Effect Of Multilayer Structure Research Articles

Effects of multilayer structure on the high-speed dry-cutting performance of AlCrBN/AlCrN multilayer coatings

To investigate the effects of different structures on the cutting performance of AlCrBN/AlCrN multilayer coatings, AlCrBN/AlCrN coatings with different multilayer structures (single layer, 10 bilayers, and 20 bilayers corresponding to T1 coating, T10 coating, and T20 coating) were synthesized using multi-arc ion plating technology. Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM) results showed that the coatings were mainly composed of fcc-(Cr, Al) N phases located on the (111) and (200) crystal planes. All coatings exhibited a good indentation adhesion to the substrates. The hardness of the T10 coating (32.6 GPa) and T20 coating (31.2 GPa) was significantly higher than that of the T1 coating (28.0 GPa). Annealing experiments show that no phase composition evolution was revealed at 800 °C. High-speed milling tests imply that the milling life of the T10 coating (13 m) and the T20 coating (10 m) was increased by 62.5% and 25.0% compared to the T1 coating (8 m), respectively. In high-speed dry turning tests, the T10 coated tool also showed the longest lifetime (16 mins), an improvement of 23.1% over T1 or T20 coated tools (13 mins). SEM analyses of wear coated tools indicated that a multilayer structure enhanced their resistance to abrasion and adhesion wear, and led to better cutting performance, probably because of their excellent mechanical properties and thermal stability.

Effects of multilayer structure on impacting fatigue resistance and high-speed dry cutting performance against Ti-6Al-4 V of AlTiN/AlTiBN multilayer coatings

AlTiN/AlTiBN multilayer coatings with various numbers of bilayers were constructed to evaluate their high-frequency cyclic impact resistances and high-speed dry cutting performances. The multilayer coatings showed improvement in adhesion, micro-hardness as well as resistance to impacting fatigue and thermal decomposition. High-speed dry cutting (80 and 100 m/min without cutting fluid) experiments manifested the enhanced resistance to crack generation, delamination and rapid failure of coated tools by construction of multilayer structure, and the C5 coated tool presented better cutting lifetime of ∼2800 m (80 m/min) and ∼1200 m (100 m/min) ascribed to the best adhesive strength of 96 N (Lc2), the highest hot-hardness (3375 HK0.025 at 1000 °C) as well as the best fatigue resistance.

Reconstituted LH2 in multilayer membranes induced by poly-l-lysine: Structure of supramolecular and electronic states

To explore the effect of cell membrane stacking on the function of light-harvesting complex 2 (LH2) in purple nonsulfur photosynthetic bacteria, LH2 from Rhodobacter sphaeroides 2.4.1 (R. sph 2.4.1) was reconstituted into lipid bilayer vesicles (LH2@liposome) and further formed multi-layer structure by electrostatic interaction with poly-l-lysine (LH2@liposome/PLL), which was characterized by cryo-electron microscopy (cryo-EM) and TEM. When embedded in liposomes and additionally in multi-layer liposomes, the absorption band, zero-crossing point of CD signals and fluorescence emission of LH2 B850 excitons were observed to uniformly have 1–2 nm red-shifting. Combining with the corresponding fluorescence quench and the generation of shorter-living fluorescence species, a new excitonic species generated through B850 structural splitting was proposed. By FT-Raman and triplet carotenoid dynamics, the structural mechanism was deduced and discussed. Briefly, all environmental changes, including LH2 aggregating and multi-layer membrane stacking, eventually applied forces on B850 exciton molecules mainly through the hydrogen bonding between the C3-acetyl carbonyl groups of B850 BChls and Tyr44 and 45 residues at C-terminus of α-polypeptides. The effect of multi-layer structure on LH2 could be assigned as a kind of photoprotection.

Effects of Multilayer Structure on the Microstructure and Optical Properties of the DC Sputtered Chromium Thin Films for Selective Solar Absorber Applications

Chromium thin films exhibit several properties that make them potential for solar thermal applications. In this work the effect of film thickness and sputtering power based multilayer structure on the optical properties of DC sputtered chromium thin films is reported. The structural, topological, and optical properties of these films were determined by X-ray diffractometer, Atomic Force Microscopy, and Ultraviolet-Visible-Near Infrared spectrophotometer, respectively. XRD spectra revealed a single peak with preferential orientation of (200) and (210) for single layer and multilayer chromium films, respectively. The grain size and roughness were relatively higher for the multilayer compared to single layer Chromium films. Spectral transmittance showed very high sensitivity to film thickness with average peak of 69% and 5% at a wavelength range of 250-2500 nm for the film thickness of 12 nm and 94 nm, respectively. Spectral transmittance was also found to be higher in single layered films than multi-layered films. Findings from this study suggest that multilayer structure have the potential of tuning the microstructure and optical properties of low thickness Cr films, hence, extending its potential applications in selective solar absorber applications.
 Keywords: Multilayer, Chromium, Sputtering, Optical constants

Reprint of: Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr

Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to −60 V and −200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2–5 nm improves the resistance to oxidation at 500–600 °C as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 °C are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at −60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x < 2) and higher wear rates compared to multilayers grown at −60 V.

Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr

Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to −60 V and −200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2–5 nm improves the resistance to oxidation at 500–600 °C as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 °C are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at −60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x < 2) and higher wear rates compared to multilayers grown at −60 V.

Production of carbon-based precursor from non-recyclable waste poly(ethylene) terephthalate: effect of multilayer structure on carbonized product

In this paper, the carbonization of multilayer PET containing an oxygen barrier layer was investigated. The oxygen barrier layer was identified as MXD6 nylon, which is widely used in the beverage industry due to its excellent barrier properties but is difficult to be mechanically separated and unsuitable for recycling. Carbonization experiment was conducted using a 2.0-L batch reactor at 400–480 °C and residence time 2 h to investigate the effects of multilayer PET on carbonization product. Char, wax, and gas were obtained and evaluated in terms of calorific value, elemental analysis, surface analysis and compound identification. Data testify that char yield was approximately 20 wt% and char obtained from all runs had high carbon content with minimal effects from oxygen barrier layer. The results showed that oxygen barrier layer had no apparent effect in the char composition and characteristics, but produced more aromatic hydrocarbons such as biphenyl and fluorene in wax and more CO2 in gaseous product.

Study on microstructure and tensile properties of 316L stainless steel fabricated by CMT wire and arc additive manufacturing

An austenitic stainless steel 316L part was fabricated by cold metal transfer wire and arc additive manufacturing (CMT-WAAM), and its microstructure, microhardness and tensile properties were investigated. Results showed that the as-built 316L part exhibited a multilayered structure along the building direction. In the transverse direction (perpendicular to scanning direction) of each layer, there was also a multilayered structure of alternating overlapping zone (OA) and re-melting zone (RA). Compared with the OA, the RA had higher ferrite content, smaller austenite dendrite size, more dispersed orientation and lower residual stress. The overall multilayered structure and the intra-layer non-equilibrium microstructure exhibit a great influence on the mechanical properties of as-built 316L part. Along the building and transverse direction, the microhardness distribution in the OA was uniform, while the RA showed a trend of lower hardness in the middle and higher hardness on both sides of the RA layer. The effect of multilayered structure on tensile properties was stronger in the transverse direction than that in the building direction. The deformation feature was obviously inconsistent between the OA and RA. Local necking and fracture always occurred in the OA. Microvoids trended to initiate at silicate impurity particles, grow into large cracks, and finally lead to material failure during tension.

Epoxy/ferrite nanocomposites as microwave absorber materials: effect of multilayered structure

In the present work, different ferrite-type nanoparticles (Ni0.5Zn0.5Fe2O4, NiFe2O4 and Fe3O4) were incorporated into an epoxy resin to obtain composites loaded with 20 and 40 wt% of filler. The morphology of these monolayered composites was investigated by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), which allow identifying a fractal structure of the ferrite-based filler with rough surface. The electromagnetic properties of the monolayer composites with 1 mm thickness were evaluated by the transmission line method in X-band (8.2–12.4 GHz), whose better response in terms of reflection loss was obtained for the composite filled with Ni0.5Zn0.5Fe2O4. Epoxy-based composites containing 20 and 40 wt% of Ni0.5Zn0.5Fe2O4 in the form of plaques were arranged in two types of three-layered structures: (i) stacked monolayers and (ii) low dielectric spacer sandwiches between monolayers (air, honeycomb and foam), whose structure sequence was built based on the reflectivity simulation. The best system, designed by mathematical simulation and experimental results, consisted of ER/NiZn(40)–honeycomb–ER/NiZn(20) arrangement, which presented RL of around − 40 dB at a frequency of 8.75 GHz. Broadband with > 90% attenuation (minimum of − 10 dB) with band width of around 1.2 GHz and minimum RL ≈ 20 dB (Eabs ≈ 99%) was achieved for both three-layered structures contain in PU foam or honeycomb as low dielectric spacer. The ferrite-based multilayer structures with only 6 mm of thickness constitute promising absorbing materials for applications in both civil and military fields.

Magneto-optical spin Hall effect of light and its application in refractive index detection

The spin Hall effect of light (SHEL) is a photonic version of the spin Hall effect in electronic systems, and it has been a focused research area in the recent ten years. However, due to the lack of effective methods dynamic modulation of spin-dependent splitting, the practical application of SHEL has remained a challenge, still urgently waiting to be resolved. In recent years, SHEL has been applied to the precise measurement and sensing of various physical quantities. Now, how to make SHEL measurement flexible is the research direction of researchers The magneto-optical spin Hall effect of light (MOSHEL) is a useful attempt to implement a dynamic transformation of SHEL. The spin–orbit coupling or non-reciprocal phase shift caused by magnetic fields in different directions applied to magneto-optical materials can be flexibly and timely controlled. This paper reports our studies on the magneto-optical effect in multilayer structure. For the first time, the refractive index of very low concentration sample solution is sensed through the method of weak measurement under the condition of transverse magneto-optical Kerr effect. The ultra-high sensitivity of 2.9×104μm/RIU was measured under the optimum parameters. This is of great significance in advancing the practical application of MOSHEL.

Effects of multi-layer structure on microstructure, wear and erosion performance of the Cr/CrN films on Ti alloy substrate

Titanium alloy usually exhibited poor wear and erosion wear resistance. In this work, Cr/CrN films with different alternating structures of metal Cr layer with ceramics CrN layer were deposited on Ti-6Al-4V (TC4) by multi-arc planting to improve their properties. The result showed the main phases of the Cr/CrN films were Cr, Cr2N and CrN. Addition of the softer Cr layers and multi-layer structures disturbed the columnar growth of CrN layers, suppressed the CrN (111) orientation while promoted the growth of CrN (200) orientation. Also, the grain size decreased and micro-strain increased with increasing the alternating layer numbers. Compared with Ti substrate, the wear resistance of Cr/CrN coated samples significantly improved by decreasing the abrasive wear, and the Cr/CrN-10 film with alternating layer numbers of 10 showed the lower friction coefficient and higher wear resistance. The erosion experiments showed the Cr/CrN-5 film with alternating layer numbers of 5 showed the lower erosion rate, which might be due to the addition of ductile Cr layer conditioning the erosion deformation.

The effect of multilayered film structure on the dielectric properties of composites films based on P(VDF-HFP)/Ni(OH)2

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Measurement and evaluation about heat insulating performance of car door and effect of multilayer structure

Measurement and evaluation about heat insulating performance of car door and effect of multilayer structure

Integrated Heterostructure of PDA/Bi‐AgIn5S8/TiO2 for Photoelectrochemical Hydrogen Production: Understanding the Synergistic Effect of Multilayer Structure

AbstractOvercoming one of most challenging limitations of bare TiO2 with large bandgap can be achieved by rational design and fabrication of heterostructures. Multicomponent sulfides with a nature of tunable band structure can be a good alternative to decorating TiO2, but there remains a major trade‐off between the high efficiency and the long‐term durability, so the stability issue must be addressed upon the use of sulfides. Here, an effective strategy is demonstrated with Bi‐doped AgIn5S8 (Bi‐AgIn5S8) decorated TiO2 photoanode, where twofold enhancement of the photocurrent is achieved. More importantly, it is the first time to integrate polydopamine passivation layer and AgIn5S8 for simultaneously enhancing the solar conversion efficiency and stability. The incident photon‐to‐current conversion efficiency value is tuned up to 45% (0.4 V vs Ag/AgCl), and the photocurrent density can keep for 90.8% after 5 h. Corresponding hydrogen evolution rate has increased to 8.6 µmol h−1, which is three times higher than that of bare TiO2.

Corn husk for noise reduction: Robust acoustic absorption and reduced thickness

Corn husk extracted from maize is a potential candidate for the application of noise reduction. The overall goal of this study is to investigate the acoustic absorption properties of corn husk. The effects of multi-layer structure on the acoustic absorption coefficient were studied. The results indicated that acoustic absorption was not improved with the increase of layers, while the acoustic absorption peak gradually moves to lower frequency direction. Furthermore, it has been observed that the increase of back cavity distance can also increase the absorption coefficient at low frequency range.

Effect of multilayer structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide.

Development of nanoelectronics requires two-dimensional (2D) systems with both direct-bandgap and tunable electronic properties as they act in response to the external electric field (E-field). Here, we present a detailed theoretical investigation to predict the effect of atomic structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide (BP). We demonstrate that the splitting of bands and bandgap of BP depends on the number of layers and the stacking order. The values for the bandgap show a monotonically decreasing relationship with increasing layer number. We also show that AB-stacking BP has a direct-bandgap, while ABA-stacking BP has an indirect-bandgap when the number of layers n > 2. In addition, for a bilayer and a trilayer, the bandgap increases (decreases) as the electric field increases along the positive direction of the external electric field (E-field) (negative direction). In the case of four-layer BP, the bandgap exhibits a nonlinearly decreasing behavior as the increase in the electric field is independent of the electric field direction. The tunable mechanism of the bandgap can be attributed to a giant Stark effect. Interestingly, the investigation also shows that a semiconductor-to-metal transition may occur for the four-layer case or more layers beyond the critical electric field. Our findings may inspire more efforts in fabricating new nanoelectronics devices based on few-layer BP.

Proximity effect in multilayer structures with alternating ferromagnetic and normal layers

The character of the penetration of superconducting correlations into multilayer FF…F, FNFN…FN, and NFNF…NF structures being in contact with a superconductor with the singlet pairing potential has been studied theoretically. Analytical expressions for the effective superconductivity penetration depth in such structures have been obtained in the limit of small layer thicknesses. Numerical calculations taking into account self-consistently the suppression of the superconductivity in the superconductor owing to the proximity effect have been performed at arbitrary thicknesses. A simple analytical dependence approximating the spatial variation of the Green’s function in a multilayer has been proposed. It has been shown that superconductivity is induced by the generation of two channels existing in parallel, one of which is characterized by the smooth (as in SN sandwiches) decay of the superconductivity, while damped oscillations (as in SF structures) take place in the second one.

Photodetectors based on single-walled carbon nanotubes and thiamonomethinecyanine J-aggregates on flexible substrates

The present paper is devoted to observations of the photoresistive effect in multilayer structures with a sensitive layer of J-aggregates of thiamonomethinecyanine polymethine dye and a transparent electrode of a conductive carbon-nanotube network on a flexible polyethylenenaphtalate substrate. The effect of narrow-band emission with a wavelength of 465 nm on a change in the conductivity of the fabricated structures is studied. The prepared samples are studied by atomic-force microscopy, Raman spectroscopy, and spectrophotometry methods. It is shown that these structures are photosensitive to the indicated spectral region, and the dye layer is a film of dye J-aggregates. The change in the sample conductivity upon exposure to light one hundred times exceeds the dark conductivity. In general, the principal possibility of developing a photoresistive detector based on J-aggregates of cyanine dyes on flexible supports on account of the use of transparent and conductive carbon-nanotube layers is shown.

A continuation fixed-point iterative method on harmonic generations with strong nonlinear optical effects in multi-layer structures

A continuation fixed-point iterative method for harmonic generations with strong nonlinear optical effects in one-dimensional nonlinear multi-layer structures, which are governed by the nonlinear Helmholtz systems, is presented in this paper. Three kinds of harmonic generations via \(\chi ^{(2)}\) or \(\chi ^{(3)}\) nonlinear process, which are important phenomena in nonlinear optics, are modeled as the application of our proposed method. In the regime of strong nonlinearity, the theoretical and computational analysis of the model problems encounters enormous challenges due to the discontinuity across layers and the strongly nonlinear coupling of modes. To overcome the difficulties in the nonlinearity and discontinuity, a fixed-point iteration with the finite element method is used to study the nonlinear conversion efficiencies by solving the weak formulations. Furthermore, a continuation technique that depends on the weak formulations to solve three model problems, is introduced to handle the iterative procedure for cases with large nonlinearity. The theoretical framework and numerical algorithm towards a uniform process is offered to study almost all the harmonic generations in \(\chi ^{(2)}\) or \(\chi ^{(3)}\) interaction. With the continuation fixed-point iterative technique, the convergence of the iterative procedure can be ensured, even in the presence of strong nonlinearity. Three numerical experiments with high conversion efficiencies are also presented to show the accuracy and efficiency of our proposed method.

Dirty limit approach for the proximity effect between a two band superconductor and a ferromagnet

The proximity effect in multilayer structures with dirty two band superconductors and ferromagnets is investigated here. With a homogeneous exchange field and interband scattering in the ferromagnetic layer, the condensate functions that penetrate the ferromagnet are coupled up. This coupling effect is intensively suppressed by the exchange field and modulated by the diffusion coefficients of the two bands. Such coupling also affects the superconductor where the condensate functions of the two bands are also coupled up through the proximity effect. An inhomogeneous exchange field raises the damped oscillation of the condensate functions as the spatial distance from the interface increases. There is a 0−π phase shift when the ferromagnetic layer thickness varies beyond the ferromagnetic coherence length.