, and aluminum chloride are used as raw materials for α‐Al2O3 synthesis. In general, the Al3+ will be hydrolyzed to form AlOOH during the hydrothermal process. But SO42− reacted with Al3+ and OH− to form Al4(OH)10SO4 during the hydrothermal process. During the calcining process, the transition temperatures from AlOOH to α‐Al2O3 were 1100°C, which can be summarized as follows: AlOOH → γ‐Al2O3 → θ‐Al2O3 → α‐Al2O3. Meanwhile, Al4(OH)10SO4 converted into pure α‐Al2O3 at only 1050°C, due to the direct conversion from γ‐Al2O3 to α‐Al2O3. This spherical α‐Al2O3 was made up by completely uniformed small particles of about 10–20 nm. Finally, an Al2O3 ceramic with 98.07% of theoretical density and .01% water absorption rate was obtained at a temperature of 1600°C. This work offers an intriguing solution toward the development of Al2O3‐based advanced ceramics.

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Effect of process factors on properties of high dispersion spherical α-Al2O3 particles prepared by hydrothermal method

Cited by 17 publications

References 29 publications

Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Fabrication of novel silicon carbide‐based nanomaterials with unique hydrophobicity and microwave absorption property

The effect of different anions on the crystallization course of α‐Al₂O₃ powder in hydrothermal method

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Effect of process factors on properties of high dispersion spherical α-Al2O3 particles prepared by hydrothermal method

Cited by 17 publications

References 29 publications

Preparation of spherical α‐Al2O3 nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Preparation of spherical α‐Al2O3 nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Fabrication of novel silicon carbide‐based nanomaterials with unique hydrophobicity and microwave absorption property

The effect of different anions on the crystallization course of α‐Al2O3 powder in hydrothermal method

Contact Info

Product

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Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

Preparation of spherical α‐Al₂O₃ nanoparticles by microwave hydrothermal synthesis and addition of nano‐Al seeds

The effect of different anions on the crystallization course of α‐Al₂O₃ powder in hydrothermal method