Phase Composition Research Articles

Phase composition of sputter deposited tungsten thin films

Sputter deposited tungsten thin films are studied by X-ray diffraction. Two phases can be identified: α-W and β-W based on the observed (110), and (200) and (210) Bragg reflections, respectively. With increasing film thickness (50 to 200 nm), the phase composition shifts from β-W towards α-W. No influence of the base pressure (3 × 10−3 – 3 × 10−5 Pa) on the phase composition is observed. Also the influence of the argon pressure (0.3 to 0.7 Pa) is rather weak. The strongest shift towards α-W composed thin films is obtained by increasing the discharge power (50 to 250 W). This trend is further studied by energy flux measurements using a calorimetric probe. These measurements rule out a strong change of the substrate temperature, and an impact of the energy flux scaled by the deposition rate (total energy per deposited atom). Test particle Monte Carlo simulations reveal the importance of the momentum of the reflected argon neutrals on the phase composition. The maximum energy of these species is mainly defined by the discharge voltage, and is higher than the directional dependent displacement energy of W. Despite the significant correlation between phase composition and the number of displacement per deposited atom, there is a strong scatter of the phase composition. As the deposition conditions were varied in random way, changes of the target erosion profile, and the changing discharge voltage over each series are probably partially responsible for the observed scatter. This scatter is also enhanced by the long term changes in the phase composition towards the more thermodynamic stable α-W phase.

Self-generated B-MAX phase composites: The effect of sintering temperature on surface morphology and phase composition

The use of metal-based MAX phase composites is widespread in the production of high-temperature structural materials, anticorrosive materials and electrode materials. Herein, novel B-Ti3AlC2 and B-Ti4AlN3 composites were prepared using the hot-pressing method at varying sintering temperatures ranging from 950 °C to 1325 °C. This study also explores the effect of sintering temperature on the surface morphology and phase composition of both B-MAX phase composites. The morphological and crystal phase composition of MAX phase composites were investigated through SEM coupled with EDS, FE-SEM, AFM, and XRD test analysis. The results revealed that higher sintering temperatures increase the clear formation of MAX phases and composites as compared to lower temperatures. The findings also expose that the in-situ formation of B-MAX composites significantly changes the structure, contributing to transforming the overall performance and making it suitable for high-stress applications like electronics, aerospace, and cutting tools.

The microstructure and mechanical property of W-TiC/Ti composites via chemical-mechanical milling method

Carbide dispersion strengthened W(CDS-W) has attracted much attention as a plasma-facing material (PFM). However, the carbide tends to segregate at W grain boundaries and has poor interface properties with W due to the large difference in the bond structure. In this work, nanometer Ti was added to improve the performance of the W/TiC interface, and nanoscaled W-TiC-x%Ti (x=0.1,0.5 and 1.0) composites were prepared by chemical-mechanical milling and ordinary sintering method. The effects of Ti on powder morphology, phase composition, microstructure and mechanical properties were systematically investigated using XRD, SEM, EDS, TEM and HADDF technologies. Simultaneously, the existence form and distribution of Ti elements, and W/TiC interface characteristics of powders and composites were analyzed. Moreover, the microstructure evolution and strengthening mechanism were preliminarily discussed. Results show that the W-TiC/Ti powder has an obvious core-shell multilayer structure with a particle size range of 50-120 nm. The addition of Ti exists in the forms of TiC, Ti, and TiO2, and has no effect on the morphology and phase composition. Besides, the phase transformation and solution-precipitation of the Ti-added occurs during the sintering process. Part of Ti precipitates on the W/TiC surface to form Ti rich region, which significantly promotes the dispersion of TiC and improves the W/TiC interface, as well as prevents the growth of W grains, and the average grain size is 2.90 μm. Moreover, the orientation relationship of [013]( 00)TiCFCC||[ 13]( 0)WBCC exists at the W/TiC interface, especially the coherent phase interface is formed. The tensile strength and microhardness at room temperature are 520 MPa and 850 HV0.2, respectively, which is attributed to the synergistic effect of fine-grained strengthening, dispersion strengthening and interface strengthening. This work can provide a new strategy and direction for preparing high-performance CDS-W materials.

Surface Structure Formation in Plasma Cutting of Aluminum and Titanium Alloys Using Direct Current Straight and Reverse Polarity

Abstract The structural features and phase composition are examined in near-surface layers of specimens of Al-Mg, Al-Cu-Mg alloys and commercially pure titanium obtained by plasma cutting using direct current straight polarity (DCSP) and direct current reverse polarity (DCRP). It is found that the flows of molten metal ejected by the gas stream from the cut cavity during cutting form the fusion and heat-affected zones, whose structural morphology, phase composition, and thickness depend on both the selected material and the cutting mode. The fusion zone is thicker in specimens cut using DCRP than in those cut with DCSP. The thickness of the adjacent heat-affected zone is also the largest in the mode that provides a thicker fused layer. Aluminum alloy specimens cut in ambient air are characterized by the presence of oxygen in the near-surface layers. The lowest degree of oxidation is observed in Al-Mg alloy. Oxygen penetrates into the fused layer to a depth of 350–500 μm in Al-Cu-Mg and up to 200–250 μm in Al-Mg alloy. In titanium alloy, the thickness of oxide layers does not exceed 100–150 μm during straight polarity cutting and 200–250 μm during reverse polarity cutting. A thin brittle layer of TiO and TiO2 oxides is formed on the titanium alloy surface. It is shown that the generation of “water mist” around the plasma jet when cutting materials of all types with DCRP leads to a more intensive oxidation of metal, less thermal effect on the material, and reduced roughness of the cut face.

Coloring Multilayer Zirconia May Affect Its Optical and Mechanical Properties

The coloring process of monolithic dental zirconia caused considerable debate on the possible effects of different coloring methods. The main objective of this study was to investigate the influence of pigments in 3 multilayer 5-mol% yttria partially stabilized zirconia (5Y-PSZ) disks (Lava Esthetic A2 [Zr-AGG_A2] and Bleach [Zr-AGG_BL], both 3M Oral Care, and Katana STML A2 [Zr-NoAGG], Kuraray Noritake). The influence of pigment addition on the translucency parameter (TP00), fracture toughness, Vickers hardness, biaxial strength, and hydrothermal stability was assessed and correlated with the microstructure and phase composition. The pigment composition and distribution were evaluated by light and fluorescence microscopy, electron probe microanalysis, and nano–scanning electron microscopy. The chemical and phase composition and aging behavior were assessed using X-ray fluorescence and X-ray diffraction, respectively, while the aging sensitivity of the pigments was evaluated using micro-Raman spectroscopy. In contrast to Zr-NoAGG, possessing a typical 5Y-PSZ microstructure, the pigment additions in both Zr-AGG_A2/BL zirconia resulted in large yellow and blue fluorescent Er-, Hf-, and Al-containing agglomerates composed of small grains (0.57 µm and 0.38 µm, respectively, vs. 0.92 µm for the surrounding grains) with lower Y2O3 content. Zr-AGG_A2 had the lowest aging resistance, with transformation degradation occurring exclusively within the pigment agglomerates. All zirconia grades had a high Y2O3 content (4.2%–5.7 mol%) tetragonal ZrO2 phase and a high (42%–55 wt%) cubic ZrO2 phase content. Although no statistical differences were measured for hardness and toughness, Zr-NoAGG had a significantly higher TP00, higher flexural strength, and lower mechanical reliability compared to both Zr-AGG_A2/BL zirconia. The rare-earth oxide-containing zirconia agglomerates that were added as pigments to the multilayered monolithic Zr-AGG_A2/BL zirconia are the cause for their lower optical and mechanical properties and reduced aging resistance.

Synthesis and Characterization of LaMnO3 Prepared by Hydrothermal Synthesis Method

Abstract LaMnO3 powders were prepared by hydrothermal synthesis method by varying citric acid to metal ions. The ratio of citric acid to metal ions is one of the parameters that have an affect on purity of LaMnO3 prepared by hydrothermal method. It is necessary to control the parameter to obtain the good quality of the final product of LaMnO3. LaMnO3 with variation molar ratio of citric acid to metal ion (CA/M) of 0, 1 and 4 were prepared. To determine the morphology, crystall structure, and phase composition, the powders were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD) techniques. The obtained results revealed that the morphology of sample CA/M = 0 has rod-like shape, CA/M = 1 was in the formed of irregular fine particles that stuck together and formed agglomerates, while the spherical morphology with various diameters were formed in the sample CA/M = 4. The XRD analysis demonstrated that sample CA/M = 1 had a single phase while in sample CA/M = 0 and CA/M = 4 others phase were detected such as La (OH)3 and La2O3. There was a change in crystall structure of the LaMnO3 phase in each sample due to the presence of citric acid. The peaks position in sample CA/M = 0, 1, dan 4 exhibit orthorhombic, rhombohendral and cubic structure with space group of Pnma, R -3c and Pm-3m respectively.

Effects of heat input on microstructure evolution and corrosion resistance of underwater laser cladding high-strength low-alloy steel coating

The effects of heat input on the microstructure evolution and corrosion resistance of the high-strength low-alloy (HSLA) steel coating obtained by wire-feed underwater laser cladding were studied. Optical digital microscope, scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscope (TEM), electron back-scattered diffraction (EBSD), electrochemical tests, laser microscope and other characterization methods were used. As the heat input increased, the smoothness of the underwater cladding coating improved, with little changes in elemental distribution and phase composition. However, the content of acicular ferrite increased, while the amounts of lath bainite, lath martensite, and granular bainite decreased. As the heat input increased from 0.4 to 0.55 kJ/mm, the grain size increased from 25.3 to 55.9 μm, the proportion of low-angle grain boundaries rose from 61.3 % to 69.1 %, and the texture intensity of the (110) crystal plane increased from 16.22 to 23.83. Meanwhile, the dislocation density decreased from 4.9 × 1014 to 4.1 × 1014 m−2. These changes enhanced the corrosion resistance of underwater coating. As the heat input increased from 0.4 to 0.55 kJ/mm, the corrosion current density decreased from 2.13 × 10−5 to 3.35 × 10−6 A/cm2, and the corrosion potential increased from −0.823 to −0.529 V. Additionally, the depth-to-width ratio of the corrosion pits decreased from 0.255 to 0.053. This study laid the foundation for high-quality in-situ underwater repairs of ships and submarines made of high-strength steel.

Preparation, characterization, and catalytic performance comparison of Ni/LaBO3 and Ru‐Ni/LaBO3 (B = Al, Fe) for methane steam reforming to hydrogen production

AbstractThe methane steam reforming (MSR) reaction is a significant process for hydrogen production, and developing catalysts with high activity and stability is crucial. In this work, the supported perovskite catalysts of Ni/LaBO3 and Ru‐Ni/LaBO3 (B = Al, Fe) were prepared by the sol–gel method using citric acid as a gelling agent for MSR to hydrogen production. The phase composition, pore structure, and surface morphology of the prepared catalysts were characterized by X‐ray diffractometer, Brunauer–Emett–Teller, scanning electron microscopy and energy dispersive spectroscopy, and X‐ray photoelectron spectroscopy. The reaction activity and stability of the prepared catalysts were tested in the fixed‐bed reactor with the temperature range of 500–800°C. The effect of Ru addition on the structure of perovskite and catalytic performance of MSR is explored. The results showed that 1wt%Ru–15wt%Ni/LaAlO3 catalyst exhibited the most excellent activity and stability during the reaction compared with the other three catalysts. The CH4 conversion, H2 selectivity, and H2 yield of the 1wt%Ru–15wt%Ni/LaAlO3 catalyst could reach 94.68%, 79.78%, and 48.65%, respectively, under the reaction temperature of 800°C and gas hourly space velocity of 36 000 mL/(gh), which were higher than those of a commercial catalyst. It was because that the relatively large surface area of perovskite support provides more active site and the addition of Ru enable Ni to have a smaller size and more dispersion. This study could provide a reference of perovskite catalysts for hydrogen production by MSR.

Impact of atmospheric plasma spraying parameters on microstructure, mechanical properties and thermal cycling performance of YSZ coatings

Yttria-stabilized zirconia (YSZ) coatings are widely utilized thermal protective layers for metal and superalloy surfaces. These coatings are employed as thermal barrier coating (TBCs) to insulate metallic parts from higher thermal energy, thereby minimizing the cooling need for the topcoat ceramic layer. The choice of material is 7 wt% YSZ due to its exceptional capability to withstand challenging conditions characterized by extremely high temperatures and pressures, typically employed by the atmospheric plasma spraying (APS) in gas turbines, effectively extending their lifespan and improving performance. The deposition process of TBCs is significantly influenced by various spraying parameters, including gas flow rate and current (amp). These key parameters mutually play a significant role in controlling thermal stability, phase composition, and improved mechanical and microstructure properties. The aim of this research is to evaluate and contrast the impact of various spraying parameters on YSZ TBC performance. Accordingly, the influence of Hydrogen (H2), Argon (Ar) flow rate, and Current (amp) was investigated. Microstructure and elemental mapping studying was conducted using Field Emission Scanning Electron Microscopy FESEM/EDS and phase studying was examined with X-ray diffraction (XRD). Porosity was measured by IMAGE J software while hardness measurement was calculated by Vickers hardness tester. Additionally, thermal cycling tests were conducted between 700 °C and 1200 °C. The porous coatings exhibited poor performance, delaminating early during the tests. In contrast, dense coatings performed significantly better, enduring up to 140 cycles before failure.

Improved gyromagnetic properties of LiZnTi ferrites co-fired with Bi2O3-La2O3 additives at low temperature

In this work, low temperature-sintered Li0.43Zn0.27Ti0.13Fe2.17O4 ferrites mixed with x wt.% (x = 0.00–0.30 wt%) of La2O3 and 1.5 wt% of Bi2O3 were successfully prepared by the solid-state reaction method. The variations in phase composition, microstructure, and gyromagnetic properties of the as-prepared samples were studied in detail. XRD patterns and refinement results show that La2O3 didn't affect the formation of the spinel phase, but a small amount of La3+ might enter into the lattice structure. The micro-morphological analysis and grain size statistics demonstrate that the addition of La2O3 significantly suppressed the grain growth, and the average grain size decreased from 2.19 μm (x = 0.00 wt%) to 1.14 μm (x = 0.15 wt%). The uniformity of the grain size distribution was improved, and the degree of densification was significantly increased. Meanwhile, the saturation magnetization (4πMs) increased from 3921 Gs to 3989 Gs, the coercivity (Hc) decreased from 457.5 A/m to 312.5 A/m, and the ferromagnetic resonance linewidth (ΔH) decreased from 328.5 Oe to 220.7 Oe. Our study indicates that the Bi2O3-La2O3 mixture is an effective sintering additive for low-temperature sintering of LiZnTi ferrite ceramics, which will play an important role in the development of low-temperature co-fired ferrites.

Mathematical modelling and validation of the mechanical properties of HVOF-sprayed WC-12Co coatings considering the phase composition and defects generated at different process parameters

The thermal spraying process involves many machine-based parameters or independent variables (fuel flow rate, oxygen flow rate, powder feed rate, stand-off distance and many others in the HVOF process). Any combination of these parameters produces only two measurable responses, namely, particle temperature and particle velocity. In this current work, first, the machine-based spray parameters are varied in specific ways to produce different particle temperatures at near-constant velocities and vice-versa. This approach has reduced the number of independent variables to only two. These two factors further influence the in-flight particle reactions, thereby affecting the phase composition and the microstructural defects in the as-sprayed coatings. The X-ray diffraction patterns of the as-sprayed coatings revealed the presence of W2C, W, Co3W9C4, and amorphous Co-W-C phases apart from the WC phase. The W2C and W originated owing to the decarburization of the WC phase. On the other hand, the dissolution of the carbide in molten binder led to the formation of Co3W9C4 and the amorphous Co-W-C phase. The nano-hardness of both the carbide and binder phases increased with an increase in particle temperature owing to a higher degree of decarburization and carbide dissolution respectively. The porosity was the most significant micro-structural defect present in the as-sprayed coatings. An increase in either particle temperature or velocity reduced the porosity present in the as-sprayed coatings. The mechanical properties (microhardness, elastic modulus and indentation fracture toughness) tend to improve as porosity decreases. A comprehensive mathematical model was proposed to predict the mechanical properties of as-sprayed coatings as a function of composition and defects. Finally, the process maps of mechanical properties were plotted in temperature-velocity space.

From mixed brookite/anatase TiO2 nanopowder to sodium titanates: Insight into morphology, structure, and photocatalytic performance

A method to obtain sodium titanate nanoribbons starting from a mixture of brookite and anatase TiO₂ nanopowder is described. As-prepared TiO2 nanopowder with a major brookite phase was used as a precursor in an alkaline hydrothermal approach, where the temperature was kept at 200 °C. The influence of hydrothermal treatment and consequent annealing temperature (T = 500 °C) on the crystal structure, phase composition, and morphology of samples were investigated by X-ray powder diffraction (XRPD), Raman and FTIR spectroscopy, and electron microscopy techniques (FESEM, HRTEM). All these methods point out that the hydrothermally treated sample, containing the NaTi3O6(OH)(H2O)2, Na2Ti3O7, and Na2Ti9O19, is dominated by layer-structured sodium hydroxititanate dihydrate. The annealing leads to the formation of rare sodium titanates, Na3Ti6O13 and Na2Ti9O19, with tunnel structures where the hexatitanate with increased sodium content prevails. The photocatalytic activity of synthesized nanostructures was tested in the degradation process of Reactive Orange (RO16) azo-dye upon UV excitation. It appears that photocatalytic activity is lower after hydrothermal treatment, but subsequent annealing makes sodium titanate nanoribbons faster in the degradation of RO16. The research implies that these sodium titanate nanostructures are promising photocatalytic materials and should be considered in the future for removing different pollutants from water.

Effect of silicon powder dosage on the microstructure and performance of SiC/Si3N4 composite ceramic microfiltration membranes

The SiC/Si3N4 composite ceramic microfiltration membranes were fabricated using the in-situ nitridation process of silicon powder at 1350 °C, utilizing SiC powder and silicon powder as the raw materials. The effects of silicon powder dosage on the phase composition, basic physical properties, pure water flux, pore size distribution, and microstructure of membrane materials were investigated. With an increase in the silicon powder quantity from 5 wt% to 20 wt%, the flexural strength of the membrane materials increased from 6.6 MPa to 42.4 MPa, while the apparent porosity remained stable at 37.0%–39.0 %. The experimental results indicated a substantial correlation between the pore size distribution and the pure water flux. As the average pore size of the ceramic membranes decreased from 463.87 nm to 132.68 nm, the pure water flux gradually decreased from 265.99 L/(m2⋅h⋅bar) to 50.34 L/(m2⋅h⋅bar). The systematic investigation reveals that the Si3N4 binding phase, generated from the in-situ nitriding reaction of silicon powder, is the primary factor responsible for enhancing the mechanical properties of the membrane material. The process of in-situ nitriding silicon powder is accompanied by an increase in volume, which is beneficial in filling and refining the pores. Moreover, the formation of silicon nitride whiskers during the nitriding process can enhance the material's mechanical properties and further divide and refine the pores.

Exploring the influence of sintering temperature on the phase composition, mechanical strength, and dielectric constant of porous ca-stabilized zirconium dioxide ceramics

ZrO2 ceramics have wide applications as structural materials in industrial, scientific, and technological fields. Despite the large number of works devoted to the influence of synthesis parameters on the formation of different phases of ZrO2 and the properties of the obtained ceramics, the effect of sintering temperature on the characteristics of the porous ZrO2 ceramics has not been addressed sufficiently. This study focuses on examining how sintering temperature affects the phase composition, microstructure, dielectric properties, and mechanical properties of porous stabilized zirconium dioxide ceramics. Phase transformations during sintering at various temperatures were identified using powder X-ray diffraction and Raman spectroscopy. The results indicate that fully stabilized cubic ZrO2 with satisfactory mechanical properties (HV0.5 = 580) and a porosity of 21.5% was achieved at temperatures of 1400 and 1500 ℃. At lower sintering temperatures, the obtained samples exhibited multiphase composition and high porosity. The reasons for the formation of the CaZrO3 phase at sintering temperatures of 1000–1200 ℃ were established using scanning electron microscopy, energy dispersive analysis, and thermodynamic considerations of the solid-phase reactions. AC dielectric measurements showed that the synthesized samples have high-Q characteristics; and that the dielectric constant can be controlled by changing the sintering temperature.

Mitigating adverse effects of Cu-containing intrauterine devices using a highly biocompatible Cu[sbnd]5Fe alloy

Copper-containing intrauterine devices (Cu-IUD) are adopted by worldwide women for contraception with the advantages of long-term effectiveness, reversibility and affordability. However, adverse effects occur in the initial implantation stage of Cu-IUD in uterine because of the burst release of Cu2+. To minimize the burst release, in this study, we designed a series of Cu–Fe alloys with 0.5 wt%, 1 wt% and 5 wt% Fe and also further produced ultrafine grained (UFG) structure for these alloys via equal-channel angular pressing. The microstructures and properties of the coarse grained (CG) Cu, CG Cu–Fe alloys and UFG Cu–Fe alloys were systematically investigated, including grain structure and phase compositions, metallic ions release behavior, electrochemical corrosion performance, and in vitro cytotoxicity. With careful comparison and selection, we chose the CG Cu–5Fe and UFG Cu–5Fe for in vivo tests using rat model, including tissue biocompatibility, in vivo corrosion behavior, and contraceptive effectiveness. Moreover, the corrosion mechanism of the Cu–5Fe alloy and its improved biocompatibility was discussed. Both CG and UFG Cu–5Fe alloys exhibited dramatic suppression of Cu2+ release in simulated uterine fluid for the long-term immersion process. The in vivo tissue compatibility was significantly improved with both CG and UFG Cu–5Fe alloys implanted in the rats’ uterine while the high contraceptive efficacy was well maintained. Due to the superior biocompatibility, the CG and UFG Cu–5Fe alloys can be the promising candidate material for Cu-IUD. Statement of significanceA highly biocompatible Cu–Fe alloy was designed and fabricated for Cu-containing intrauterine devices (Cu-IUD). With 5 wt% Fe, the burst release of Cu2+ is inhibited due to the formed galvanic cell of Cu and Fe, resulting in earlier release of Fe3+. As Fe is the most abundant essential trace element of human body, it can mitigate the toxic effects of Cu2+, thus significantly improving both in vitro cell compatibility and in vivo tissue compatibility. More importantly, the Cu–5Fe alloy exhibits 100 % contraceptive efficiency as the CG Cu, but with greatly reduced adverse effects to the uterus tissues. An advanced Cu-IUD can be developed using Cu–Fe alloys.

Effect of chelator on carbon sequestration and mechanical properties of CO2-cured cement pastes with different pore structures

Chelator can accelerate the mineralization reaction of cement-based materials, playing a positive role in reducing CO2 emissions into the atmosphere. Cement pastes with different pore structures were prepared by adjusting the water cement ratio, and effects of chelator on the microstructure, phase composition, carbon sequestration and mechanical properties of CO2-cured cement pastes with different pore structures were investigated in this study. The results indicated that chelator could promote CO2 transport in dense cement paste with more gel pore and transition pore and medium dense cement paste with many transition pore and capillary pore, and induce mineralization reaction to repair larger pores in loose cement paste with more capillary pore and megalopore (LCM). Chelator had the most significant effect on improving the performance of cement paste of LCM, increasing the carbonation sequestration rate and compressive strength of cement paste cured for 48 h by 19.0 % and 28.1 %, respectively.

On the effect of energy input on microstructure evolution and mechanical properties of laser beam powder bed fusion processed Ti-27Nb-6Ta biomedical alloy

Additive manufacturing of pre-alloyed Ti-27Nb-6Ta powder by laser beam powder bed fusion (PBF-LB/M) employing a wide range of processing parameters is reported. An in-depth microstructure analysis along the whole process chain from powder feedstock material to additively manufactured bulk structures was conducted employing scanning electron microscopy (SEM) as well as X-ray and high-energy synchrotron diffraction. It is shown that near-fully dense parts (≥ 99.96%) with β+α’’ dual-phase microstructure and very homogenous element distribution are obtained in a large process window. In particular, a considerable influence of the energy input during PBF-LB/M on the solidification microstructure, i.e. phase composition and texture, is found. With increasing energy per unit area (EA) values both an increase in the volume fraction of the bcc β-phase and more pronounced texture components are seen. Furthermore, the mechanical behavior was evaluated under monotonic tensile loading. The PBF-LB/M processed Ti-27Nb-6Ta structures feature good mechanical properties with ultimate tensile strength (UTS) and strain to failure values of up to 768 MPa and 33.8 %, respectively. Due to the strong impact of the energy input during additive manufacturing on the microstructure evolution, however, a significant inverse strength-ductility behavior is observed. While UTS clearly decreases with increasing EA values, strain to failure increases at the same time. The underlying relationships between processing (energy input), microstructure and mechanical properties are explored and rationalized.

Surface-modified composites of metal–organic framework and wood-derived carbon for high-performance supercapacitors

The renewable nature, high carbon content, and unique hierarchical structure of wood-derived carbon make it an optimal self-supporting electrode for energy storage. However, the limitations in specific surface area and electrical conductivity defects pose challenges to achieving satisfactory charge storage in wood-derived carbon electrodes. Therefore, exploring diverse and effective surface strategies is crucial for enhancing the electrochemical energy storage performance. Herein, a decoration technique for enhancing aesthetic appeal involves applying a metal–organic framework (Ni/Co-MOF) containing nickel and cobalt onto the inner walls of wood tracheids. The sequential modification steps include carbonization, oxidation activation, and acid-etching. The Ni/NiO/CoO-CW-4 electrode, made by acid-etching carbonized wood (CW) doped with nickel, nickel oxide, and cobalt oxide for 4 h, has excellent surface area and pore size distribution, high graphitization degree, and exceptional conductivity. Furthermore, surface modification optimizes the surface chemistry and phase composition, resulting in a 0.8 mm thick Ni/NiO/CoO-CW-4 electrode with an exceptionally high areal capacitance of 16.76 F cm−2 at 5 mA cm−2. Meanwhile, the fabricated solid-state supercapacitor achieves an impressive energy density of 0.67 mWh cm−2 (8.38 mWh cm−3) at 2.5 mW cm−2 (31.25 mW cm−3), surpassing representative modified wood-based carbon electrodes by approximately 2–7 times. Additionally, the supercapacitor demonstrates exceptional stability, maintaining 96.21 % of capacitance even over 10,000 cycles. The parameters presented here demonstrate a significant improvement compared to those typically observed in most modified wood-derived carbon-based supercapacitors, effectively addressing common issues of low energy density and suboptimal cycling performance with wood carbon composites.

Vat photopolymerization of complex-shaped silicon nitride ceramics with high mechanical and thermal performance by optimization sintering aids and kinetics

In this study, the impact of sintering aid content and sintering time on the density, phase composition, microstructure, thermal conductivity, and mechanical properties of silicon nitride (Si3N4) ceramics through vat photopolymerization (VPP) was systematically investigated. The results revealed that an increase in sintering aid amount promoted the network distribution of the grain boundary phase along with densification, grain coarsening and microstructure uniformity. The extension of sintering time improved density, thermal conductivity, and mechanical properties of the material. Superior performance with density of 99.4%, thermal conductivity of 64.4W·m-1·K-1, flexural strength of 879 ± 37MPa, and hardness of 15.0 ± 0.4GPa was achieved in sample containing 8wt.% MgO/Y2O3 sintered for 12h. Finally, high-precision Si3N4 ceramic heat sink elements were successfully fabricated via VPP, opening up new prospects in thermal management applications associated with electronics and automotive industries.

Effect of Tween 80 on the Electrocatalytic Performance of a Ti/PbO2‐MWCNTs Electrode

AbstractIn this work, Ti/PbO2‐MWCNTs anodes modified with different amount with different amount of Tween 80 (0.0–2.0 g/L) were prepared by the direct current electrodeposition method used as anode materials for Zinc electrowinning. The MWCNTs were dispersed in a lead nitrate solution with Tween 80, and the effects of the amount of added Tween 80 on the morphology, phase composition and electrocatalytical performance of lead dioxide coating were investigated. Physical characterizations show that with the increase of the amount of Tween 80, both grain size of PbO2 and carbon content in PbO2 layer firstly increased and then decreased, the preferential orientation and crystallinity of the PbO2 grain growth in the deposition process changed. Electrochemical tests demonstrate that the optimal modified electrode achieved the minimum Eo value and maximum j0 of 2.038 V and 3.781×10−4 A, respectively, an increase of capacitance to 368.8 μF cm−2, and a decrease of charge transfer resistance to 92.74 Ω cm2, which is mainly attributed to the PbO2 electrode modified with Tween 80, coupled with the synergistic effects of MWCNTs doping.