Ball Milling Process Research Articles

Effect of Ball Milling Time on the Microstructure and Properties of High-Silicon-Aluminum Composite.

The duration of ball milling greatly influences the characteristics of high-silicon-aluminum composite during the ball milling process. This study examines how the microstructure, thermal conductivity, and hardness of a high-silicon-aluminum composite are affected by different ball milling times. We exposed the powder to various durations of ball milling and employed different pellet ratios. Following this treatment, the powder underwent consolidation via discharge plasma sintering. Our findings show that with a pellet ratio of 10:1 and a milling duration of 8 h, the powder particles were refined, resulting in a more uniform and dense material composition. This refined material boasted a thermal conductivity of 111.6 W/m·K, a Brinell hardness of 136.8 HBW, and a density of 2.304 g/cm3. This method facilitates the creation of a uniform composite powder composition. It encourages the development of a fine-grain structure, which enables the production of particle-reinforced composites with superior properties.

Biowaste valorization into valuable nanomaterials: Synthesis of green carbon nanodots and anode material for lithium-ion batteries from watermelon seeds

In this study, a solid biowaste watermelon seed is introduced for the first time as an alternative precursor for the production of fluorescent carbon nanodots and nanostructured activated carbon. Firstly, the seeds are carburized and then activated by using KOH after the ball milling process. The activated carbon is used as anode material in lithium-ion batteries and exhibits ∼360 mAh g − 1 capacity after the 200th cycle, with a coulombic efficiency of 98%. Additionally, carbon dots are fabricated by hydrothermally treating carburized seeds at different conditions. The obtained carbon dots show a remarkable fluorescence effect at 458 nm (when excited at 365 nm) and have the potential to be used in biomedical applications. The results show that by means of proper material selection and process design, low carbon footprint nanomaterials suitable for use in various applications can be synthesized successfully from organic wastes.

Two-step pressureless sintering of ultrafine powders for the preparation of high strength and transmittance AlON ceramics

AlON ceramics with high transmittance and strength are essential for transparent armor application. However, high-temperature sintering for long time would result in large grain sizes associated with low strength. In this paper, a low + high temperature two-step sintering method with ultrafine AlON powders was reported for the preparation of high-strength and high-transmittance AlON ceramics. Firstly, the high-purity AlON powders with high specific surface area of 29.77 m2/g was synthesized by solution combustion synthesis-nitridation method and subsequently ball-milling process. Thereafter a sample with 97% density and small grain size (less than 4 μm) can be obtained after sintered at 1750 °C for 3 h, in which the difference of kinetics between grain-boundary diffusion and grain-boundary migration was used to suppress the final stage of grain growth. Further increasing sintering temperature to 1850 °C resulted in the elimination of the residual porosity, and realizing transparent AlON ceramics with high optical transmission (85.4%) and high flexural strength (375.1 MPa) could be achieved.

LiBH4 hydrogen storage system with low dehydrogenation temperature and favorable reversibility promoted by metallocene additives

LiBH4 is of great potential as hydrogen storage material due to its high theoretical hydrogen storage capacity. However, it suffers from high thermal stability, sluggish dehydrogenation/hydrogenation kinetics and poor reversibility. Introduction of catalysts is an effective way to improve the hydrogen storage properties of LiBH4. In the present study, chromocene and nickelocene are used as catalytic additives to LiBH4 by a simple ball-milling. Nickelocene is mostly decomposed, forming CNTs (carbon nanotubes) cross-linking the LiBH4 particles, while chromocene maintains stable during the ball-milling process. But they are fully decomposed to Cr and Ni nanoparticles after the initial dehydrogenation and further transferred to CrB2 and Ni2B nanoparticles after initial hydrogenation. The in situ formed CrB2 and Ni2B show superfine nanoparticles and are uniformly dispersed in the matrix, acting as highly active catalysts. The dehydrogenation temperature of the combined system is evidently reduced, and the hydrogen storage kinetics and reversibility are significantly improved. The highly thermal conductive CNTs are considered helpful in heat transfer during dehydrogenation and hydrogenation. The method for the introduction of the catalysts is facile and low cost. The present work provides a new insight into the design of novel catalysts for LiBH4.

Novel synthesis of LaH2 and La2O3 through mechanochemistry and sintering

Some hydrogen storage materials have been created by a mechanochemical method utilizing ball milling and hydrogen gas. This study developed a novel method for employing hydrogen gas in a ball milling process followed by sintering to dissociate La(OH)3 into La2O3 and produce LaH2. This study aimed to sinter and mill La(OH)3 in a planetary ball with hydrogen, determine the underlying sub-reaction pathways, and characterize the resultant products. The materials characterization was performed through XRD, PSA, DSC/TGA, and SEM-EDS. The rate of hydrogen pressure decrease during ball milling was from 0.0037 to 0.0049 bar/h. The longer the ball milling time, the higher the amount of LaH2. The resulting intermediate compounds after ball milling were LaH2, La, and H2O2, whose composition variations depended upon the initial hydrogen pressure and milling time. LaH2 and La2O3 were the final products following sintering, whose compositions varied depending on the intermediate compounds and their susceptibility to oxygen.

Effect of ball milling time on the formation and thermal properties of Ag2Se and Cu2Se compounds

The thermoelectric materials community has made significant progress on nanostructured and processable materials to improve efficiency and flexibility, reducing manufacturing costs. Selenide compounds, such as Ag2Se and Cu2Se, have received a lot of attention because of their promising capabilities in thermoelectric applications. Additionally, Se is significantly more abundant than Te, with approximately ten times higher availability. High-energy ball milling (HEBM) process is a powerful solid-state synthesis/powder mechanical alloying method. The objective of this work is to form selenide compounds at different milling times (1–20 h) by HEBM process. The structural characterization of the compounds was studied by X-ray Diffraction and X-ray Photoelectron Spectroscopy, while the thermal stability of the prepared samples was examined by Thermogravimetric Analysis. The experimental results show that the Ag2Se sample synthesized at 20 h presents lower thermal stability because of the higher specific surface area and the increased porosity as a result of the hardening effect. Additionally, Cu2Se presents Cu2O(SeO3) as the main phase at low temperatures, while at higher temperatures, CuO is the dominant phase. Therefore, as the heating temperature increases, there is a complete evaporation of Se and a conversion of the remaining copper into copper oxide. The present study demonstrates a simple method for the synthesis of Ag2Se and Cu2Se thermoelectric materials with high oxidation resistance.

Electrochemical Determination of Ascorbic Acid by Mechanically Alloyed Super Duplex Stainless Steel Powders

SAF-2507 super duplex stainless steel powders (SDSS) were prepared using a high-energy planetary ball milling process. The X-ray diffraction (XRD) shows peak broadening after 20 h of ball milling and revealed a phase transformation resulting in a two-phase alloy mixture containing nearly equal amounts of ferrite (α) and austenite (γ). After 20 h of ball milling the particle size was reduced to ~201 nm. Scanning electron microscope (SEM) micrographs showed small-size irregular grains with an average particle size ranging from 5–7 µm. The high-resolution transmission microscope (HRTEM) analysis confirmed the presence of nanocrystalline particles with sizes ranging from 10 to 50 nm. The presence of ferrite phase is visible in the corresponding diffraction pattern as well. In this paper, we have discussed the electrochemical sensor application of mechanically alloyed nano-structured duplex stainless steel powders. The fabricated 4 mg duplex stainless steel modified carbon paste electrode (SDSS-MCPE) has shown excellent current sensitivity in comparison with 2, 6, 8, and 10 mg SDSS-MCPEs during the detection of ascorbic acid (AA) in a phosphate buffer solution with a pH of 6.8. The calculated electrode active surface area of SDSS-MCPE was found to be almost two times larger than the surface area of the bare carbon paste electrode (BCPE). The limit of detection (LD) and limit of quantification (LQ) were found to be 0.206 × 10−8 M and 0.688 × 10−8 M, respectively, for the fabricated 4 mg SDSS-MCPE.

Effect of High-Energy Ball Milling in Ternary Material System of (Mg-Sn-Na)

In this study, the nature of the ball-milling mechanism in a ternary materials system (Mg-6Sn-1Na) is investigated for proper mechanical alloying. An identical powder mixture for this material system is exposed to different milling durations for a suitable mixture. First, the platelet structure formation is observed on particles with increasing milling duration, mainly formed in <200> direction of the hexagonal crystal structure of the Mg matrix. Then, the flake structure with texture formation is broken into smaller spherical particles with further ball milling up to 12 h. According to EDS analysis, the secondary phases in the Mg matrix are homogenously distributed with a 12-h milling duration which advises a proper mixture in this material system. The solid solution formation is triggered with an 8-h milling duration according to XRD analysis on 101 reflections. Conventional sintering is performed at 350 °C in 2 h for each sample. In bulk samples, XRD data reveal that secondary phases (Mg2Sn) with island-like structures are formed on the Mg matrix for a milling duration of up to 8 h. These bigger secondary phases are mainly constituted as Mg2Sn intermetallic forms, which have a negative effect on physical and mechanical properties due to a mismatch in the grain boundary formation. However, the homogenous distribution of secondary phases with a smaller particle size distribution, acquired with 12 h milling time, provides the highest density, modulus of elasticity, and hardness values for this ternary materials system. The ternary materials produced with the 12-h ball-milling process provide an improvement of about 117% in hardness value compared with the cast form.

Carbon-Fiber-Recycling Strategies: A Secondary Waste Stream Used for PA6,6 Thermoplastic Composite Applications.

With a view to achieving sustainable development and a circular economy, this work focused on the possibility to valorize a secondary waste stream of recycled carbon fiber (rCF) to produce a 3D printing usable material with a PA6,6 polymer matrix. The reinforcing fibers implemented in the research are the result of a double-recovery action: starting with pyrolysis, long fibers are obtained, which are used to produce non-woven fabrics, and subsequently, fiber agglomerate wastes obtained from this last process are ground in a ball mill. The effect of different amounts of reinforcement at 5% and 10% by weight on the mechanical properties of 3D-printed thermoplastic composites was investigated. Although the recycled fraction was successfully integrated in the production of filaments for 3D printing and therefore in the production of specimens via the fused deposition modeling technique, the results showed that fibers did not improve the mechanical properties as expected, due to an unsuitable average size distribution and the presence of a predominant dusty fraction ascribed to the non-optimized ball milling process. PA6,6 + 10 wt.% rCF composites exhibited a tensile strength of 59.53 MPa and a tensile modulus of 2.24 GPa, which correspond to an improvement in mechanical behavior of 5% and 21% compared to the neat PA6,6 specimens, respectively. The printed composite specimens loaded with the lowest content of rCF provided the greatest improvement in strength (+9% over the neat sample). Next, a prediction of the "optimum" critical length of carbon fibers was proposed that could be used for future optimization of recycled fiber processing.

Investigations on thermo–physical properties of ethylene glycol-based hybrid Al2O3 and ZrO2 nanofluid as coolant

In the current study, a hybrid Al2O3 and ZrO2 nanofluid based on ethylene glycol was made using the sonication method, and combinations of Al2O3 and ZrO2 nanoparticles were produced by the ball milling process. The development of a suspension with an average particle size of less than 100 nm has been confirmed by zeta-sizing analysis, which measures the average particle size, and zeta potential analysis, which examines the stability of the nanofluid system. The primary goal of the current work is to better understand how thermal conductivity affects machining parameters like cutting force and surface roughness, as well as how nanofluid acts as a coolant. Moreover, thermal conductivity is assessed because it is thought to be one of a nano fluid's most important thermo-physical characteristics. The thermal conductivity value increases as particle concentration increases. The addition of dispersant (Poly vinyl alcohol, sodium dodecyl sulphate) to nanofluid is essential for the stability and suspension of nanoparticles throughout the fluid system. At 27 °C and 3.0% vol. of generated hybrid nano fluid, the experimental examination of thermal conductivity shows a 15% improvement above base fluid data. The findings of the machinability research in the hybrid Al2O3 and ZrO2 nano cutting fluid environment show improvements in tool life and surface quality with less cutting force.

Embedding Hierarchical Pores by Mechanochemistry in Carbonates with Superior Chemoselective Catalysis and Stability.

Hierarchical porosity of carbonates can facilitate their performance in massive applications as compared to their corresponding bulk samples. Traditional solution-based precipitation is typically utilized to fabricate porous carbonates. However, this tactic is generally employed under humid conditions, which demand soluble metal precursors, solvents, and extended dry periods. A salt-assisted mechanochemistry is exploited in contemporary work to settle the shortcomings. Enlighted by solid-state technology, this approach eliminates the utilization of solvents, and the process of ball milling can create pores in 5 min. A range of highly porous carbonates and their derivatives are acquired, with several materials surpassing recording surface areas (e.g., H-CaCO3: 108 m2/g, SrCO3: 125 m2/g, BaCO3: 172 m2/g, Pd/H-CaCO3 catalyst: 101 m2/g). The results display that Pd/H-CaCO3 shows superior catalytic efficiency in the synthesis of aniline (turnover frequency [TON] = 1.33 × 104/h-1, yield ≥ 99%, and recycle stability: 11 cycles) and dye degradation. Combining mechanochemistry and salt-assisted tactic provides a facile and efficient pathway for processing porous materials.

Analysis of failure characteristics and mechanical mechanisms of sandstone during spherical indenter intrusion based on acoustic emission experiment

This paper aims to investigate the effects of steel ball diameter on failure characteristics and mechanical mechanisms of sandstone during the spherical indenter intrusion process. By using equipment such as acoustic emission (AE), the process of spherical indenter intrusion into sandstone was monitored and recorded for analysis of the fracture characteristics, load-depth relationship, and specific energy of sandstone under spherical indenters with different diameters. The results showed that as the diameter of the spherical indenter increased, the peak load of the sandstone increased continuously, and the failure mode transitioned from “jump-type” to plastic, with the acoustic emission count exhibiting a staged variation characteristic. During this process, the accumulated acoustic emission count, intrusion coefficient, and specific energy of intrusion all exhibited a “parabolic” law of first decreasing and then increasing, all of which reached minimum values when the ratio of the diameter of indenter to sandstone was close to 1.0. This indicated that as the diameter of the indenter approaches that of the sandstone, the intrusion process becomes more facile and efficient. Finally, the study revealed the formation mechanism of dense core and crack inside the sandstone during intrusion, and discussed the law of the crushing rate in ball milling from the perspective of compression. The conclusions contribute to revealing the fragmentation mechanics of rocks in the ball milling process and aid in determining the ball loading parameters in the milling process based on rock properties, aiming to achieve energy-saving and cost reduction.

Improvement of Ball Mill Performance in Recycled Ultrafine Graphite Waste Production for Carbon Block Applications.

A carbon block is a carbonaceous material used in various applications such as bearings, mechanical seals, and electrical brushes. This work aims to fabricate carbon blocks from industrial graphite waste, a residue from the cutting and tooling process of graphite block production. The ball milling process was used to fabricate ultrafine graphite waste to enhance the packing of carbon blocks. The milling performance was profoundly affected by dispersing agents in which sodium dodecyl sulfate (SDS), lignosulfonate (LS), and mixed dispersant (LS-SDS) were applied. The results showed that LS-SDS had the best milling performance, the greatest grinding index, and a flowable slurry, indicating the potentiality of this formulation for the environmentally friendly manufacture of ultrafine graphite waste. Carbon blocks were prepared from oven-dried ultrafine graphite waste, which was mixed with amorphous carbon and pitch. This carbon mixture was formed a block by compaction before carbonization and impregnation. The density of the fabricated carbon blocks increased from 1.76 to 1.83 g/cm3 after impregnation along with the increase in hardness, flexural strength, and reduction in electrical resistivity from 83, 62 MPa, and 40 μΩ m to 88, 81 MPa, and 39 μΩ m, respectively. The physical properties of carbon blocks prepared from ultrafine graphite waste were comparable to the properties of typical pristine carbon products.

Microstructural and thermal evaluation of the formation of tin–tellurium (Sn[sbnd]Te) alloy by ball milling process

A mechanically induced phase transition in tin‑tellurium (SnTe) system and its dependence on the milling time of the masses of metastable SnTe phase(s) produced during ball milling have been investigated. The synthesis approach involves top-down ball milling of elemental Sn and Te powders in an argon environment with a milling time of 1 to 5 h at a low ball milling speed of 300 RPM. The SnTe solid solution forms as particles, resulting in large masses due to the ball milling operation. Ball milling of initial micron-sized powders of Sn and Te resulted in a homogenized nano-sized powder mixture. This mechanical mixture of Sn and Te powders exhibiting intermediate phases with a crystal structure similar to that of elemental Sn and Te were detected in the ball-milled mixtures at various milling times, which resulted in a stable phase that ultimately transformed into a SnTe solid solution. Morphological and structural modifications at different stages of ball milling were investigated through X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, dynamic light scattering, density measurement, and surface analysis. Subsequently, dense pellets were fabricated by spark plasma sintering from synthesized SnTe solid-solution powders produced by ball milling for 5 h. The sintered samples showed excellent structural integrity with densities of up to 6.35 g/cm3. It is to be noted that the formation of large quantities of uniform SnTe powder alloy produced by ball milling is reported for the first time in this study. These findings could be extended in the future to prepare bulk quantities of many solid solutions of the elements of the same periodic group.

Cork-Derived Carbon Sheets for High-Performance Na-Ion Capacitors.

S-doped carbon sheets have been easily prepared by deconstructing the 3D cellular structure of a fully sustainable and renewable biomass material such as cork through a mild ball-milling process. S-doping of the material (>14 wt % S) has been achieved by using sulfur as an earth-abundant, cost-effective, and environmentally benign S-dopant. Such synthesized materials provide large Na storage capacities in the range of 300-550 mAh g-1 at 0.1 A g-1 and can handle large current densities of 10 A g-1, providing 55-140 mAh g-1. Their increased packing density compared to the 3D pristine structure allows them to also provide good volumetric capacities in the range of 285-522 mAh cm-3 at 0.1 A g-1 and 53-133 mAh cm-3 at 10 A g-1. In addition, highly porous carbon sheets (SBET > 2700 m2 g-1) have been produced from the same carbon precursor by rationally designing the chemical activation approach. These materials are able to provide good anion storage capacities/capacitances of up to 100-114 mAh g-1/163-196 F g-1. A sodium-ion capacitor assembled with the optimized S-doped carbon sheets and the highly porous carbon sheets with mass matching ratios provided the best energy/power characteristics (90 Wh kg-1 at 29 kW kg-1) in combination with robust cycling stability over 10,000 cycles, with a capacity fade of only 0.0018% per cycle.

Insight into the effect of chemical structure for microbial lignite methanation

The chemical structure of lignite plays a fundamental role in microbial degradation, which can be altered to increase gas production. In this study, the structural changes in lignite were analyzed by conducting pretreatment and biomethane gas production experiments using crushing and ball milling processes, respectively. The results revealed that different particle size ranges of lignite considerably influence gas production. The maximum methane yield under both treatments corresponded to a particle size range of 400–500 mesh. The gas production after ball milling was higher than that after crushing, irrespective of particle size. Compared with lignite subjected to crushing, that subjected to ball milling exhibited more oxygen-containing functional groups, less coalification, more disordered structures, and small aromatic ring structures, demonstrating more unstable properties, which are typically favorable to microbial flora for the utilization and degradation of lignite. Additionally, a symbiotic microbial community comprising multiple species was established during the microbial degradation of lignite into biogas. This study provides new insights and a strong scientific foundation for further research on microbial lignite methanation.

Preparation of α-Al2O3 by low-temperature calcining γ-Al2O3 with α-phase seed in-situ obtained by ball milling

Due to the high activation energy barrier and the sporadic nature of nucleation, the temperature required for the transition from cubic dense γ-Al2O3 to tripartite α-Al2O3 is as high as 1100–1200 °C. In this work, a two-step strategy was employed to reduce the phase transformation temperature, and prepare α-Al2O3 particles with good dispersion. As the first step, 10 nm sheet γ-Al2O3 was obtained by ammonium aluminum carbonate (AACH) decomposition, which was more favorable to the crystal transformation in the next ball-milling processing. In the second step, γ-Al2O3 powder with partial α-Al2O3 produced in situ by ball-milling γ-Al2O3 was calcined, and α-Al2O3 nanoparticles were obtained at just 850 °C. The content of the α-Al2O3 is determined by the Rietveld Refine method. The relationship between ball-milling time and α-Al2O3 content was clarified, and the effect of α-Al2O3 content on the transformation temperature and morphology of γ-Al2O3 was discussed. The results showed that the α-Al2O3 content rises with the increase of ball milling time, and spherical α-Al2O3 nanoparticles can be obtained when the α-Al2O3 content is 5 %. The addition of α-Al2O3 seeds reduces the phase transition temperature but agglomeration exists. Our proposed two-step low-temperature calcination strategy is an important method for the preparation of alumina nanoparticles

The influence of Dy3+ ions doping and annealing temperature on structural, morphological, and spectroscopic properties of lanthanum orthovanadate (LaVO4) material

In the current work, we present the results of nanocrystalline lanthanum orthovanadate (LaVO4) doped with dysprosium ions, which was synthesized by a high-energy ball milling (HEBM) process. Lanthanum, vanadium, and dysprosium oxides were employed as starting reagents. These materials were turned into LaVO4:Dy3+ powder with two polymorphic phases after HEBM and subsequent heating that was carried out in the air in the temperature range from 800 °C to 1200 °C. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and DRS (UV–vis) spectroscopy were used to characterize the obtained Dy-doped LaVO4 powders. The excitation and photoluminescence (PL) emission spectra, and time decay (lifetime) curves of the dysprosium (III) ions in LaVO4 material were measured and analyzed. The influence of annealing temperature and the concentration of dysprosium (III) ions (1%, 2%, and 3% at.) on spectroscopic properties was discussed. The qualitative phase analysis of Dy-doped LaVO4 powders indicated the dominant presence of a monoclinic LaVO4 structure. The presence of the tetragonal solid-solution (La, Dy)VO4 phase was also revealed. The structural transformation consists of an increase of Zr type LaVO4:Dy3+ phase, resulting in a higher structure and site symmetry of t-LaVO4:Dy3+. With increasing Dy3+ content, the relative fraction of the tetragonal (La, Dy)VO4 phase was also increased in all samples. Furthermore, XRD investigations showed that Dy3+ ions were incorporated mainly into the t-(La, Dy)VO4 structure. The increase of the amount of tetragonal phase in polymorphic LaVO4:Dy3+ material results in higher emission intensity caused by more efficient energy transfer from VO43− vanadate group to Dy3+ ions. The average sizes of the m-LaVO4 crystallites, estimated using the Rietveld method, were in a narrow range from 53 to 77 nm. Two main intense emission peaks were observed in the blue (466–495 nm) and yellow (557–594 nm) wavelength ranges and can be ascribed to transitions involving 4F9/2 to the stark split sublevels of 6H15/2 and 6H13/2, respectively. The overall intensity of the emission strongly depends on the annealing temperature. The best results were achieved for powder heated at 1200 °C. The values of the calculated average decay lifetime τavg of the LaVO4 powders doped with 1%, 2%, and 3% at. Dy heated at 800 °C, 1000 °C and 1200 °C were very similar, but one can observe that with increasing heating temperature the average decay lifetime of LaVO4:Dy powders slightly decreased regardless of the Dy concentration.

Enhancing the thermal stability of S/Se based thermoelectric materials using self-generated oxide films

This study focuses on the thermal stability of Cu1.8S materials. During the ball milling process, metal powder is added to the milled Cu1.8S powder, and then the obtained powder is sintered using current assisted sintering to obtain dense blocks. The aim is to enable the added metal elements to spontaneously grow an oxide film on the surface of the material block at high temperature, achieving protection of the material matrix. The thermal stability of materials is evaluated by utilizing changes in room temperature phase composition before and after high-temperature heat treatment, changes in material electrical conductivity during high-temperature processes, and cyclic electrical transmission performance testing. By observing the surface oxide film state of the material after high-temperature treatment, the commonalities and differences in the effects of different element additions on the thermal stability of the material were analyzed. The effects of different metal elements on material hardness and electrical transmission performance were evaluated. It is found that adding metal powder can effectively improve the thermal stability of Cu1.8S, improve material hardness, and regulate the electrical transmission performance of the material. The characteristics of the oxide film formed by the spontaneous growth of metal elements and oxygen on the surface of the material substrate determine the effectiveness of the oxide film in protecting the material from high temperatures. The pure Cu1.8S bulk can only maintain stability at 300 oC, and the addition of Cr, Al, 316L, Fe, and Mn powder respectively increased the stable temperature of the material to 400, 400, 450, 450, 500 oC. Adding metal elements to the material matrix to grow an oxide film on the surface of the material to prevent high-temperature oxidation or decomposition is an effective way to improve the thermal stability of S/Se compounds.

Polydopamine coating grown on the surface of fluorinated polymer to enhance the self-lubricating properties of lignin-cellulose based composites

In this paper, a novel ethanol-water Tris buffer system was developed to construct a polydopamine (PDA) protective layer on the surface of polytetrafluoro-wax (PFW) to obtain PFW@PDA with excellent hydrophilicity. The wood-based slurry was obtained by solvent encapsulation and lignin-cellulose assisted ball milling process using waste poplar powder and flake graphite as raw materials. PFW@PDA exhibited excellent dispersion stability in such aqueous slurry and the water was removed from the slurry by vacuum filtration to obtain paper-based composite films. Based on the self-reinforcement of the lignin-cellulose cross-linked network, construction of graphene thermal conductivity network, and the effectiveness of PFW@PDA for wear reduction and self-lubricating. This composite film exhibits excellent water resistance, good thermal stability, and superior mechanical properties. The friction coefficient and wear rate were reduced by 71.3 % and 166.7 %, respectively, compared with the unmodified material. Besides, the end-of-life products can be recycled by mechanical crushing in water, which exhibits a good balance between wear resistance and sustainability, providing a new idea for improving the hydrophilicity of fluorinated polymers and enhancing paper-based friction materials.