Novel nonaqueous precipitation synthesis of alumina powders

Feng, Guo; Jiang, Weihui; Liu, Jianmin; Liu, Cong; Zhang, Quan; Liu, Miao; Wu, Qian

doi:10.1016/j.ceramint.2017.07.050

Cited by 17 publications

(3 citation statements)

References 31 publications

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“…In the glove-box, 13.5 mL tetraethyl orthosilicate (TEOS) was dissolved in 120 mL anhydrous ethanol with the formation of TEOS-ethanol solution (0.5 mol/L). Then 15.116 g (theoretical amount (TA) for mullite synthesis, A 0 ), 16.628 g (1.1 of TA, A 1 ), 18.139 g (1.2 of TA, A 2 ), 19.651 g (1.3 of TA, A 3 ) and 21.162 g (1.4 of TA, A 4 ) anhydrous aluminum fluoride was added to the ethanol solution of TEOS, respectively. Mixtures were transformed to a kettle with the nominal volume of 200 mL, and then held at 130 • C for 12 h. After washed repeatedly with ethanol and filtered, the precipitate powders were obtained.…”

Section: Methodsmentioning

confidence: 99%

“…Various processing techniques have been utilized to prepare mullite whiskers, including the mineral decomposition method [6], vapor-phase reaction method [7], molten salt method [8], hydrolytic sol-gel method [9], nonhydrolytic sol-gel method [10], nonhydrolytic sol-gel combined with the molten salt method [11][12][13][14], etc. The nonaqueous precipitation method is a novel materials synthesis method, and it holds the merits of simple process, short cycle, non-aggregation of products [15][16][17]. However, in order to give full play to the advantages of nonaqueous precipitation method, the precursor materials must undergo nonhydrolytic polycondensation.…”

Section: Introductionmentioning

confidence: 99%

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Pressure Field Assisted Polycondensation Nonaqueous Precipitation Synthesis of Mullite Whiskers and Their Application as Epoxy Resin Reinforcement

Feng

Jiang

et al. 2019

Polymers

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Mullite whiskers were novelty prepared via pressure field assisted polycondensation nonaqueous precipitation method. The precipitate phase transition in heating process, phase compositions and microstructure of samples calcined at different temperatures, effect of pressure field on precursors polycondensation and AlF3 amount on sample morphology, the structure and the growth mechanism of whiskers were investigated. The results indicate that pressure field caused by kettle treatment promotes the polycondensation reaction between AlF3 and tetraethyl orthosilicate (TEOS), the excess aluminum fluoride coordinates with the precipitate skeleton of the =Al–O–Si≡, which brings about the low mullitization temperature (900 °C). The sample prepared with the optimal amount of aluminum fluoride (1.3 of the theoretical amount) calcined at 1100 °C presents high yield and aspect ratio (>15, 100 nm in diameter) of mullite whiskers. Growth of whiskers prepared via pressure field assisted polycondensation nonaqueous precipitation method is attributed to a vapor-solid (VS) mechanism with the inducement of screw. These mullite whiskers with the structure of multi-needle whiskers connected in the same center can be distributed evenly in epoxy resin, which greatly improves the mechanical properties of epoxy resin.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pressure Field Assisted Polycondensation Nonaqueous Precipitation Synthesis of Mullite Whiskers and Their Application as Epoxy Resin Reinforcement

Feng

Jiang

et al. 2019

Polymers

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“…Alumina is a compound that exhibits several phases like α, γ, β and θ, etc [1]. While the most stable phase is α-alumina with very interesting properties such as high hardness, high melting temperature, chemical stability and high elastic modulus [1][2][3][4]. Moreover, the combination of a high thermal coefficient, low thermal expansion and high compressive strength provides αalumina a good resistance to thermal shock [1,5].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of submicronic α-alumina from local aluminum slags

ahmed

Elkolli

Hamidouche

2022

J min metall B Metall

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In this study, a high valued product submicronic ?-alumina is successfully extracted from aluminum slags generated by the local aluminum industry. The extraction technique is based on the leaching of slags by H2SO4 followed by precipitation. The coarser aluminum-rich fractions of the slags are used in this study instead of the finer oxide-rich fractions that were commonly used in previous studies. The precipitation of the leached slags by NH4OH is controlled by zetameter in order to determine the optimal precipitation pH. Then, the obtained gel showing the higher precipitation rate and the finer particle size is calcined at 1200 ?C and characterized by XRF, XRD, FTIR, SEM, EDS and laser granulometry. Even without any pretreatment of slags, the XRF analysis reveals that a high purity and high extraction efficiency of 99.2% and 93.75% respectively can be achieved just at a leaching acid concentration of 15%. XRD spectrum shows that the produced alumina is a pure a-corundum, which is confirmed by FTIR spectrum showing only the Al-O bonds. The laser granulometry shows that the recovered powder exhibit a wide particle size distribution. It is between 50 nm and 20 ?m while the average particle size (d50) is about 400 nm. SEM observations reveal that the grains are in the form of submicronic whiskers. The above characteristics allow the obtained alumina powder in this study to be used in the usual applications of alumina such as refractory, ceramic fibers, abrasive, etc. The obtained powders may assume also applications as a thermally stable substitute for the commonly used transition alumina powders, which need further investigations in future studies.

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