Graphitization Temperature Research Articles

Catalytic effect of carbide-forming oxides on the graphitization of carbon objects used in metallurgy

The paper aims to study the possibility of using carbide-forming oxides as catalysts for the graphitization of objects used in metallurgy. Published data on the role of catalysts (carbide-forming metals and their oxides) for the graphitization of carbon materials was analyzed. These graphitization catalysts are shown to be able to significantly reduce the graphitization temperature. The physicochemical properties characteristic of carbon materials graphitized without the use of catalysts are preserved. It was revealed that in the case of bulk materials, the graphitization temperature can be reduced to 1200–1500℃ with the use of catalysts (as opposed to 2000ºС and above). The mechanism of catalytic graphitization involving two reactions is described: interaction between a metal (or its oxide) and carbon with the formation of carbide; subsequent formation of pure metal and carbide-like graphite with increasing temperature. The resulting graphite phase constitutes the crystallization nucleus. The main problem associated with the use of catalysts in the production of graphitized objects was identified—the removal of reaction products, including metals. It is shown that additional catalyst charging can be performed at the stage of mixing and forming, which results in the removal of a part of the reaction products at the stage of baking. The mechanism of removing reaction products is expected to be comparable to ash removal from the piece to be graphitized. It was proven effective for objects to contain carbide-forming oxides, even in insignificant amounts (up to 5 wt%). Due to this, as well as given the possibility of catalyst selection, the negative effect of excessive oxide content in the charge can be reduced depending on further operating conditions. Thus, the use of catalysts for the graphitization of electrodes used in metallurgy is a promising way to reduce the process temperature. However, it is required to select the optimal oxide content and adjust the conditions of electrothermal processes in order to adapt the technology for large-sized products.

Analysis and Joint Correlation Models on Pore Structures of Graphitized Phenolic Resin Char Under Ni-Zn-B Catalytic Effect

Phenolic resin plastic is mainly composed of phenolic resin and pyrolysis is often used to perform the important task of treating it. While there are large quantities of char generating, the char can be graphitized for upgrading under Ni-Zn-B catalytic effect. Pore structure is an important index for evaluating graphitic carbon. In this study, the phenolic resin char was graphitized with Ni-Zn-B at low temperature based on orthogonal rules (graphitization temperature: 1300 °C, 1400 °C, 1500 °C; retention time: 60 min, 120 min, 180 min; catalyst additive ratio: 5%, 10%, 15%), and their pore structures were determined by N2 adsorption and desorption method. The graphitized phenolic resin chars were porous carbon materials whose specific surface areas were commonly between 110 to 160 m2/g; they also mainly consisted of wholly equivalent micropores and mesopores. The effects of the graphitization conditions on pore structures of GPRCs were analyzed; this revealed that the increase in graphitization temperature destroyed micropores to form mesopores, with a longer retention time leading to the production of small quantities of micropores and mesopores, some micropore spaces were occupied and mesopore skeletons were destroyed to from large pores with more Ni-Zn-B addition. The correlation models of the pore structures and reaction parameters were built; it was found that the multiple linear regression model showed an advantage in predicting micropore structures and the built artificial neural network model was better at predicting the total pore and mesopore.

Mechanisms Behind Graphitization Modification in Polycrystalline Diamond by Nanosecond Pulsed Laser.

The ultraprecision machining of diamond presents certain difficulties due to its extreme hardness. However, the graphitization modification can enhance its machinability. This work presents an investigation into the characteristics of the graphitization modification in polycrystalline diamond induced by a nanosecond pulsed laser. In this paper, the morphology of microgrooves under laser modification was observed, material deposition and graphitization in different regions were researched, and the regularities of microgrooves at different laser powers were obtained. A molecular dynamics (MD) simulation was carried out to reveal the mechanism behind graphitization modification; when the pulse laser acts on the diamond surface and the temperature rises to the critical temperature of graphitization, the graphite crystal nuclei form and grow, resulting in the graphitization modification. It was confirmed that the existence of grain boundaries (GBs) contributed to the graphitization of polycrystalline diamond during laser modification. It was predicted that a lower laser power could cause a higher proportion of graphitization. The results of ablation thresholds and the effect of the defocusing position on the graphitization of diamond showed that for a fixed laser power, the highest graphitization ratio could be obtained when the defocusing quantity was optimized. Finally, the results of precision grinding experiments verified the feasibility of using laser graphitization pretreatment to improve the efficiency and quality of precision grinding.

Experimental Investigation of Fast-Charging Protocols Derived from Physicochemical and Thermal Simulations Using 5.4 Ah Multilayer Pouch Cells with Silicon-Dominant Anodes over Aging

Fast-charging capability remains a main concern for consumers buying an electric vehicle as a sustainable transportation solution. For lithium-ion batteries with typical graphite anodes, lithium-plating and temperature limitations due to the electrolyte are the two main limitations for fast-charging. Silicon as next-generation anode active material promises faster charging times due to its higher averaged potential versus 0 V Li+/Li avoiding lithium plating,[1] especially if silicon is only partially lithiated.[2] Further advantages are the lower coating thickness and the lower ionic resistance for silicon-dominant anodes when compared to graphite anodes with the same areal capacity, also leading to better fast-charging capability.[1]In this study, a validated physicochemical Newman-type p2D model[3] for a 70 wt% microscale silicon||NCA cell is extended by a 3D thermal model to account for thermal limitations at high-currents for a 5.4 Ah multilayer pouch cell (MLP). The thermal model includes the MLP, compression pads, and the cell holder, while the tab temperature was measured for validation. Experimental and theoretical parameterization of the thermal model includes the heat capacity and the thermal conductivity.[4] The coupled thermal-physicochemical model is depicted in Figure 1 and was used to simulatively derive different fast-charging protocols for the following input parameters: different state-of-charge windows (SoC Start and SoC End), different electrochemical limitations as security buffers to prevent lithium plating (U Sec vs. 0 V Li+/Li), and different thermal limits as different maximal cell temperatures T Cell,max were simulated. The cell’s charging current I Cell was controlled according to four different charging phases: constant current (CC), constant anode potential (CAP), temperature-limited (TDER), and constant voltage (CV) are switched and the applied cell current is controlled based on the simulated anode potential U Anode or the simulated maximal cell temperature in the cell core T Cell,max. The resulting simulated cell voltage U Cell during fast-charging was then experimentally applied to 5.4 Ah multilayer pouch cells as a voltage trajectory, while the cell current I Cell followed according to the voltage trajectory and the cell impedance. In total, 12 MLPs were aged until 70% state of health (SoH) for 25% - 75% SoC for USec=140 mV and 170 mV as well as for 10%-70% for USec=140 mV. As fast-charging reference, charging at 2C was tested for 25%-75% SoC and all results are compared to our previous study[6] aging identical MLPs at C/2.In the electrochemical results, the capacity retention could be significantly improved by utilizing the SoC window from 25%-75% SoC compared to 100% SoC from our previous study[6]. At the beginning of life, fast-charging times of 10.2 (±0.3) min for 25%-75% SoC with USec=140 mV and 11.8 (±0.1) mins for 25%-75% SoC with USec=140 mV were achieved. Fast-charging simulations for 25%-75% SoC with USec=140 mV predicted a comparable fast-charging time of 11.2 mins. Comparing the different fast-charging profiles over aging, a similar capacity retention is experimentally measured hinting towards loss of lithium inventory being the main aging mechanism while no charging profile seems to be particularly harmful to the cells. Regarding fast-charging time over aging, an increase in charging time is measured since the cell resistance increases over aging leading to a decreased overpotential being released during fast-charging according to the voltage trajectory.The trade-off between protecting the MLPs over lifetime versus the increased charging time could be further investigated in future work by adjusting the voltage trajectory based on the SoH. Moreover, even more aggressive charging protocols could be tested to derive the physicochemical limitation U Sec, e.g., 0 V Li+/Li. Acknowledgments: S.F. gratefully acknowledges the financial support from the BMBF (Federal Ministry of Education and Research, Germany) under the auspices of the ExZellTUM III project (grant number 03XP0255). The authors want to thank the research battery production team of iwb at TUM for the multilayer pouch cell production. We also thank Wacker Chemie AG for providing the microscale silicon material (CLM 00001).

PEFC Electrocatalysts using Highly-Graphitized Mesoporous Carbon Supports

The electrocatalysts used in polymer electrolyte fuel cells (PEFCs) are subject to oxidative corrosion of the carbon catalyst support due to start-stop cycling, as well as aggregation of Pt nanoparticles due to load fluctuations. The use of mesoporous carbon (MC) as a catalyst support has previously been shown to suppress aggregation. In this study, highly graphitized MC is prepared as a catalyst support to suppress both carbon corrosion and aggregation in Pt/MC electrocatalysts. The effect of graphitization temperature on the catalytic performance is evaluated, as well as the effect of pretreatment via either ball milling or pulverization to achieve suitable particle size. The results indicate that the initial activity of the electrocatalysts is improved by graphitization of the MC support after milling, and that the graphitization step improves the start-stop cycle durability.

Fabrication of high-performance graphene fiber: Structural evolution strategy from a two-step green reduction method

Graphene fibers (GFs) have a bright future in a variety of applications ascribing to their excellent performance. However, strict preparation conditions with extremely high graphitization temperature or toxic chemical reagents severely restrict their extensive implementation. Meanwhile, researchers are seeking easily scalable and eco-friendly GFs production methods. Here, we propose a green two-step reduction strategy involving L-ascorbic acid (LAA) chemical reduction followed by low-temperature annealing for the preparation of high-performance GFs. Benefiting from the elimination of macro-, micro- and nano-scaled defects and recombination of graphene nanosheets, the prepared GFs demonstrated amazing tensile strength of 778.49 MPa, Young's modulus of 92.61 GPa and an outstanding electrical conductivity of 3.2 × 104 S m−1, outperforming most of the chemically reduced GFs. This two-step green reduction strategy provides a new insight for constructing integrated high-performance GFs for sustainable application in many fields.

Low-Temperature Annealing of Nanoscale Defects in Polycrystalline Graphite

Polycrystalline graphite contains multi-scale defects, which are difficult to anneal thermally because of the extremely high temperatures involved in the manufacturing process. In this study, we demonstrate annealing of nuclear graphite NBG-18 at temperatures below 28 °C, exploiting the electron wind force, a non-thermal stimulus. High current density pulses were passed through the specimens with a very low-duty cycle so that the electron momentum could mobilize the defects without heating the specimen. The effectiveness of this technique is presented with a significant decrease in electrical resistivity, defect counts from X-ray computed tomography, Raman spectroscopy, and nanoindentation-based mechanical characterization. Such multi-modal evidence highlights the feasibility of nanoscale defect control at temperatures about two orders of magnitude below the graphitization temperature.

Sensitivity analysis and fuel performance of a control rod withdrawal in the generic fluoride-salt-cooled high temperature reactor

The purpose of this study is to develop boundary conditions with respect to input parameter uncertainty for fuel performance assessment of a control rod withdrawal transient in a fluoride-salt-cooled high-temperature reactor (FHR). Sensitivity analysis was performed to determine how certain key input parameters impacted the uncertainty of the outputs needed for the boundary conditions. The generated boundary conditions can be used in fuel performance codes to obtain failure probabilities and fuel performance envelopes. To accomplish this, we utilized a KP-AGREE model of the generic fluoride-salt-cooled high-temperature reactor (gFHR) and a pebble bed benchmark developed by Kairos Power. The key boundary conditions that were developed included the total power, maximum fuel region temperature, maximum fuel kernel temperature, and maximum moderator (graphite) temperature within the core. The sensitivity analysis was run until the Sobol indices and output converged within a 95 % confidence level; it was found that the coolant inlet temperature consistently had the highest impact on the uncertainty of the key core temperature values. The maximum bound of these temperatures also did not exceed 1123.5 °C for the fuel kernel and 973.7 °C for the moderator after the transient, demonstrating that there is a large margin between the predicted fuel and moderator temperature and accepted safety limits, given a 1650 °C limit for Tristructural Isotropic (TRISO) fuel. These boundary conditions were implemented into a BISON model to demonstrate their use in fuel performance and obtain a brief failure profile of the fuel. The maximum magnitude of the hoop stress on the SiC layer was −12.02 MPa, resulting in a failure probability of 4.90·10−19. Thus, the fuel performance simulations also emphasized the robustness of the TRISO fuel design utilized in the gFHR, as the predictions reveal substantial margin of the TRISO particles relative to temperature limits during the control rod withdrawal. The limiting temperature is expected to be the reactor vessel temperature and the fuel is not expected to be challenged at all by mechanical failure of the SiC layer during these events.

Boron-doped polyhedral graphite catalyzed by h-BN via structural induction for lithium storage

Artificial graphite is extensively used in power lithium-ion batteries for its exceptional stability and high-rate performance. However, the commercial high-temperature graphitization process is conducted at temperatures up to 3000 °C to enhance the degree of graphitization, resulting in significant electricity consumption and lengthy production cycles. This study aimed to lower graphitization temperatures and shorten times by using h-BN as a catalyst. Employing anthracite coal as the precursor and catalyzing with BN at 2800 °C for just 2 h, we achieved a remarkable graphitization degree of 93.3 %, compared to 83.5 % without BN. This indicates BN's effectiveness in accelerating graphite phase formation. Interestingly, the resultant graphite exhibited polyhedral morphology and incorporated boron doping. As edges increased, lithium-ion diffusion pathways and boron doping enhanced stability within the graphite layers, imparting high rate capability and robust cycle performance. The material delivered reversible specific capacities of 369.6 and 226 mA h g−1 at current densities of 0.1 and 3C, and maintained capacity retentions of 95 % and 92 % after 500 cycles at 0.5C and 1C. These results substantiate the potential for large-scale production of artificial graphite from anthracite coal using BN catalysis and underscore its promise as a superior anode material for lithium-ion batteries.

Effect mechanism of phosphorous-containing additives on carbon structure evolution and biochar stability enhancement

The regulation of the pyrolysis process is a key step in increasing the carbon sequestration capacity of biochar. The effect of K3PO4 addition on the yield, chemical composition, characteristic functional groups, macromolecular skeleton, graphite crystallites, and stability of biochar was studied in this paper using two-dimensional infrared correlation spectroscopy (2D-PCIS), X-ray photoelectron spectroscopy, Raman spectrum, and other characterization methods combined with thermal/chemical oxidation analysis. It is discovered that adding K3PO4 may effectively minimize the graphitization temperature range and increase biochar's yield, aromaticity, H/C ratio, and proportion of refractory/recalcitrant organic carbon. The 2D-PCIS and Raman analysis revealed that K3PO4 mostly promoted the dehydrogenation and polycondensation process of the aromatic rings in the char precursor, transforming the amorphous carbon structure of biochar into an ordered turbostratic microcrystalline structure. K3PO4 enhanced biochar stability mostly at medium-high temperatures (350 ~ 750℃) by stimulating the transformation of unstable structures of biochar to stable carbon-containing structures or by inhibiting the interaction of its active sites with oxidants through the mineralization process. A 20% phosphorus addition increased biochar's refractory index (R50) by roughly 11%, and it also boosted biochar's oxidation resistance (H2O2 or K2CrO4) efficiency, reducing carbon oxidation loss by up to 7.31%. However, at higher temperatures (> 750 ℃), the doping of phosphorus atoms into the carbon skeleton degraded the biochar structure's stability. The results of this study suggest that using exogenous phosphorus-containing additives is an efficient way to improve the stability of biochar.Graphical abstract

Utilizing Constant Energy Difference between sp-Peak and C 1s Core Level in Photoelectron Spectra for Unambiguous Identification and Quantification of Diamond Phase in Nanodiamonds.

The modification of nanodiamond (ND) surfaces has significant applications in sensing devices, drug delivery, bioimaging, and tissue engineering. Precise control of the diamond phase composition and bond configurations during ND processing and surface finalization is crucial. In this study, we conducted a comparative analysis of the graphitization process in various types of hydrogenated NDs, considering differences in ND size and quality. We prepared three types of hydrogenated NDs: high-pressure high-temperature NDs (HPHT ND-H; 0-30 nm), conventional detonation nanodiamonds (DND-H; ~5 nm), and size- and nitrogen-reduced hydrogenated nanodiamonds (snr-DND-H; 2-3 nm). The samples underwent annealing in an ultra-high vacuum and sputtering by Ar cluster ion beam (ArCIB). Samples were investigated by in situ X-ray photoelectron spectroscopy (XPS), in situ ultraviolet photoelectron spectroscopy (UPS), and Raman spectroscopy (RS). Our investigation revealed that the graphitization temperature of NDs ranges from 600 °C to 700 °C and depends on the size and crystallinity of the NDs. Smaller DND particles with a high density of defects exhibit a lower graphitization temperature. We revealed a constant energy difference of 271.3 eV between the sp-peak in the valence band spectra (at around 13.7 eV) and the sp3 component in the C 1s core level spectra (at 285.0 eV). The identification of this energy difference helps in calibrating charge shifts and serves the unambiguous identification of the sp3 bond contribution in the C 1s spectra obtained from ND samples. Results were validated through reference measurements on hydrogenated single crystal C(111)-H and highly-ordered pyrolytic graphite (HOPG).

Effects of Graphite Additive Ratio and Temperature on Rheological Properties of Magnetorheological Grease

Effects of Graphite Additive Ratio and Temperature on Rheological Properties of Magnetorheological Grease

Preparation of Ti3SiC2-based diamond composites by Ni–Al assisted self-propagating reaction of Ti–SiC–C system in microwave field

In this paper, the self-propagating reaction of the Ti–SiC–C system for synthesising Ti3SiC2-based diamond composites is ignited by the combustion of Ni–Al alloy powders in a microwave field. The heating curves of Ni–Al-assisted microwave sintering show that the self-propagating reaction could be successfully ignited after heating samples to 685.2 °C in a microwave field for 456 s. This finding indicates that ignition could occur at temperatures below the diamond graphitisation temperature (727 °C). X-ray diffraction analysis indicates that the sintered samples primarily comprise Ti3SiC2, TiC, Ti5Si3 and C. Scanning electron microscopy coupled with energy dispersive spectroscopy observations demonstrates that the diamond grains are tightly bonded with the surrounding matrix and are intact. The best wear ratio of 302.26 was obtained for the Ti3SiC2-bonded diamond composite when the diamond grain size was 140/170 mesh and the molar ratio of Ti, SiC and C was 3:1.1:0.9.

Effect of Impregnation and Graphitization on EDM Performance of Graphite Blocks Using Recycled Graphite Scrap

In the present study, graphite scrap powder from machining of commercial graphite blocks for electrical discharge machining (EDM) applications was recycled as a filler material for manufacturing graphite blocks, and its suitability for use as EDM electrodes was thoroughly assessed. The effects of process parameters applied in EDM electrode manufacturing, including the number of impregnations and graphitization temperatures, on the physical properties of the resulting graphite blocks, were examined. Additionally, EDM performance was evaluated with respect to the above process parameters. In blocks subjected to three impregnation treatments, followed by graphitization at 2200 °C, surface protrusions formed during the EDM process, indicating that the EDM process did not proceed smoothly. On the other hand, in blocks that underwent three impregnation treatments, followed by graphitization at 2800 °C, no surface protrusions were observed, indicating successful EDM operation. This observation further confirms the suitability of these recycled materials for use in EDM electrodes. The graphite block electrodes fabricated using recycled graphite scrap exhibited inferior cyclic stability, with an electrode wear rate of 0.82%, higher than that of a commercial graphite block electrode (0.04%). Nevertheless, using recycled graphite scrap contributes to reducing product costs and CO2 emissions, making the developed graphite electrodes a favorable choice.

Synergistic advancements in sewage-driven microbial fuel cells: novel carbon nanotube cathodes and biomass-derived anodes for efficient renewable energy generation and wastewater treatment

Microbial fuel cells (MFCs) offer a dual solution of generating electrical energy from organic pollutants-laden wastewater while treating it. This study focuses on enhancing MFC performance through innovative electrode design. Three-dimensional (3D) anodes, created from corncobs and mango seeds via controlled graphitization, achieved remarkable power densities. The newly developed electrode configurations were evaluated within sewage wastewater-driven MFCs without the introduction of external microorganisms or prior treatment of the wastewater. At 1,000°C and 1,100°C graphitization temperatures, corncob and mango seed anodes produced 1,963 and 2,171 mW/m2, respectively, nearly 20 times higher than conventional carbon cloth and paper anodes. An advanced cathode composed of an activated carbon-carbon nanotube composite was introduced, rivaling expensive platinum-based cathodes. By optimizing the thermal treatment temperature and carbon nanotube content of the proposed cathode, comparable or superior performance to standard Pt/C commercial cathodes was achieved. Specifically, MFCs assembled with corncob anode with the proposed and standard Pt/C cathodes reached power densities of 1,963.1 and 2,178.6 mW/m2, respectively. Similarly, when utilizing graphitized mango seeds at 1,100°C, power densities of 2,171 and 2,151 mW/m2 were achieved for the new and standard cathodes, respectively. Furthermore, in continuous operation with a flow rate of 2 L/h, impressive chemical oxygen demand (COD) removal rates of 77% and 85% were achieved with corncob and mango seed anodes, respectively. This work highlights the significance of electrode design for enhancing MFC efficiency in electricity generation and wastewater treatment.

Graphitization of anthracite catalyzed by single metal oxides and its enhanced electrical conductivity

ABSTRACT A series of synthetic graphite was fabricated through metal oxide catalytic graphitization using purified anthracite (TYC). The effects of graphitization temperature, catalyst type and its addition methods on structure and properties of graphite products were investigated through the methods of XRD, Raman spectra, SEM, TEM, FTIR and resistivity tester. Increasing graphitization temperature favors the enhancement of order and size of graphite microcrystals, graphitization degree, and conductivity of graphitized products. TiO2 exhibited the best catalytic effects in catalytic graphitization. Compared to directly graphitized TYC at 2800°C (TYC-28), the graphite catalyzed by TiO2 added physically (TYC-28-TiO2) and added chemically (TYC-28-C-TiO2) demonstrated a 13.0 and 16.7% increase in graphitization degree, respectively. Meanwhile, chemical addition method (0.61 × 10−4 Ω·m) outperformed physical addition method (1.21 × 10−4 Ω·m) in improving the electrical conductivity of graphitized products. Moreover, at 2400°C, TYC catalyzed by TiO2 added physically and added chemically presented a graphitization degree of 73.7 and 77.6%, respectively, both exceeding that of TYC-28 (70.7%). Therefore, metallic oxides can enhance the graphitization degree while lowering the required graphitization temperature. This method holds promise for cost-effective and energy-efficient production of high-conductivity graphitized anthracite for batteries, supercapacitors, conductive coatings, and conductive adhesives.

Genesis of the Graphite from the Tugeman Graphite Deposit, Xinjiang, China: Evidence for Carbon Isotope Refining by Fluids Associated with the Ductile Shear Zone

The Altun orogenic belt is situated along the northern boundary of the Tibetan Plateau. In this study, we present an analysis of the ore deposit, mineral composition, and carbon isotope signatures of the Tugeman graphite deposit within the Altun orogenic belt. The graphite in the Tugeman graphite deposit occurs within graphite-bearing schists and marble. Graphite enrichment is observed in the ductile shear zone. The carbon isotope values of graphite range between −18.90‰ and −10.03‰ (with an average value of −12.70‰). These values differ significantly from those observed in organic matter and marine carbonates, suggesting the occurrence of a mixing process involving reduced carbon fluid derived from biological organic material during regional metamorphism as well as a potential influx of oxidized carbon fluid from external sources. In addition, the metamorphic temperature of Tugeman graphite calculated from Raman spectroscopy is between 494 °C and 570 °C, which indicates that the disordered material is transformed from greenschist-amphibolite facies metamorphism to moderate-crystalline graphite. Combining the geological and carbon isotope characteristics of the Tugeman graphite deposit, we argue that the Tugeman graphite deposit is a regional metamorphic graphite deposit of biogenic origin, and during the late stage of metamorphism, it underwent interaction with fluids.

Feasibility for High-Temperature Graphitization of Deformed Meager Coal.

The flattening of nanoscale pores is a crucial step in the process of anthracite graphitization, which primarily occurs due to lithostatic pressure or tectonic stress. Anthracite, a highly metamorphosed form of carbonaceous material, is a primary component of artificial graphite, but its availability is limited in China. Therefore, it is necessary to investigate the graphitization of low metamorphic coal. Note that the pores of deformed coal are substantially compressed, and the evolution of macromolecular structure is accelerated owing to strong tectonic extrusion and shearing action. Herein, the feasibility analysis of coal-based graphite at temperatures of 2200 and 2600 °C was investigated using mylonitized meager coal (YA-M; Ro,max = 2.34%), which exhibits the most intense deformation intensity, and it was compared with undeformed coal (YA-U; Ro,max = 1.87%) from the same coal seam. Results indicate that YA-U primarily consists of cylindrical pores with an average pore diameter of 10 nm, while YA-M exhibits extensive fine bottleneck and parallel plate pores with an average pore size of ∼4 nm. Additionally, interlayer spacing decreases from 0.3592 nm in YA-U to 0.3575 nm in YA-M, while crystallite height increases from 1.9633 nm in YA-U to 2.1424 nm in YA-M. The undeformed coal YA-U exhibits short and disordered aromatic fringes with a localized turbostratic structure that hinders graphitization. In contrast, YA-M exhibits more and longer localized fringe pairs arranged in parallel with improved structural ordering, indicating a favorable environment for graphitization. Ductile deformation narrows the pore diameter distribution, causing deformation pores on the mylonitic granules' surface to close, shrink directionally, collapse, or connect, resulting in obvious flattening characteristics of nanoscale. Based on these results, the graphitization degree of the graphitized products YA-GM-2200 and YA-GM-2600 was 80.23% and 88.37%, respectively, with interlayer spacings of 0.3371 and 0.3364 nm, indicating that these products have entered the semigraphite (medium graphitization) and graphite range, respectively. In contrast, the graphitization degree of YA-GU-2200 and YA-GU-2600 was only 51.16% and 56.98%, respectively, indicating that they have only progressed from anthracite to meta-anthracite (the preliminary graphitization stage). These findings confirm the view that the shear stress generated by the geological age flattens the pores of mylonitized meager coal and optimizes the aromatic lattice arrangement and orientation, facilitating graphitization and lowering the graphitization temperature (from 2800 to 2200 °C). Deformed coal is soft and can be easily crushed into powdered form using the human hand, making it less suitable for transportation. Additionally, owing to the unfavorable separation of minerals and lower hydrocarbon-generating potential, deformed coal application potential and price are consistently lower than those of undeformed coal. However, deformed coal is widely distributed in various coal measures in China, making these research findings valuable in promoting the high value-added utilization of low-rank deformed coal resources and expanding the carbon source of coal-based graphite materials.

Preparation and Characterization of Corn Straw-Based Graphitized Carbon with Ferric Acetylacetonate as Catalyst

Graphitized carbon exhibits exceptional thermal stability, electrical conductivity, corrosion resistance, and various intricate physical and chemical properties. Consequently, it has found extensive applications in diverse fields, such as electrodes, refractory materials, nuclear reactors, and supercapacitors. However, natural graphite is a limited nonrenewable resource, so finding other materials, exploring reliable graphitization methods, and achieving efficient green graphite production as an essential trend in the future is essential. In this paper, with corn straw liquefied product (CSLP) as raw material, ferric acetone catalyst, using carbonization, catalytic graphitization preparation of corn straw based graphitic carbon (CSBGC). When the graphitization temperature was 850 °C and the amount of ferric acetylpropionate (Fe(acac)3) was 7.0 mmol/g, the graphitized carbon showed better graphitization, micro fragmentation structure, and more minor defects, which effectively reduced the graphitization temperature, and the graphitic carbon rate of corn straw (CS) reached 25.2%. This study not only presents a highly efficient approach for synthesizing superior biomass-derived graphite carbon but also introduces usable perspectives on using corn straws.

In situ high-temperature X-Ray diffraction study of tantalum metal

An in-situ thermal behavior study was conducted on the metallic tantalum under two conditions. The experimentation was carried out on tantalum pellets which were heated progressively “underwent reaction and under continuous pumping or under controlled monoxide pressure” in a graphite resistance high temperature X-ray diffractometer up to 2300 K. Through the in-situ study, a thermodynamic analysis showed that this involved the formation of Ta2O, Ta2O5 (low temperature modification) and Ta2C likely to be formed between 293 and 2300 K, in agreement with a reaction mechanism that we established to occur in four stages.