Crystalline Microstructure Research Articles

Activation and development of direct plasma spark sintering and this method after the synthesis of combustion of ceramic-metal compositions through different mixtures of metal melts and/or intermetallic compounds

The article shows the effect of different mixtures melts of metals and/or intermetallic compounds with various oxide, non-oxide additives, obtained solid solutions of metallic phases during spark plasma sintering, spark plasma sintering after combustion synthesis on the phase composition, micrstructure, grains sizes of crystalline phases, relative density, linear shrinkage, microstructural featres of boundary layers, paths of microcracks, physical-mechanical properties, values of standart erors of properties of samples. Synthesized powders of h-BN, B4C, NiTi, NiZr are characterisized by high intensity of crystallization of h-BN, B4C, NiTi, NiZr. Sintered by spark plasma method c-ZrO2, c-BC2N at pressing loadings 35 MPa and 1400 oC, 5 GPa and 2327 oC in boron melt show evoluted crystalli-zation of c-ZrO2, с-BC2N phases, respectively, crystalline, uniform and dense microstructures. Obtained by combustion synthesis powder shows multi-phase composition with various crystallization of phases. Sintered by direct spark plasma method samples show evoluted mullitization, crystallization of c-ZrO2, solid solutions of metallic phases, but in the samples, obtained by spark plasma method in different sintering conditions after combustion synthesis are visible crystalline, multi-intensive phases. The samples show crystalline, multi-uniform and multi-dense microstructures, variously dispersed grains of crystalline phases. Sintered samples are differ by the relative density, linear shrikage, density, uniformity, width, path of boundary layers and propagating microcracks across these boundary layers, the resistance to the cracking, values of physical-mechanical properties, values of standart errors of properties of samples.

The influence of tectonic action on the characteristics of microcrystalline and pore structure of anthracite in Qianbei Coalfield

Tectonic action strongly impacts the coal's microcrystalline and pore structural features. X-ray diffraction (XRD) was employed to analyze the impact of tectonic action on the microcrystalline structure of coal. The pore structure of anthracite was investigated through electron microscope image, mercury intrusion porosimetry and low pressure N2/CO2 adsorption, with a focus on exploring the relationship between the microcrystalline structure of coal and its micropore structure. The results show that under tectonic action, interlayer spacing of the aromatic layer d002 decreases from 0.345 to 0.342 nm, the stacking height Lc decreases from 2.73 to 2.23 nm, the average number of the effective aromatic layer Nave slightly decreases from 6.61 to 6.51, and the crystallite diameter La increases by 0.13 nm, which indicates that tectonic action changes the microcrystalline structure of anthracite. The microcrystalline structure changes from "short and thick" to "long and thin", thus schematic diagram of the anthracite basic structural unit (BSU) under tectonic action was established. The fa of tectonic coal increased by 16.92% compared with that of original coal, and the g increased from 0.85 (original) to 0.89 (tectonic), indicating that the process of aromatization and graphitization of coal was accelerated by tectonic action. Tectonic action plays an important role in promoting pore development, which makes the pore surface of anthracite more rough, the lattice fringe more dense and clear, and increases the pore volume and specific surface area of anthracite by 1.21 and 1.08 times, respectively. Tectonic action can change the BSU of coal, thus producing more nanoscale space. This study holds important implications for comprehending how tectonic action affect the microcrystalline structure of coal as well as its relationship with nanopore structures in tectonic coal.

Effects of Reduction‐Oxidation Cycles on the Structure, Heat and Corrosion Resistance of Haynes 282 Nickel Alloy Manufactured by Using Powder Bed Fusion‐Laser Beam Method

ABSTRACTThe study investigated the effect of the oxidation–reduction cycles on the structure and corrosion resistance of the Haynes 282 nickel superalloy at ambient and elevated temperatures. The comparative studies were performed on specimens produced by the Powder Bed Fusion‐Laser Beam (PBF‐LB) process and those in the as‐received state. The microstructure of the PBF‐LB specimens was studied using optical and scanning electron microscopy, whereas the chemical composition of the scale formed after isothermal oxidation in an air atmosphere at 750°C was analysed using energy‐dispersive X‐ray spectroscopy and X‐ray Photoelectron Spectroscopy. The phase composition of the formed scale was determined by X‐ray diffraction. Laboratory‐induced hydrogen atmosphere was adopted through cathodic charging. A comparison of corrosion resistance was carried out on two types of Haynes 282 specimens, before and after the oxidation and cathodic charging processes. It was found that PBF‐LB process could be effectively used to manufacture Haynes 282 nickel superalloy with low porosity and a fine crystalline microstructure. The low‐porous, fine‐crystalline microstructure of the tested specimens produced by the PBF‐LB technique exhibited good resistance to electrochemical corrosion, slightly lower than wrought Haynes 282 nickel superalloy specimens.

Growth mechanism and tribological behavior of electroless Ni-P plating with ultrasonic assistance on titanium alloy substrate

The aim of this paper is to study the growth mechanism and tribological behavior of electroless Ni-P plating with ultrasonic assistance on TC4 titanium alloy substrate pretreated by zincating and alkaline pre-plating process. The morphology, composition and structure of zincating, pre-plating and electroless Ni-P plating were studied to analyze its growth mechanism. The tribological behavior of electroless Ni-P plating at room temperature was investigated. The results showed that the electroless Ni-P plating had a typical cauliflower-like morphology and microcrystalline structure characteristic. And the morphology of the Ni-P plating under the action of ultrasonic was uniform, compact and smooth. Compared with the TC4 substrate, the friction coefficient and the wear scar width of the plating were reduced by approximately 35 and 70%, indicating that the Ni-P plating improved the wear resistance of TC4. The wear mechanism of the Ni-P plating was adhesive wear under the dominant of plastic deformation, and slightly abrasive wear, while the wear mechanism of TC4 was dominated by adhesive wear, accompanied by abrasive wear and oxidative wear. The ultrasonic cavitation promoted the elemental interdiffusion between the substrate and Ni-P plating resulting in the formation of the diffusion layer. The ultrasonic cavitation and mass transfer effects improve the activity of the deposition surface and the generation of atomic hydrogen, and promote the nucleation and growth of nickel on the deposition surface, as well as the diffusion of Ni2+ and H2PO2− to the deposition surface. The growth rate of the Ni-P cell-like structures in the parallel direction is greater than in the perpendicular direction. The Ni-P plating grows in a layered manner, and the growth mechanism is the heterogeneous nucleation growth mechanism.

Study on the Effect of Coal Grain Size on the Morphology of Soot Generated During Combustion

This study performed an experimental exploration to analyze the influence of different grain sizes of coal on the nanostructure and morphological parameters of soot generated during combustion. Initially, primary and mature soot samples were gained from the combustion flames of two different grain sizes of coal (less than 150 μm, named sample #1, and 6–8 mm, named sample #2) by using thermophoresis sampling technology. Subsequently, the transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to investigate and analyze the soot samples, with the aim of obtaining their morphological parameters and nanostructure characteristics. The TEM images indicate that the nascent soot produced during the flame formed by small-sized coal is relatively uniform, with individual particles 8–14 nm in size. The grain size of the nascent soot produced by large-sized coal is much larger, within a wide range of 50–350 nm. Additionally, the nanostructures of the nascent soot particles produced by samples #1 and #2 mainly consist of upright parallel crystal stripes. The crystal stripes of the soot particles formed by sample #1 have obvious microcrystalline structures, whereas only a small amount of microcrystalline structure is found at the edge of sample #2. Compared with sample #2, the soot formed during the combustion of sample #1 exhibits a denser crystalline structure. The SEM results indicate that the mature soot agglomerates formed in sample #2 are larger and more in quantity compared to sample #1. Furthermore, the mature soot agglomerates formed in sample #2 have a stronger coagulation performance and a more compact structure than that formed in sample #1.

Cellulose intercalation activation of natural ramie fiber derived carbon electrode for flexible supercapacitors

The complex structure of cellulose leads to its low accessibility to reagents, which hinders the further development of cellulose-based natural fibers in supercapacitors. The key issue is how to achieve deep internal activation while maintaining the flexible self-supporting skeleton structure of cellulose. In this work, an intercalation activation method was proposed. The activator infiltrated into the cellulose microcrystalline structure under rapid swelling to construct a new hydrogen bond network. RC/N2 has a large specific surface area (1897 m2 g−1) and exhibits excellent electrochemical performance due to the uniform activation of NaOH pre-inserted between cellulose layers while ensuring the flexibility of cellulose. At a current density of 0.1 A g−1, it reaches 352 F g−1, and the assembled symmetric supercapacitor has a capacitance retention rate of 98 % after 70,000 cycles. In addition, the symmetric flexible supercapacitor assembled based on RC/N2 has good stability after multi-angle bending, which opens up further possibilities for the development of flexible energy storage devices.

Physicochemical properties, non-volatile flavor components and antioxidant activity analysis of Ganoderma lucidum (Curtis) P. Karst. extracts dried by different methods

The objective of this present study is to evaluate the effect of different drying methods (spray drying, freeze drying and hot-air drying) on physicochemical properties and antioxidant ability of G. lucidum extracts (GLEs) using various techniques. Meanwhile, combined with free amino acids (FAA) analysis, taste activity values (TAV) analysis and electronic tongue to investigate the relationship between the drying method and the sensory quality of GLEs. The study demonstrates that spray drying GLEs (SDE) has a high water solubility of 96.04% ± 0.10% due to its low crystallinity and hollow spherical microstructure. SDE and freeze drying GLEs (FDE) contain high levels of polysaccharides and proteins, which facilitates the formation of polysaccharide-protein chelates, thereby improving antioxidant capacity. However, SDE has higher antioxidant activity when its polysaccharide content is the same. SDE has higher thermal stability to maintain the molecular structure of GLEs. Meanwhile, FDE has a bitter FAAs content up to 65.84 ± 1.12 mg/g and TAV of Histidine is 178.70. Overall, the results suggest that spray drying is an appropriate and preferred drying method to maintain the bioactivity and bioavailability of GLEs. These findings may enhance the understanding of the GLEs flavor property and bioavailability associated with drying methods and provide a theoretical basis for G. lucidum processing.

Synergy of Nanocrystallinity, Temperature, and "the Third Element Effect" for Uncommon Oxidation Resistance of Fe-Cr-Al Alloys.

Nanocrystalline structure, oxidation temperature, and "The Third Element Effect" are among the factors that can profoundly govern the characteristics of the oxide scales that develop on oxidation-resistant alloys, thereby, their synergistic effect can considerably influence alloys' oxidation kinetics. As a result of the synergy, certain iron-chromium-aluminium (Fe-Cr-Al) alloy showed superior oxidation resistance at 800°C than at 700°C (whereas oxidation resistance commonly decreases with the increase in temperature). The superior resistance at higher temperatures is considerably enhanced when the structure of the alloy is nanocrystalline vis-à-vis the common microcrystalline structure. Nanocrystalline alloy oxidizes at a negligible rate (c.f., its microcrystalline counterpart). The characterization of the oxide scale demonstrates that the oxidation temperature governs the formation of the protective oxide scale with/without the assistance of the "Third element Effect". The findings may potentially have considerable commercial implications.

Microcrystalline-Fe2P4O12 as eco-friendly and efficient anode for high-performance dual-ion battery

Dual-ion batteries (DIBs) have garnered significant interest because of their cost-effectiveness and high level of safety. However, the anode typically utilized tends to show low cyclic stability in complete batteries when the only sources of lithium are primarily consumed in the electrolyte following the development of a solid electrolyte interphase (SEI) during the initial electrochemical process. Here, a simple approach is used to produce microcrystalline carbon-coated Fe2P4O12 at a mild temperature. This material has the ability to store lithium ions, resulting in a specific capacity of 215 mAh/g at a potential range of 1 to 2.5 V vs Li+/Li0. Furthermore, it demonstrates a remarkable coulombic efficiency of 99 % in the initial cycles, even in the absence of a solid electrolyte interphase (SEI) formation. On the other hand, the issue of the high voltage plateau of the graphite cathode is addressed by selecting a total of 4.2 V as the optimal voltage range in DIBs. Simultaneously, the composite Fe2P4O12 also demonstrates exceptional ion diffusion kinetics and reduced interfacial impedance due to its microcrystalline structure. The utilization of the proposed Fe2P4O12 anode addresses a crucial deficiency in the complete range of deep in-situ bioremediation techniques, hence expediting the industrialization process.

3D-printed laponite bioceramic triply periodic minimal surface scaffolds with excellent bioactivity for bone regeneration

Laponite (LAP) is a promising biomaterial for bone regeneration due to its reliable biocompatibility and excellent osteoinductivity in bone tissue engineering. However, the personalized manufacture of LAP bioceramic scaffolds with controlled complex architecture and high porosity remains challenging. This study used vat photopolymerization (VPP) to manufacture LAP bioceramic scaffolds with high precision and biological activity. We first selected a 40 wt% LAP bioceramic slurry for subsequent VPP printing based on stability experiments and viscosity characterization results. The curing parameters of the photosensitive bioceramic slurry and the degassing sintering process were studied to ensure the quality of the ceramic green bodies. Then, we characterized the effects of different sintering temperatures (1150 °C, 1200 °C, 1250 °C) on the crystalline phase composition, microstructure, and mechanical properties of the LAP bioceramic. The research showed that the densification and compressive strength of the LAP bioceramic sintered at 1250 °C reached 2.51 g/cm3 and 15 Mpa, respectively. Finally, the bioceramic scaffolds with different sintering temperatures were co-cultured with rat bone marrow mesenchymal stem cells to detect biocompatibility. The results showed that the three groups of scaffolds enhanced cell proliferation, adhesion, and osteogenic capacity. In conclusion, the LAP bone scaffolds by VPP presented the potential for bone repair.

Relationship of CO2 adsorption performance and physicochemical property of biochar prepared by different types of biomass waste

The physicochemical property of biochar prepared by biomass waste is crucial for CO2 adsorption performance. However, the quantified relationship between the physicochemical property and CO2 adsorption capacity for biochar is still unclear. In this study, biochar samples with different physicochemical properties were prepared from six representative biomass of sewage sludge, chicken manure, apple and prickly ash branch, corn and rice straw. The quantitative investigation was conducted and the relationship between the physicochemical properties and CO2 adsorption capacity of biochar was analysed using Pearson correlation analysis method. The results showed that the biochar prepared from prickly ash branch at 800 °C pyrolysis exhibited a better CO2 adsorption capacity of 154.44 mg/g and larger specific surface area of 160.83 m2/g, compared with other biochars. According to the quantitative data about physicochemical properties of twenty-four kinds of biochar samples, the correlations between CO2 adsorption capacity and microcrystalline structure, surface functional groups, nitrogen content and specific surface area were obtained. The CO2 adsorption capacity showed a significant positive correlation with the specific surface area (SBET), stacking height of aromatic layers (Lc), number of aromatic layers (N) and nitrogen content, and the correlation order was SBET >N >Lc = nitrogen content. Moreover, the CO2 adsorption capacity showed a negative correlation with diameter of aromatic planes (La), CO, O-H and index of aromaticity (Aal/Aar), and the order of correlation was CO > O-H >La >Aal/Aar. The effect mechanism of physicochemical properties on CO2 adsorption of biochar was that microcrystalline structure had an influence on CO2 adsorption by van der Waals force, and nitrogen, oxygen-containing functional groups, and so on by Lewis acid-base interaction and hydrogen bonding.

Substrate and Step Rate Dependence Electrodeposition of Nickel–Cobalt–Molybdenum–Phosphorous Alloy for Efficient Hydrogen Evolution Reaction

Understanding the hydrogen economy involves recognizing the crucial role of water‐splitting in producing green, clean, and carbon‐free hydrogen. In that respect, the role of catalyst is very important as it enhances the reaction rate and efficiency, making hydrogen production more viable and sustainable. Herein, nickel–cobalt–molybdenum–phosphorous (Ni–Co–Mo–P) alloy has shown efficient catalysis properties for hydrogen evolution reaction (HER) in an alkaline medium. The quaternary alloys are directly grown on different substrates like nickel sheet, copper sheet, and stainless‐steel sheet by employing a simple pulse electrodeposition method. The method is conducted with a pulse interval time of 15 s at various pulse rates while maintaining the pH of 4 at room temperature. The alloy deposition is performed at a potential range from −1.5 V to −0.15 V (vs Ag/AgCl). The electrodeposition of the alloy in different substrates is first established with X‐Ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), and Raman spectroscopy. The deposited quaternary alloy exhibits the lowest overpotential of −163 mV at 10 mA cm−2 for copper substrate with a Tafel slope of 154 mV dec−1. The microcrystalline structure or amorphous nature and the rough grain surface of Ni‐Co‐Mo‐P alloys have characterized by XRD and scanning electron microscopy micrograph, respectively.

Periodically Sinusoidal Magnetic Stray Field and Improved Film Quality of CoMnP Micro-Magnet Arrays for Magnetic Encoders by Electrodeposition with the Assistance of Ultrasound

Magnetic encoders are composed of a magnetic sensor, a hard magnetic recording medium and a signal processing circuit. Electrodeposited micro-magnet arrays produced by micro-fabrication are promising recording media for enhancing encoder performance. However, two major engineering issues have yet to be resolved. One issue is an unknown relationship between the feature sizes of micro-magnet arrays and their stray field shapes, and another issue is the formation of micro-cracks due to the built-up residual stresses of thick films. In this study, we investigated the effect of feature sizes on the emanating stray field shape at various observation heights. Feature sizes include two height (i.e., film thickness) values of 78 μm and 176 μm, and both width and spacing with three values of 360 μm, 520 μm and 680 μm. Ultrasound-assisted agitation was adopted for investigating the effects of electrodepositing current densities on the film crystalline microstructures and magnetic properties. Narrowing the width of micro-magnets helps the stray field to become a sinusoidal profile. Thinner film, i.e., thickness 78 μm in this study, supports the stray field taking on a sinusoidal profile. Moreover, the spacing between the micro-magnets plays a key factor in determining the shape of the stray field. Under 37 kHz/156 W ultrasound agitation, the optimal hard magnetic properties of electrodeposited CoMnP films are residual magnetization 2329 G and coercivity 968 Oe by a current density of 10.0 mA/cm2. Ultrasound-assisted electrodeposition, along with duly designed feature size, facilitates the micro-magnet arrays having a sinusoidal stray field shape using high quality films. Furthermore, for the first time, a systematic understanding of feature-size-dependent stray field evolution and improved polarities quality has been realized for the recording media of sinusoidal magnetic encoders.

Sulfuric acid treatment to control the microcrystalline structure of starch-based hard carbon for sodium storage

By treating starch with different concentrations of sulfuric acid, we investigated the effect of cross-linked starch-based hard carbon on the performance of sodium-ion batteries (SIBs) at various concentrations. After treatment, the optimal sample exhibits a spherical microstructure, which can provide effective active sites and enhance structural stability, thereby achieving high capacity and long cycle life for SIB electrodes. In subsequent electrochemical tests, after 100 cycles at low current density of 0.1 A g−1, the capacity of H40 remains of 306 mA h g−1. And under the high current density of 1 A g−1, the capacity of H40 can still maintain of 228 mA h g−1, exhibiting a high capacity retention rate of 89 %, which is higher than other samples. This study provides a promising approach for the large-scale production of biomass-derived carbonaceous SIBs anodes.

Improved thermal, mechanical, and dielectric properties of thermotropic liquid crystalline poly(ester amide)s containing lactam-derived segmental units

We prepared two different series of thermotropic liquid crystalline poly(ester amide)s (TPEAs) via bulk polycondensation reactions of 4-hydroxybenzoic acid (HBA, 75.0 mol %) and 6-hydroxy-2-naphthoic acid (HNA, 25.0–17.5 mol %) with ε-caprolactam (CL, 0.0–7.5 mol %) or γ-butyrolactam (BL, 0.0–7.5 mol %). Our investigation aimed to explore the impact of lactam-derived aliphatic amide units’ length and content on the liquid crystalline feature, microstructure, thermal transition, thermal stability, mechanical/relaxational/rheological behavior, and dielectric characteristics of TPEAs. The molecular structure and fibrillar formation of TPEAs containing aliphatic amide units were confirmed through FT-IR and SEM analysis. With increasing CL or BL-derived units from 1.0 mol % to 5.0 mol %, we observed an increase in crystallinity, glass transition temperature, melting temperature, complex melt viscosity, and storage modulus of TPEAs, attributed to the enhanced intermolecular hydrogen bonding interactions. However, at 7.5 mol % CL or BL-derived unit content, these properties decreased due to increased chain irregularity as well as lowered crystallinity. Notably, the dielectric constants (3.31–3.04 at 2 MHz) of TPEAs decreased with the increase of lactam-derived aliphatic amide units owing to the restricted chain mobility by intermolecular hydrogen bonding interactions. We believe that the TPEAs synthesized in this study hold significant potential for applications in technical plastics, superfibers, and printed circuit board materials.

Potential skincare benefits and self-healing properties of Lignosus rhinocerotis polysaccharides as affected by ultrasound-assisted H2O2/Vc treatment

Natural polysaccharides have been recognized as major bioactive components in skincare and wound care products. In this study, the skincare benefits and self-healing properties of Lignosus rhinocerotis polysaccharides (LRP) and its degraded products (DLRP-1, DLRP-2 and DLRP-3) by ultrasound assisted H2O2/Vc treatment (U-H/V) at different ultrasonic intensity (28.14, 70.35, and 112.56 W/cm2) were investigated. U-H/V altered the internal crystalline structure and microstructure of LRP, and enhanced the thermal stability. Due to the breakage of molecular chains after U-H/V, the moisture absorption of LRP was enhanced but the moisturizing property showed a different degree of reduction. U-H/V significantly improved the antioxidant, anti-tyrosinase and anti-inflammatory activities of LRP. Furthermore, the results of enzyme kinetic studies showed a mixed competitive-noncompetitive inhibition of tyrosinase activity by DLRP-3 and the inhibition constant of DLRP-3 on tyrosinase was 2.97 mg/mL. The apparent viscosity of LRP dispersions showed a first increasing followed by decreasing trend as ultrasonic intensity rose. U-H/V enhanced the viscoelastic properties of LRP gels without destroying their self-healing properties. This findings reveal that U-H/V is beneficial for improving the skincare efficacy of LRP, providing a theoretical foundation for the applicability of LRP in wound dressings.

Nitrogen‐Induced Microcrystalline‐to‐Nanocrystalline Structure Transition in Diamond Films Grown by Microwave Plasma Chemical Vapor Deposition: Comparison of N2 and NH3 Precursors

The structure and properties of polycrystalline chemical vapor deposition (CVD) diamond coatings grown by microwave plasma CVD in H2–CH4 mixtures can be effectively controlled by nitrogen admixture in the process gas. Here, a comparative study of adding nitrogen from different precursors, N2 and ammonia NH3, in concentrations up to 0.4%vol on grain size, texture, surface roughness, and sp2/sp3 ratio of the produced films on Si substrates is performed. A transition from microcrystalline to smooth nanocrystalline diamond structure is found to occur at a certain concentration of the precursor, for NH3 this threshold concentration being much lower, 0.02–0.1%, than for N2. The higher activity of ammonia is associated with easier formation of cyano radicals in the plasma as detected with optical emission spectroscopy, in accord with the lower bond‐dissociation energy for NH3 compared to N2. On the contrary, a smaller addition (0.004%) of either N2 or NH3 promotes almost doubling of the growth rate, while preserving the microcrystalline structure of the film. The results establish ammonia as a convenient alternative precursor to commonly used N2 added in the plasma for the diamond film structure modifications.

Microcrystalline and nanocrystalline structure of diamond films grown by MPCVD with nitrogen additions: Study of transitional synthesis conditions

This research explores the complex influence of nitrogen concentration and substrate temperature on the resultant properties of polycrystalline diamond (PCD) films grown by microwave plasma chemical vapor deposition (CVD). In particular, we investigated the growth parameters to find the exact conditions for changing the morphology of the resulting film from microcrystalline (MCD) to nanocrystalline (NCD). A series of 2 µm-thick polycrystalline diamond films was grown on Si substrates in methane-hydrogen–nitrogen gas mixtures with varied: (i) nitrogen concentration (0–2 %) and (ii) substrate temperature (700–1050 °C). Comprehensive characterization techniques, including scanning electron microscopy (SEM), micro-Raman spectroscopy, and X-ray diffraction, were employed to assess the morphological, structural, and spectroscopic properties of the films. The study reveals that even minor additions of nitrogen significantly modulate secondary nucleation, impacting both film morphology and phase composition. Furthermore, substrate temperature emerges as another critical parameter, influencing the growth kinetics and crystallite size. The comparison of the characteristics of grown PCD films allowed us to find conditions for the formation of NCD films with minimal surface roughness and maximal growth rate: nitrogen concentration [N2] ≈ 0.2–0.5 % and temperature T ≈ 850–900 °C. These findings can be used to optimize the CVD synthesis parameters of PCD films for applications as protective or friction-reducing layers, as well as for superhard cutting tools and optical devices.

Cellulose nanocrystal (CNC) from okra plant (Abelmoschus esculentus L.) stalks as a reinforcement in bionanocomposite fabrication: Extraction, processing, and characterization study

Currently, CNC is attractive to the researchers to fabricate multifunctional bionanocomposite because of their outstanding physicochemical, thermomechanical, morphological properties, and eco-friendly nature. Whereas in most cases CNC is extracted from the bast/bark of primary plants, which have other beneficial applications in several sectors. Hence, it is crucial to find out alternative sources of CNCs to diminish the extra pressure on the primary plants. While the useless agrowaste biomass of okra stalks would be a new and beneficial alternative to produce CNCs as a reinforcement. Here, a series of chemical reactions were directed to produce CNCs. The samples were characterized by FTIR-ATR,TGA/DTA,FESEM,EDX,XRD,UV–vis-NIR, and DLS analysis. The obtained results suggested that the newly produced CNCs possessed substantial active functional groups(–OH,CO-C,–NH), high thermal stability, greater crystallinity(86.09±0.001 %), and notable microstructure indicating a well-organized porous surface with encouraging spherical shapes. The CNCs are free from impurities and coloring materials; additionally, they exhibit a highly negative surface charge and smaller particle sizes. It can be stated that the produced CNCs should have a good agreement with the sustainable environment and be beneficially applied as a reinforcing agent to fabricate bionanocomposites. Also acts as a sustainable alternative to the fossil-based hazardous ones for various uses.

Effect of equal channel angular pressing on microstructure and mechanical properties of a Cu-Cr-Ni-Si-Co alloy

The microstructural and properties of a Cu-Cr-Ni-Co-Si alloy produced by equal channel angular pressing (ECAP) were systematically investigated. After the fourth-pass ECAP deformation, the average grain size was refined from 30 μm (solid solution state) to below 3 μm, resulting in a fine and regularly shaped equiaxed crystalline microstructure. The distribution of grain boundaries became more uniform. During ECAP deformation, the volume fraction of Copper texture {001} <100> decreased, while that of the Brass {011} <211> increased, and the Shear {123} <634> remained nearly constant. An increase in the number of ECAP deformation passes facilitated dynamic recrystallization, leading to an increase in the fraction of the recrystallized texture. After thermomechanical treatment (first-pass ECAP +450 °C aged/120 min + 80 % cold-deformation +450 °C aged/30 min), the alloy exhibited good mechanical properties, with a tensile strength of 546 MPa, a yield strength of 475 MPa, an elongation of 18.2 %, and an electrical conductivity of 52.8 %IACS. The main strengthening mechanisms included precipitation strengthening, dislocation strengthening and grain boundary strengthening, with the precipitation strengthening accounting for 45.6 % of the yield strength.