Mechanical strengths and thermal properties of titania-doped alumina aerogels and the application as high-temperature thermal insulator

Gao, Min; Liu, Benxue; Zhao, Ping; Yi, Xibin; Shen, Xiaodong; Xu, Yue

doi:10.1007/s10971-019-05057-5

Cited by 37 publications

(24 citation statements)

References 35 publications

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“…As presented in Figure 13, these composites show quite low RT and hightemperature thermal conductivity (e.g., 0.08 W/(m⋅K) and 0.09 W/(m⋅K) at 1000 and 1100 • C, respectively, for the SA composite) compared to reported values. [36][37][38] With a bulk density as low as 0.24 cm 3 /g, the compressive stress of the SA composite at 10% strain reaches 0.192 MPa, suggesting that the composite exhibits practical mechanical strength.…”

Section: Resultsmentioning

confidence: 99%

Foreign element doping and thermal stability of alumina aerogels

Peng

Feng

et al. 2021

J Am Ceram Soc.

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The addition of foreign elements is considered as an effective method to improve the thermal stability of alumina aerogels at a higher temperature. However, the location and stabilizing mechanism of the foreign elements in the alumina aerogel have not been carefully studied. In this work, Si or La was introduced into the network of alumina aerogels through a sol-gel strategy. The Si-doped alumina aerogel maintained high surface area (92 m 2 /g) and pore volume (0.572 cm 3 /g) even at 1300 • C. The dopants prevented α-Al 2 O 3 transformation at elevated temperatures (1200 • C-1300 • C). The distribution of foreign ions and their stabilizing mechanism were discussed in detail. The doped alumina aerogels reinforced by mullite fiber felt, with quite low density and thermal conductivity, can be used as high-temperature thermal insulations.

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Section: Resultsmentioning

confidence: 99%

Foreign element doping and thermal stability of alumina aerogels

Peng

Feng

et al. 2021

J Am Ceram Soc.

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“…Note that we expected such a phase separation for higher alumina loadings but wanted to cover and to explore the crystallization behavior in the whole range, i.e., from full titania up to full alumina, to highlight the capability of super-cycle ALD processing. The addition of titania as a second phase in alumina has been demonstrated to improve the mechanical properties of powder metallurgy products [ 73 ] and also increase thermal insulation [ 74 ]. Of course, these properties are not the focus of this work, but photonic crystal structures have also been reported to be excellent thermal insulators [ 75 ] and mechanical meta materials [ 76 ].…”

Section: Resultsmentioning

confidence: 99%

Influence of Alumina Addition on the Optical Properties and the Thermal Stability of Titania Thin Films and Inverse Opals Produced by Atomic Layer Deposition

et al. 2021

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TiO2 thin films deposited by atomic layer deposition (ALD) at low temperatures (<100 °C) are, in general, amorphous and exhibit a smaller refractive index in comparison to their crystalline counterparts. Nonetheless, low-temperature ALD is needed when the substrates or templates are based on polymeric materials, as the deposition has to be performed below their glass transition or melting temperatures. This is the case for photonic crystals generated via ALD infiltration of self-assembled polystyrene templates. When heated up, crystal phase transformations take place in the thin films or photonic structures, and the accompanying volume reduction as well as the burn-out of residual impurities can lead to mechanical instability. The introduction of cation doping (e.g., Al or Nb) in bulk TiO2 parts is known to alter phase transitions and to stabilize crystalline phases. In this work, we have developed low-temperature ALD super-cycles to introduce Al2O3 into TiO2 thin films and photonic crystals. The aluminum oxide content was adjusted by varying the TiO2:Al2O3 internal loop ratio within the ALD super-cycle. Both thin films and inverse opal photonic crystal structures were subjected to thermal treatments ranging from 200 to 1200 °C and were characterized by in- and ex-situ X-ray diffraction, spectroscopic ellipsometry, and spectroscopic reflectance measurements. The results show that the introduction of alumina affects the crystallization and phase transition temperatures of titania as well as the optical properties of the inverse opal photonic crystals (iPhC). The thermal stability of the titania iPhCs was increased by the alumina introduction, maintaining their photonic bandgap even after heat treatment at 900 °C and outperforming the pure titania, with the best results being achieved with the super-cycles corresponding to an estimated alumina content of 26 wt.%.

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“…Compared with SiO 2 aerogels' sintering temperatures (above 600 ℃), alumina aerogels have higher sintering temperatures (above 1000 ℃), presenting one of the best heat resistance oxide aerogels. [113] Zu et al [70] drew support from innovative acetone-aniline in situ water formation (ISWF) method and two modification techniques to develop super heat-resistant and robust alumina aerogels. The highest heat resistant temperature of the alumina aerogels was up to 1300 ℃.…”

Section: Alumina (Al 2 O 3 ) Aerogelmentioning

confidence: 99%

Design, Synthesis, and Use of High Temperature Resistant Aerogels Exceeding 800 oC

Hu¹,

Liu²,

Zhao³

et al. 2021

ES Mater. Manuf.

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As a type of ultra-light and super thermal insulation solid state porous materials, aerogels have attracted increasing attention for aerospace, transportation, and building insulation applications. However, when aerogels are applied in these fields, resistance to high temperature is a prerequisite for them. The most traditional silica aerogels can resist up to 600 ℃, but their porous structures are destroyed at higher temperatures and no longer possess the excellent thermal insulation capacity and low density. Though a great number of new aerogels have been reported in the past two decades, the number of aerogels that could resist to ultra-high temperature, e.g. >800 ℃, is relative few. Nevertheless, it's exciting to see that more and more aerogels that can resist to temperatures higher than 1000 ℃, and even up to 1500 ℃, have been reported in the past few years. This paper gives an overview of aerogels that could resist to more than 800 ℃, and they defined as high temperature resistant aerogels (HTRAs) in this review. The synthetic strategies, mechanisms, chemical compositions, and specific applications of the HTRAs will be reviewed and discussed. This paper would be a timely review to summarized the most recent progress in the HTRAs, and provide insights into the designing of various HTRAs.

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Mechanical strengths and thermal properties of titania-doped alumina aerogels and the application as high-temperature thermal insulator

Cited by 37 publications

References 35 publications

Foreign element doping and thermal stability of alumina aerogels

Foreign element doping and thermal stability of alumina aerogels

Influence of Alumina Addition on the Optical Properties and the Thermal Stability of Titania Thin Films and Inverse Opals Produced by Atomic Layer Deposition

Design, Synthesis, and Use of High Temperature Resistant Aerogels Exceeding 800 oC

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