Composite Interlayer Research Articles

High-performance hybrid coatings based on diamond-like carbon and copper for carbon steel protection

High performance double-layer coatings composed of copper (Cu) interlayer and the Cu/diamond-like carbon (DLC) composite top layer were prepared via magnetron sputtering for protection of carbon steel. The effect of Cu content in the composite layer on the internal stress, contact angle, mechanical, tribological, and corrosion performance of coatings was discussed. Raman spectroscopy confirmed formation of DLC phase. Double-layer Cu-rich coatings exhibited high degree of sp2 carbon clustering, but low diamond-like sp3 bonding. The internal stress of double layer Cu-(Cu/DLC composite) coatings was decreased with Cu content increase. The double-layer Cu-(Cu/DLC composite) thin films with low Cu content did not pose a significant effect on hardness and Young's modulus of the steel substrate, while increase of Cu content enhanced hardness of coating up to 28GPa. The contact angle of steel substrate showed an increase when coated with double-layer Cu-(Cu/DLC composite) thin film, but not that much at such inadequate Cu content. Inclusion of Cu interlayer improved to some extent corrosion properties, where increase of Cu content assisted in protection. Double-layer coatings with the highest performance were compared with single-layer Cu/DLC coating. Elimination of interlayer deteriorated mechanical properties, but increased electrochemical performance, signifying the importance of controlling Cu/DLC composition and Cu interlayer inclusion.

Nd:YAG pulsed laser welding of TC4 Ti alloy to 301L stainless steel using Ta/V/Fe composite interlayer

The present article reports the feasibility of Nd:YAG laser welding of Ti alloy to stainless steel through composite layer Ta/V/Fe. The laser beam was focused on the centerline of Ta and Fe sheets respectively to ensure that V interlayer was not completely melted. Two pass welding was employed involving creation of a joint with two weld zones separated by remaining unmelted V. Composite interlayer Ta/V/Fe was used to prevent the formation of Ti-Fe intermetallics and improve microstructure and properties of the Ti alloy-SS joint. The joint fractured at the unmelted V with the tensile strength of 627 MPa.

Annealing-Free ZnO:PEI Composite Cathode Interfacial Layer for Efficient Organic Solar Cells

The polymer solar cells owning organic–inorganic composite cathode interlayer are fabricated to achieve well electron extraction compared to the devices with single inorganic semiconductor materials, leading to a significant enhancement of short-circuit current density (Jsc) and fill factor (FF) as well as slight improvement of open-circuit voltage (Voc). The incorporation of PEI mainly contributes to the decreased work function of the ZnO layer and the reduced interfacial barrier, which are beneficial for the easy electrons extraction and the declined charge recombination. Strikingly, a postannealing treatment is employed for the completed device with electrode to improve the interfacial characteristics between the active layer and the MoO3 layer, which is a successful method to further increase the Voc for the device based on PTB7:PC71BM. Our work provides a simple fabrication technology to improve the interfacial contact between active layer and adjacent interlayer, while possessing the major roles on ...

Rational design of composite interlayer for diffusion bonding of tungsten–steel joints

Large residual stresses and brittle intermetallic compounds are two detrimental factors in the mechanical reliability of tungsten–steel joints. In this work, we conduct a rational design of interlayer structure to tackle these two pitfalls by combining finite element model (FEM) and Hume–Rothery rules. The FEM results show that the selection of interlayer materials for tungsten–steel joining depends not only on thermal expansion mismatch, but also on the plastic deformation of interlayer. In practice, it is better to relax the residual stress by a soft interlayer with high ductility than to transfer the stress from W by a hard interlayer with a low coefficient of thermal expansion. However, the Hume–Rothery rules indicate adding a single interlayer cannot prevent the formation of brittle intermetallic compounds. A composite interlayer design is then proposed in this study to minimize the possibility of intermetallic compounds formation in the meantime reduce the residual stress. Using V/Cu and V/Ni as typical examples, we demonstrate that composite interlayer can greatly improve joint performance because of the lower residual stresses and less detrimental intermetallic compounds.

Electronic structure and phase composition of silicon oxide in the metal-containing composite layers of a [(Co40Fe40B20)34(SiO2)66/C]46 multilayer amorphous nanostructure with carbon interlayers

A [(Co40Fe40B20)34(SiO2)66/C]46 multilayer amorphous nanostructure, consisting of alternating metal-containing composite layers and carbon interlayers, has been grown on a rotating glass-ceramic substrate by ion-beam-sputtering two targets, one of which had the form of a metallic plate of the Co40Fe40B20 alloy with quartz inserts. The nonmetallic interlayers were grown by sputtering graphite (second target). In the multilayer nanostructure (MNS), the thickness (~4–8 nm) of the bilayers, consisting of the (Co40Fe40B20)34(SiO2)66 metal- and silicon oxide-containing composite layers and nonmetallic carbon interlayers, was determined by small-angle X-ray diffraction. Experimental data obtained by nondestructive depth profiling of the MNS using ultrasoft X-ray emission spectroscopy of the (Co40Fe40B20)34(SiO2)66 composite layers demonstrate that the composition of the dielectric component of the composite deviates from the stoichiometry of the quartz in the sputter target toward lower oxygen content, leading to the formation of the SiO1.7 suboxide. Fitting Si L 2,3 spectra with reference spectra of known phases indicates that the content of the silicon suboxide phase in the composition of the composite layers can reach half of the composition of the dielectric component, with the second half being SiO2. This circumstance can be favorable for increasing the role of a second carrier transport channel (granule–interlayer–granule) and contribute to the previously observed sharp drop in the resistivity and the overall rise in the magnetic permeability of the MNS.

Simply modified indium tin oxides by ultrathin aluminum and sodium chloride composite interlayer for high performance inverted polymer solar cells

We report the fabrication of high performance inverted polymer solar cells with simply modified indium tin oxide (ITO) by an ultrathin aluminum (Al) and sodium chloride (NaCl) composite layer. The device efficiency and stability were both improved. The optimized device with poly(3-hexylthiophene) as the donor and [6,6]-phenyl-C61-butyric acid methylester as the acceptor under AM 1.5 (100 mw cm−2) radiation achieved a high power conversion efficiency of 3.88% with an open-circuit voltage of 0.60 V and a fill factor of 0.61, which is significantly higher than those of the inverted devices with only Al or NaCl as modification interlayer, respectively. Moreover, the stability is enhanced by about 70% more than that of the conventional device. The significant enhancement is attributed to the reduced work function of ITO electrode from 4.75 to 3.90 eV by modification as well as the improvement of the electrode interface.

Diamond/β-SiC film as adhesion-enhanced interlayer for top diamond coatings on cemented tungsten carbide substrate

In present work, diamond/β-SiC composite interlayers were deposited on cemented tungsten carbide (WC-6%Co) substrates by microwave plasma enhanced chemical vapor deposition (MPCVD) using H2, CH4 and tetramethylsilane (TMS) gas mixtures. The microstructure, chemical bonding, element distribution and crystalline quality of the composite interlayers were systematically characterized by means of field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), electron probe microanalysis (EPMA), Raman spectroscopy and transmission electron microscropy (TEM). The influences of varying TMS flow rates on the diamond/β-SiC composite interlayers were investigated. Through changing the TMS flow rates in the reaction gas, the volume fraction of β-SiC in the composite interlayers were tunable in the range of 12.0%–68.1%. XPS and EPMA analysis reveal that the composite interlayers are composed of C, Si element with little cobalt distribution. The better crystallinity of the diamond in the composite is characterized based on the Raman spectroscopy, which are helpful to deposit top diamond coatings with high quality. Then, the adhesion of top diamond coatings were estimated using Rockwell C indentation analysis, revealing that the adhesion of top diamond coatings on the WC-6%Co substrates can be improved by the interlayers with the diamond/β-SiC composite structures. Comprehensive TEM interfacial analysis exhibits that the cobalt diffusion is weak from WC-6%Co substrate to the composite interlayer. The homogeneous microcrystalline diamond coatings with the most excellent adhesion can be fabricated on the substrates with the composite interlayer with the β-SiC/diamond ratio of about 45%. The composite structures are appropriate for the application in high-efficiency mechanical tool as a buffer layer for the deposition of the diamond coating.

Deposition of Diamond/β-SiC Composite Interlayers for Improved Machining Performance of Diamond Coated Cemented Carbide Cutting Tools

Diamond/β-SiC composite films and diamond film with composite interlayers were synthesized on cemented carbide substrates and hard metal cutting tools. Diamond top layers and the interlayers were deposited in one single process by hot filament chemical vapor deposition (HFCVD) technique using a gas mixture of hydrogen, methane and tetramethylsilane (TMS). Two different kinds of interlayers have been employed, namely, gradient interlayer and interlayer with constant composition. The gradient composite film, featuring a cross-sectional gradient with increasing diamond/β-SiC content from film-substrate interface to the top of the film, showed the best film adhesion. Turning test was carried out using diamond coated and uncoated cutting tools to machine aluminum alloy. It was confirmed that the diamond films with gradient interlayer showed best adhesion to the hard metal cutting tools. Diamond coated cutting tool with gradient composite interlayer showed also higher wear resistance than uncoated cutting tool. The tool lifetime of such diamond coated cutting tool was 10 times higher than that of uncoated cutting tool. Moreover, diamond coated cutting tools performed non-sticking machining, which leaded to much higher surface quality of machined surface than uncoated insert.

The dynamic sublayers for improving the adhesion of CVD diamond films on copper

Polycrystalline diamond films were fabricated on copper substrates by a multi-step process comprised of physical vapor deposition of Al-based composite interlayer on Cu substrate and depositing continuous diamond film on composite interlayer by plasma assisted chemical vapor deposition (PACVD). The interface characteristics and adhesion strength were investigated by Auger electron spectroscopy, Raman analysis, calotest and indentation test. The results show that the continuous film without cracks is successfully obtained. The improved adhesion between diamond film and substrate results from the low residual stress in the film due to their compensation by Al interlayer in the sample cooling process.

Vacuum brazing Nb and BN-SiO2 ceramic using a composite interlayer with network reinforcement architecture

A novel composite interlayer with a reinforced network was designed using a SiC ceramic with a network structure and Ti-Ni-Nb composite filler foils, to which the Nb and BN-SiO2 ceramic were successfully brazed under vacuum. For a brazing temperature of 1160°C and holding time of 10min, the interfacial microstructure of the Nb/BN-SiO2 ceramic joint was Nb/(βTi,Nb)-TiNi eutectic structure+(βTi,Nb)2Ni+SiC+TiC/TiN+Ti2N+TiB+Ti5Si3+TiO/BN-SiO2 ceramic. In addition, the shear strength and nano-hardness were analyzed to evaluate the effect of the composite interlayer with a network reinforcement architecture on the mechanical properties of the joint. During brazing, the Ti-Ni-Nb filler metal infiltrated and reacted with the SiC to form the network reinforcement architecture, resulting in the residual stress being relieved and the mechanical performance of the joint being significantly improved. A maximum shear strength of 102MPa was achieved, which was 60MPa (142%) higher than that of the joint brazed without the network reinforcement architecture. A reduction in the residual stress on the BN-SiO2 ceramic side from 328MPa to 210MPa was observed with the network reinforcement architecture, and the fracture path of the joint changed from the surface of the BN-SiO2 ceramic to the interfacial reaction zone.

Comparing the Performance of Fiberglass Grid with Composite Interlayer Systems in Asphalt Concrete

Geosynthetics, such as fabrics, grids, and composites, were introduced to asphalt pavements to mitigate reflective cracking or the creation of moisture barriers or both. Reinforcing interlayer systems, such as grids, have been shown to be effective in retarding the reflection of cracks in the underlying pavement into the upper layers. However, the effect of different interlayer systems on the performance of the pavement varies. The aim of this research was to compare the effects of fiberglass grids, paving fabric, and paving mat systems on the fatigue and fracture performance of double-layer beam specimens under four-point notched bending beam fatigue loading. Double-layer asphalt concrete beam specimens were loaded in a displacement control mode until full-depth cracking was observed. Haversine displacements with zero and maximum deflection peaks were applied to the specimens at frequencies of 5 and 10 Hz. The digital image correlation technique was used to determine and compare the damage mechanisms with stiffness curves plotted by using load and displacement data. A comparison of the results from beams with different interlayer systems showed that the type of interlayer system can noticeably affect the damage mechanisms and the performance of the fatigue specimen. In general, grid systems performed better when the interface bond was stronger. In nongrid interlayers, while interfacial damage created a discontinuity that increased the risk of interfacial debonding, a more flexible interlayer dissipated more energy at the interface and delayed the full vertical cracking of the beams under four-point bending beam fatigue loading.

Graphene-enhanced Cu composite interlayer for contact reaction brazing aluminum alloy 6061

Contact Reaction Brazing of aluminum alloy 6061 using pure Cu nanoparticle interlayer usually encounters cracks and holes due to the intensive Al-Cu eutectic reaction. In order to solve these problems, here we report a new type of graphene-enhanced Cu composite (G-Cu) interlayer prepared by CVD to contact reaction braze aluminum alloy 6061. Results show that the G-Cu interlayer is conducive to retarding the intensive Al-Cu eutectic reaction. The average shear strength of the joint brazed with G-Cu interlayer reached 74 MPa.

Recent Development of Carbonaceous Materials for Lithium–Sulphur Batteries

The effects of climate change are just beginning to be felt, and as such, society must work towards strategies of reducing humanity’s impact on the environment. Due to the fact that energy production is one of the primary contributors to greenhouse gas emissions, it is obvious that more environmentally friendly sources of power are required. Technologies such as solar and wind power are constantly being improved through research; however, as these technologies are often sporadic in their power generation, efforts must be made to establish ways to store this sustainable energy when conditions for generation are not ideal. Battery storage is one possible supplement to these renewable energy technologies; however, as current Li-ion technology is reaching its theoretical capacity, new battery technology must be investigated. Lithium–sulphur (Li–S) batteries are receiving much attention as a potential replacement for Li-ion batteries due to their superior capacity, and also their abundant and environmentally benign active materials. In the spirit of environmental harm minimization, efforts have been made to use sustainable carbonaceous materials for applications as carbon–sulphur (C–S) composite cathodes, carbon interlayers, and carbon-modified separators. This work reports on the various applications of carbonaceous materials applied to Li–S batteries, and provides perspectives for the future development of Li–S batteries with the aim of preparing a high energy density, environmentally friendly, and sustainable sulphur-based cathode with long cycle life.

Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy

Electrochemical analysis of corrosion performance of a transient liquid phase (TLP) bonded nickel-based superalloy was performed. The TLP bonding process resulted in significant reduction in corrosion resistance due to the formation of non-equilibrium solidification reaction micro-constituents within the joint region. The corrosion resistance degradation is completely eliminated through a new application of composite interlayer that had been previously considered unusable for joining single-crystal superalloys. The effectiveness of the new approach becomes more pronounced as the severity of environment increases.

Improving the compatibility of an Y-TZP/porcelain system using a new composite interlayer composition

The aim of this study was to evaluate the effects of different cooling procedures and a new composite interlayer composition on the flexural strength, and veneer delamination resistance, of an all-ceramic veneered translucent Y-TZP core. One hundred twenty bar-shaped specimens of a translucent Y-TZP ceramic were prepared and divided into three groups: (1) no composite interlayer; (2) a glass interlayer (silica-based glass); (3) a mixed composite interlayer of glass and porcelain veneer material. A veneering porcelain (with and without a composite interlayer) was applied on the specimen surface and sintered. Each core–veneer group was cooled using a rapid or a slow cooling rate. All specimens were tested in four-point bending. Data were statistically analyzed using two-way ANOVA, followed by Post-Hoc tests with Bonferroni correction (α=0.05) and Weibull analysis. The group with no interlayer using the rapid cooling technique exhibited the highest flexural strength. However, with low reliability and the greatest delaminated area of porcelain under tension. A glass interlayer between porcelain veneer and zirconia core presents as a good alternative for maintaining flexural strength and porcelain veneer delamination resistance in zirconia based restorations.

Functionally graded doped lanthanum cobalt ferrite and ceria-based composite interlayers for advancing the performance stability in solid oxide fuel cell

Abstract Functionally graded composite interlayer based on 50% of La 0.54 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and 50% of La 0.54 Sr 0.4 Fe 0.2 Co 0.8 O 3-δ (CF-1) and cobalt and gadolinium doped ceria (CoCGO) is synthesized varying the mass ratio as CF-1:CoCGO = 80:20(L80-C20), 50:50(L50-C50) and 20:80(L20-C80). Detail study using impedance spectroscopy of symmetrical cell fabricated with CoCGO as electrolyte reveals the lowest electrode polarization 0.04 Ω cm 2 at 800 °C for L80-C20 composite. Electrode and ohmic polarization is also evaluated configuring the symmetric cell as CF-1/L80-C20||CoCGO||L80-C20/CF-1. Symmetric cell with varying composition of the composite interlayer (L80-C20/L50-C50/L20-C80||CoCGO||L20-C80/L50-C50/L80-C20) shows considerably low electrode polarization of 0.067 Ω cm 2 at 800 °C with activation energy 1.19 eV. Electrochemical performances evaluated using single cell configuration Ni-YSZ||YSZ||CoCGO/L20-C80/L50-C50/L80-C20/CF-1 shows power density as high as 2.03 W cm −2 at 800 °C at 0.7 V. Addition of composite interlayers increases the stability significantly and the voltage degradation is found negligible (0.9%) for first 300 h at a constant load of 0.5 A cm −2 which is further increased to 2.9% for next 300 h. The cell stability is clinically correlated with layer wise elemental ‘Sr’ mapping in the applied quad interlayers.

Soldering aluminium to copper with the use of interlayers deposited by cold spraying

The article presents the application of interlayers deposited by Low Pressure Cold Spraying (LPCS) in the soldering process. The problems concerning soft soldering of aluminium and copper were indicated and a solution with the use of metallic and composite interlayers was proposed. Wettability and spreadability tests with selected solders were performed to evaluate a solderability of various aluminium and copper LPCS coatings. Light and scanning microscopes were used to analyze solder dissimilar Al–Cu joints with previously deposited LPCS interlayer. What is more mechanical properties of the joints, e.g. microhardness and shear strength, were examined. Strength of the soldered Al–Cu joints with the LCPS interlayer highly depend on shape of powder used in spraying process. The joints with the interlayer sprayed with dendritic copper powder have low strength of about 20MPa. However, the strength of soldered joints with the LPCS interlayer of spherical copper powder is significantly higher and amounts to 36.7MPa.

Design of pane-like laminated glass columns

To achieve transparency of buildings, load-bearing elements made of glass are essential, such as pane-like glass columns with laminated sections of heat-strengthened or toughened glass. An ultimate limit state design of such structures requires consideration of the composite interlayer. Using second order theory and the elastic shear bond between the glass layers allows the prediction of load–deflection of a laminated glass section under axial compression force. The introduction of a limit state function then results in equations for European buckling curves, which are also presented in this paper. The validity of these analytical equations is shown by experimental studies. Stability experiments on laminated glass columns were performed under variation of loading type and loading rate at room temperature. Laminated glass sections of heat-strengthened and toughened glass are the focus of this study.

Low-velocity impact resistance of aluminium glass laminates – Experimental and numerical investigation

The purpose of the present study was to determine the nature and area of damage in fibre metal laminates subjected to low-velocity impact using a numerical model based on defined damage criteria in relation to executed experimental tests. The plates 1.5–3.5mm thick made of aluminium/epoxy–glass composite produced in autoclave process were subjected to tests. The low-velocity impact test was performed at room temperature using a drop-weight impact tester with impact energy 10J and 25J. On the basis of obtained results, the results of experimental tests and numerical analyses have been found compatible in the scope of specific relationships i.e. force vs. time, internal damage areas and laminates damage mechanism prevailing in their structure. The principal laminates damage forms encompassed delaminations occurring in composite interlayers and on metal-composite interface, cracks in composite layers and in lower layers of metal. Presented modelling of impact in fibre metal laminates using VUMAT code enables the evaluation of their structure damage and the selection of proper laminate configuration in future in terms of their resistance to low-velocity impact.

Co/Fe oxide and Ce0.8Gd0.2O2-δ composite interlayer for solid oxide electrolysis cell

A composite interlayer comprised of gadolinia doped ceria (GDC) and Co/Fe oxide was prepared and investigated for solid oxide electrolysis cell with yttrium stabilized zirconia (YSZ) electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) anode. The interlayer was constructed of a base layer of GDC and a top layer of discrete Co3O4/FeCo2O4 particles. The presence of the GDC layer drastically alleviated the undesired reactions between LSCF and YSZ, and the presence of Co/Fe oxide led to further performance improvement. At 800°C and 45% humidity, the cell with 70% Co/Fe-GDC interlayer achieved 0.98A/cm2 at 1.18V, 14% higher than the cell without Co/Fe oxide. Electrochemical impedance spectroscopy (EIS) revealed that with higher Co/Fe content, both the ohmic resistance and the polarization resistance of the cell were reduced. It is suggested that Co/Fe oxide can react with the Sr species segregated from LSCF and Sr1-x(Co,Fe)O3-δ, a compound with high catalytic activity and electronic conductivity. The Sr-capturing ability of Co/Fe oxide in combination with the Sr-blocking ability of GDC layer can effectively suppress the undesired reaction between LSCF and YSZ, and consequently improve the cell performance.