Structural Defects and Changes in Al-Pd-Fe Crystalline Approximant

2007 ◽  
Vol 26-28 ◽  
pp. 687-690 ◽  
Author(s):  
J.P. Wang ◽  
Wei Sun ◽  
Z. Zhang
Keyword(s):  
Heat Treatment ◽  
High Resolution Electron Microscopy ◽  
Structural Defects ◽  
Decagonal Quasicrystal ◽  
High Temperature Heat Treatment ◽  
Atom Clusters ◽  
Heat Treated ◽  
Resolution Electron ◽  
The Relationship ◽  
Temperature Heat Treatment

Crystalline approximants structurally related to decagonal quasicrystal in the as-cast and heat-treated Al75Pd15Fe10 alloys and defect structures in them have been studied by means of high-resolution electron microscopy (HREM). Structural defects of linear and planar types were found to exist extensively in the orthorhombic ε16-phase formed in the as-cast Al75Pd15Fe10 alloy. In contrast with the distribution and configuration of the defects in the as-cast ε16-phase, we found that high-temperature heat treatment promotes the formation of a kind of regular network of structural defects in the ε16-phase. This suggests that rearrangements of atom clusters and as well as defects occurred due to the heat treatment. The relationship between the distribution of atom clusters and the configuration of defects will be discussed.

Pyrolysis Characteristic of Nitrogen in Carbon Fibers during High-Temperature Heat Treatment

2015 ◽  
Vol 723 ◽  
pp. 752-756
Author(s):  
Ai Jun Gao ◽  
Zuo Guang Zhang ◽  
Liang Hua Xu
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Carbon Fibers ◽  
Amorphous Region ◽  
Pyrolysis Mechanism ◽  
High Temperature Heat Treatment ◽  
Heat Treated ◽  
Temperature Heat ◽  
Graphite Sheets ◽  
Temperature Heat Treatment

Pyrolysis mechanism of nitrogen in carbon fibers, heat-treated at various temperatures, was investigated, in relation to the nitrogen chemical bonding states. Nitrogen content shows exponential decreasing with increased temperature and extended time. The pyrolysis of nitrogen exhibited time-temperature equivalence. Nitrogen atoms containing hydrogen in the amorphous region and at the edge of microcrystalline, and the double-bonded nitrogen in pyridine rings are easily pyrolyzed, while nitrogen atoms in the six-member ring of the graphite sheets are difficult to be pyrolyzed.

Synthesis of Ti3AlC2 Powder by High Energy Ball Milling and High Temperature Heat Treatment

2010 ◽  
Vol 658 ◽  
pp. 181-184 ◽  
Author(s):  
Jian Feng Zhu ◽  
Guo Quan Qi ◽  
Hai Bo Yang ◽  
Fen Wang
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Phase Evolution ◽  
High Energy ◽  
High Energy Milling ◽  
High Temperature Heat Treatment ◽  
Heat Treated ◽  
Temperature Heat ◽  
Energy Ball ◽  
Temperature Heat Treatment

Highly pure Ti3AlC2 powder was fabricated by combination of high energy milling and heat treatment with Ti, C and Al as starting materials. The details of reactions and phase evolution in fabrication process were investigated. The results shown that the Ti-Al intermetallics, Ti3AlC2 and TiC were formed in high energy milling. The as-milled powders were heat treated subsequently, and the Ti3AlC2 powder with high purity was produced from the reaction among Ti-Al intermetallics, Ti3AlC2 and TiC at relative low temperature (1100 °C).

High-temperature heat treatment of carbon microcoils obtained by chemical vapor deposition process and their properties

2000 ◽  
Vol 15 (3) ◽  
pp. 808-814 ◽  
Author(s):  
Xiuqin Chen ◽  
Wan In-Hwang ◽  
Shiro Shimada ◽  
Mituhiro Fujii ◽  
Hiroshi Iwanaga ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Catalytic Pyrolysis ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Fiber Axis ◽  
High Temperature Heat Treatment ◽  
Heat Treated ◽  
Temperature Heat ◽  
Herringbone Structure ◽  
Temperature Heat Treatment

Carbon microcoils obtained by the catalytic pyrolysis of acetylene at 770 °C were heat treated at 3000 °C for 6 h in a CO + CO2 atmosphere. The effect of the heat treatment on the morphology, microstructure, and properties was examined. The coiling morphology of the carbon coils was almost preserved even after the heat treatment, though it became brittle. The ruptured cross section of the two fibers, which form the coils, generally has either a trigonal pyramidlike form or negative pyramidal hollow. These characteristic ruptured patterns demonstrate the growth mechanism of the carbon coils. Distinct graphite layers (d = 0.339 nm) were developed by the heat treatment with an inclination of 10–40° versus the fiber axis to form a “herringbone” structure. The bulk electrical resistivity, density, and specific surface area were 10–0.1 Ωcm, 2.2077–2.087 g/cm3, and 6–8 m2/g, respectively.

scholarly journals Enhancing Graphene Retention and Electrical Conductivity of Plasma-Sprayed Alumina/Graphene Nanoplatelets Coating by Powder Heat Treatment

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 643
Author(s):  
Xiaoyu Wu ◽  
Shufeng Xie ◽  
Kangwei Xu ◽  
Lei Huang ◽  
Daling Wei ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Structural Integrity ◽  
Ceramic Coatings ◽  
Treatment Temperature ◽  
Graphene Nanoplatelets ◽  
Structural Defects ◽  
Temperature Plasma ◽  
Heat Treated ◽  
Plasma Sprayed

Burning loss of graphene in the high-temperature plasma-spraying process is a critical issue, significantly limiting the remarkable performance improvement in graphene reinforced ceramic coatings. Here, we reported an effective approach to enhance the graphene retention, and thus improve the performance of plasma-sprayed alumina/graphene nanoplatelets (Al2O3/GNPs) coatings by heat treatment of agglomerated Al2O3/GNPs powders. The effect of powder heat treatment on the microstructure, GNPs retention, and electrical conductivity of Al2O3/GNPs coatings were systematically investigated. The results indicated that, with the increase in the powder heat treatment temperature, the plasma-sprayed Al2O3/GNPs coatings exhibited decreased porosity and improved adhesive strength. Thermogravimetric analysis and Raman spectra results indicated that increased GNPs retention from 12.9% to 28.4%, and further to 37.4%, as well as decreased structural defects, were obtained for the AG, AG850, and AG1280 coatings, respectively, which were fabricated by using AG powders without heat treatment, powders heat-treated at 850 °C, and powders heat-treated at 1280 °C. Moreover, the electrical conductivities of AG, AG850, and AG1280 coatings exhibited 3 orders, 4 orders, and 7 orders of magnitude higher than that of Al2O3 coating, respectively. Powder heat treatment is considered to increase the melting degree of agglomerated alumina particles, eventually leaving less thermal energy for GNPs to burn; thus, a high retention amount and structural integrity of GNPs and significantly enhanced electrical conductivity were achieved for the plasma-sprayed Al2O3/GNPs coatings.

scholarly journals Investigating Corrosion Resistance of Heavy-Duty Steel Fasteners Regarding Assemblies Operating in Maritime Climates under High Pressures Power, Metallurgical and Chemical Engineering

2020 ◽  
pp. 94-106
Author(s):  
K.I. Nedashkovskiy ◽  
A.V. Gulshin ◽  
Yu.M. Averina ◽  
V.A. Naumkina ◽  
V.V. Menshikov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Grain Refinement ◽  
Chemical Engineering ◽  
High Pressures ◽  
Heavy Duty ◽  
High Temperature Heat Treatment ◽  
Temperature Heat ◽  
Temperature Heat Treatment

The paper presents investigation results and a technology for manufacturing fastener workpieces out of the 07Kh16N6-Sh (07Х16Н6-Ш) steel using high-temperature heat treatment. The steel undergoing our testing was additionally doped with molybdenum, as reflected in the 07Kh16N6M-Sh (07Х16Н6М-Ш) designation, which facilitated grain refinement. We implemented accelerated climate testing of bolts in order to assess the corrosion cracking resistance of 07Kh16N6-Sh (07Х16Н6-Ш), 07Kh16N6M-Sh (07Х16Н6М-Ш) and 13Kh15N4AM3-Sh (13Х15Н4АМ3-Ш) steel fasteners in maritime climates.

Vapor Phase Growth of Carbon Microcoils / Nanocoils

2005 ◽  
Vol 23 ◽  
pp. 387-0
Author(s):  
S. Yang ◽  
X. Chen ◽  
S. Motojima
Keyword(s):  
Heat Treatment ◽  
Catalytic Pyrolysis ◽  
Double Helix ◽  
Phase Growth ◽  
High Temperature Heat Treatment ◽  
Coil Diameter ◽  
Temperature Heat ◽  
Α Helix ◽  
Temperature Heat Treatment ◽  
Single Helix

The carbon microcoils and carbon nanocoils were prepared by the catalytic pyrolysis of acetylene under the Ni and/or Fe-containing catalysts, and the growth pattern, morphology and growth mechanism of the carbon coils were examined in detail. The inner coil diameter of carbon microcoils are of several µm and coil gap from zero to several µm. The inner coil diameter of carbon nanocoils are from zero to several ten nm and coil gap from zero to several nm. The carbon microcoils are generally of double helix coils such as DNA while carbon nanocoils were single helix coils such as α-helix proteins, with spring-like or twisted forms. A catalyst grain was usually observed on the tip of carbon coil. The carbon nanocoils are almost amorphous and can be graphitized by the high temperature heat-treatment.

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