Progress in fabrication and characterization of mullite whiskers

2021 ◽  
pp. 2150003
Author(s):  
Zhuohao Xiao ◽  
Wenqiang Wang ◽  
Xiuying Li ◽  
Ling Zhang ◽  
Tianshu Zhang ◽  
...  
Keyword(s):  
Ceramic Matrix Composites ◽  
High Energy ◽  
Milling Process ◽  
Synthesis Methods ◽  
Phase Reaction ◽  
Matrix Composites ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Mullite Whiskers ◽  
Underlying Mechanisms

Mullite has an orthorhombic crystal structure, with various advantages, such as high mechanical strength, and stable chemical and physical properties. Especially, mullite whiskers have been widely acknowledged to be potential candidates as reinforcing elements in the fabrication of ceramic-matrix composites. Various strategies have been developed to synthesize mullite whiskers, such as catalytic methods, liquid-phase reaction, molten salt reaction, solid-state reaction and high-energy ball milling process. In different synthesis methods, the underlying mechanisms governing the anisotropic grain growth of mullite grains vary. This paper aims to offer an overview on the progress in fabrication of mullite whiskers with different methods, and the perspectives on these special materials are briefly discussed.

scholarly journals In situ characterization of residual stress evolution during heat treatment of SiC/SiC ceramic matrix composites using high‐energy X‐ray diffraction

2020 ◽  
Vol 104 (3) ◽  
pp. 1424-1435
Author(s):  
Michael W. Knauf ◽  
Craig P. Przybyla ◽  
Paul A. Shade ◽  
Jun‐Sang Park ◽  
Andrew J. Ritchey ◽  
...  
Keyword(s):  
Ceramic Matrix Composites ◽  
High Energy ◽  
Matrix Composites ◽  
Stress Evolution ◽  
X Ray Diffraction ◽  
In Situ Characterization ◽  
X Ray ◽  
Sic Ceramic

Fabrication of TiAl/B4C Composites from an Al-Ti-B4C System Reinforced by TiC, TiB2 In Situ

2009 ◽  
Vol 79-82 ◽  
pp. 477-480 ◽  
Author(s):  
Li Hua Dong ◽  
Wei Ke Zhang ◽  
Jian Li ◽  
Yan Sheng Yin
Keyword(s):  
Bending Strength ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
High Energy ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hot Pressing Sintering ◽  
Different Content

Near full dense B4C ceramic matrix composites were fabricated from Ti-Al-B4C system by combining high energy milling with hot pressing sintering. The effect of different content of Ti-Al on the mechanical properties and microstructure of the as-prepared composites was investigated. A TiAl/B4C composite, whose typical bending strength and fracture toughness are 437.3 MPa and 4.85 MPa•m1/2, respectively, was made. The sintering mechanism and reinforcement mechanism were discussed with the assistant of X-Ray diffraction and electron microscopy.

Magnesium Hydride of Orthorhombic Crystal from High-Energy Ball Milling under Hydrogen Atmosphere

2013 ◽  
Vol 724-725 ◽  
pp. 1033-1036 ◽  
Author(s):  
Shi Xue Zhou ◽  
Wei Xian Ran ◽  
Min Jian Yang ◽  
De Xi Wang ◽  
Guo Qiang Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ball Milling ◽  
High Energy ◽  
Hydrogen Atmosphere ◽  
Magnesium Hydride ◽  
High Energy Ball Milling ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Anthracite Coal ◽  
Energy Ball

The crystal structure of magnesium hydride affects the properties of magnesium for hydrogen storage. The crystal phase and dehydriding temperature of magnesium hydride from magnesium by high-energy ball milling under hydrogen atmosphere with anthracite carbon, which was prepared from anthracite coal by demineralization and carbonization, as milling aid was investigated. The HRTEM observation and XRD characterization showed that the Mg hydrided into nanocrystalline β-MgH2of tetrahedral crystal structure and γ-MgH2of orthorhombic crystal structure during milling under 1 MPa of hydrogen, and the γ-MgH2increased with the extension of milling time. The DSC analysis showed that the endothermic peak of γ-MgH2was 53 °C lower than that of β-MgH2in the material from 10 h of milling.

IMPEDANCE SPECTROSCOPY STUDIES OF NANO-CRYSTALLINE LiFePO4 CATHODE SYNTHESIZED BY HYDROTHERMAL METHOD

2013 ◽  
Vol 22 ◽  
pp. 517-524 ◽  
Author(s):  
P. ROSAIAH ◽  
O. M. HUSSAIN
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Lithium Iron Phosphate ◽  
Raw Materials ◽  
Ionic Mobility ◽  
High Energy ◽  
High Energy Density ◽  
Rechargeable Lithium Batteries ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure

LiFePO 4 has become of great interest as storage cathodes for rechargeable lithium batteries because of their high energy density, low raw materials cost, environmental friendliness, high thermal stability. In the present investigation, lithium iron phosphate ( LiFePO 4) cathode material has been prepared by using hydrothermal synthesis. The structure of the sample has been studies by using X-ray diffraction. The XRD spectrum exhibited different characteristic peaks along with (311) predominant orientation corresponding to an orthorhombic crystal structure with Pnma space group. Electrical and dielectric properties were studied over a frequency range of 1 Hz – 1 MHz at different temperatures. The electrical conductivity was found to be increased with increasing temperature following Arrhenius relation with an estimated activation energy of 0.44 eV. The dielectric properties were analyzed in the framework of complex dielectric permittivity and complex electric modulus formalisms. The evolution of the complex permittivity as a function of frequency and temperature was investigated. Several important parameters such as activation energy, ionic hopping frequency, carrier concentration, ionic mobility and diffusion coefficient etc, were determined.

scholarly journals A comparative study of hyperfine interactions in Aurivillius compounds prepared by mechanical activation and solid-state sintering

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 153-157 ◽  
Author(s):  
Mariusz Mazurek ◽  
Elżbieta Jartych
Keyword(s):  
Solid State ◽  
Mechanical Activation ◽  
Hyperfine Interactions ◽  
High Energy ◽  
Lattice Parameter ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
High Energy Ball Mill ◽  
Solid State Sintering ◽  
Paramagnetic Materials

Abstract X-ray diffraction and Mössbauer spectroscopy techniques were used to study the structure and hyperfine interactions of multiferroic Aurivillius compounds Bim+1Ti3Fem-3O3m+3. Samples were synthesized by two methods, that is, the solid-state sintering at various temperatures and mechanical activation in a high-energy ball mill. The compounds were obtained from a mixture of three polycrystalline powder oxides, that is, TiO2, Fe2O3 and Bi2O3. At room temperature, the Aurivillius compounds are paramagnetic materials with orthorhombic crystal structure. The c lattice parameter of the unit cell depends linearly on the m − number of layers with perovskite-like structure. Based on the Mössbauer studies, it is concluded that the hyperfine interactions parameters do not change with m number.

scholarly journals B4C Particles Reinforced Al2024 Composites via Mechanical Milling

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 647 ◽  
Author(s):  
Caleb Carreño-Gallardo ◽  
Ivanovich Estrada-Guel ◽  
Claudia López-Meléndez ◽  
Ernesto Ledezma-Sillas ◽  
Rubén Castañeda-Balderas ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Mechanical Milling ◽  
Aluminum Matrix ◽  
High Energy ◽  
Milling Process ◽  
Homogeneous Distribution ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
2024 Alloy ◽  
B4c Particles

The control of a homogeneous distribution of the reinforcing phase in aluminum matrix composites is the main issue during the synthesis of this kind of material. In this work, 2024 aluminum matrix composites reinforced with boron carbide were produced by mechanical milling, using 1 and 2 h of milling. After milling, powdered samples were cold consolidated, sintered and T6 heat treated. The morphology and microstructure of Al2024/B4C composites were investigated by scanning electron microscopy; analysis of X-ray diffraction peaks were used for the calculation of the crystallite size and microstrains by the Williamson–Hall method. The mechanical properties were evaluated by compression and hardness tests. B4C particles were found to be well dispersed into the aluminum matrix as a result of the high-energy milling process. The crystallite size of composites milled for 2 h was lower than those milled for 1 h. The hardness, yield strength and maximum strength were significantly improved in the composites processed for 2 h, in comparison to those processed for 1 h and the monolithic 2024 alloy.

Dispersion of CNTs in Aluminum 2024 Alloy by Milling Process

2011 ◽  
Vol 691 ◽  
pp. 27-31 ◽  
Author(s):  
R. Pérez-Bustamante ◽  
F. Pérez-Bustamante ◽  
J. I. Barajas-Villaruel ◽  
J. Martin Herrera-Ramírez ◽  
Ivanovich Estrada-Guel ◽  
...  
Keyword(s):  
Milling Time ◽  
Vickers Microhardness ◽  
Aluminum Matrix ◽  
High Energy ◽  
Milling Process ◽  
Matrix Composites ◽  
Strengthening Mechanisms ◽  
Important Improvement ◽  
2024 Alloy ◽  
Reference Samples

Elemental powders and carbon nanotubes (CNTs) were mixed and milled in a high energy shaker mill (SPEX-8000M), to produce 2024 aluminum (Al2024) matrix composites reinforced with CNTs. Milled products were consolidated by uniaxial load pressing followed by pressure-less sintering under argon atmosphere for 2 h at 773 K. The effect of CNTs concentration and milling time on Vickers microhardness (µHV) was studied. Scanning electron microscopy (SEM) micrographs show that by milling process it is possible to obtain a homogeneous dispersion of CNTs into the aluminum matrix. The mechanical properties of the composites show an important improvement with respect to reference samples. The possible strengthening mechanisms are discussed in the present work.

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