Interlayer Properties Research Articles

Overall response of 2-ply laminated glass plates under out-of-plane loading

The results of an experimental and numerical investigation on the mechanical response of undamaged and damaged 2-ply Laminated Glass (LG) plates with different interlayers are presented in the paper. Three different interlayers, polyvinyl butyral (PVB), SentryGlas (SG) and Saflex DG41 (DG41) characterized by different rheological properties and fully tempered glass plates were considered. Simply supported plates under out of plane loads were tested in three different configurations: configuration 0, undamaged; configuration I, partially damaged, with a broken ply below (bottom ply) and configuration II, partially damaged, with a broken ply above (top ply). In the three configurations the top ply is always subjected to compression while the bottom one is in tension. The main aspects and the different response of each configuration were discussed and compared. Experimental results highlighted the influence of the interlayer properties on both the pre- and post-breakage behavior. Moreover, numerical models were developed to reproduce the experimental results. For the post-breakage response two different strategies were developed: a) the equivalent temperature variation and b) elastic-brittle constitutive law. Differences and advantages associated with both solutions are discussed. Finally, extensive parametric numerical analyses are proposed to underline the influence on the mechanical response of different parameters: i) plate geometry (size effect); ii) interlayer thickness; iii) glass thickness; iv) additional glass ply (3-ply LG plate). It is underlined that the size effect plays an important role on the mechanical response of LG plates and it should be always considered in the design. The numerical findings were used to define a critical length from which the plates behave as monolithic, independently of the stiffness of the interlayer.

On mode I/II interlaminar fracture toughness of double-sided-loop 2D woven laminated composites

Two-dimensional (2D) plain fabric is prone to delamination when subjected to bending, shear, impact loads. To enhance the interlayer properties of 2D plain fabrics, standing up loops is added. In this paper, specimens of the double-sided-loop 2D woven laminated composites (DWLC) and general 2D woven laminated composites (GWLC) are made for double cantilever beam (DCB) tests and end-notch flexure (ENF) tests to study their toughening mechanism. Test results show that the values of model I and mode II interlaminar fracture toughness are increased by 870% and 250% for the DWLC compared with the GWLC. Based on the three-linear cohesive zone model (CZM), finite element (FE) models of composite laminates specimens of DCB and ENF considering the phenomenon of interlaminar bridging are established, and numerical results are in good agreement with the experimental data, that verifies the accuracy of the FE models. Using the verified FE models, model I and mode II fracture properties of the DWLC specimens of DCB and ENF with different initial crack lengths are investigated, and the results show that the stress is redistributed and the load gradually decreases as the length of the prefabricated cracks increases. The obtained fracture toughness of the DWLC provides a reference for the toughening methods and the engineering applications of DWLC.

Experimental study on microstructure response and mechanical properties of weak interlayer in acidic environment

Experimental study on microstructure response and mechanical properties of weak interlayer in acidic environment

Gas pressure casting technique for manufacturing of W/OFHC-Cu monoblock

The important engineering part of the divertor vertical target is the quality of joint between armor materials and heat sink. To reduce the joint interface stresses, a pure copper (Cu) interlayer was provided between the tungsten(W) armor and the CuCrZr cooling tube. Gas pressure casting method was developed to reduce the porosity and improve the mechanical properties of the Cu interlayer of W/Cu monoblock. In the vacuum casting sample without pressure, porosities were found in Cu. These porosities become defects at the interface between W and Cu and decrease the mechanical properties of the Cu interlayer. In the cooling process of casting, argon gas was pressurized into a porous tube inserted in the Cu and tungsten monoblock applying perpendicular force on the joint surface. This method was effective to remove the porosity in Cu generated during the cooling process and to increase the bonding strength between Cu and tungsten. The quality of bonding interface, depth of the Cu diffusion, and hardness of Cu were compared by SEM, EDS, and Vickers hardness measurement. In the samples made by gas pressure casting method, the porosity was decreased in Cu, no defects on the interface between tungsten and Cu, Cu was diffused into tungsten with a depth of 2∼3 μm and the hardness of Cu was increased about 15%.Small mock-ups were manufactured by hot radial pressing (HRP) with gas pressure casted W/Cu monoblock and CuCrZr cooling tube and underwent high heat flux (HHF) of 10 MW/m2 up to 5,000 cycles. The ultrasonic test (UT) results before and after the HHF test showed no defects on interfaces and was confirmed by observation of SEM on the cutting surface of the monoblock mock-up after the HHF test.

Experimental Study on Vertical Propagation Behavior of Hydraulic Fracture Affected by Artificial Interlayer for Thick Oil Reservoirs

Crude oil distribution in thick oil reservoirs is vertically heterogeneous; therefore, there is usually a dominant sublayer where oil resources are higher than that in other sublayers. The region of hydraulic fracture away from the dominant sublayer plays a negative role in production. In order to enhance efficiency of hydraulic fracturing, the hydraulic fracture height should be restricted around the dominant sublayer and the artificial interlayer is believed as an effective method. However, the propagation mechanism of fracture affected by artificial interlayer has been rarely investigated, which restricts the advance of optimization of artificial interlayer. In this paper, the impact of artificial interlayer on vertical propagation of hydraulic fracture is analyzed by hydraulic fracturing experiments and then the mechanism of artificial interlayer affecting propagation of hydraulic fracture is discussed. Based on the understanding of experimental observations and theory of fracture mechanics, the theoretical model of stress intensity factor for the fracture affected by artificial interlayer is proposed. The experimental data shows that the artificial interlayer can significantly decrease the hydraulic fracture height and the corresponding decrease magnitude of hydraulic fracture height depends on the thickness of artificial interlayer, proppant size, and fracture fluid pumping rate. The dominant mechanism of artificial interlayer restricting hydraulic fracture height is that the drop of fluid pressure induced by the artificial interlayer decreases the stress intensity factor at fracture tip. Based on the theory of fracture mechanics, the stress intensity factor at fracture tip is built and it can consider key factors shown by experimental observations. The fracture height solution from this model is consistent with experimental data, so this model can be used to optimize properties of artificial interlayer.

Recent Advances on Tuning the Interlayer Coupling and Properties in van der Waals Heterostructures

2D van der Waals (vdW) heterostructures are receiving increasing research attention due to the theoretically amazing properties and unprecedented application potential. However, the as-synthesized heterostructures are generally underperforming due to the weak interlayer coupling, which inspires the researchers to find ways to modulate the interlayer coupling and properties, realizing the tailored performance for actual applications. There have been a lot of publications regarding the controllable regulation of the structures and properties of 2D vdW heterostructures in the past few years, while a review work summarizing the current advances is not yet available, though it is significant. This paper conducts a state-of-the-art review regarding the current research progress of performance modulation of vdW heterostructures by different techniques. First, the general synthesis methods of vdW heterostructures are summarized. Then, different performance modulation techniques, that is, mechanical-based, external fields-assisted, and particle beam irradiation-based methods, are discussed and compared in detail. Some of the newly proposed concepts are described. Thereafter, applications of vdW heterostructures with tailored properties are reviewed for the application prospects of the topic around this area. Moreover, the future research challenges and prospects are discussed, aiming at triggering more research interest and device applications around this topic.

Nano-Interlayers Fabricated via Interfacial Azo-Coupling Polymerization: Effect of Pore Properties of Interlayers on Overall Performance of Thin-Film Composite for Nanofiltration.

The supporting layer of nanofiltration membranes is critical to the overall nanofiltration performance. However, conventional supports lack efficient surface porosity, which leads to the limited utilization rate of the polyamide (PA) layer. Herein a double-skin-layer nanofiltration membrane with porous organic polymer nanointerlayers prepared via a two-step interfacial polymerization technique is presented to investigate the effect of the interlayers' pore properties on the performance of the thin-film composite. Nanometer interlayers with different pore sizes are fabricated via interfacial azo-coupling polymerization. The pore properties of the nanointerlayer extremely influence the permeance, where a suitable pore size of 4.22 nm promotes pure water permeance of up to 32.2 L m-2 h-1 bar-1, which is ∼3.8-fold greater than the membrane without an interlayer. However, an interlayer with 0.54 nm pores limits the performance (4.7 L m-2 h-1 bar-1), which is even lower than the unmodified membrane (7.5 L m-2 h-1 bar-1), because of the narrow pores and confined transport mode. However, the confined diffusion rate of amino monomers from the support to interface leads to a thinner PA layer of ∼45 nm and results in high flux. This work provides a facial route for the fabrication of interlayers and facilitate the design of high-performance membrane materials with interlayers.

The relationship between the rheological behavior and interlayer bonding properties of 3D printing cementitious materials with the addition of attapulgite

The rheological behavior of fresh 3D printing concrete (3DPC) not only determines the pumpability, extrudability and buildability, but also strongly affects the interlayer properties. Which is one of the most important characteristics of 3D printing construction that shaped layer by layer. This paper systematically studied the relationship between the rheological behavior (tuned by attapulgite) and the interlayer bonding properties of 3DPC. The results showed that the interlayer bonding strength and interlayer durability strongly depend on the rheological parameters (i.e., dynamic yield stress, plastic viscosity, static yield stress and structural build-up rate). With the increase of dynamic yield stress and structural build-up rate, the interlayer bonding strength and interlayer durability both decreased. Moreover, an empirical formula combining interlayer bonding strength with the dynamic yield stress and the structural build-up rate of 3DPC, considering the porosity and hydration degree, was proposed for the first time.

Inkjet Printing Infiltration of the Doped Ceria Interlayer in Commercial Anode-Supported SOFCs.

Single-step inkjet printing infiltration with doped ceria Ce0.9Ye0.1O1.95 (YDC) and cobalt oxide (CoxOy) precursor inks was performed in order to modify the properties of the doped ceria interlayer in commercial (50 × 50 × 0.5 mm3 size) anode-supported SOFCs. The penetration of the inks throughout the La0.8Sr0.2Co0.5Fe0.5O3−δ porous cathode to the Gd0.1Ce0.9O2 (GDC) interlayer was achieved by optimisation of the inks’ rheology jetting parameters. The low-temperature calcination (750 °C) resulted in densification of the Gd-doped ceria porous interlayer as well as decoration of the cathode scaffold with nanoparticles (~20–50 nm in size). The I–V testing in pure hydrogen showed a maximum power density gain of ~20% at 700 °C and ~97% at 800 °C for the infiltrated cells. The latter effect was largely assigned to the improvement in the interfacial Ohmic resistance due to the densification of the interlayer. The EIS study of the polarisation losses of the reference and infiltrated cells revealed a reduction in the activation polarisations losses at 700 °C due to the nano-decoration of the La0.8Sr0.2Co0.5Fe0.5O3−δ scaffold surface. Such was not the case at 800 °C, where the drop in Ohmic losses was dominant. This work demonstrated that single-step inkjet printing infiltration, a non-disruptive, low-cost technique, can produce significant and scalable performance enhancements in commercial anode-supported SOFCs.

Correlation of interlayer properties and rheological behaviors of 3DPC with various printing time intervals

The weak interlayer of 3D printing cementitious materials (3DPC) remains a critical challenge for 3D printing technology, which can print fresh materials layer by layer based on a pre-defined computer model. In this paper, the effects of the printing time interval on rheological behavior, shear bond strength, penetration resistance to chloride and CO 2 of 3DPC interlayers were investigated, and the correlations among them were analyzed based on the gray relational analysis(GRA) method, a statistical method for measuring correlations between factors by their trends. The results showed that the carbonation resistance is the most sensitive to the printing time interval, followed by chloride penetration and shear bond strength. The rheological behaviors of 3DPC had weaker correlation with the shear bond strength when comparing with the interlayer surface moisture. Additionally, the porosity was more related to the shear bond strength than the number of pores. Furthermore, a quantitative relationship between shear bond strength and printing time interval was established.

Interfacial Passivation Engineering of Perovskite Solar Cells with Fill Factor over 82% and Outstanding Operational Stability on n-i-p Architecture.

Tremendous efforts have been dedicated toward minimizing the open-circuit voltage deficits on perovskite solar cells (PSCs), and the fill factors are still relatively low. This hinders their further application in large scalable modules. Herein, we employ a newly designed ammonium salt, cyclohexylethylammonium iodide (CEAI), for interfacial engineering between the perovskite and hole-transporting layer (HTL), which enhanced the fill factor to 82.6% and consequent PCE of 23.57% on the target device. This can be associated with a reduction of the trap-assisted recombination rate at the 3D perovskite surface, via formation of a 2D perovskite interlayer. Remarkably, the property of the 2D perovskite interlayer along with the cyclohexylethyl group introduced by CEAI treatment also determines a pronounced enhancement in the surface hydrophobicity, leading to an outstanding stability of over 96% remaining efficiency of the passivated devices under maximum power point tracking with one sun illumination under N2 atmosphere at room temperature after 1500 h.

Analysis of the Forming of Interlock Textile Composites Using a Hypoelastic Approach

Numerical simulation of the textile composites forming plays an important role in improving the manufacturing quality, reducing the manufacturing cycle, and manufacturing cost. The focus is on the shaping of one or several layers of G1151 interlock reinforcement. Based on the continuous approach at the macroscale, an approach using a hypoelastic behavior is proposed considering the specific interlock textile material behavior. The stress accumulation is carried out in frames defined by the direction of the warp and weft yarns. The approach is implemented in the commercial software Abaqus. By adding inter-layer contact properties, this approach can realize the simulation of multi-layers textile composites with different yarn orientation configurations. Experimental analyses have shown that this approach can correctly trace the specific behavior of interlock textile composites.

The influence of interlayer properties on the response of laminated glass to low-velocity hard-object impact

In this combined experimental-numerical study, we intend to clarify how the interlayer properties of laminated glass plates affect their response to the low-velocity impact of a hard object. To this end, we tested twelve large laminated glass plates with polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) interlayers combined with two annealed or heat-strengthened soda-lime-silica glass layers—three testing samples for each combination. In laboratory impact tests, both the laminated glass plate and the impactor were suspended on thin steel wire ropes to minimise the effects of boundary conditions; the velocities of the impactor and the resultant contact force were increased in repeated tests until the glass fractured. Because of the large scatter of fracture strengths, we derived the contact force for all non-destructive and destructive tests using the motion of the impactor and analysed how the contact force evolved. The laboratory impact tests also provided a dataset for validation of numerical simulations that reliably predicted the velocities at measured points and contact forces for both kinds of polymer interlayer foils, thereby validating the viscoelastic parameters of polymers determined in our previous experimental study. Using the validated numerical model, we analysed how the type of interlayer polymer material influences the impact response of laminated glass in terms of contact force and stresses and in relation to surrounding temperature conditions and impactor mass and velocity. Finally, we approximated time/temperature-dependent foil as being an elastic material with different values of constant shear moduli. For laminated glass plates containing PVB, such approximation remained valid only at low temperatures and responses could be estimated using the temperature-independent initial shear modulus. For simulations with EVA-based laminated glass plates, the elastic model with the shear modulus for prescribed temperatures and load durations provided an accurate approximation of the viscoelastic response.

Study on preparation, microstructure and properties of gradient composite interlayer with copper/steel

In order to optimize the interface performance of copper/steel bimetallic composite and avoid the degradation of the composite performance owing to the difference of thermal-physical properties, HS211/ER50-6 composite structure was fabricated by arc additive technology, and Fe–Ni and Cu–Al flux-cored wires were designed as transition materials to realize the gradient connection of the interface area. Microstructure observation and mechanical properties testing were used to characterize the properties of the samples. The results showed that gradient connection can be achieved by adding the transition layer of Fe–Ni and Cu–Al flux-cored wires. Fe-rich phases with different morphologies were found in the interface region, which strengthened the matrix as the second phase. The corrosion resistance of the Fe–Ni transition layer region was better than Cu–Al, and the impact absorption energy reached 925 kJ/m2. The tensile strength of Fe–Ni samples reached 326.5 MPa, and the fracture location of the two groups of samples were both the copper side deposition.

Mechanistic-Empirical Faulting Prediction Model for Unbonded Concrete Overlays of Concrete

Transverse joint faulting is a distress that develops in unbonded concrete overlays (UBOL). Historically, faulting models used for predicting the performance of a UBOL have not accounted for the effects of the interlayer between the overlay and the existing pavement on the development of faulting. This is a significant limitation since characteristics of the interlayer play a primary role in the rate at which faulting develops in UBOLs. To develop a more robust faulting prediction model for UBOLs, enhancements were made to the current process to address this limitation. This includes the use of a structural response model that can account for the effects of the interlayer properties on the response of the UBOL. Additional enhancements include the use of a deflection basin of the overlay (in lieu of corner deflections of an equivalent slab system for accumulating differential energy [DE]), the incorporation of an erosion model that can account for the erodibility of the interlayer material, the adjustment of the incremental faulting equations to accommodate small slab sizes that are common in UBOLs, and a national calibration using faulting data from in-service UBOLs. This enhanced faulting model has been implemented in the mechanistic-empirical design tool Pitt UBOL-ME.

Structure and mechanical properties of WC interlayers between iron substrate and thin tungsten plate

To improve the mechanical properties of cast iron (Fe) surface, tungsten carbide (WC) interlayers were fabricated by the in-situ reaction at 1050 °C and 1100 °C for different heat-treatment times. The structure and phase composition of the layer were investigated via scanning electron microscopy, transmission electron microscopy and X-ray diffraction analyses. The effect of vacuum atmosphere temperature on the interfacial structure of sample was discussed. The results indicate that the thickness of the layer, consisting of a dominant WC phase, has a range of 11.12 ± 1.32 to 51.51 ± 1.36 μm obtained at 1050 °C. Based on growth kinetics, the diffusion coefficient of carbon in the WC layer is calculated to be 1.57×10−9 cm2/s. Furthermore, under the load of 100 mN, nanoindentation tests demonstrate that values of hardness and elastic modulus of the layer are approximately 25.09–39.74 GPa and 649.54–834.17 GPa, which are 2.4–3.8 times and 3.5–4.4 times larger than that of the substrate, respectively. By means of Vickers indentation mode using the available equation for Palmqvist crack system, the value of the calculated fracture toughness for the layer changes in a range from 2.55 ± 0.14 to 6.34 ± 0.54 MPa⋅m1/2, and the value decreases with the increasing load. This result may be caused by the reason that the fracture resistance also strongly depends on the applied load.

Research on Interlayer Bonding Quality Control Method of Dam Concrete Based on Equivalent Age.

Interlayer bonding quality is the key to the stability and durability of dam concrete. In this study, interlayer splitting tensile strength, relative permeability coefficient, and electric flux of dam concrete at different temperatures were tested. The relationships between equivalent age and strength coefficient, relative permeability coefficient ratio, and electric flux ratio were established. Meanwhile, a comprehensive early-warning and control system of dam interlayer bonding quality based on the above relationships was proposed. The results showed that the interlayer mechanical properties, impermeability, and anti-chloride ion permeability of dam concrete decreased with the increase of temperature. Moreover, the equivalent age was linearly correlated with strength coefficient, relative permeability coefficient ratio, and electric flux ratio of concrete. The correlation coefficients were 0.986, 0.973, and 0.924, respectively. In addition, the interlayer bonding quality of dam concrete can be effectively controlled by the early-warning system established according to the relationship between equivalent age and interlayer properties parameters.

Interlayer properties of tungsten fibre-reinforced composites and their determination by different methods

Tungsten features a unique combination of properties which makes it a candidate for the use as a plasma-facing material in fusion reactors. The main drawbacks of tungsten are its brittleness at moderate temperature and the susceptibility to embrittlement during operation. To overcome this limitations tungsten fibre-reinforced tungsten composites (W f /W) have been developed. The interlayer between the tungsten fibre and tungsten matrix enables the activation of extrinsic mechanisms to improve the toughness similar to ceramic fibre-reinforced ceramics. In addition, the evaluation of the interlayer parameter is a necessary for the efforts to model the composite behaviour. Therefore, single fibre model systems with Er 2 O 3 and Y 2 O 3 as interlayer were evaluated by push-out and pull-out tests. The results were used to determine the interfacial shear strength ( τ d e b ), the interfacial frictional shear stress ( τ f r ) and the fracture energy of the interlayer ( Γ i ). In addition, tensile tests on the composite material were performed to evaluate the interfacial frictional shear stress. The evaluation methods were critically discussed as the results show that the influence of the evaluation method is larger than the actual tested interlayer material. • Evaluation of the interlayer properties of W f /W with three different methods. • The interlayer testing method has a larger influence on the evaluated values than the actual tested interlayer material. • For the further material screening pull-out test is preferred over push-out test for W f /W.

Multiscale modelling of graphene sheet and its application in laminated composites

Multiscale modeling strategy development of graphene and its composites is of critical importance in engineering and technological applications. In this work, we systematically developed a chirality preserved coarse-grained graphene model and the corresponding potential, TersoffCG(16–1). The robustness of this potential is verified through structural and mechanical characterization analysis comparison between coarse-grained and all-atomistic models. The Lennard-Jones potential is emphasized to adjust the interlayer properties of the interlayer distance and binding energy. Furthermore, in-plane properties of multilayer graphene assembly tensile and monolayer graphene crack, and out-of-plane properties of nanoindentation are fully analyzed. The copper/graphene nanocomposite tensile test indicated that the coarse-grained graphene model is compatible with the copper matrix. Our efficient and portable coarse-grained graphene model successfully reproduced the architectural parameters, elastic, fracture, and interlayer adhesion properties of graphene sheets compare with the reported experiment and theoretical results, which can serve as an effective strategy to research more hybrid composite systems.

Impact of Pregrown SiOx on the Carrier Selectivity and Thermal Stability of Molybdenum-Oxide-Passivated Contact for Si Solar Cells.

Thin SiOx interlayers are often formed naturally during the deposition of transition metal oxides on silicon surfaces due to interfacial reaction. The SiOx layer, often only several atomic layers thick, becomes the interface between the Si and deposited metal oxide and can therefore influence the electrical properties and thermal stability of the deposited stack. This work explores the potential benefits of controlling the properties of the SiOx interlayer by the introduction of pregrown high-quality SiOx which also inhibits the formation of low-quality SiOx from the metal-oxide deposition process. This work demonstrates that a high-quality pregrown SiOx can reduce the interfacial reaction and results in a more stoichiometric MoOx with improved surface passivation and thermal stability linked to its lower Dit. Detailed experimental data on carrier selectivity, carrier transport efficiency, annealing stability up to 250 °C, and in-depth material analysis are presented.