scholarly journals Effects of Milling pH and Hydrothermal Treatment on Formation of Nanostructured Boehmite Binder for Alumina Extrusion

2017 ◽  
Vol 2017 ◽  
pp. 1-14
Author(s):  
Maurício Batista de Lima ◽  
Marcela Bergamaschi Tercini ◽  
Sydney Ferreira Santos ◽  
Fernando dos Santos Ortega ◽  
Humberto Naoyuki Yoshimura
Keyword(s):  
Hydrothermal Treatment ◽  
Aluminum Hydroxide ◽  
Alumina Powder ◽  
Acidic Ph ◽  
Aluminum Hydroxides ◽  
Boehmite Nanoparticles ◽  
Alumina Particles ◽  
In Situ Formation ◽  
Suspension Ph

The in situ formation of nanostructured aluminum hydroxides on the surface of alumina particles, which can work as inorganic binder, was reported in this paper. The effect of the suspension pH during milling of alumina powder and subsequent hydrothermal treatment for the hydroxide formation and microstructure was depicted. Under acidic pH condition, the formation of hydroxides was not observed. When the pH of suspension changed from acidic to basic during milling, bayerite [Al(OH)3] nanoparticles were formed, but only a fraction of this hydroxide was converted to boehmite (AlOOH) during subsequent hydrothermal treatment. The aluminum hydroxide and oxyhydroxide formed in this condition improved the smoothness of extruded rods and the strength of presintered segments. For the powder milled under basic pH condition, the mechanochemically formed bayerite was completely converted into boehmite nanoparticles during the hydrothermal treatment. The presence of boehmite nanoparticles contributed to improving plasticity during extrusion, which allowed the reduction of organic binder and increased the strength of presintered alumina rods.

Microstructure Development and Mechanical Properties of Ce-TZP/La- β-Alumina Composites

1992 ◽  
Vol 274 ◽  
Author(s):  
Takashi Fujii ◽  
Hironobu Muragaki ◽  
Hiraku Hatano ◽  
Shin-Ichi Hirano
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Hydrothermal Treatment ◽  
Fracture Strength ◽  
Sintered Body ◽  
Microstructure Development ◽  
Lanthanum Aluminate ◽  
Alumina Composites ◽  
In Situ Formation

ABSTRACTSimultaneous additions of lanthanum aluminate(LAL) and Al2O3 to Ce-TZP (12mol% CeO2-ZrO2) lead to the in-situ formation of lanthanum- β-alumina(LBA) platelets (∼1.0.μ m in width and 5 ∼10 μ m in length) in the Ce-TZP matrix during sintering. The composites showed a fracture toughness(SEPB method) of 9.5 MPa · m0.5 and fracture strength of 960 MPa. which are remarkably improved from Ce-TZP sintered body (8.5 MPa · m0.5 and 560 MPa).The composites also exhibit the no degradation by hydrothermal treatment.

The Effect of Hydrothermal Treatment on the Micromorphology of Aluminum Sulfate Hydrolysis Product

2010 ◽  
Vol 152-153 ◽  
pp. 653-658
Author(s):  
Jing Wang ◽  
Li Jun Zhong
Keyword(s):  
Hydrothermal Method ◽  
Hydrothermal Treatment ◽  
Aluminum Hydroxide ◽  
Hollow Sphere ◽  
Aluminum Sulfate ◽  
Hydrolysis Product ◽  
Hydrothermal Temperature ◽  
Lower Temperature

The sphere aluminum hydroxide sulfate and hollow sphere boehmite were synthesized by using urea as precipitator with Al2(SO4)3•18H2O as precursor via a hydrothermal method. The effects of hydrothermal temperature on micromorphology were studied. Results showed that sphere aluminum hydroxide sulfate could obtain on lower temperature. As the hydrothermal temperature increased, sphere aluminum hydroxide sulfate begin to dissolve in situ and recrystallize. In the end, hollow sphere boehmite assembled by flake was formed.

Evaluation of Mechanochemical and Hydrothermal Transformations in a Wet-Milled Alumina by Transmission Electron Microscopy and Thermal Analysis

2016 ◽  
Vol 881 ◽  
pp. 46-51
Author(s):  
Humberto Naoyuki Yoshimura ◽  
Maurício Batista de Lima ◽  
Sydney Ferreira Santos ◽  
Fernando dos Santos Ortega
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Basic Medium ◽  
Alumina Powder ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Aluminum Hydroxides ◽  
Transmission Electron

Milling and hydrothermal treatment of alumina powders in aqueous medium can result in surface transformations generating aluminum hydroxides. The aim of this work was to advance the understanding on these transformations. A α-alumina powder was ball milled in water at different pHs for 10 h, and then autoclaved (150 °C, 3 atm, 3 h). The powders were analyzed by transmission electron microscopy, differential scanning calorimetry simultaneously with thermogravimetry, X-ray diffraction, and infrared spectroscopy. It was observed that milling in basic medium caused the formation of doyleite [Al (OH3)] nanoparticles, which were fully converted to boehmite (AlOOH) by hydrothermal treatment. The boehmite fraction determined by thermal analysis was 1.7 wt%. The powder milled in acid medium had no mechanochemical and hydrothermal transformations.

scholarly journals Formation of compact systems of super-Earths via dynamical instabilities and giant impacts

2019 ◽  
Vol 491 (4) ◽  
pp. 5595-5620 ◽  
Author(s):  
Sanson T S Poon ◽  
Richard P Nelson ◽  
Seth A Jacobson ◽  
Alessandro Morbidelli
Keyword(s):  
Initial Conditions ◽  
Post Processing ◽  
Significant Modification ◽  
Kepler Mission ◽  
Giant Impacts ◽  
Low Mass ◽  
In Situ Formation ◽  
Dynamical Instabilities ◽  
Gaseous Envelopes

ABSTRACT The NASA’s Kepler mission discovered ∼700 planets in multiplanet systems containing three or more transiting bodies, many of which are super-Earths and mini-Neptunes in compact configurations. Using N-body simulations, we examine the in situ, final stage assembly of multiplanet systems via the collisional accretion of protoplanets. Our initial conditions are constructed using a subset of the Kepler five-planet systems as templates. Two different prescriptions for treating planetary collisions are adopted. The simulations address numerous questions: Do the results depend on the accretion prescription?; do the resulting systems resemble the Kepler systems, and do they reproduce the observed distribution of planetary multiplicities when synthetically observed?; do collisions lead to significant modification of protoplanet compositions, or to stripping of gaseous envelopes?; do the eccentricity distributions agree with those inferred for the Kepler planets? We find that the accretion prescription is unimportant in determining the outcomes. The final planetary systems look broadly similar to the Kepler templates adopted, but the observed distributions of planetary multiplicities or eccentricities are not reproduced, because scattering does not excite the systems sufficiently. In addition, we find that ∼1 per cent of our final systems contain a co-orbital planet pair in horseshoe or tadpole orbits. Post-processing the collision outcomes suggests that they would not significantly change the ice fractions of initially ice-rich protoplanets, but significant stripping of gaseous envelopes appears likely. Hence, it may be difficult to reconcile the observation that many low-mass Kepler planets have H/He envelopes with an in situ formation scenario that involves giant impacts after dispersal of the gas disc.

scholarly journals Method for determining the thermal conductivity of in situ formation rock using drilling cuttings

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065015
Author(s):  
Fu Yi ◽  
Xupeng Qi ◽  
Xuexin Zheng ◽  
Huize Yu ◽  
Wenming Bai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
In Situ Formation

scholarly journals In situ formation of a carbon nanotube buckypaper for improving the interlaminar properties of carbon fiber composites

2021 ◽  
Vol 202 ◽  
pp. 109535
Author(s):  
Yadong Wu ◽  
Xiuyan Cheng ◽  
Shaoyun Chen ◽  
Bo Qu ◽  
Rui Wang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Carbon Fiber ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
In Situ Formation

In Situ Formation of Ag Nanoparticles for Fiber Strain Sensors: Toward Textile-Based Wearable Applications

2021 ◽  
Author(s):  
Hwajoong Kim ◽  
Ammar Shaqeel ◽  
Solbi Han ◽  
Junseo Kang ◽  
Jieun Yun ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Strain Sensors ◽  
In Situ Formation

A novel and facile route to in-situ formation of composites with dual coupling interactions for considerable millimeter-wave absorption performance

2021 ◽  
Author(s):  
Chuyang Liu ◽  
Tao Jiang ◽  
Tian Gao ◽  
Guangxian Xia ◽  
Yufan Cao ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Exchange Coupling ◽  
Ferromagnetic Coupling ◽  
Soft Magnetic ◽  
Magnetic Exchange ◽  
Magnetic Exchange Coupling ◽  
Absorption Performance ◽  
In Situ Formation ◽  
Facile Route

It is well known that both hard/soft magnetic exchange-coupling and ferroelectric-ferromagnetic coupling could facilitate the microwave absorption behavior. Herein, we propose the BaZrxFe12-xO19/Fe3O4/BaZrO3 composites to integrate the advantages of the...

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