Graphitization Process Research Articles

Tuning microstructures of polyacrylonitrile-based carbon fibers by catalytic influence of boron for enhancement of mechanical properties and oxidation resistance

Boron catalytic graphitization of carbon fibers (CFs) is an effective methodology for reducing energy costs with the enhancement of tensile and oxidation resistance properties by re-constructing the crystal structure of CFs. Herein, a microwave plasma graphitization system for boron catalytic graphitization was devised. The effect of boron on microstructure and properties of CFs during boron catalytic graphitization process was investigated and analyzed. The mechanism of boron doping in different graphitization times was proposed. Furthermore, the results show that the tensile properties and oxidation resistance of CFs are improved and directly related to the microstructure of CFs, which depends on the different boron catalytic graphitization stages. This work provides the effect of boron on microstructure and properties of CFs during microwave plasma catalytic graphitization in different graphitization times and has important implications for deeply understanding the boron catalytic graphitization process which is beneficial for the preparation of CFs with excellent performance.

Turbostratic Carbon Nano Onion Electrode for High Power Density Vanadium Redox Flow Battery

The redox flow battery (RFB) is one of the most promising technologies for stationary energy storage. It consists of a voltaic cell whose electrolytes are stored in tanks outside the system. Whilst the chemistries of the anodic and cathodic electrolytes define the energy density of a RFB system, its power density is determined primarily by its electrodes. These are typically porous carbon media on the surface of which the redox reactions occur. They are a critical component since they require a detailed engineering of electrocatalytically active surface area and mass transport. Still today, they remain the main cause of RFB low power density. In this work, we are showing a novel deposition method to improve the performance of commercially available carbon paper already used in RFB.The gain is thanks to the deposition of turbostratic carbon nano-onion (TCNO) nanoparticles on the carbon fibers of the paper. This process is performed with a proprietary technology called NanoJeD: a CVD in supersonic flow, which promises easy industrial scalability and a fine tunability of the nanoparticle properties. Moreover, with this system is possible to deposit over any substrate.NanoJeD consists in two chambers separated by a high aspect ratio slit. A precursor gas is injected through a porous plug from the top and a vacuum system is connected from the bottom. The slit allows the establishment of a high-pressure ratio between the two chambers and hence the formation of a supersonic jet. The precursor gas, a mixture of Argon (98.4%) and Acetylene (1.6%) flows between two electrodes where a radio frequency (RF) signal is fed (13.56 MHz). The RF ignites a non-thermal plasma in which the precursor molecules are ionized and dissociated into radicals, which polymerize forming hydrogenated carbon clusters and nanoparticles (NPs) of different sizes. Once formed, NPs are dragged through the slit by the gas stream and finally impact on the substrate. Therefore, it is possible to achieve a high throughput (500 mg h-1) and to deposit on a large area of 100 cm2 while precisely controlling the properties of the film. The resulting film has hundreds of squared meters per gram of surface area. For TCNO formation, the NP film is further annealed in vacuum at 1000°C for 2 hours. Using in situ transmission electron microscopy (TEM) and energy electron loss spectroscopy (EELS), we were able to visualize the progression of graphitization and changes in structural properties during annealing. The graphitization process starts in the outer layer and proceeds into the interior of the particle. The geometrical constrains of the NP (average diameter of 20nm) and shrinkage of the NP, allow the formation of curved, turbostratic, defective graphitic sheets. UV photoelectron spectroscopy (UPS) and Raman spectroscopy performed ex-situ allow the analysis of valence bands and structural defects. The high presence of defects and general disorder structure are accompanied with a remarkable increase in catalytic activity. Moreover, the annealing process leads to the sintering of the nanoparticles and the formation of an interface between the carbon fibre and the nanoparticles, as demonstrated by the increased thermal stability tested by. Both phenomena improve the adhesion between nanoparticles and with the surface, making the electrode suitable to be adopted in fluxed systems.The TCNO deposited on a carbon paper was tested as electrode in a Vanadium RFB. The kinetic activity and electrochemical properties were tested via in-situ Raman and in a three-electrode cell set-up. The results reveal an increased kinetic activity with respect to the untreated paper. Using in situ Raman we were able to show differences in redox mechanism between TCNO and bare carbon paper. A chronoamperometry test was used to obtain the transfer coefficient from a Tafel plot. These studies allow the correlation of the catalytic activity with the defectiveness of the TCNO nanoparticle. Vanadium RFB full cell measurements of the TCNO electrode show a drastic increase in performance, reaching an energy efficiency of 70.8% and 86.2% at current densities of 600 mA cm-2 and 200 mA cm-2, respectively. The electrolyte utilisation for these current densities is 59% for the former and 80% for the latter. To investigate the chemical and mechanical stability a stability test was performed. Results showed a low degradation rate of 0.004% EE per cycle. Moreover, TCNO can be used for other electrochemical applications only by adjusting the deposition and annealing parameters.

Computer simulation of carbonization and graphitization of coal

This study describes computer simulations of carbonization and graphite formation, including the effects of hydrogen, nitrogen, oxygen, and sulfur. We introduce a novel technique to simulate carbonization, ‘Simulation of Thermal Emission of Atoms and Molecules (STEAM)’, designed to elucidate volatile outgassing and density variations in the intermediate material during carbonization. The investigation analyzes the functional groups that endure through high-temperature carbonization and examines the graphitization processes in carbon-rich materials containing non-carbon impurity elements. The physical, vibrational, and electronic attributes of impure amorphous graphite are analyzed, and the impact of nitrogen on electronic conduction is investigated.

3D Stretchable Devices: Laser‐Patterned Electronic and Photonic Structures

AbstractRealizing three‐dimensional stretchable structures of functional materials with a minimum footprint on Silicone polymer is highly desirable in soft robotics, stretchable electronics, and photonics. However, material processing on a stretchable substrate requires a sophisticated deposition system with integrated substrate cooling facilities, delamination of materials from the stretchable substrate due to stretching‐releasing cycles, and coating the functional materials. Here, a methodology to address these challenges using in situ graphitization within silicone polymer, referring to transforming the material into graphite‐like structures using three‐dimensional laser printing is reported. In this case, the graphitization process occurs due to the interaction of the material with a spatially controllable, tightly focused femtosecond laser beam in the confined region within the polymer. Three‐dimensional printed embedded, stretchable electrodes and varifocal lenses of thickness 1/20th compared to the epidermis layer thickness of human skin, which can contribute to achieving compact, highly sensitive wearable sensing and imaging systems are demonstrated and characterized. This process will open a new door for forming non‐metallic stretchable three‐dimensional conductors and photonics with minimum exposure to atmospheric conditions and a pathway to interface with thin films to develop low‐dimensional devices. These graphitized three‐dimensional structures can make them integral to intelligent skins, e‐textiles, and implantable devices.

In-situ Raman spectroscopy study on coal pyrolysis and subsequent char low temperature oxidation and gasification

Thermal conversion is pivotal for clean and efficient coal utilization. Evolution of solid structure profoundly affects the gasification mechanism. However, in-situ study on coal structure evolution during gasification is limited. In this study, in-situ Raman spectroscopy was used to investigate the carbon structure evolution during thermal conversion. Results revealed two stages in coal pyrolysis: polycondensation and aromatic ring fusion. During polycondensation, numerous side chain groups break, while aromatic compounds condensed and rings fused in the aromatic ring fusion stage, increasing molecular size. In char gasification, larger particles required more time to achieve stable shrinkage, thus delaying coal char graphitization process. Low temperature oxidation led to decreased order due to oxygen-containing structure formation, evolving into a graphite-like structure as disordered carbon diminished. In addition, oxygen-containing groups acted as active oxidation sites. The insights into real-time structure evolution enhance understanding of the particle behavior during thermal conversion of coal.

Porous Graphitic Carbon from Coconut Coir Biochar Developed by Ni–KOH Single-Pot Graphitization Process for Lithium-Ion Battery Anodes

Porous Graphitic Carbon from Coconut Coir Biochar Developed by Ni–KOH Single-Pot Graphitization Process for Lithium-Ion Battery Anodes

Processing of Aqueous Graphite–Silicon Oxide Slurries and Its Impact on Rheology, Coating Behavior, Microstructure, and Cell Performance

The mixing process is the basis of the electrode microstructure, which defines key cell performance indicators. This work investigated the effects of varying the energy input within the mixing procedure on slurry rheology, coating behavior, mechanical and electrical properties of dry electrodes and electrochemical performance of cells fabricated from these negative electrodes. Energy input differences were achieved by varying the solids content within the mixing procedure; however, the final total solids content of the slurries was always the same. The slurries, produced with graphite and silicon oxide as active materials and carboxymethylcellulose (CMC) and styrene-butadiene rubber as binders, showed large differences in flow behavior which were explained by changes in CMC adsorption and mechanical degradation because of increasing energy input. Low shear viscosity and the degree of shear thinning decreased with increasing energy input, resulting in a narrower stability window for slot-die coating. The resistance between the electrode and current collector decreased as more CMC was adsorbed on the active material. Electrode adhesion drastically dropped at the highest energy input, presumably due to a change in SBR distribution. Despite these variations, all fabricated pouch cells demonstrated excellent electrochemical performance and a slight trend of increased charge capability was observed in cells prepared with higher energy input.

Peculiarities of high-temperature refining of carbon materials

The purpose of the study was to determine the influence of the main following factors on the efficiency of the process of high-temperature refining of natural and artificial graphite: processing temperature, distribution of metal oxides, and changes in the aggregate state of ash impurities. Thermal processing of natural graphite from Ukrainian deposits and anthracite from Donetsk coal basin was carried out in a chamber furnace at a holding time of 10–20 minutes in a temperature range of 1500–30000С. The quality of refining was carried out by ICP-OES and XRF analysis methods. It was established that the refining process may be divided into three following periods: 0–16000С (removal of moisture, volatiles, and decomposition of carbonates); 1600–26000С (evaporation of main ash-forming metals Fe, Si, Al, Ca, Mg in the form of oxides, silicides, and carbides); and 2600–30000С (evaporation of refractory compounds Ti, V, Mo, the content of which in the initial raw material determines the processing temperature and the quality of the final product). The distribution of metal oxides in the initial carbon material is not uniform, which complicates the use of equilibrium state models. The transition of ash into the liquid and then gaseous state has a significant impact on the result of heat treatment. This is what determines the choice of the process scheme. Intermittent process is the heating by an external heater in an inert gas environment. Continuous process is the heating of the material in moving containers or processing in an electrothermal fluidized bed.

Different graphitization degrees of carbon matter in rocks of a same metamorphic evolution

Two X-ray diffraction methods were chosen to determine the degree of structural order (degree of graphitization) of natural carbonaceous matter. Factors influencing the graphitization processes during the progressive and regressive stages of metamorphism are examined. The correlation of the degrees of structural order of the carbonaceous material with the sequence of mineral growth allows the metamorphic history of the graphite-bearing rocks to be traced. The obtained data can be used for the evaluation of graphite as a raw material.

Production of graphitic carbon from Hibiscus sabdariffa and Typha latifolia for photoreduction of hexavalent chromium under natural sunlight

Graphitic carbons (GCs) have the potential to effectively remove pollutants from water due to their low cost, chemical stability, and environmental friendliness. Graphitic carbons with a large specific surface area are good candidates for pollutant removal. This study demonstrates the direct thermal pyrolysis production of HS-GCs and TL- GCs from plant-based biomass obtained from Ambadi (Hibiscus sabdariffa) and Cattail (Typha latifolia). The biomass underwent thermal pyrolysis in a horizontal tube furnace at 900 °C for 2 h. By utilizing a chemical activation technique, the surface area of the synthesized GCs was enhanced, leading to the process of graphitization. The surface area of GCs that originated from plant biomasses was measured to be 48.69 m2/g and 96.78 m2/g for HS-GCs and TL-GCs, respectively. The obtained carbon based material were utilized in photoreduction of Cr(VI). The photoreduction process took 60 min for HS-GCs and 50 min for TL-GCs respectively, to convert toxic Cr(VI) to less toxic Cr(III).

Polycrystalline diamond obtained in the diamond-Mo system with enhanced thermal stability sintered by HPHT

This study provides thermoanalytical data on polycrystalline diamond (PCD) sintered in the diamond-Mo system at high pressure-high temperatures (HPHT). PCD is a key material for the abrasive tool industry, given its unprecedented hardness and wear resistance, as well as its excellent thermal conductivity. These characteristics make it highly effective in drilling into rock formations and machining non-ferrous materials, such as titanium alloys. A critical issue in the performance and lifetime of polycrystalline diamond, however, is its low thermal stability, which limits its potential applications. Accordingly, PCD with enhanced thermostability was obtained in the diamond-Mo system, with resistance graphitization and oxidation around 200 °C higher than conventional PCD. The superior thermal performance seen for PCD-Mo may be due to the formation of in situ carbides (MoC and Mo2C), which inhibit the evolution of graphitization and oxidative processes.

Efficiently regenerating spent lithium battery graphite anode materials through heat treatment processes for impurity dissipation and crystal structure repair

The recovery of graphite materials from spent lithium-ion batteries plays a crucial role in mitigating graphite shortages, achieving environmental protection, and promoting sustainable development. This paper conducts heat treatment regeneration experiments of spent graphite at temperatures ranging from 2000 °C to 2800 °C. By analyzing the dissipation of impurities, the changing pattern of impurity content in the spent graphite anode during the heat treatment was elucidated. Simultaneously, through XRD and Raman analysis, the evolution process of carbon atom graphitization at high temperatures was revealed. The results indicate that as the temperature increases, it is beneficial for impurity removal and graphite crystal structure repair. After assembling the battery, RG-2800 exhibits excellent electrochemical performance, with an initial charge capacity of 346.3 mAh/g, a first coulombic efficiency of up to 88.8 %. Through this method, the efficiency of regenerating graphite materials will be further improved, providing more possibilities for the development of the green energy sector.

Modification on Flower Defects and Electronic Properties of Epitaxial Graphene by Erbium.

Manipulating the topological defects and electronic properties of graphene has been a subject of great interest. In this work, we have investigated the influence of Er predeposition on flower defects and electronic band structures of epitaxial graphene on SiC. It is shown that Er atoms grown on the SiC substrate actually work as an activator to induce flower defect formation with a density of 1.52 × 1012 cm-2 during the graphitization process when the Er coverage is 1.6 ML, about 5 times as much as that of pristine graphene. First-principles calculations demonstrate that Er greatly decreases the formation energy of the flower defect. We have discussed Er promoting effects on flower defect formation as well as its formation mechanism. Scanning tunneling microscopy (STM) and Raman and X-ray photoelectron spectroscopy (XPS) have been utilized to reveal the Er doping effect and its modification to electronic structures of graphene. N-doping enhancement and band gap opening can be observed by using angle-resolved photoemission spectroscopy (ARPES). With Er coverage increasing from 0 to 1.6 ML, the Dirac point energy decreases from -0.34 to -0.37 eV and the band gap gradually increases from 320 to 360 meV. The opening of the band gap is attributed to the synergistic effect of substitution doping of Er atoms and high-density flower defects.

Preparation and characterization of high performance coal tar pitch-based carbon fiber

High performance carbon fiber based on coal tar pitch is a new type of functional material with unique properties, such as light weight, high strength, high modulus, high thermal conductivity, high electrical conductivity and low thermal expansion coefficient. It is a new type of functional material for both military and civilian use. In order to study the preparation of high performance carbon fiber based on coal tar pitch, this article obtained high performance carbon fiber based on coal tar pitch through raw material pretreatment, spinnable asphalt modulation, asphalt melt spinning, non-melting, carbonization, graphitization and other processes, and characterized the performance of spinnable mesocase asphalt and carbon fiber. The results show that high-performance spinnable mesophase pitch can be prepared by three steps raw material refining, hydrogenation modification and thermal polymerization. The mesophase content is 95%, the softening point is 280 °C, and the 3000 m filament can be spun under melt spinning conditions of 375 °C and 0.01 MPa. After graphitization, the coal pitch-based carbon fiber has excellent mechanical properties, small structural defects and a diameter of 12 μm. The tensile strength is 3089 MPa, the elastic modulus is 689 GPa, and the thermal conductivity is 902 w/(m·K).

Formation of diamond and lonsdaleite in ureilites by impact shock processing of graphite

AbstractThe origin of diamond in ureilites has been frequently debated. We investigated carbon phase assemblages (CPAs) in five ureilitic samples of the brecciated asteroid 2008 TC3, found within the Almahata Sitta (AHS) strewn field, by transmission electron microscopy, Raman spectroscopy, synchrotron X‐ray diffraction, and cathodoluminescence. Samples MS‐MU 006, MS‐187, and MS‐170, are of low to moderate shock degree (U‐S2 and U‐S3), and samples MS‐MU 027 (U‐S4) and MS‐MU 045 (U‐S5) have a higher shock degree. In MS‐MU 006 and MS‐187, we did not find any diamond grains. MS‐170 contains disordered and distorted graphite with diamond grains up to 12 μm in size and containing inclusions of Fe,Ni‐metal, FeS, Fe‐phosphide, and Cr,Fe‐oxide. These diamond grains formed under relatively low (5–15 GPa) shock pressures through a catalytic process in the presence of a Fe,Ni,Cr,S,P‐rich melt. The highly shocked and fine‐grained ureilites MS‐MU 027 and MS‐MU 045 have three different types of CPAs, namely a nanopolycrystalline assemblage of diamond and defect‐rich diamond/lonsdaleite, disordered and distorted graphite, and polycrystalline diamond with abundant Fe‐rich mineral inclusions. The CPAs that have only diamond and planar defect‐rich diamond (e.g., MS‐MU 027) most likely formed through martensitic transformation of graphite to diamond and lonsdaleite at >15 GPa and >2000 K. The assemblage of diamond, defect‐rich diamond, and disordered and distorted graphite (e.g., MS‐MU 045) formed by martensitic transformation of graphite to diamond and lonsdaleite, followed by back‐transformation to disordered graphite. We did not find any conclusive evidence to support the formation of diamond grains under high static pressure.

Enrichment of Coal-Hosted Graphite Deposits Caused by Magmatic Heat Transfer and Tectonic Stress at Feng County, Western Qinling Orogen, China

China has ranked first worldwide in graphite imports in recent years, facing a graphite supply risk. Coal-hosted graphite is the focus of future graphite deposit exploration. The current research on the enrichment and mineralization mechanism of coal-hosted graphite is superficial, and the identification standard of coal-hosted graphite is incomprehensive, restricting the exploration of coal-hosted graphite mineral resources and the development of coal metamorphic evolution theory. In this study, the Caotangou–Meigoucoal-hosted graphite deposit in western Qinling Mountain was taken as a case study for dissection. Based on the data from 1/50,000 and 1/200,000 regional geological mapping and the data of graphite mines in the study area, the samples were systematically collected and analyzed to explore the mechanism of coal graphitization through a 1:5000 geological profile survey, 1/10,000 geological mapping in key areas, and the investigation and cataloguing of abandoned coal-hosted graphite adit. The result was that there were two main coal-hosted graphite ore bodies, striking from nearly east to west. The Rmax values of the samples were 7.23–8.15%, the average values of Vdaf were around 5.0%, the d002 value of the II ore body was 0.3433–0.3389 nm, the d002 value of the I ore body was mainly 0.3418–0.3429 nm, the graphitization degree G value of the II ore body was 8.14–59.30%, the graphitization degree G value of the II ore body was 12.79–25.58%. The II ore body was coal-hosted graphite, while some samples of the I ore body were coal-hosted graphite, and some samples were coal. The magmatic heat controls the thermal metamorphism of coal seams to form graphite. The closer the distance to the magma body, the larger the crystals, and the higher the euhedral degree, indicating the higher degree of coal seam metamorphism. The nearly north–south compressive structures mainly provided effective tectonic stress for the evolution of coal graphitization during the Yanshan period; the basic structural units (BSUs) rotated and rearranged, eventually forming a straight graphite structure, and tectonic stress catalyzed the graphitization process. The coal-hosted graphite deposits formed under the dual effects of magmatic heat transfer and tectonic stress.

Importance of resonance-stabilized radicals in soot formation mechanism of diphenyl ether pyrolysis

Soot formation during fuel pyrolysis can pose environmental and human health hazards. As a typical coal-related model compound, diphenyl ether (DPE) represents the specific structures in coal. In this study, soot formation mechanism of DPE pyrolysis was systematically investigated from theoretical principle. The molecular dynamics (MD) simulations show that the variety and number of DPE pyrolysis products increase with the raising temperature. In addition, the higher temperature also promotes the soot formation. Quantum mechanics (QM) calculations indicate that the energy barrier of CO removal from the phenoxy radical is lower than that of the phenyl isomerization reaction, leading to the easier depletion of the phenoxy radical. It is consistent with the result observed from the MD simulation that the phenoxy is consumed more rapidly than phenyl. The main pathways for initial ring formation are the isomerization of polyyne-like chains and the decomposition of DPE molecules which form the ring molecules of C6H5 and C5H5. C2H2 molecule and resonance-stabilized radical (RSR) species like C3H3, C6H5 and C5H5 are precursors for the growth of polycyclic aromatic hydrocarbons (PAHs), which have an important role in the growth process of soot. Subsequently, larger PAHs aggregate with each other to form incipient soot particles which will undergo surface growth and graphitization processes. We hope this work can provide worthy insights into the mechanism of soot formation in DPE and the suppression of carbon soot.

Modification of Diamond Surface by Femtosecond Laser Pulses

The basic mechanisms of laser interaction with synthetic diamond are reviewed. The characteristics of the main regimes of diamond surface etching are considered. In addition to the well-known graphitization and ablation processes, nanoablation and accumulative graphitization, which have attracted relatively recent attention, are described in detail. The focus is on femtosecond (fs) laser exposure, which allows for the formation of a dense cold electron–hole plasma in the focal zone and minimal overheating in the surrounding area. This potentially opens the way to the development of unique laser-based technologies that combine physical and chemical processes for precise surface treatment and functionalization. The physical limitations that determine how precisely the diamond surface can be treated by short-pulsed laser radiation and possible ways to overcome them with the ultimate goal of removing ultrathin layers of the material are discussed. Special attention is paid to the novel possibility of inducing the local formation of point active defects—nitrogen vacancy (NV) complexes in the laser-irradiated zone. Such defects have been at the forefront of solid-state physics for the past thirty years due to continuous attempts to exploit their unique properties in quantum optics, quantum computing, magnetometry, probing, and other fields. Both regimes of NV center formation with and without graphitization of the diamond lattice are considered. Thus, it is shown that intense pulsed laser irradiation is a perfect tool for the processing of synthetic diamonds at the micro-, nano-, and even at the atomic level, which can be well controlled and managed.

Squeeze infiltration processing of lightweight smart aluminum graphite functionally graded composite for enhanced wear resistance

Aluminum - Graphite functionally graded metal matrix composites (A356-Gr FGMMC) with 20‐60 volume percentage (vol%) of natural graphite (Gr) as reinforcement are developed by liquid metal squeeze infiltration technique. The density of A356-Gr FGMMC with 60 % Gr is reduced by 27 % (1.968 g/cm3) in particle rich region from the value of the base A356 alloy (2.68 g/cm3) making the FGMMC lighter. In comparison to monolithic A356 alloy, the coefficient of thermal expansion (CTE) of composites decreases with an increase in the volume fraction of Gr reinforcement. The CTE value is significantly reduced from 22.24 × 10−6/°C for A356 alloy to 9.62 × 10−6/°C for the composite with 60 % Gr. With the addition of Gr from 20 % to 60 %, the microhardness is found to be decreased from 74 HV to 46 HV and the compressive strength decreased from 364 MPa for the unreinforced matrix to 42 MPa for A356-Gr FGMMC with 60 % of Gr addition. Wear studies carried out on A356-Gr FGMMC using pin-on-disc tribometer shows excellent wear resistance with the addition of Gr particles compared to matrix alloy. The wear rate reduces with increasing Gr vol%, reaching a minimum at 60 % Gr. The scanning electron microscopy (SEM) analysis of worn surfaces indicate the formation of self-lubricating tribolayer which limits the interaction between matrix metal and the counter surface leading to the development of a smart composite with functionally graded properties in the particle rich region.

Effects of temperature on reaction path, spreading and wetting mechanism of Cu–20Sn–2Cr/graphite

The non-wetting of the carbon/copper interface makes the conventional hot-pressing preparation process of copper-impregnated graphite (CIG) composites complex, energy-consuming, and costly. Pressureless infiltration can be achieved by the simultaneous addition of low melting point alloying elements and active elements to the Cu matrix. Given the strong dependence of this process on temperature, a modified sessile drop method was used to investigate the reaction path, spreading and wetting mechanisms of Cu–20Sn–2Cr/graphite system under vacuum at 800–1100 °C. The results showed that the equilibrium contact angle θe decreased from 38° (800 °C) to 14° (1100 °C), mainly because the microstructure and distribution of the reaction product layer (RPL) were transformed from an in-compact and discontinuous layer composed of irregular Cr3C2 particles to a dense and continuous layer composed of regular nanospheres or nanorod-like Cr7C3 particles. In addition, the spreading mechanism was controlled by the local reaction of [Cr] and [C] atoms at the triple line (TL) at 800 °C, and by the diffusion of [Cr] atoms to the front of TL at 900–1100 °C. The wetting experiment of the Cu–20Sn–2Cr alloy on the Cr7C3 substrate prepared in situ verified that the Cu–20Sn–2Cr/Cgr system followed the reaction product controlled (RPC) wettability theory.