Composite Interlayer Research Articles

Microstructure and mechanical properties of Al0·3CoCrFeNi high-entropy alloy joints brazed using a FeCoCrNiCu/Ti composite interlayer

This study introduces a brazing technique for joining Al0·3CoCrFeNi high-entropy alloy (HEA) utilizing a FeCoCrNiCu/Ti composite interlayer. The primary objectives of this investigation encompass an examination of the microstructure of the Al0·3CoCrFeNi joint, as well as an evaluation of the shear strength of the brazed joints under diverse brazing parameters. The characteristic microstructure of the Al0·3CoCrFeNi brazing seam is comprised of Ti (s, s), Cu (s, s) from the FeCoCrNiCu interlayer, and face-centered cubic (FCC) phases containing more than five elements. When the brazing temperature increases from 1100 °C to 1180 °C, there is a gradual augmentation in the diffusion of Ti element and subsequent reactions involving Cu, Ti, and Ni. Furthermore, the impact of holding time on the brazing seam is investigated. The findings suggest that prolonging the holding time has a relatively negligible effect on the reaction layer formed by the Ti foil. However, it does lead to a reduction of the Cu (s, s) content within the FeCoCrNiCu interlayer. Notably, the highest shear strength reaches up to 280 MPa when the joint brazed at 1160 °C for 10 min. In addition, the shear strength did not decrease below 800 °C. During the shear test, ductile fractures are observed in the joint, indicating favorable mechanical properties. Overall, this study successfully demonstrates the potential of the proposed brazing technique employing a FeCoCrNiCu/Ti composite interlayer for the effective joining of Al0·3CoCrFeNi HEA. By optimizing the brazing parameters, it is possible to achieve robust joints with exceptional mechanical characteristics.

Highly permeable polyamide nanofiltration membranes fabricated via the construction of anionic covalent organic frameworks /polydopamine composite interlayer

Thin-film composite nanofiltration (TFC NF) membranes can separate neutral/charged solutes and play an essential role in water purification. However, the permeability of traditional NF membranes is severely limited by excessive mass transfer resistance due to the thick polyamide (PA) layer. Introducing porous nanomaterials as an interlayer into PA NF membranes has been recognized as an effective approach to improve permeability. Herein, a novel composite interlayer consisting of anionic covalent organic frameworks with abundant sulfonic acid groups (COF-SO3H) and polydopamine was designed to regulate interfacial polymerization to construct the highly permeable TFC NF membranes. The surface negative charge and hydrophilicity of the TFC NF membranes can be controlled by the abundant polar groups in the composite interlayer. Moreover, mass transfer resistance can be reduced by introducing COF-SO3H to create additional water transport channels. The results showed that the optimal membrane manifested attractive permeability (44.2 L⋅m−2⋅h−1⋅bar−1) and a high Na2SO4 rejection (98.7 %), almost 3-fold higher than that of the original TFC membrane. Furthermore, the optimal membrane exhibited favorable anti-fouling performance and stability. This work provides insight into strategies for fabricating highly permeable TFC NF membranes through the introduction of an interlayer.

Interface Engineering to Operate Reversible Protonic Ceramic Electrochemical Cells Below 500 °C

AbstractThe low‐temperature (<500 °C) operation of reversible protonic ceramic electrochemical cells (PCECs) is desirable in achieving efficient and sustainable electricity generation, as well as green hydrogen production. However, significant interfacial resistance, which contributes to both ohmic and polarization resistance, remains a hurdle in lowering the operating temperature. In this study, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and BaZr0.4Ce0.4Y0.1Yb0.1O3‐δ (BZCYYb) mono‐grain composite interlayers are introduced, which significantly extend the electrode/electrolyte interface and increase the concentration of vertically aligned oxygen vacancies along the heterointerface. This unique design achieves the lowest ohmic and polarization resistances among previously reported values in solid electrolyte‐based electrochemical cells. As a result, the PCEC can operate at extremely low temperature of 350 °C with an exceptional peak power density of 0.50 W cm−2 in fuel cell mode and current density of 0.25 A cm−2 at 1.3 V in electrolysis cell mode. Furthermore, it demonstrates high energy conversion efficiency and excellent stability under static and dynamic operating conditions.

Performance improvement of enhancement-mode GaN-based HEMT power devices by employing a vertical gate structure and composite interlayers*

In this work, p-n junction vertical gate (JVG) and polarization junction vertical gate (PVG) structures are for the first time proposed to improve the performance of GaN-based enhancement-mode (E-mode) high electron mobility transistor (HEMT) devices. Compared with the control group featuring the vertical gate structure, a highly improved threshold voltage (V th) and breakdown voltage (BV) are achieved with the assistance of the extended depletion regions formed by inserting single or composite interlayers. The structure dimensions and physical parameters for device interlayers are optimized by TCAD simulation to adjust the spatial electric field distribution and hence improve the device off-state characteristics. The optimal JVG-HEMT device can reach a V th of 3.4 V, a low on-state resistance (R on) of 0.64 mΩ cm2, and a BV of 1245 V, while the PVG-HEMT device exhibits a V th of 3.7 V, an R on of 0.65 mΩ cm2, and a BV of 1184 V, which could be further boosted when an additional field plate design is employed. Thus, the figure-of-merit value of JVG- and PVG-HEMT devices rise to 2.4 and 2.2 GW cm−2, respectively, much higher than that for the VG-HEMT control group (1.0 GW cm−2). This work provides a novel technical approach to realize higher-performance E-mode HEMTs.

Growth of multiferroic γ-BaFe2O4 thin films by Pulsed Electron Deposition technique

Multiferroic materials have attracted significant attention due to their potential to revolutionize logic and memory devices by reducing energy consumption or increasing information density. Barium monoferrite (γ-BaFe2O4 or BaFeO) is a promising lead- and bismuth-free multiferroic material with a stuffed tridymite-like structure, exhibiting both ferroelectricity and antiferromagnetism at room temperature. BaFeO thin films with engineered grain orientation, composition, elastic strain, and magnetic interlayer couplings could open new avenues for novel devices. However, synthesizing the stoichiometric "1–2–4" phase in the BaO-Fe2O3 system remains a challenge. This study focuses on the deposition of pure and crystalline γ-BaFe2O4 thin films using the Pulsed Electron Deposition (PED) method. An analysis of the plasma plume revealed that two main mechanisms govern the dynamics of BaFeO deposition: a congruent ablation process occurring far from thermodynamic equilibrium and an incongruent low-energy evaporation process. The regions of the film with maximized ablative/evaporative ratios are free from the secondary Ba2Fe2O5 phase, suggesting that the thermal evaporative contribution is the primary factor responsible for the out-of-stoichiometry composition. The influence of the substrate type on the structural properties of BaFeO films was also evaluated. It was confirmed that (h00)-oriented BaFeO tends to grow on amorphous quartz and polycrystalline Pt-coated quartz in the 700–800°C temperature range. Conversely, the growth on SiO2/Si leads to the preferential grain orientation along the (0k0) and (0kl) directions by increasing the temperature. These findings demonstrate the potential of PED for producing high-quality γ-BaFe2O4 polycrystalline thin films. A fully heteroepitaxial (h00)-BaFeO/(111)-MgO system was even achieved by depositing on a single-crystal MgO substrate. This unprecedented result paves the way for utilizing such thin films in multiferroic applications, where phase purity, structural orientation, and defect-free structures can be exploited to enhance the magnetoelectric properties of the device.

Suppressing Trap‐Assisted Nonradiative Recombination via Interface Modification for Achieving Efficient Organic Solar Cells

AbstractTrap states in organic solar cells (OSCs) can capture free charges, leading to a reduction in current density and significant energy loss. Since charge collection is primarily dependent on the interface layer, minimizing trap states at interfaces can effectively suppress energy losses, a topic that has been rarely explored. Herein, an interface strategy is proposed by combining Me‐4PACz and PEDOT:PSS to mitigate the trap‐assisted nonradiative recombination at the hole transport layer (HTL). OSCs based on the Me‐4PACz/PEDOT:PSS exhibit reduced trap densities and low energy losses compared to devices fabricated with a single‐layer HTL. This reduction can be attributed to a lower nonradiative recombination rate during hole transport at the interface. Changes in the work function of the two interlayers due to contact result in the existence of a built‐in potential inside the composite interlayer, promoting charge collection and reducing energy loss from charge recombination. Furthermore, the composite HTL interface induces vertical phase separation of active layer, leading to significant improvements of the fill factor for OSCs. As a result, high power conversion efficiencies (PCEs) of 18.70% and 19.02% are achieved for binary all‐polymer solar cells and polymer donor/small molecule acceptor solar cells, respectively.

Brazing of C/C composites and 304 stainless steels via Ni/Mo composite interlayer

Brazing of C/C composites and 304 stainless steels via Ni/Mo composite interlayer

A gelatin-zirconium phosphate nanoparticles composite interlayer for enhancing compaction resistance and antifouling performance of TFC NF membrane

From a practical point of view, the thin-film composite (TFC) nanofiltration (NF) membrane should not only have superior separation performance but also excellent compaction resistance and antifouling properties. Generally, polyamide (PA) separation layers of the TFC NF membrane prepared on the support with hydrophilic interlayer are crumpled, which may be detrimental to the compaction resistance and antifouling properties of TFC NF membranes. A flexible polymer-rigid nanoparticles composite interlayer was constructed on the pristine polysulfone (PSF) support in this work to design a TFC NF membrane with compaction resistance, antifouling, and excellent separation performance. Morphology and crosslinking degree of PA separation layers were investigated by scanning electron microscopy (SEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the composite interlayer can not only regulate the distribution and diffusion of piperazine (PIP) but also act as a template to induce the generation and growth of PA during the interfacial polymerization (IP) process, leading to the formation of the PA separation layer with a small nodular structure. The compaction resistance, antifouling properties, and separation performance of the TFC membrane were also investigated by nanoindentation, fouling experiment, and filtration test, respectively. The TFC NF membrane with the composite interlayer showed greatly improved mechanical properties with its hardness and elastic modulus approximately 1.5 and 1.6 times that of the reference, respectively. Furthermore, the flux recovery of the TFC NF membrane with the composite interlayer (93.8 %) was higher than that of the control (87.2 %), indicating that the TFC NF membrane with the composite interlayer had better antifouling properties. In addition, the obtained TFC NF membrane with the composite interlayer showed a water flux approximately twice as high as that of the reference with satisfactory rejection. This advancement will contribute to the development of more efficient and stable TFC NF membranes for industrial wastewater treatment.

Deposition voltages on the phase evolutions, microstructures, and oxidation behaviors of thermal-resistance Glass-MoSi2-SiC coating

ABSTRACT Due to the high oxidation activities at high temperatures, traditional SiC coating was difficult to act as an antioxidant material for ages. In this case, the multilayered Glass-MoSi2-SiC coating was fabricated on the C/C substrate, combined with hydrothermal electrophoresis deposition and simple embedding process. It was found that the composite obtained at 10 V performed outstanding combinations of oxidation resistance and thermal shock resistance properties. The weight loss of this Glass-MoSi2-SiC-C/C composite was only 0.99% after 212 h oxidation at 1773 K. After thermal shock for 130 times, the mass was just 0.05% lower than that of the initial. These excellent heat-resistant performances were much better than those in similar reports, which was attributed to the suitable coating composition and dense interlayer structure. As oxidized at 1773 K, the in-situ SiO2 phases had a self-healing ability to fill micropores and microcracks to protect the structure. The structure failure was related to SiO2 volatilization. This study emphasized the importance of simple techniques in the thermal-resistance coating fields at multiple length scales.

Enhancing performance and microstructure analysis in laser welded of R60702 zirconium alloy and 304 stainless steel with TA2/ Q235 composite interlayer

Zirconium (Zr) alloy and stainless steel (SS) will form brittle intermetallic compounds (IMCs) during the welding process, which will reduce the performance and reliability of the joint. To solve this problem, the TA2/Q235 composite interlayer was added between the Zr alloy and the SS. The microstructure and mechanical properties of the joint were evaluated. The experimental results show that the formation of IMCs in Zr alloy and SS joints can be completely inhibited by laser welded with the addition of interlayer. The final mechanical properties of the joint were determined by the weld of TA2-Zr alloy, when the joint strength reaches 161.64 MPa. The fracture surface of the joint presents a brittle fracture mode. The main product of the fracture surface is α-Zr and a small amount of α-Ti and (Ti, Zr) solid solution.

Enhanced performance polyamide membrane by introducing high-porosity SOD/GO composite interlayer to tailor the interfacial polymerization process

Controllable preparation of high-performance polyamide nanofiltration (NF) membranes that can be used in various applications such as seawater desalination and wastewater treatment is very promising. In this work, a high-performance polyamide NF membrane was designed using high-porosity hydroxy sodalite/graphene oxide (SOD/GO) composite interlayer to slow down the diffusion of amine monomer and control the interfacial polymerization (IP) process. The unique tortuous effect and hydrogen bonds with amine monomers caused by the dense interlayer significantly inhibit the diffusion of amine monomers (reduction of 50 % in diffusion rate), thereby resulting in the controllable slow IP process. The slowing IP process facilitates the formation of thinner dense polyamide (PA) layer with stripe morphology and narrow pore size. Consequently, the optimal polyamide membrane with composite interlayer possesses a superior water permeability of 22.05 L m-2h−1⋅bar−1, nearly 2.5 fold that of the controlled one, while retaining an excellent rejection of Na2SO4 (97.25 ± 0.81 %). Moreover, the polyamide membrane depicts outstanding antifouling propensity (flux-recovery ratio (FRR) = 82 %), long-term stability (80 h) and pressure resistance (9 bar). This work provides a novel strategy for controllable construction of high-performance NF membrane and deepens the slights into the interlayer influences IP process.

Inducing low-temperature melting of TiNiCuNb eutectic alloy for manufacturing strong C/C-SiC composite joints

This work designed a novel TiNiCuNb eutectic alloy for manufacturing C/C-SiC composite joints. By introducing Ti into the semi-solid TiNiCuNb alloy, low-temperature melting of this eutectic alloy was induced. Ti/TiNiCuNb/Ti composite interlayers were utilized to join C/C-SiC composite lower than the melting temperature of TiNiCuNb alloy. Effects of joining temperature on the microstructure evolution and mechanical property of joints were investigated. The melting range of this TiNiCuNb alloy was 944 °C to 1064 °C. During the initial melting of the TiNiCuNb alloy, a thin liquid layer formed on the alloy's surface, which provided a path for the rapid diffusion of elements. Without pressure, Ti could be easily introduced into the TiNiCuNb alloy, which induced the complete melting of this alloy at 950 °C. Based on this, we successfully brazed C/C-SiC composite using Ti/TiNiCuNb/Ti interlayers. It not only hindered the formation of brittle compounds in the joints, but also weakened the overreaction between filler and C/C-SiC composite. Due to the high solubility of Si in liquid filler, the joint microstructure was controlled by the interaction between filler and SiC at different temperatures. At 1010 °C for 10 min, the maximum shear strength of 28.5 MPa was obtained. This work contributed to preparing and repairing the C/C-SiC composite.

Soy protein isolate/MXene decorated acidified carbon paper interlayer for long‐cycling Li–S batteries

AbstractThe terrible shuttling of lithium polysulfides (LiPSs) is a major obstacle for commercializing lithium–sulfur (Li–S) batteries as high‐performance energy storage systems. In this study, a carbon‐based interlayer with effective suppression capability on the shuttle effect is developed by simply coating a well‐dispersed mixture of soybean protein isolate/MXene onto the acidified carbon paper (ACP). The resultant composite interlayer (SM@ACP) is able to synergistically diminish the shuttle effect through chemical adsorption and physical blocking. Meanwhile, this interlayer displays excellent conductivity and facilitates the diffusion of Li ions due to the composite coating to promote both electron/ion conduction as well as the porous structure of ACP. Benefiting from the unique properties of the composite interlayer, the as‐assembled Li–S batteries with SM@ACP interlayers show a great improvement in the cycling stability and rate performance, delivering a very low‐capacity decay rate of 0.071% per cycle at 0.5 C even after 800 cycles. This work provides a feasible route to realize rational design and commercial mass production of desirable interlayers for promoting the commercialization of Li–S batteries.

Titanium/steel composites were prepared by composite interlayer and two pass laser welding

In this study, a composite sandwich was used as an intermediate layer and TC4/304 stainless steel was joined by explosion welding. First, intermetallic compounds with different butt joint sizes were added. When the length of the butt joint was kept at 4 mm, the mechanical properties of the joint increased with the extension length. The maximum tensile strength of the joint was 600 MPa when the extension length was varied between 1 and 2.5 mm. A "net basket organization" was formed in the titanium-side weld, and α → β and β → α ′ phase transitions occurred. Comparative microstructural analysis shows that the aspect ratio of the organization decreases with the increase of the length of the titanium side weld.

Interfacial microstructure and mechanical properties of diffusion bonded joints of additive manufactured 17-4 PH stainless steel and TC4 titanium alloy

A novel atomic diffusion additive manufactured 17-4 PH stainless steel and TC4 titanium alloy was successfully joined by vacuum diffusion bonding with Cu foil + Ni foil interlayers at the temperature range of 880°C–960 °C for 60 min with 2 MPa pressure. The interfacial microstructural evolution, interfacial diffusion of elements, and mechanical properties of joints were analyzed. The results indicated that the interfacial transition zone was composed of diffusion affect zone (DAZ) and interface reaction zone (IRZ). With Cu foil + Ni foil composite interlayers, reaction layers such as DAZ 1/IRZ 1/IRZ 2/DAZ 2 were formed in the transition zone, and the interface consisted of CuTi + CuTi2 eutectic phase, CuTi2, Ti (Cu, Ni) and α-Ti. Striped Ti (Cu, Ni) phases were surrounded by serrated CuTi2 phases, which contained Cu-poor, Ni poor areas, and the segregation of Ti atoms. The maximum microhardness of 693 HV0.1 and the maximum shear strength of 163 MPa were obtained at the bonding temperature of 920 °C and 960 °C, respectively.

Microstructure and shear strength of SiC/Zr joint brazed with LiAlSiO4/graphene-coated Cu-foam composite interlayer

In the present work, the microstructures and mechanical properties of Cu-foam-(graphene, LiAlSiO4 and graphene/LiAlSiO4) and a CoCrNiFeCuSn high-entropy alloy as a composite interlayer for brazing Zr and silicon carbide (SiC) ceramics are explored. Further, the effects of graphene, LiAlSiO4, and graphene/LiAlSiO4 on the mechanical properties and microstructure of the SiC/Zr joint are investigated. The results of the data analysis reveal a good connection between SiC and Zr at 1040 °C for 20 min using the different composite interlayers, Cu-foam-graphene, Cu-foam-LiAlSiO4, or Cu-foam-graphene-LiAlSiO4, with shear strengths of 122, 147, and 235 MPa, respectively. Particularly, the Cu-foam-graphene-LiAlSiO4 brazed joint demonstrates the highest shear strength. Furthermore, the dispersion of LiAlSiO4 in the joint reduces the coefficients of thermal expansion of difference between the brazing materials and ceramics, as well as the residual stress in the joint. Moreover, the synergistic effect of the solid-solution phase, Zr(s, s), with excellent plastic deformation, and enhanced Zr(Cr, Fe)2 phase further improves the strength and plasticity of the joint.

Electron beam welding of 4J36 invar alloy to TC4 titanium alloy using Cu-Nb composite diffused metal interlayer

Electron beam welding of 4J36 invar alloy and TC4 titanium alloy was carried out with Cu-Nb composite diffused metal interlayer. The results showed that the depth to width ratio and the tensile strength of welded joints increased with the increase of electron beam current. Under the designed process parameters, two melting zones (MZ) in welded joints formed solid solutions (ss), the welded joint tensile strength reached maximum value of 244.1 MPa, and the fracture location was mainly located at 4J36/Cu interface.

Development of SiC Ceramic Reinforced Composite Interlayer Cladding with AISI304 Stainless Steel Wire on Low Carbon Steel Substrate Using TIG Cladding Process

Development of SiC Ceramic Reinforced Composite Interlayer Cladding with AISI304 Stainless Steel Wire on Low Carbon Steel Substrate Using TIG Cladding Process

Investigation of effects of processing parameters on the impact strength and microstructure of thick tri-material based layered composite fabricated via extrusion based additive manufacturing

Additive manufacturing composites have been employed in applications including, aerospace, automotive industries etc. and there are a number of properties required for such applications including better impact strength (I-S) which is the resistance to withstand impact loading. The present study investigates for the first time the effects of processing parameters on the I-S of thick tri-material based layered (Tmbl) composite of Polylactic acid (PLA), Polyethylene Terephthalate Glycol (PETG), and Acrylonitrile Butadiene Styrene (ABS) fabricated via Fused Filament Fabrication (FFF). 3 process parameters are varied in three levels each, whereas the I-S is chosen as output. Analysis of variance (ANOVA) is conducted. The surface plots of the significant parameter interactions are plotted showing the effects-trends of each variable on the I-S of the composite and various inter-layer, macro and micro observation of the composite was also performed using optical microscopy. It was observed that various shortcomings such as pores, delamination, peeling-like structure formation occurred at high layer thickness (t), high printing speed (v) and low infill density (ρ) whereas, there was absence of substantial defects at high ρ. Therefore, it was concluded that the selected parameters are significantly affecting the I-S of the composite. At the end, optimization of processing conditions was performed which resulted in enhanced I-S to weight ratio as compared to the highest I-S of single solid three dimensional (3d) printed base material.

Developing high-strength titanium/steel composite structures by adding composite interlayer

Welding is currently the most effective method of joining TC4/304SS dissimilar metals. However, due to the large differences in the physical and chemical properties of titanium/steel, direct welding produces a large number of brittle intermetallic compounds such as TiFe, Ti2Fe, etc., and the joints usually fracture on their own after welding, making it impossible to obtain safe and reliable composite joints. In this study, a composite interlayer was used to realize the TC4/304 SS joint and the effect of YZ on the mechanical properties of the joint was investigated. It was found that the tensile strength of the titanium side of the composite sandwich was 968 MPa when YZ = was 8 mm. This connection method effectively avoids the generation of brittle intermetallic compounds such as Ti-Fe, and optimizes and improves the mechanical properties of the joint to a large extent, which is of great importance to the research value.