Search Results (30)

With the rapid advancement of high-precision optical systems, increasingly stringent demands are imposed on the surface figure accuracy of optical components. The magnitude of residual stress in multilayer films directly influences the post-coating surface figure stability of these components, making the control of multilayer film stress a critical factor in enhancing optical surface figure accuracy. In this study, which addresses the process constraints and substrate damage risks associated with conventional annealing-based stress compensation for large-aperture optical components, we introduce an active stress engineering strategy rooted in in situ deposition process optimization. By systematically tailoring film deposition parameters and adjusting the thickness modulation ratio of TiO₂ and SiO₂, we achieve dynamic compensation of residual stress in multilayer structures. This approach demonstrates broad applicability across diverse optical coatings, where it effectively mitigates stress-induced surface distortions. Unlike annealing methods, this intrinsic stress polarity manipulation strategy obviates the need for high-temperature post-processing, eliminating risks of material decomposition or substrate degradation. By enabling precise nanoscale stress regulation in large-aperture films through controlled process parameters, it provides essential technical support for manufacturing ultra-precision optical devices, such as next-generation laser systems and space-based stress wave detection instruments, where minimal stress-induced deformation is paramount to functional performance. Full article

This study investigates the nanomechanical and tribological behavior of multilayered nitride/carbonitride nanostructured superlattice type coatings (NTCs) composed of alternating TiAlSiNb-N and TiCr-CN sublayers, deposited via high-power ion-plasma magnetron sputtering (HiPIPMS) technique. Reinforced with refractory elements Cr and Nb, the NTC samples exhibit high nanohardness (39–59 GPa), low friction, and excellent wear resistance. A novel analytical approach was introduced to extract stress–strain field (SSF) gradients and divergences from nanoindentation data, revealing alternating strain-hardening and strain-softening cycles beneath the incrementally loaded indenter. The discovered oscillatory behavior, consistent across all samples under the investigation, suggests a general deformation mechanism in thin films under incremental loading. Fourier analysis of the SSF gradient oscillatory pattern revealed a variety of characteristic dominant wavelengths within the length-scale interval (0.84–8.10) nm, indicating multi-scale nanomechanical responses. Additionally, the NTC samples display an anisotropic coating morphology exhibited as unidirectional undulating surface roughness waves, potentially attributed to atomic shadowing, strain-induced instabilities, and limited adatom diffusion. These findings deepen our understanding of nanoscale deformation in advanced PVD coatings and underscore the utility of SSF analysis for probing thin-film mechanics. Full article

TiAlSiN and AlCrN coatings are two representative coatings with excellent properties in TiN-based and CrN-based coatings, respectively. Multilayering is one of the most important directions for coating performance optimization. In this paper, nanoscale monolayer TiAlSiN, AlCrN, and multilayer TiAlSiN/AlCrN coatings were prepared. The microstructure, mechanical properties, oxidation resistance, and wear resistance of the above three coatings were investigated. The following properties of the TiAlSiN/AlCrN coating, including phase, nanohardness, elastic modulus, adhesion strength, and oxidation resistance, fall between those of the TiAlSiN and AlCrN coatings and conform to the “law of mixtures”. Due to the interfacial effect of the multilayer coating, the residual stress of the TiAlSiN/AlCrN coating is less than that of the two monolayer coatings. At 500 °C, the order of wear resistance of the three coatings is consistent with the order of H³/E*² values, i.e., TiAlSiN > TiAlSiN/AlCrN > AlCrN; at 800 °C, the order of wear resistance becomes TiAlSiN/AlCrN > TiAlSiN > AlCrN because TiAlSiN coating has entered the rapid oxidization stage first, reducing its wear resistance. Full article

This research is aimed at studying the properties of polymer anticorrosion coatings based on ED-20 resin widely used in practice and industrial wastes. In this work, three basic types of nanoscale nanofillers were chosen: dispersed particles—microsilica, microspheres obtained at Kazakh enterprises, and carbon nanotubes. Physicochemical research methods were used in the research: a laser analyzer for studying the dispersibility of industrial waste and spectrometric research methods. The properties of materials were investigated by standardized methods. The obtained results show that the introduction of microsilica and microspheres obtained at Kazakhstani enterprises, used as additives, improves both the physical and mechanical properties of epoxy composites compared to the standard (control) material. The results of experiments have shown that the optimal content of additives of microsilica and microspheres provides an improvement in the physical and mechanical properties of epoxy composites in comparison with the standard (control) material. Studies have shown that the introduction of microspheres into ED-20 polymer increases impact toughness. The introduction of microsilica into the matrix contributes to the increase of elastic modulus. Experimental studies of optical properties of samples of carbon composite polymer films based on polystyrene (PS) with additives of carbon nanotubes C₆₀ and C₇₀ and multilayer carbon nanotubes were also carried out. The experimental results obtained for the optical properties of polymer composites based on basic polymers from solid waste and carbon nanotubes showed that the optical properties of polymer composites undergo noticeable changes. Full article

This paper presents the results of the study of stress relaxation fields, deformation, and temperature of the system of nanostructured multilayer coatings. In the work, a nonlinear relationship between strain and stress was used to take into account nonlinear effects in the mechanism of nanostructure formation. The paper assumes that a friction surface is provided by the self-organization of shear components: both stress and strain on the one hand, and temperature on the other. The studied objects are described in the adiabatic approximation, taking into account the fact of the evolution of stresses and strains. With the help of phase portraits of the system, the dependence of the deformation processes on the stresses arising in the system without coating and with coating is shown. It is shown that the rate of change of deformation depends on the characteristics of the mechanical impact on the coating and on the amount of stress and deformation. A conclusion is drawn regarding the transition process in the presence of two regions (Hooke and plastic deformation) in the corresponding phase portrait of the strain–stress field of the system. The results of the work can be used to determine the effective parameters of a coating in the analysis of experimental time dependences of stresses. Full article

Zr/Nb nanoscale multilayer coatings (NMCs) were studied after hydrogenation in a gaseous environment at 400 °C. The hydrogen distribution and content were determined by pressure and hydrogenation time. Increasing the pressure from 0.2 to 2 MPa resulted in different hydrogen distribution within the Zr/Nb NMCs, while the concentration remained constant at 0.0150 ± 0.0015 wt. %. The hydrogen concentration increased from 0.0165 ± 0.001 to 0.0370 ± 0.0015 wt. % when the hydrogenation time was extended from 1 to 7 h. The δ-ZrH hydride phase was formed in the Zr layers with Zr crystals reorienting towards the [100] direction. The Nb(110) diffraction reflex shifted towards smaller angles and the interplanar distance in the niobium layers increased, indicating significant lateral compressive stresses. Despite an increase in pressure, the nanohardness and Young’s modulus of the Zr/Nb NMCs remained stable. Increasing the hydrogen concentration to 0.0370 ± 0.0015 wt. % resulted in a 40% increase in nanohardness. At this concentration, the relative values of the Doppler broadening variable energy positron annihilation spectroscopy (S/S₀) increased above the initial level, indicating an increase in excess free volume due to hydrogen-induced defects and changes. However, the predominant positron capture center remained intact. The Zr/Nb NMCs with hydrogen content ranging from 0.0150 ± 0.0015 to 0.0180 ± 0.001 wt. % exhibited a decrease in the free volume probed by positrons, as demonstrated by the Doppler broadening variable energy positron annihilation spectroscopy. This was evidenced by opposite changes in S and W (S↓W↑). The microstructural changes are attributed to defect annihilation during hydrogen accumulation near interfaces with the formation of hydrogen–vacancy clusters and hydrides. Full article

CrWN/MoN nano-multilayer coatings were deposited in pure N₂ by multi-arc ion plating using CrW and Mo targets, with the cathode co-controlled by a permanent magnet combined with an electromagnet. The effects of the thickness modulation period on the microstructure and mechanical and tribological performance were systematically analyzed by grazing-incident X-ray diffraction (GIXRD), transmission electron microscopy (TEM), Nanoindentation, scanning electron microscope (SEM) and profilometry using a Talysurf profilometer. The local coherent interfaces and nanoscale modulation period were confirmed by TEM, while the coatings were confirmed to be composed of fcc-CrWN and hexagonal δ-MoN by GIXRD. With the increase in the modulation period, the hardness of the CrWN/MoN nano-multilayer coatings decreased, and the values of the H/E ratio and friction coefficient showed the same variation trend. At an 8.0 nm modulation period, the CrWN/MoN nano-multilayer coating showed the maximum hardness (30.2 GPa), the lowest H/E value (0.082) and an H³/E*² value of 0.16. With the decrease in the modulation period, the average friction coefficient of the CrWN/MoN nano-multilayer coatings gradually decreased from 0.45 to 0.29, while the wear rate decreased from 4.2 × 10⁻⁷ mm³/Nm to 3.3 × 10⁻⁷ mm³/Nm. Full article

Deposition of (Ti-Al)N/MoN multilayered coatings was carried out through a cathodic ion-plating system in an argon and then nitrogen atmosphere. Bilayer thickness (Λ) of all the samples were achieved, from 22 to 104 nm, by organizing substrate holder rotational speed (SRS). To obtain the optimum properties of the (Ti-Al)N/MoN coatings, the Ti and Al ratio was maintained at a level of 1:1. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were utilized to analyze the crystal structure and morphology of the coatings. Mechanical and tribological properties were examined by nanohardness and atomic force microscopy (AFM). The preferred orientation of the (Ti-Al)N/MoN nanoscale multilayer films was TiAlN (200) and MoN (200), which had face centered cubic (fcc) and hexagonal structures, respectively. The hardness increased with the decrease in Λ (104 nm to 26 nm), and then it increased. The highest hardness of 37 GPa was revealed at Λ = 26 nm, whereas the least wear rate of 8.09 × 10⁻⁷ mm³/N.m was attained at Λ = 22 nm. Wear rate, roughness, and coefficient of friction were decreased with decreasing bilayer period. EDS results showed that Al and Ti contents were almost the same in all samples, as per design of the experiment. Full article

A first-principles study of the atomic structure and electron density distribution at the Zr/Nb interface under the influence of helium impurities and helium–vacancy complexes was performed using the optimised Vanderbilt pseudopotential method. For the determination of the preferred positions of the helium atom, the vacancy and the helium–vacancy complex at the interface, the formation energy of the Zr-Nb-He system has been calculated. The preferred positions of the helium atoms are in the first two atomic layers of Zr at the interface, where helium–vacancy complexes form. This leads to a noticeable increase in the size of the reduced electron density areas induced by vacancies in the first Zr layers at the interface. The formation of the helium–vacancy complex reduces the size of the reduced electron density areas in the third Zr and Nb layers as well as in the Zr and Nb bulk. Vacancies in the first niobium layer near the interface attract the nearest zirconium atoms and partially replenish the electron density. This may indicate a possible self-healing of this type of defect. Full article

The effect of proton irradiation on the structure, phase composition, defect state and nanohardness of Zr/Nb nanoscale multilayer coatings was investigated. Preservation of the Zr/Nb layered structure with 50 and 100 nm thick layers, was observed after irradiation with protons at 1720 keV energy and 3.4 × 10¹⁵, 8.6 × 10¹⁵ and 3.4 × 10¹⁶ ions/cm² fluences, and the interfaces remained incoherent. In the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10 and 25 nm, there were insignificant fluctuations in interplanar distance, which were influenced by changes in irradiation fluence, and the interfaces were partially destroyed and became semicoherent. Changing irradiation fluence in the investigated ranges led to a decrease in the nanohardness of the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10–50 nm. Variable-energy positron Doppler broadening analysis revealed that these changes are primarily caused by peculiarities of the localization and accumulation of the embedded ions and do not cause a significant increase in the S-parameters of Zr/Nb nanoscale multilayer coatings with a layer thickness less than 100 nm. Full article

The effect of helium ion irradiation on the microstructure and properties of composites based on Zr/Nb nanoscale multilayer coatings (NMCs) was studied. X-ray diffraction (XRD), transmission electron microscopy (TEM), and variable-energy Doppler broadening spectroscopy (DBS) were used for the in-depth analysis of defects in the irradiated NMCs. After irradiation of the Zr/Nb NMCs with helium ions at a 10¹⁷ ion/cm² dose, the layered structure was generally retained, but the internal stresses in the layers were increased, which caused wave-like distortion in the ion deposition zone. The Zr/Nb NMCs with an individual layer thickness of 25 nm were characterized by the smallest microstress changes, but single blisters were formed in the near-surface region. The microstructure of the Zr/Nb NMCs with a layer thickness of 100 nm exhibited relatively smaller changes upon helium ion irradiation. The prevailing positron-trapping center was the reduced-electron-density area at the interfaces before and after irradiation of the Zr/Nb NMCs regardless of the layer thickness. However, the layer thickness affected the DBS parameter profiles depending on the positron energy, which was probably due to the different localization of implanted ions within the layers or at the interfaces. Full article

Radiation damage is one of the significant factors limiting the operating time of many structural materials working under extreme conditions. One of the promising directions in the development of materials that are resistant to radiation damage and have improved physical and mechanical properties is the creation of nanoscale multilayer coatings (NMCs). The paper is devoted to the experimental comprehension of changes in the defect structure and mechanical properties of nanoscale multilayer coatings (NMCs) with alternating layers of Zr and Nb under irradiation. Series of Zr/Nb NMCs with different thicknesses of individual layers were fabricated by magnetron sputtering and subjected to H+ irradiation. The evolution of structure and phase states, as well as the defect state under proton irradiation, was studied using the methods of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction analysis (XRD), glow discharge optical emission spectroscopy (GDOES), and positron annihilation spectroscopy (PAS). The layer-by-layer analysis of structural defects was carried out by Doppler broadening spectroscopy (DBS) using a variable-energy positron beam. To estimate the binding energy and the energy paths for the hydrogen diffusion in Zr/Nb NMCs, calculations from the first principles were used. When the thickness of individual layers is less than 25 nm, irradiation causes destruction of the interfaces, but there is no significant increase in the defect level, the S parameter (open volume defects amount) before and after irradiation is practically unchanged. After irradiation of NMC Zr/Nb with a thickness of layers 50 and 100 nm, the initial microstructure is retained, and the S parameter is significantly reduced. The GDOES data reveal the irregular H accumulation at the interface caused by significant differences in H diffusion barriers in the bulk of Zr and Nb multilayers as well as near the interface’s region. Full article

Optimization of the composition of a new generation of bi-nano-multilayered TiAlCrSiN/TiAlCrN-based coatings is outlined in this study for the machining of direct aged (DA) Inconel 718 alloy. Three types of TiAlCrSiN/TiAlCrN-based bi-nano-multi-layer coatings with varying chemical compositions were investigated: (1) a previous state-of-the-art Ti_0.2Al_0.55Cr_0.2Si_0.03Y_0.02N/Ti_0.25Al_0.65Cr_0.1N (coating A); (2) Ti_0.2Al_0.52Cr_0.2Si_0.08N/Ti_0.25Al_0.65Cr_0.1N with increased amount of Si (up to 8 at.%; coating B); (3) a new Ti_0.18Al_0.55Cr_0.17Si_0.05Y_0.05N/Ti_0.25Al_0.65Cr_0.1N coating (coating C) with an increased amount of both Si and Y (up to 5 at.% each). The structure of each coating was evaluated by XRD analysis. Micro-mechanical characteristics were investigated using a MicroMaterials NanoTest system and an Anton Paar-RST3 tester. The wear performance of nano-multilayered TiAlCrSiN/TiAlCrN-based coatings was evaluated during the finish turning of direct aged (DA) Inconel 718 alloy. The wear patterns were assessed using optical microscopy imaging. The tribological performance was evaluated through (a) a detailed chip characteristic study and (b) XPS studies of the worn surface of the coated cutting tool. The difference in tribological performance was found to correspond with the type and amount of tribo-films formed on the friction surface under operation. Simultaneous formation of various thermal barrier tribo-films, such as sapphire, mullite, and garnet, was observed. The overall amount of beneficial tribo-films was found to be greater in the new Ti_0.18Al_0.55Cr_0.17Si _0.05Y_0.05N/Ti_0.25Al_0.65Cr_0.1N nano-bi-multilayer coating (coating C) than in the previous state-of-the-art coatings (A and B). This resulted in over two-fold improvement of this coating’s tool life compared with those of the commercial benchmark AlTiN coating and coating B, as well as a 40% improvement of the tool life of the previous state-of-the-art coating A. Multi-scale self-organization processes were observed: nano-scale tribo-film formation on the cutting tool surface combined with micro-scale generation of strain-induced martensite zones as a result of intensive metal flow during chip formation. Both of these processes are strongly enhanced in the newly developed coating C. Full article

Nanomaterials and nanostructures provide new opportunities to achieve high-performance optical and optoelectronic devices. Three-dimensional (3D) surfaces commonly exist in those devices (such as light-trapping structures or intrinsic grains), and here, we propose requests for nanoscale control over nanostructures on 3D substrates. In this paper, a simple self-assembly strategy of nanospheres for 3D substrates is demonstrated, featuring controllable density (from sparse to close-packed) and controllable layer (from a monolayer to multi-layers). Taking the assembly of wavelength-scale SiO₂ nanospheres as an example, it has been found that textured 3D substrate promotes close-packed SiO₂ spheres compared to the planar substrate. Distribution density and layers of SiO₂ coating can be well controlled by tuning the assembly time and repeating the assembly process. With such a versatile strategy, the enhancement effects of SiO₂ coating on textured silicon solar cells were systematically examined by varying assembly conditions. It was found that the close-packed SiO₂ monolayer yielded a maximum relative efficiency enhancement of 9.35%. Combining simulation and macro/micro optical measurements, we attributed the enhancement to the nanosphere-induced concentration and anti-reflection of incident light. The proposed self-assembly strategy provides a facile and cost-effective approach for engineering nanomaterials at 3D interfaces. Full article

Nanoscale coatings are attractive for managing the biological/material interface as well as for transport control in medical device applications. Construction of biologically derived and mimicking polyelectrolyte multilayers (BioPEMs) and their chemically crosslinked derivatives was evaluated at the nanometer scale and the glucose mass transfer properties were characterized in a physiological environment. Glucose diffusivity through all the BioPEMs was found to be three to four orders of magnitude lower than that of bare substrate. In contrast, permeation rates (dC/dt) were significantly higher than when compared to films comprising the same number of bilayers of synthetic materials—poly(acrylic acid)/poly(allylamine hydrochloride). Crosslinked BioPEMs exhibited decreased diffusivity of glucose up to 51% compared to native BioPEMs. These findings provide fundamental insight into the transport properties of BioPEM coatings that may be useful in maximizing biomimetic properties while also controlling permeation of small molecules in applications such as sensors, filtration, and drug delivery systems. Full article