Selectivity Heating Effect of Microwave on Purifying of Natural Graphite

2012 ◽  
Vol 174-177 ◽  
pp. 810-815 ◽  
Author(s):  
Yu Feng Li ◽  
Shi Fu Zhu ◽  
Yun An
Keyword(s):  
Carbon Content ◽  
Hydrofluoric Acid ◽  
Microwave Field ◽  
Volume Fraction ◽  
Flake Graphite ◽  
Acid System ◽  
Natural Graphite ◽  
Reaction Pressure ◽  
Mixed Acid ◽  
Microwave Assisted

The effect of non-thermal microwave on purifying natural graphite was studied. It was found that with existence of microwave field, the carbon content of the product was improved from 95.840% to 99.125% and the result of the purifying was affected by the power of the microwave，the reaction pressure and the reaction time. Add 5% (volume fraction) of hydrofluoric acid in the mixed acid system can improve the carbon content of greater than 99.9% of the natural flake graphite. The use of mixed acid of microwave-assisted purification of natural flake graphite is a better way of producing high-purity graphite.

scholarly journals Low-carbon cast microalloyed steel intercritically heat-treated at different temperatures: microstructure and mechanical properties

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Hadi Torkamani ◽  
Shahram Raygan ◽  
Carlos Garcia Mateo ◽  
Yahya Palizdar ◽  
Jafar Rassizadehghani ◽  
...  
Keyword(s):  
Carbon Content ◽  
Volume Fraction ◽  
Block Size ◽  
Tensile Tests ◽  
Total Elongation ◽  
Martensite Phase ◽  
Low Carbon ◽  
Steel Increase ◽  
Different Temperatures ◽  
The Impact

AbstractIn this study, dual-phase (DP, ferrite + martensite) microstructures were obtained by performing intercritical heat treatments (IHT) at 750 and 800 °C followed by quenching. Decreasing the IHT temperature from 800 to 750 °C leads to: (i) a decrease in the volume fraction of austenite (martensite after quenching) from 0.68 to 0.36; (ii) ~ 100 °C decrease in martensite start temperature (Ms), mainly due to the higher carbon content of austenite and its smaller grains at 750 °C; (iii) a reduction in the block size of martensite from 1.9 to 1.2 μm as measured by EBSD. Having a higher carbon content and a finer block size, the localized microhardness of martensite islands increases from 380 HV (800 °C) to 504 HV (750 °C). Moreover, despite the different volume fractions of martensite obtained in DP microstructures, the hardness of the steels remained unchanged by changing the IHT temperature (~ 234 to 238 HV). Applying lower IHT temperature (lower fraction of martensite), the impact energy even decreased from 12 to 9 J due to the brittleness of the martensite phase. The results of the tensile tests indicate that by increasing the IHT temperature, the yield and ultimate tensile strengths of the DP steel increase from 493 to 770 MPa, and from 908 to 1080 MPa, respectively, while the total elongation decreases from 9.8 to 4.5%. In contrast to the normalized sample, formation of martensite in the DP steels could eliminate the yield point phenomenon in the tensile curves, as it generates free dislocations in adjacent ferrite.

Research on Purification Technology of Ultra-Large Flake Graphite Based on Alkali-Acid Method

2021 ◽  
Vol 1036 ◽  
pp. 104-113
Author(s):  
Hong Fei Guo ◽  
Bao Chao ◽  
Zeng Qi Zhao ◽  
Ding Nan
Keyword(s):  
Carbon Content ◽  
High Purity ◽  
Raw Materials ◽  
Acid Leaching ◽  
Flake Graphite ◽  
Fixed Carbon ◽  
Fusion Temperature ◽  
Acid Method ◽  
Fixed Carbon Content ◽  
Flake Structure

Graphite is a strategically scarce resource, and the preparation of high-purity graphite is the prerequisite and basis for the application of graphite. In order to determine the optimal purification technology parameters of an ultra-large flake graphite mine pneumatic separation ore with a fixed carbon content of 77.69%, a particle size of mainly 10 to 40 mesh, and main impurities of calcium carbonate, iron oxide and silica , two additional experiments of acid method and alkali method were added on the basis of alkali-acid method, to investigate the purification effect of different technological processes and acid leaching times on graphite raw materials, as well as to analyze the retention extent of different methods and alkali fusion temperature on graphite ultra-large flake structure. The results show that all three methods can increase the fixed carbon content of graphite to above 99%. However, compared with the acid method and the alkali method, the alkali-acid method can obtain high-purity graphite while also better protecting the graphite's ultra-large flake structure. The optimal fusion temperature is 400 °C, the optimal acid leaching time is 30% sulfuric acid thrice and 5% hydrofluoric acid once. After purification, the fixed carbon content of the product exceeds 99.97%.

scholarly journals Microwave-assisted Depolymerization of Lignin with Metal Chloride in a Hydrochloric Acid and Formic Acid System

BioResources ◽  
2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Rongge Zou ◽  
Yunfeng Zhao ◽  
Yunpu Wang ◽  
Dengle Duan ◽  
Liangliang Fan ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Formic Acid ◽  
Metal Chloride ◽  
Acid System ◽  
Microwave Assisted

scholarly journals PURIFICATION OF INDONESIAN NATURAL GRAPHITE AS CANDIDATE FOR NUCLEAR FUEL MATRIX BY ACID LEACHING METHOD: CHEMICAL CHARACTERIZATION

2020 ◽  
Vol 26 (3) ◽  
Author(s):  
Deni Mustika ◽  
Torowati Torowati ◽  
Arbi Dimyati ◽  
Sudirman Sudirman ◽  
Adel Fisli ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Nuclear Fuel ◽  
Hydrofluoric Acid ◽  
Acid Leaching ◽  
Chemical Characterization ◽  
Ash Content ◽  
Natural Graphite ◽  
Nuclear Graphite ◽  
Purity Level ◽  
Graphite Matrix

PURIFICATION OF INDONESIAN NATURAL GRAPHITE AS CANDIDATE FOR NUCLEAR FUEL MATRIX BY ACID LEACHING METHOD: CHEMICAL CHARACTERIZATION. Graphite matrix in Pebble Bed Reactor (PBR) – High Temperature Gas Cooled Reactor (HTGR) has an important role as heat transfer medium, neutron moderator and structural material to protect fuel. Thus, graphite matrix must fulfill chemical and physical characteristics for PBR-HTGR fuel. Indonesia has graphite sources in several regions that can potentially be purified. This research aimed to purify Indonesian natural graphite by several variation of acids and to perform chemical characterizations. Natural graphite from flotation process was purified by several variations of acid, i. e., hydrofluoric acid (HF), sulphuric acid + nitric acid (H2SO4 + HNO3) and hydrofluoric acid + hydrochloric acid + sulphuric acid (HF + HCl + H2SO4) and subsequently followed by chemical characterizations such as purity level, ash content, and boron quivalent. The highest purity was obtained in the purification process by HF with carbon content up to 99.52%; this purity level fulfills the specification of nuclear graphite (>99%). Ash content analysis shows a value in compliance with the specification requirement, i.e., < 100 ppm, and boron equivalent value also fulfills the specification value of < 1 ppm. It can be concluded from this study that the graphite purified by acid leaching with HF can be used as fuel matrix candidate but is qualified as low quality. Futher research is required to produce high quality nuclear graphite, particularly research in the minimization of the impurity by evaporation at temperatures over 950 oC to by far lower the ash content.Keywords:  Indonesian natural graphite, purification, nuclear fuel matrix, acid leaching, chemical characterization.

Microwave-assisted exfoliation method to develop platinum-decorated graphene nanosheets as a low cost counter electrode for dye-sensitized solar cells

RSC Advances ◽  
2014 ◽  
Vol 4 (68) ◽  
pp. 36226-36233 ◽  
Author(s):  
K. Saranya ◽  
N. Sivasankar ◽  
A. Subramania
Keyword(s):  
Solar Cells ◽  
Counter Electrode ◽  
Graphene Nanosheets ◽  
Low Cost ◽  
Dye Sensitized Solar Cells ◽  
Natural Graphite ◽  
Dye Sensitized ◽  
Microwave Assisted ◽  
Sensitized Solar Cells

Graphene nanosheets (GNs) are prepared from natural graphite by a simple ecofriendly microwave-assisted exfoliation technique.

Formation of Ultrafine Grained Ferrite by Warm Deformation of Tempered Lath Martensite in Low Alloy Steels

2007 ◽  
Vol 558-559 ◽  
pp. 557-562 ◽  
Author(s):  
Behrang Poorganji ◽  
Takuto Yamaguchi ◽  
Tadashi Maki ◽  
G. Miyamoto ◽  
Tadashi Furuhara
Keyword(s):  
Grain Size ◽  
Carbon Content ◽  
Volume Fraction ◽  
Boundary Migration ◽  
Lath Martensite ◽  
Second Phase ◽  
Low Alloy Steels ◽  
Warm Deformation ◽  
Alloy Steels ◽  
Block Width

Microstructure change during warm deformation of tempered lath martensite in Fe-2mass%Mn-C alloys with different carbon contents in the range between 0.1 and 0.8mass%C was investigated. Specimens of the alloys after being quenched and tempered at 923K for 0.3ks were compressed by 50% with a strain rate varying from 10-3 to 10-4s-1 at 923K. EBSD analysis of the deformed microstructures has revealed that fine equiaxed ferrite (α) grains surrounded by high-angle boundaries are formed by dynamic recrystallization (DRX). As carbon content increases, the DRX α grain size decreases. This could be attributed to the change in volume fraction of the cementite (θ) phase as boundary dragging particles. The sub-micron θ particles can suppress the coarsening of the DRX α grains by exerting a pinning effect on grain boundary migration. Furthermore, the fraction of recrystallized region increases by increasing carbon content, presumably due to a decrease in the martensite block width as an initial α grain size and a larger volume fraction of hard second phase (θ) particles. Both of these should increase inhomogeneous plastic deformation which promotes the recrystallization. It seems that continuous DRX is responsible for the formation of ultrafine α grains in the tempered lath martensite.

Study on the Determination of Manganese in Alloy Steel Materials by Spectrophotometry

2013 ◽  
Vol 803 ◽  
pp. 196-199
Author(s):  
Mei Mei Li ◽  
Nai Jun Li
Keyword(s):  
Sulfuric Acid ◽  
Phosphoric Acid ◽  
Alloy Steel ◽  
Acid System ◽  
Mixed Acid ◽  
Relative Standard ◽  
Beer's Law ◽  
Beer’S Law ◽  
Standard Deviations

With samples decomposed by mixed acid of sulfuric acid-phosphoric acid, manganese in alloy steel was determined by periodate spectrophotometry. The acid system for dissolving samples was established, and 525 nm as the optimal measuring wavelength was selected. The results showed that Beer's law was obeyed in range of 0 to 36μg/mL for manganese (II). The relative standard deviations were between 0.6% to 2.0%(n=6). The recoveries of samples were between 95.1to 101.4%.

Microwave assisted reduction of Schiff bases by triethylammonium formate/formic acid system

2001 ◽  
Vol 2001 (12) ◽  
pp. 525-527 ◽  
Author(s):  
Firouz Matloubi Moghaddam ◽  
Omid Khakshoor ◽  
Mohammad Ghaffarzadeh
Keyword(s):  
Formic Acid ◽  
Schiff Bases ◽  
Acid System ◽  
Microwave Assisted
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