scholarly journals In-situ formation and densification of MgAl2O4-Y3Al5O12 and MgAl2O4-MgNb2O6 ceramics via a single-stage SRS process

2017 ◽  
Vol 49 (3) ◽  
pp. 285-297 ◽  
Author(s):  
Bowen Zhang ◽  
Beiyue Ma ◽  
Qiang Zhu ◽  
Shiming Li ◽  
Yikun Chen ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Bulk Density ◽  
Single Stage ◽  
Reaction Sintering ◽  
Shrinkage Ratio ◽  
Average Grain Size ◽  
In Situ Formation ◽  
Diameter Shrinkage ◽  
Intergranular Space

MgAl2O4 (MA)-Y3Al5O12 (YAG) and MA-MgNb2O6 (MN) ceramics with high density were successfully fabricated via a single-stage solid-state reaction sintering (SRS) process at 1580?C for 4 h. The effect of Y2O3 or Nb2O5 additions from 2.5 wt% to 7.5 wt% on the phase compositions, microstructures, shrinkage ratio, apparent porosity, bulk density and cold compressive strength of MA-YAG and MA-MN ceramics has been investigated. It was found that MgO and Y2O3 reacted with Al2O3 to form MA and YAG during sintering while Nb2O5 reacted with MgO to form MN. YAG and MA grains in the MA-YAG ceramics exist as granular shape, and their average grain size is about 1 ?m and 5 ?m, respectively. YAG grains distribute on the intergranular space of MA particles. Polygonal MA particles can be observed in the MA-MN ceramics, and MN grains distribute on the intergranular space of MA particles as well as on MA particles. Rod-like MN grains can be formed in the MA-MN ceramics by addition of 7.5 wt% Nb2O5. The diameter shrinkage ratio, volume shrinkage ratio, bulk density and cold compressive strength of MA-YAG and MA-MN ceramics are greatly improved by doping Y2O3 and Nb2O5, respectively.

Effect of Sintering Temperature on the Physical Properties and Microstructure of In Situ Nitrides Bonded MgAl2O4-C Refractories

2016 ◽  
Vol 697 ◽  
pp. 591-594
Author(s):  
Shao Hua Wang ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu ◽  
Wen Jie Yuan
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Bulk Density ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Silicon Powder ◽  
Flake Graphite ◽  
High Quality ◽  
Liquid Calcium

The in situ nitrides bonded MgAl2O4-C refractories were prepared by using high quality fused spinel (MgAl2O4≥ 97%), natural flake graphite (C ≥ 96%) and silicon powder (Si ≥ 98%) as raw materials and the liquid calcium lignosulfonate with a concentration of 1.25 g/ml was used as binder (4 wt%). The effect of sintering temperatures on physical properties and phase compositions were investigated. The results show that β-sialon and α-Si3N4were formed in the samples sintered at 1400°C, 1450°C and 1500°C, and AlON and AlN were formed in the samples sintered at 1550°C. The sample that sintered at 1450°C exhibits the best bulk density and apparent porosity of 2.84 g/cm3 and 14.73%, respectively, and the highest compressive strength

Effect of In-Situ Formation of Nanoscale γ-Al2O3 and AlN on Thermal Stability of Cryomilled Nanocrystalline Fe

1995 ◽  
Vol 400 ◽  
Author(s):  
R.J. Perez ◽  
B. Huang ◽  
E.J. Lavernia
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Grain Size ◽  
Subsequent Heat Treatment ◽  
Nanometer Scale ◽  
Average Grain Size ◽  
Attritor Milling ◽  
In Situ Formation ◽  
Thermal Stability Of

AbstractCryogenic attritor milling (cryomilling) is used to synthesize nanocrystalline Fe-10wt.%Al powders. Following consolidation in a rigid die at 823 K and heat treatment for 1 hour at 1223 K, an average grain size of 16±7 nm is maintained. This level of thermal stability is shown to exceed that of pure Fe processed under identical conditions. The significant increase in thermal stability is attributed primarily to the presence of nanometer-scale γ-Al2O3 and AIN dispersoids formed during cryomilling and subsequent heat treatment.

In Situ Formation of Ti Matrix Composites Reinforced Nanometric TiC by Powder Metallurgy Technique

2014 ◽  
Vol 1061-1062 ◽  
pp. 100-103
Author(s):  
Chun Ming Wang ◽  
Si Yu Gao ◽  
Su Fen Xiao ◽  
Yun Gui Chen
Keyword(s):  
Compressive Strength ◽  
Powder Metallurgy ◽  
Yield Strength ◽  
Preparation Method ◽  
Matrix Composites ◽  
Powder Metallurgy Technique ◽  
Compressive Properties ◽  
In Situ Formation ◽  
Tic Nanoparticles

In-situ formation of nanometric TiC reinforcements based on Ti matrix composites were researched by a novel preparation method, which including glucose polymers coating and powder metallurgy. The results showed that TiC nanoparticles were homogeneously distributed in Ti matrix, and the as-sintered Ti-TiC composites displayed excellent compressive properties which ultimate compressive strength was 2500 MPa, yield strength was 1450 MPa and strain to fracture was 53 %.

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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