Interlayer Defects Research Articles

Regulating Ion Transfer Dynamics and Potassium Polyselenide Dissolution in Dual‐Defect MoSe2‐x@NC for Ultrafast and Stable Potassium‐Ion Storage

AbstractMolybdenum diselenide (MoSe2), a promising anode material for potassium‐ion batteries (KIBs), often suffers from sluggish kinetics, substantial volumetric expansion, and dissolution and shuttling of intermediate phases, resulting in unsatisfactory cycle stability and rate performance. In this work, a dual‐defect MoSe2 (equipped with interlayer defects and Se vacancies) is introduced by a novel plasma‐induced etching process, encapsulated in nitrogen‐doped porous carbon nanofibers (denoted as dd‐MoSe2‐x@NC). These modifications create multidimensional potassium‐ion insertion channels, improve ion transfer dynamics, enhance intrinsic conductivity, and expose more reactive sites. Moreover, the nitrogen‐doped porous carbon matrix mitigates volumetric expansion and suppresses potassium‐polyselenide (K‐pSex) dissolution and shuttling through a physicochemical dual‐anchoring strategy. The dd‐MoSe2‐x@NC electrode demonstrates remarkable electrochemical performance, achieving a high specific capacity of 418.5 mAh g−1 at 0.05 A g−1, reliable cycling stability over 1400 cycles at 2.0 A g−1, and superior rate performance with 125.0 mAh g−1 at 10.0 A g−1. The findings elucidate the “intercalation‐conversion” reaction mechanism and show that the dd‐MoSe2‐x@NC//PTCDA full cell attains high energy density (115.8 W h kg−1) and high power density (1057.2 W kg−1). This work highlights the enhanced potassium storage kinetics and cycling stability of layered transition metal chalcogenides, demonstrating the potential of MoSe2 in high‐performance KIBs.

Different post-heat treatment responses on microstructure and mechanical characteristics of maraging steel 1.2709 samples produced by LPBF

Abstract The study focuses on the enhancement of microstructural and microhardness characteristics of Laser-Based Powder Bed Fusion (LPBF) maraging steel 1.2709 with the effect of different heat treatment (HT) conditions including aging (AT), double aging (DAT), and solutioning (ST) and compared with the as-built (AB) condition. The samples were fabricated with the LPBF process parameters, utilizing 120 W of laser power, 500 mm s−1 of scanning speed, maintaining 20 μm layer thicknesses, with the laser spot width and hatch spacing of 0.0550 mm and 100 μm respectively in the argon environment with the 45° rotating raster scanning pattern. Further the as-built and heat treated samples were evaluated utilizing electron backscatter diffraction (EBSD), Field Emission Scanning Electron Microscope (FESEM), microhardness, x-ray diffraction (XRD) and relative density. The FESEM analysis indicated that the DAT samples exhibit a more refined and uniform interdendritic grain growth of precipitates Ni3 (Al, Ti) compared to the as-built sample, which exhibited porosity and lack of fusion. Aging reduces the presence of interlayer defects, while the solution-heat-treated sample reveals the formation of lath martensite. The microhardness exhibited an increase following three distinct heat treatment conditions: AB, AT, DAT, and ST, measuring 450 HV, 650 HV, 760 HV, and 520 HV, respectively. The ferrite content was recorded at 99.6%, 87.4%, 99%, and 99.4%, while the austenite content was 0.4%, 12.6%, 1%, and 0.6%. The grain size in the ferrite phase was 8.72 μm, 6.087 μm, 6.86 μm, and 0.32 μm, and in the austenite phase the grain size was 0.26 μm, 0.86 μm, 2.51 μm, and 6.89 μm.

Research on Graphitic Carbon Nitride (g-C3N4) prepared by template-based method and its photocatalytic properties

Abstract. The Graphitic Carbon Nitride (g-C3N4), a non-metallic polymer photocatalytic material, has a wide range of raw materials and a simple preparation process. Due to its unique electronic structure and excellent photocatalytic performance, g-C3N4 has attracted wide attention in the field of environmental purification and energy conversion in recent years. However, g-C3N4 faces a lot of challenges, including a wide band gap, many interlayer defects, and poor interlayer electron transport. Nevertheless, its unique semiconductor structure and chemical stability still provide the possibility to explore the effect of its piezoelectric properties on photocatalysis, which paves the way for a novel approach to environmentally friendly hydrogen production. Therefore, the paper delves into the application of different template methods in the preparation of g-C3N4 by reviewing the related literature, and analyzes the role of different template materials in the preparation. In addition, in this paper, the photocatalytic properties of g-C3N4 are explored, which are mainly reflected in the photocatalytic water separation performance and photocatalytic degradation of organic dyes. It is found that the g-C3N4 shows great potential in the fields of photocatalytic water decomposition for hydrogen production and degradation of organic pollutants due to its unique band gap, nontoxicity, low cost and wide range of sources. Future research should continue to explore more kinds of template materials and their preparation processes, with the aim of realizing further enhancement of the performance of g-C3N4 photocatalysts and promoting their practical applications in the fields of environment and energy.

Effect of hydration process on the interlayer bond tensile mechanical properties of ultra-high performance concrete for 3D printing

It is crucial to reveal interlayer interface characteristics for fully analysing the mechanical properties of 3D printed ultra-high performance concrete (3DP-UHPC). Despite its significance, the interlayer bonding behaviour of 3DP-UHPC has not been fully explored. To fill this gap, this study adopted different curing times and conditions to investigate the effect of hydration process on the interlayer microstructure and mechanical properties under different interlayer interval times. As the result show that, the interlayer microstructure remained dense for interval times less than 5 minutes, but interlayer gaps became increasingly apparent as the interval time exceeded this threshold. Promoting hydration, however, helped heal interlayer defects in 3DP-UHPC. Additionally, the interlayer bond tensile strength gradually decreased with increasing interval time but remained almost unchanged when the interval time exceeded 1 day. Notably, hot water bath curing enhanced the bond tensile strength of specimens with interval times within 60 minutes, but its improvement was insignificant for interval times exceeding 1 day. Based on these experimental results, a preliminary interlayer bond tensile stress-strain equation of 3DP-UHPC was derived. The findings of this study offer promising avenues for the improvement and promotion of 3DP-UHPC technology.

Magnetorheological and magnetic actuation behaviour of solvent cast 4D printed styrene-ethylene-butylene-styrene block copolymer based magnetorheological elastomeric materials

In this work styrene-ethylene-butylene-styrene (SEBS) block copolymer based smart magnetorheological elastomeric (MREs) materials have been additively manufactured using solvent-cast 4D Printing (SC-4DP) technique. The effect of carbonyl iron powder (CIP) content on the particle distribution, particle–matrix adhesion, surface and layer morphology of the 4D Printed MRE sample was investigated. CIP particles were observed to be well embedded and dispersed up to 60 wt% content. However, at higher CIP content the tendency of the particles to agglomerate increased significantly. Furthermore, samples with CIP content ≥70 wt% showed poor particle–matrix adhesion and possessed inter-layer coalescence defects. Investigations were also performed to evaluate the magnetic properties of MREs at room temperature. Magnetorheological behaviour was studied to evaluate the effect of varying magnetic field on dynamic viscoelastic properties. Magnetorheological effect increased from ∼79 % to ∼211 % with an increase in CIP content. However, the particle–matrix adhesion also significantly affected the magnetorheological effect for higher CIP content samples. Magnetic actuation capability of flexible MRE samples was evaluated for gripper-based application. SC-4D Printed flexible grippers were able to successfully grip, lift, and drop both the soft deformable and rigid freeform profile objects in different media (air and sodium hydroxide solution) suggesting suitability for remotely actuated gripper-based applications.

Study on the Key Parameters Affecting the Power Conversion Efficiency of Cs2AgBiBr6-Based Perovskite Solar Cells

The lead-free halide double perovskite material A2BB’X6 represented by Cs2AgBiBr6, has higher potential as a photovoltaic material since it has good electronic and optical properties in recent years. However, the highest power conversion efficiency (PCE) achieved for solar cells made with Cs2AgBiBr6 as the light-absorbing layer in experiments is only 2.51%. To investigate this phenomenon, we used the Solar Cell Capacitance Simulator (SCAPS) simulation software to build five solar cell models with the structure of FTO/ZnO/Light-absorbing layer/Cu2O/Au based on different light-absorption layer materials. Two reasons causing the low PCE of Cs2AgBiBr6 solar cells were identified. On the one hand, interlayer defects in Cs2AgBiBr6 film synthesis significantly decreased the fill factor (FF), thereby reducing the quantum efficiency (QE). On the other hand, Cs2AgBiBr6’s larger indirect bandgap resulted in a narrower absorption range. Additionally, it was demonstrated that adjusting the material thickness and alloying method could, respectively, improve the two aforementioned issues. When the thickness of the light-absorbing layer material was 300[Formula: see text]nm, the FF increased from 39.88% to 55.01%, resulting in an optimal PCE of 3.88% for the solar cell. Alloying increased the short-circuit current ([Formula: see text]) from 8.44[Formula: see text]mA/cm2 to 21.24[Formula: see text]mA/cm2, leading to a simulated PCE increase of 8.92% for solar cells based on Cs2NaSb[Formula: see text]In[Formula: see text]I6. This work, from the perspective of device simulation, is highly significant for improving the photoelectric conversion efficiency of Cs2AgBiBr6-based perovskite solar cells in experimental settings. It offers new insights for optimizing solar cell efficiency.

Interlayer enhancement of 3D printed CF/PLA composites via localized microwave welding and annealing-induced crystallization

Interlayer defects and insufficient diffusion are detrimental to the structural integrity of 3D printed composites. This study introduces a facile approach to enhance the interlayer adhesion and structural integrity of 3D printed carbon fiber/polylactic acid (CF/PLA) composites, utilizing graphene-coated CF/PLA filaments for localized microwave welding and annealing-induced crystallization. This method promotes localized PLA melting at the interlayer interfaces, facilitating polymer diffusion and transcrystallization, which are crucial for effective interlayer repair and enhancement. The unique microwave dissipation properties of graphene ensure selective heating at the interlayer interfaces without largely affecting the intralayer CF, which is crucial for maintaining the overall structural integrity. Combining microwave welding with post-annealing treatment promotes transcrystalline growth at interlayer interfaces, which results in a 26.4 % increase in 90° tensile strength of the 3D printed CF/PLA composites, demonstrating the effectiveness of our approach. These findings provide new insights into strategies for enhancing the mechanical properties of 3D printed carbon fiber thermoplastic composites through precise interlayer enhancement and interfacial defect repair.

2D Reconfigurable Memory Device Enabled by Defect Engineering for Multifunctional Neuromorphic Computing.

In this era of artificial intelligence and Internet of Things, emerging new computing paradigms such as in-sensor and in-memory computing call for both structurally simple and multifunctional memory devices. Although emerging two-dimensional (2D) memory devices provide promising solutions, the most reported devices either suffer from single functionalities or structural complexity. Here, this work reports a reconfigurable memory device (RMD) based on MoS2/CuInP2S6 heterostructure, which integrates the defect engineering-enabled interlayer defects and the ferroelectric polarization in CuInP2S6, to realize a simplified structure device for all-in-one sensing, memory and computing. The plasma treatment-induced defect engineering of the CuInP2S6 nanosheet effectively increases the interlayer defect density, which significantly enhances the charge-trapping ability in synergy with ferroelectric properties. The reported device not only can serve as a non-volatile electronic memory device, but also can be reconfigured into optoelectronic memory mode or synaptic mode after controlling the ferroelectric polarization states in CuInP2S6. When operated in optoelectronic memory mode, the all-in-one RMD could diagnose ophthalmic disease by segmenting vasculature within biological retinas. On the other hand, operating as an optoelectronic synapse, this work showcases in-sensor reservoir computing for gesture recognition with high energy efficiency.

Manipulating 2D Membrane Interlayer Channels with Accelerated Mass-Transfer Behavior to Boost Solar Desalination.

The scarcity of fresh water necessitates sustainable and efficient water desalination strategies. Solar-driven steam generation (SSG), which employs solar energy for water evaporation, has emerged as a promising approach. Graphene oxide (GO)-based membranes possess advantages like capillary action and Marangoni effect, but their stacking defects and dead zones of flexible flakes hinders efficient water transportation, thus the evaporation rate lag behind unobstructed-porous 3D evaporators. Therefore, fundamental mass-transfer approach for optimizing SSG evaporators offers new horizons. Herein, a universal multi-force-fields-based method is presented to regularize membrane channels, which can mechanically eliminate inherent interlayer stackings and defects. Both characterization and simulation demonstrate the effectiveness of this approach across different scales and explain the intrinsic mechanism of mass-transfer enhancement. When combined with a structurally optimized substrate, the 4Laponite@GO-1 achieves evaporation rate of 2.782kg m-2 h-1 with 94.48% evaporation efficiency, which is comparable with most 3D evaporators. Moreover, the optimized membrane exhibits excellent cycling stability (10 days) and tolerance to extreme conditions (pH 1-14, salinity 1%-15%), verifies the robust structural stability of regularized channels. This optimization strategy provides simple but efficient way to enhance the SSG performance of GO-based membranes, facilitating their extensive application in sustainable water purification technologies.

Selection strategy of curing depth for vat photopolymerization 3D printing of Al2O3 ceramics

Vat photopolymerization (VPP) 3D printing technology allows the fabrication of complex ceramic structure components through the layer-by-layer stacking strategy. The curing depth is a crucial parameter for the stacking process, as it directly impacts the printing quality. Furthermore, this parameter exerts a profound effect on the final quality of the printed part. However, there is currently a lack of comprehensive research on how the curing depth affects VPP ceramic 3D printing. This study aims to thoroughly evaluate the impact of curing depth parameters on critical aspects of the 3D printing process, including the forming accuracy, surface quality, monomer conversion, resin pyrolysis, interlayer defects, and mechanical properties. The results of our investigation clearly demonstrate the significant influence of curing depth on the precision and performance of VPP 3D printed ceramic parts. Ceramic samples produced with higher curing depth exhibited superior surface quality (Ra<1.6 μm) but lower forming accuracy. Increasing the curing depth improved interlayer adhesion but excessive depth led to a decreased monomer conversion content from 5.2 % to 2.0 % and an internal stress in the green body. Moreover, increasing the curing depth intensified the pyrolysis process and increased the propensity for cracks forming, as confirmed by simultaneous thermal analysis and microstructure observations. The flexural strength of the sintered samples reached its maximum value of 630 MPa at three times the printing layer thickness. This study provides valuable insights for selecting appropriate curing depth parameters in VPP ceramic 3D printing.

The features of interlayer fracture of composite materials with a variable layup angle under impact loading

Interlayer defects in structural components made of composite materials are caused by the imperfection of the manufacturing process, complex interactions of the constituents, and the effect of impact loads. The presence of these defects decreases the strength of such components and severely affects residual strength. The paper presents a numerical and experimental study of the behavior of a composite material plate with a variable layup angle under impact loading. Impactor velocities before and after multilayer plate perforation, as well as the dimensions of delamination-type defects, are determined experimentally. The Ansys LS-DYNA software in double precision mode is used to simulate the failure of composite plates under impact loading. It has been found that a significant contribution to the decrease in the impact energy is made by the delamination dimensions depending on the layup angle in the stack. The delamination area is related to the residual velocity of the impactor; namely, the larger the delamination area, the greater the decrease in the impactor velocity.

Correlation of microstructure, mechanical properties, and residual stress of 17-4 PH stainless steel fabricated by laser powder bed fusion

17-4 precipitation hardening (PH) stainless steel is a multi-purpose engineering alloy offering an excellent trade-off between strength, toughness, and corrosion properties. It is commonly employed in additive manufacturing via laser powder bed fusion owing to its good weldability. However, there are remaining gaps in the processing-structure-property relationships for AM 17-4 PH that need to be addressed. For instance, discrepancies in literature regarding the as-built microstructure, subsequent development of the matrix phase upon heat treatment, as well as the as-built residual stress should be addressed to enable reproducible printing of 17-4 builds with superior properties. As such, this work applies a comprehensive characterisation and testing approach to 17-4 PH builds fabricated with different processing parameters, both in the as-built state and after standard heat treatments. Tensile properties in as-built samples both along and normal to the build direction were benchmarked against standard wrought samples in the solution annealed and quenched condition (CA). When testing along the build direction, higher ductility was observed for samples produced with a higher laser power (energy density) due to the promotion of interlayer cohesion and, hence, reduction of interlayer defects. Following the CA heat treatment, the austenite volume fraction increased to ∼35 %, resulting in a lower yield stress and greater work hardening capacity than the as-built specimens due to the transformation induced plasticity effect. Neutron diffraction revealed a slight reduction in the magnitude of residual stress with laser power. A concentric scanning strategy led to a higher magnitude of residual stress than a bidirectional raster pattern.

Real-time in-situ process monitoring method based on the self-conductivity of carbon fiber prepreg for automated fiber placement (AFP)

Real-time online monitoring is of great significance for the manufacturing of carbon fiber reinforced composites, contributing to improving and ensuring the quality of the final manufactured part. An in-situ real-time process monitoring method based on the conductivity of continuous carbon fiber reinforced thermoplastic matrix prepreg was proposed for automated fiber placement (AFP). The detection capability of several different defects was investigated, including foreign object debris, tape breakage, weak edge bonding, gaps/overlaps, and even debonding. In addition, the influence of placement speed and laser power on the detection capacity was also discussed. The number, position, length, and width of various interlayer defects were detected through the resistance change between the current placement layer and the laid layers. Furthermore, accurate detection of defects in different layers was also achieved, indicating the detection capability of existing defects. This method of timely defect detection during the manufacturing process allows for an early manual intervention to improve the quality of manufactured structures and the intelligence of AFP technology.

An energy-saving structural optimization strategy for high-performance multifunctional graphene films

Graphene has been widely studied for its excellent properties of outstanding conductivity, strength, and flexibility. However, interlayer defects formed during the macroscopic assembly of graphene nanosheets will severely degrade the performance of graphene films. Herein, a strategy combined with trace carboxyl graphene oxide (GO), mild reduction, and chemical crosslinking is employed to minimize the interlayer defects for enhancing both the conductivity and mechanical strength of graphene films. The trace carboxyl feature of GO allows nanosheets to assemble orderly into highly oriented GO films. Subsequently, the mild chemical reduction preserves the highly oriented and packed microstructure. Coupling with further crosslinking by introducing conjugated molecules with pyrene terminal groups (1-pyrene butyric acid-1,6-hexane diamine, PHD) to provide extra π-π bonds, both the mechanical strength and conductivity of graphene films are improved to 548.4 MPa and 1.7 × 105 S m−1, respectively. In addition, the graphene film with only ∼2 μm in thickness possesses an excellent electromagnetic interference shielding effectiveness (EMI SE) of ∼40 dB and a specific shielding effectiveness of up to 74 278 dB cm2 g−1 in a wide frequency range of 8.2–40.0 GHz. Thus, this study provides an energy-saving fabrication route for mechanically strong, effective thermal management and EMI shielding films.

Phonon thermal transport in bilayer polycrystalline graphene nanoribbons: effects of interlayer interaction, grain size, and vacancy defects

In this paper, molecular dynamics simulations have been employed to investigate the phonon thermal transport in bilayer polycrystalline graphene nanoribbon (pGNR/pGNR), compared with bilayer graphene nanoribbon (GNR/GNR) and pGNR/GNR heterostructure. The interfacial thermal resistance (ITR) of bilayer structures was also calculated using the heat dissipation method. The effects of interlayer interaction, grain size, and vacancy defects on ITR and in-plane phonon thermal conductivity of bilayer structures were investigated. It was found that the ITR as well as in-plane phonon thermal conductivity of pGNR/pGNR was less than that of pGNR/GNR and much less than that of GNR/GNR, for the same size. For the studied bilayer structures, both the ITR and in-plane phonon thermal conductivity decrease with increasing interlayer interactions. Moreover, ITR increases with increasing grain area size whereas decreases with increasing vacancy defects in pGNR-based bilayers. The introduction of pGNR interface roughness and vacancy defects results in an enhanced phonon coupling in pGNR-based bilayers compared to pure GNR/GNR bilayers. Presented simulation investigations will help to understand the interlayer thermal transport properties of polycrystalline graphene and provide essential guidance for experimentally regulating phonon thermal transport between layers of polycrystalline graphene.

Effect of hot isostatic pressing on microstructure and properties of high chromium K648 superalloy manufacturing by extreme high-speed laser metal deposition

High chromium superalloys have good overall mechanical properties and are widely used in critical hot-end components. The current manufacturing process still faces the problem of low forming efficiency. Extreme high-speed laser metal deposition (EHLMD) is a new and efficient additive manufacturing technology that can quickly and directly shape the direct forming of difficult-to-process materials. However, EHLMD still possesses some inter-layer defects in EHLMD alloy due to its excessively fast scanning speed, implying that there is potential for further improvement in its properties. Hot isostatic pressing (HIP) as a post-heat treatment is primarily used for the removal of defects in additive manufacturing components. In this study, the defects, microstructure, and properties of the EHLMD K648 superalloy using Micro-CT, XRD, SEM and TEM under HIP treatment were investigated. The results show that the porosity of the HIP EHLMD K648 superalloy decreased, and slender needle-shaped α-Cr phase, γ′ phase and coarse M6C carbides were precipitated. The tensile strength of the HIP EHLMD K648 superalloy increased by about 240 MPa. However, its plasticity was reduced. To further improve the plasticity of the HIP EHLMD K648 superalloy, subsequent heat treatment was carried out. The outcomes of this study are expected to promote the manufacturing of high-quality chromium superalloys and the development of EHLMD technology.

Pulse electrodeposition of a duplex-layer structured composite nickel-based coating with improved corrosion and abrasion resistance

In this study, a dual amorphous/crystalline nanocomposite coating of Ni–P/Ni–Mo–ZrO2 was designed and successfully deposited on pure copper substrates by pulse electrodeposition. The design of the Ni–P/Ni–Mo–ZrO2 dual coating takes advantage of the properties of the different structures and incorporates second phase reinforcing particles resulting in more comprehensive protective coatings. The surface morphology and microstructure were evaluated by SEM, EDS, WLI, XRD and TEM. The mechanical properties and electrochemical behaviors of the coating in a 3.5 wt% NaCl solution were investigated by wear tests, Tafel and EIS. The results show that the Ni–P/Ni–Mo and Ni–P/Ni–Mo–ZrO2 dual coatings are uniform, dense and crack-free, and the duplex interface is homogeneous. Compared with the Ni–Mo coating, the average friction coefficient and wear rate of the Ni–P/Ni–Mo duplex coating decreased to 0.18 and 5.433 × 10−4 mm3/N·m, respectively. The corrosion potential is positively shifted to −0.43 with a maximum impedance of 308 kΩ cm2. The mismatch of the interlayer defects causes a deviation in the corrosion path, resulting in a transformation from longitudinal pinhole corrosion into extended transverse corrosion, which effectively strengthens the capacity of the coating for corrosion resistance while maintaining the high hardness of its outer coating. Furthermore, the hardness of the dual Ni–P/Ni–Mo coating can be obviously reinforced by nanoparticles from 730 HV to 810 HV, the corrosion potential is shifted to −0.41 V, and the corrosion current density decrease to 7.7803 × 10−7 A/cm2. The improvement in the mechanical properties can be attributed to the ZrO2 nanoparticles, which could carry stress and transfer loads during the wear process. Meanwhile, the ZrO2 nanoparticles can reduce the nodule size by filling the binding boundary which is the main corrosion path, and reduce the number of surface defects, such as pinholes, which leads to a lower corrosion rate. In addition, the corrosion inhibition and nanoparticle codeposition mechanisms of the duplex coatings were further discussed.

NH4 + Pre-Intercalation and Mo Doping VS2 to Regulate Nanostructure and Electronic Properties for High Efficiency Sodium Storage.

Sodium-ion hybrid capacitors (SIHCs) have attracted much attention due to integrating the high energy density of battery and high out power of supercapacitors. However, rapid Na+ diffusion kinetics in cathode is counterbalanced with sluggish anode, hindering the further advancement and commercialization of SIHCs. Here, aiming at conversion-type metal sulfide anode, taking typical VS2 as an example, a comprehensive regulation of nanostructure and electronic properties through NH4 + pre-intercalation and Mo-doping VS2 (Mo-NVS2) is reported. It is demonstrated that NH4 + pre-intercalation can enlarge the interplanar spacing and Mo-doping can induce interlayer defects and sulfur vacancies that are favorable to construct new ion transport channels, thus resulting in significantly enhanced Na+ diffusion kinetics and pseudocapacitance. Density functional theory calculations further reveal that the introduction of NH4 + and Mo-doping enhances the electronic conductivity, lowers the diffusion energy barrier of Na+, and produces stronger d-p hybridization to promote conversion kinetics of Na+ intercalation intermediates. Consequently, Mo-NVS2 delivers a record-high reversible capacity of 453 mAh g-1 at 3 A g-1 and an ultra-stable cycle life of over 20000 cycles. The assembled SIHCs achieve impressive energy density/power density of 98Wh kg-1/11.84kW kg-1, ultralong cycling life of over 15000 cycles, and very low self-discharge rate (0.84mV h-1).

Improving the strength of β-TCP scaffolds produced by Digital Light Processing using two-step sintering

Digital Light Processing is combined with two-step sintering to obtain bioactive scaffolds with improved strength and mechanical isotropy. Highly loaded photosensitive suspensions were prepared from β-TCP powder to create scaffolds consisting of interpenetrating struts with two different designs. Two sintering methods were used: conventional sintering (CS) and two-step sintering (2SS). The latter resulted in a microstructure with uniformly shaped grains and reduced porosity. Their compressive strength was determined by uniaxial testing under two different load configurations, with the force applied parallel or perpendicular to the building plane of the scaffolds. Design optimisation and fine-tuning of the sintering process helped in reducing the presence of interlayer defects and minimise the shear-dominated fractures. Isotropic fracture behaviour was achieved, with similar central values of the Weibull distribution (49 ± 1 MPa vs. 51 ± 1 MPa) along both testing directions, showing a great potential for their use in load-bearing bone tissue engineering applications.

Blown-powder direct-energy-deposition of titanium-diboride-strengthened IN718 Ni-base superalloy

This paper reports on the adoption of TiB2 as an inoculant to fabricate IN718 via the direct energy deposition (DED) process. Effective grain refinement and low texture were achieved in IN718/TiB2 using a TiB2 powder size of d90 = 10 μm and mass fraction of 1.5 wt%. The use of low linear energy density (33.08 J/mm) produced IN718/TiB2 deposits free from large grains (>300 μm), however at the cost of the formation of interlayer defects. By comparison, the large grains were present in deposits made with a linear energy density of 78.74 J/mm and also in deposits manufactured without an included inoculant. Production of deposits at lower energies without interlayer defects was possible by reducing the powder flow rate to 7 g/min. However, this caused a moderate increase in grain size. The TiB2 inoculant reduced the Laves phase network by replacing it with homogeneously distributed Cr-, Mo-, Nb-, and B-enriched needle-shaped precipitates. Tensile strength increased by 300–500 MPa with TiB2 addition, but at the cost of significant ductility drop, regardless of the deposition conditions. The IN718 deposit displayed many micro-cracks at the network of Laves phase during tensile loading, whereas micro-cracks in the IN718/TiB2 occurred at the interface between the needle-shaped precipitates and the matrix. The strength enhancement in IN718/TiB2 was by a combination of strengthening mechanisms: grain boundary, dislocation structure formation, Orowan-type and load transfer related to the needle-shaped precipitates.