Characterization Of Heattreated Polyparaphenylene-Based Carbons

1995 ◽  
Vol 413 ◽  
Author(s):  
M. J. Matthewsa ◽  
M. Endo ◽  
T. Takahashi ◽  
Y. Nishimura ◽  
T. Takamuku ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Anode Materials ◽  
Carbon Matrix ◽  
Treatment Temperature ◽  
Heat Treated ◽  
Disordered Carbon ◽  
B Doping ◽  
Carbon Anodes ◽  
Very High

ABSTRACTRaman spectroscopy and TEM measurements were recently performed on a series of polyparaphenylene (PPP)-based carbon samples which were heat-treated to temperatures between 600°C and 3000°C. Particular attention is focused on the development of carbonaceous structures at low heat-treatment temperatures (THT) in the range 600°C ≤ THT ≥ 800°C. PPP-based carbons heat treated in this temperature range have been found to have a very high affinity for the electrochemical introduction of lithium, which is of particular interest in ‘rocking-chair’ rechargeable Li batteries. Specific (Faradaic) capacities of up to 1120 mAh/g have been obtained for PPPbased carbon anodes with a THT of 700°C, which is about three times the capacity of GIC-based anode materials. At a heat-treatment temperature of 700° C, the PPPbased carbon has a disordered-granular appearance, as observed from TEM, while a ribbon-like graphitic structure is seen for heat treatment near 3000°C. Furthermore, Raman spectra show that, near a THT of 700° C, these PPP-based materials undergo a carbonization transformation from a mostly polymer-type extended lattice to a disordered carbon matrix, which undergoes partial graphitization at higher THT. Upon the introduction of small amounts of substitutionally-doped Boron (1% - 3% atomic), various properties are substantially modified. In this work we briefly discuss the effect of B-doping on the PPP-based carbon structure.

Study of the overtones and combination bands in the Raman spectra of polyparaphenylene-based carbons

1999 ◽  
Vol 14 (8) ◽  
pp. 3447-3454 ◽  
Author(s):  
A. Marucci ◽  
M. A. Pimenta ◽  
S. D. M. Brown ◽  
M. J. Matthews ◽  
M. S. Dresselhaus ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Frequency ◽  
Laser Excitation ◽  
Treatment Temperature ◽  
Visible Range ◽  
Excitation Energies ◽  
First Order ◽  
Heat Treated ◽  
Disordered Carbon ◽  
Combination Bands

A detailed study of the second-order Raman spectrum of the polymer polyparaphenylene (PPP) prepared according to the Kovacic method and heat treated at temperatures THT between 650 and 750 °C is presented. The Raman experiments have been performed with five different laser excitation energies in the visible range between 1.92 and 3.05 eV. Several Raman bands in the region between 2400 and 3400 cm−1 have been detected and assigned to the overtones and combination bands of the two conformations of the PPP polymer (benzenoid and quinoid) that co-exist in our samples. Due to the carbonization process, these bands broaden and decrease in intensity with increasing heat treatment temperature, as is also observed for the corresponding first-order Raman features. The complete absence of these high-frequency Raman bands for PPP with heat treatment temperatures in excess of 750 °C indicates complete transformation of the polymer into a disordered carbon material.

Structural characterization of carbons obtained from polyparaphenylenes prepared by the Kovacic and Yamamoto methods

1998 ◽  
Vol 13 (7) ◽  
pp. 2023-2030 ◽  
Author(s):  
M. Endo ◽  
C. Kim ◽  
T. Hiraoka ◽  
T. Karaki ◽  
K. Nishimura ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Layer Structure ◽  
Treatment Temperature ◽  
Li Ion Batteries ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Crystallite Structure ◽  
Li Ion

The structure of polyparaphenylene (PPP)-based carbons prepared by the Kovacic and Yamamoto methods heat-treated at 650–3000 °C have been characterized comparatively by using x-ray diffraction, SEM, TEM, and Raman spectroscopy. Both kinds of carbons indicate not typical but poor graphitizing behavior, especially for the case of PPP Yamamoto samples, and much less for PPP Kovacic samples, by heat treatment up to 3000 °C. The Kovacic-based samples heat-treated at 600–2400 °C have a more developed layer structure than that of Yamamoto-based samples. In contrast, for HTT's (heat-treatment temperature) more than about 2400 °C, PPP Yamamoto-based carbons exhibit a more developed crystallite structure than PPP Kovacic-based carbons. At a given HTT, PPP Kovacic-based carbons have a much more quinoid-like structure and graphene-type structure than PPP Yamamoto-based carbons, as indicated by the carbon yield and Raman scattering measurements. It is suggested that the detailed structure of the starting polymers influences the texture as well as the microstructure of resultant carbons even though both are obtained from the same kinds of precursors. These microstructures also largely influence the anode performance when these carbons are used in Li ion batteries.

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 Water Resistance and Creep Behavior of Heat-Treated Moso Bamboo Determined by the Stepped Isostress Method

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1264
Author(s):  
Teng-Chun Yang ◽  
Tung-Lin Wu ◽  
Chin-Hao Yeh
Keyword(s):  
Heat Treatment ◽  
Water Absorption ◽  
Creep Behavior ◽  
Heat Treatment Temperature ◽  
Water Resistance ◽  
Absorption Efficiency ◽  
Treatment Temperature ◽  
Moso Bamboo ◽  
Phyllostachys Pubescens ◽  
Heat Treated

The influence of heat treatment on the physico-mechanical properties, water resistance, and creep behavior of moso bamboo (Phyllostachys pubescens) was determined in this study. The results revealed that the density, moisture content, and flexural properties showed negative relationships with the heat treatment temperature, while an improvement in the dimensional stability (anti-swelling efficiency and anti-water absorption efficiency) of heat-treated samples was observed during water absorption tests. Additionally, the creep master curves of the untreated and heat-treated samples were successfully constructed using the stepped isostress method (SSM) at a series of elevated stresses. Furthermore, the SSM-predicted creep compliance curves fit well with the 90-day full-scale experimental data. When the heat treatment temperature increased to 180 °C, the degradation ratio of the creep resistance (rd) significantly increased over all periods. However, the rd of the tested bamboo decreased as the heat treatment temperature increased up to 220 °C.

Effect of Heat Treatment on the Microstructure and Property of TiAl Alloys Prepared by Gas Atomization Powders

2013 ◽  
Vol 747-748 ◽  
pp. 497-501
Author(s):  
Na Liu ◽  
Zhou Li ◽  
Guo Qing Zhang ◽  
Hua Yuan ◽  
Wen Yong Xu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Tial Alloy ◽  
Lamellar Microstructure ◽  
Treatment Temperature ◽  
Gas Atomization ◽  
Thermally Induced ◽  
Heat Treated ◽  
Fine Duplex ◽  
Step Heat Treatment

Powder metallurgical TiAl alloy was fabricated by gas atomization powders, and the effect of heat treatment temperature on the microstructure evolution and room tensile properties of PM TiAl alloy was investigated. The uniform fine duplex microstructure was formed in PM TiAl based alloy after being heat treated at 1250/2h followed by furnace cooling (FC)+ 900/6h (FC). When the first step heat treatment temperature was improved to 1360/1h, the near lamellar microstructure was achieved. The ductility of the alloy after heat treatment improved markedly to 1.2% and 0.6%, but the tensile strength decreased to 570MPa and 600MPa compared to 655MPa of as-HIP TiAl alloy. Post heat treatment at the higher temperature in the alpha plus gamma field would regenerate thermally induced porosity (TIP).

Mechanical and Superelastic Properties of Au-51Ti-18Co Biomedical Shape Memory Alloy Heat-Treated at 1173 K to 1373 K

2016 ◽  
Vol 97 ◽  
pp. 141-146 ◽  
Author(s):  
Taywin Buasri ◽  
Hyunbo Shim ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Kenji Goto ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Critical Stress ◽  
Biomedical Applications ◽  
Shape Recovery ◽  
Treatment Temperature ◽  
Recovery Ratio ◽  
Recovery Strain ◽  
Heat Treated ◽  
Alloy Heat

The effect of heat treatment temperature from 1173 K to 1373 K for 3.6 ks on mechanical and superelastic properties of an Ni-free Au-51Ti-18Co alloy (mol%) was investigated. The stress for inducing martensitic transformation (SIMT) and the critical stress for slip deformation (CSS) slightly decrease with increasing the heat–treatment temperature. Regardless of heat–treatment temperature, good superelasticity was definitely recognized with the maximum shape recovery ratio up to 95 % and 4 % superelastic shape recovery strain. As the mentioned reasons, the Au-51Ti-18Co alloy is promising for practical biomedical applications.

A- and B-site doping effect on physicochemical properties of Sr2−xBaxMMoO6 (M = Mg, Mn, Fe) double perovskites — candidate anode materials for SOFCs

2016 ◽  
Vol 09 (04) ◽  
pp. 1641002 ◽  
Author(s):  
Kun Zheng ◽  
Konrad Świerczek
Keyword(s):  
Physicochemical Properties ◽  
Solid Oxide Fuel Cells ◽  
Anode Materials ◽  
Full Range ◽  
Solid Oxide ◽  
Double Perovskites ◽  
Reducing Conditions ◽  
Redox Stability ◽  
Very High

In this work, we evaluate the physicochemical properties of Sr[Formula: see text]BaxMMoO6 (M [Formula: see text] Mg, Mn, Fe) double perovskites as alternative anode materials for solid oxide fuel cells, for which the effect of substitution of strontium by barium in a full range of compositions is studied. The crystal structure, microstructure, characterization of transport properties (electrical conductivity, Seebeck coefficient) and oxygen content as a function of temperature, as well as chemical stability in oxidizing and reducing conditions are discussed. Fe- and Mo-containing Sr[Formula: see text]BaxFeMoO6 oxides show very high total conductivities with values of 100–1000 S[Formula: see text][Formula: see text]cm[Formula: see text], while Sr[Formula: see text]BaxMgMoO6 present good redox stability.

Investigation of Heat Treated Electrodeposited CoNiFe on Microstructure and Hardness

2015 ◽  
Vol 1113 ◽  
pp. 56-61
Author(s):  
Nor Azrina Resali ◽  
Koay Mei Hyie ◽  
M.N. Berhan ◽  
C.M. Mardziah
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Crystallographic Structure ◽  
Face Centered Cubic ◽  
Heat Treated ◽  
Hardness Property ◽  
Finishing Process ◽  
The Face ◽  
Face Centered

In this research, heat treatment is the final finishing process applied on nanocrystalline CoNiFe to improve microstructure for good hardness property. Nanocrystalline CoNiFe has been synthesized using the electrodeposition method. This study investigated the effect of heat treatment at 500°C, 600°C, 700°C and 800°C on electrodeposited nanocrystalline CoNiFe. The heat treatment process was performed in the tube furnace with flowing Argon gas. By changing the heat treatment temperature, physical properties such as phase and crystallographic structure, surface morphology, grain size and hardness of nanocrystalline CoNiFe was studied. The nanocrystalline CoNiFe phase revealed the Face Centered Cubic (FCC) and Body Centered Cubic (BCC) crystal structure. FESEM micrographs showed that the grain sizes of the coatings were in the range of 78.76 nm to 132 nm. Dendrite shape was found in the microstructure of nanocrystalline CoNiFe. The nanocrystalline CoNiFe prepared in heat treatment temperature of 700°C, achieved the highest hardness of 449 HVN. The surface roughness of nanocrystalline CoNiFe heated at 700°C was found to be smaller than other temperatures.

Characterization of Ultrafine Glassy Powder for Al-Si-Ca-P-O-F Polynary System by Liquid Precipitation

2010 ◽  
Vol 177 ◽  
pp. 433-436 ◽  
Author(s):  
G.C. Yuan ◽  
Q.G. Wu ◽  
Guo Xun Zeng ◽  
Z.Y. Ling
Keyword(s):  
Heat Treatment ◽  
Network Structure ◽  
Inorganic Compounds ◽  
Amorphous State ◽  
Precipitation Method ◽  
Hollow Particles ◽  
Heat Treated ◽  
Quenched Glass ◽  
Liquid Precipitation

The ultrafine glassy powder of Al-Si-Ca-P-O-F polynary system was prepared by liquid precipitation method with several inorganic compounds as reactants containing the ions such as Al3+, SiO32-, P3O105-, Ca2+, F-, respectively. The powder was heat-treated in the range of temperature from 773 to 1173K and its crystallized processes were ascertained. The morphology, composition, bonding state and structure, crystallized behavior of the glassy powder were characterized by means of TEM, XRD, EDAX, IR, DSC etc methods. The results show that the powder containing Al, Si, Ca, P, O, F elements belongs to typical amorphous state, and the particles appeared hollow and near spherical morphology with the size from 30 to 70nm. The hollow particles collapsed as plate like conglutination state and a series of crystallized phases CaF2, Al2SiO5, Ca2SiO4, and Ca3(PO4)2 were separated sequentially during heat treatment in the range of temperature above. The characteristics of the glassy powder are similar to those of popular melting-quenched glass of the system. The network structure of the glass was mainly formed by the tetrahedrons of [SiO4], [AlO4] and [PO4], which were linked by the oxygen atoms of the angle in the tetrahedrons.

Characterization of Microstructure and Mechanical Properties of 6060 Aluminum Alloy Processed by ECAP

2018 ◽  
Vol 275 ◽  
pp. 81-88
Author(s):  
Monika Karoń ◽  
Marcin Adamiak
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Internal Stresses ◽  
Refined Grains ◽  
Angular Pressing ◽  
Heat Treated ◽  
Evolution Of Microstructure

The purpose of this paper is to present the microstructure and mechanical behavior of 6060 aluminum alloy after intense plastic deformation. Equal Channel Angular Pressing (ECAP) was used as a method of severe plastic deformation. Before ECAP part of the samples were heat treated to remove internal stresses in the commercially available aluminium alloy. The evolution of microstructure and tensile strength were tested after 1, 3, 6 and 9 ECAP passes in annealed and non annealed states. It was found that intensely plastically deformed refined grains were present in the tested samples and exhibited increased mechanical properties. Differences were noted between samples without and after heat treatment

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