Multicomponent Coatings Research Articles

Multifunctional Erosion-Resistant Gas-Diffusion Coatings on Steels

Multicomponent coatings on 20 and Kh18N10T steels formed by the method of vacuum activated diffusion saturation are studied. A mixture of B4C, Al, Ni, Si, Cr, and C powders is used as the saturating medium. A thermodynamic analysis of reactions that accompany the titanizing process. Metallographic, micro-hardness, and X-ray diffraction data are discussed. The cavitation–erosion resistance of multicomponent coatings on steels is studied. It is established that these coatings improve the resistance of steel 20; the destruction rate being the same for both 20 and Kh18N10T steels.

Growth of nanowires on the surfaces of multicomponent oxide coatings on titanium

The thermal behavior of Ni- and Cu-containing coatings on titanium formed by plasma electrolytic oxidation and additionally modified with nickel and copper oxides is studied. Annealing of the produced multiphase coatings in air at a temperature of 750°C or higher is shown to result in the growth of surface nanowires, the main components of which are nickel, oxygen, and titanium. The sizes of nanowires depend on the temperature of annealing, and the diameters can be as large as tens or hundreds of nanometers at a length of several to tens of microns. Experimental and literature data show that the combination of plasma electrolytic oxidation with impregnation and annealing is promising for the production of both nanowires bound to metal-oxide substrates and individual nanostructures of certain compositions.

Vapor‐Based Multicomponent Coatings for Antifouling and Biofunctional Synergic Modifications

A general concept is introduced featuring an ideal multifunctional surface that can avoid fouling problems while allowing the installed groups to perform with the high efficacy and accuracy necessary for delivering cascading and spontaneous biological activities. The idea is realized by using a direct synthesis of a multicomponent coating containing the two functionalities of 4‐methyl‐propiolate and 4‐N‐maleimidomethyl that is achieved via chemical vapor deposition copolymerization on various substrates. The novel coating can simultaneously perform specific bio‐orthogonal reactions, including the azide‐alkyne click reaction and a thiol‐maleimide coupling reaction. In the study, azide‐terminated polyethylene glycols are first immobilized on the methyl propiolate groups to impart an antifouling property, while bioactivity is enabled by tethering biotinylated thiols or Cys‐Arg‐Glu‐Asp‐Val (CREDV) peptides on the maleimide groups. The induced antifouling properties and bioactivities are confirmed by quartz crystal microbalance and cell culture studies. Finally, precisely manipulated endothelial cells, namely, human umbilical vein endothelial cells and bovine arterial endothelial cells, are observed on a complex stent substrate and on confined areas of the poly(methyl methacrylate) substrates.

Protection of specimens against friction and wear using titanium-based multicomponent nanocomposite coatings: A review

A review of the experimental results of studying multicomponent nanocomposite protective coatings of various chemical compositions (TiAlCrYN, TiAlSiBN, TiAlSiCuN, CrTiAlSiN, and TiHfSiN/NbN/Al2O3) developed in recent years is presented. An analysis of the available data on the chemical composition, hardness, oxidation resistance, thermal stability, friction, wear, adhesion strength, and corrosion properties of nanocomposite coatings with high physicomechanical characteristics is carried out. The application of the nanocomposite coatings in industry is exemplified using the performance characteristics of drills made from a high-speed steel covered with a multicomponent protective coating.

Electrochemical behavior of multicomponent bioactive nanostructured coatings based on titanium carbonitride

To increase the biointegration of titanium implants, hard bioactive nanostructured coatings based on titanium carbonitride alloyed with phosphorus, calcium, tantalum, and silicon have been suggested and successfully passed approbation. Their influence on the electrochemical properties of coatings in a model biological solution is considered in this study. All coatings are shown to be in a stable passive state, while alloying does not substantially worsen their electrochemical properties. An example of optimizing parameters of vacuum deposition of the coating with the purpose of improving its electrochemical characteristics is considered for one of the compositions.

Superhard coatings of the (Zr-Ti-Si)N and (Ti-Hf-Si)N systems produced by vacuum-arc deposition from a separated flow

Multicomponent hard coatings based on nitrides of Si-doped transition metals have been produced by vacuum-arc deposition with the use of a RF generator and separation of an ion-plasma flux. Physico-mechanical and tribotechnical characteristics of coatings have been studied. The possibility of their use as efficient protective coatings has been shown.

Nanomechanical Properties and Deformation Behaviors of Multi-Component (AlCrTaTiZr)NxSiy High-Entropy Coatings

In this study multi-component (AlCrTaTiZr)NxSiy high-entropy coatings were developed by co-sputtering of AlCrTaTiZr alloy and Si in an Ar/N2 mixed atmosphere with the application of different substrate biases and Si-target powers. Their nanomechanical properties and deformation behaviors were characterized by nanoindentation tests. Because of the effect of high mixing entropies, all the deposited multi-component (AlCrTaTiZr)NxSiy high-entropy coatings exhibited a simple face-centered cubic solid-solution structure. With an increased substrate bias and Si-target power, their microstructures changed from large columns with a [111] preferred orientation to a nanocomposite form with ultrafine grains. The hardness, H/E ratio and H3/E2 ratio of (AlCrTaTiZr)N1.07Si0.15 coating reached 30.2 GPa, 0.12 and 0.41 GPa, respectively, suggesting markedly suppressed dislocation activities and a very high resistance to wear and plastic deformation, attributable to grain refinements and film densification by the application of substrate bias, a nanocomposite structure by the introduction of silicon nitrides, and a strengthening effect induced by severe lattice distortions. In the deformed regions under indents, stacking faults or partial dislocations were formed, while in the stress-released regions, near-perfect lattices recovered.

Predicting self-assembled patterns on spheres with multicomponent coatings

Patchy colloids are promising candidates for building blocks in directed self-assembly, but large scale synthesis of colloids with controlled surface patterns remains challenging. One potential fabrication method is to self-assemble the surface patterns themselves, allowing complex morphologies to organize spontaneously. For this approach to be competitive, prediction and control of the pattern formation process are necessary. However, structure formation in many-body systems is fundamentally hard to understand, and new theoretical methods are needed. Here we present a theory for self-assembling pattern formation in multi-component systems on the surfaces of colloidal particles, formulated as an analytic technique that predicts morphologies directly from the interactions in an effective model. As a demonstration we formulate an isotropic model of alkanethiols on gold, a suggested system for directed self-assembly, and predict its morphologies and transitions as a function of the interaction parameters.

Investigation of (Ti–Zr–Hf–V–Nb)N Multicomponent Nanostructured Coatings before and after Thermal Annealing by Nuclear Physics Methods of Analysis

(Ti–Zr–Hf–V–Nb)N multicomponent nanostructured coatings with thickness of 1.0–1.4 μm synthesized by the method of cathode arc-vapor deposition at temperatures of 250–300°С are investigated by various mutually complementary methods of elemental structural analysis using slow positron beams (SPB), proton microbeam based particle-induced x-ray emission (μ-PIXE), energy-dispersive x-ray spectroscopy (EDS) and scanning electron microscopy (SEM) analyses based on electron micro- and nanobeams, x-ray diffraction (XRD) method of phase structural analysis, and the “a–sin2φ” method of measuring a stressed-strained state (x-ray tensometry). The elemental composition, microstructure, residual stress in nanograins, profiles of defect and atom distributions with depth and over the coating surface in 3D-representation are studied for these coatings, and their phase composition, severely strained state, and composition of coatings before and after annealing at Tann = 600°С for annealing time τ = 30 min are investigated. It is demonstrated that the oxidation resistance of the examined coatings can be significantly increased by high-temperature annealing that leads to the formation of elastic severely strained compression state of the coating. Redistribution of elements and defects, their segregation near the interface boundaries and around grains and subgrains in the process of thermostimulated diffusion, and termination of spinodal segregation without considerable change of the average nanograin size are revealed.

Effective Processes for Arc-Plasma Treatment in Large Vacuum Chambers of Technological Facilities

Characteristics and design features of electrode systems for sources of gas-discharge plasmas produced in an arc discharge in gas sustained by electron emission from a hot cathode and advanced vacuum-plasma facilities relying on them are presented. High values of the parameters and advantageous properties of the plasmas generated by the proposed sources in large vacuum volumes are obtained. Effective techniques and technological processes designed for surface modification of metal parts by the methods of cleaning, alloying (doping), and forming multicomponent composite coatings using low-pressure arc discharges are demonstrated.

AlCuFe(Cr) and AlCoFeCr coatings for improvement of elevated temperature oxidation resistance of a near-α titanium alloy

In this work, an AlCuFe, AlCuFeCr and AlCoFeCr multicomponent coatings were deposited on a near-α titanium alloy, TIMETAL 834, by a non-reactive magnetron sputtering. A microstructure, phase composition, coatings adhesion to the substrate, micro-mechanical properties and oxidation resistance were investigated. The AlCuFe coating was quasicrystalline and consisted of icosahedral ψ-Al65Cu20Fe15 phase grains. The AlCuFeCr coating consisted mainly of decagonal d-AlCuFeCr phase and some Al6.1Cu1.2Ti2.7 phase grains. The AlCoFeCr coating microstructure was composed of AlCrFe2 nanocrystals embedded in an Al13Co4 matrix.It was established that all multicomponent coatings exhibit higher hardness and elastic moduli than the titanium alloy substrate. Among all investigated coatings, the AlCoFeCr one exhibits the best adhesion to the substrate. It was found that a very brittle, non-protective scale formed on the uncoated alloy during isothermal oxidation consisted of TiO2 (rutile) grains. The oxidation resistance of the TIMETAL 834 alloy at elevated temperature (750°C) was significantly improved by the coatings deposition. The smallest weight gain during oxidation test, 82% lower than in the case of uncoated sample, was found for the AlCoFeCr coated alloy. The microstructure investigation of the specimen after oxidation test was performed by SEM and TEM. It was found that the improvement of oxidation resistance of TIMETAL 834 by the coatings deposited in the present work is mainly due to an occurrence of the protective α-Al2O3 scale.

Influence of vacuum-plasma nitride coatings on contact processes and a mechanism of wear of working surfaces of high-speed steel cutting tool at interrupted cutting

The paper presents the studies of mono- and multicomponent nitride vacuum and plasma coatings (Ti100 − xAlx)N, etc. at interrupted cutting. The contact processes during milling and the effect of the coatings on cutting forces, coefficient of friction, tool surface tension, and tool vibration due to variable tangential forces are considered. The influence of the coatings on abrasive wear resistance and resistance to cracking at variable thermal power loading is proved.

Selection of boron based tribological hard coatings using multi-criteria decision making methods

Mechanical and tribological properties of hard coatings can be enhanced using boron as alloying element. Therefore, multicomponent nanostructured boron based hard coatings are deposited on cutting tools by different methods at different parameters. Different mechanical and tribological properties are obtained after deposition, and it is a difficult task to select the best coating material. In this paper, therefore, a systematic evaluation model was proposed to tackle the difficulty of the material selection with specific properties among a set of available alternatives. The alternatives consist of multicomponent nanostructured TiBN, TiCrBN, TiSiBN and TiAlSiBN coatings deposited by magnetron sputtering and ion implantation assisted magnetron sputtering at different parameters. The alternative coating materials were ranked by using three multi-criteria decision-making (MCDM) methods, i.e. EXPROM2 (preference ranking organization method for enrichment evaluation), TOPSIS (technique for order performance by similarity to ideal solution) and VIKOR (VIšekriterijumsko KOmpromisno Rangiranje), in order to determine the best coating material for cutting tools. Hardness (H), Young’s modulus (E), elastic recovery, friction coefficient, critical load, H/E and H3/E2 ratios were considered as material selection criteria. In order to determine the importance weights of the evaluation criteria, a compromised weighting method, which composes of the analytic hierarchy process and Entropy methods, were used. The ranking results showed that TiBN and TiSiBN coatings deposited at given parameters are the best coatings for cutting tools.

Peculiarities of structural phase and elastic stress states of superhard TiN-based nanocomposite coatings

A new concept of designing nanocomposite coatings is proposed. The concept consists in microstructural self-organization through simultaneous nucleation of islands of different mutually insoluble or slightly soluble phases at the stage of coating formation. Physical principles on which to select compositions of the coatings were developed and were experimentally verified on multicomponent nanocomposite coatings. With a Sprut magnetron arc plasma complex, superhard (Hμ > 40 GPa) multicomponent nanocomposite coatings of the system Ti-Al-Si-Cr-Ni-Cu-O-C-N were obtained. The peculiarities of structural phase and elastic stress states of the multicomponent coatings before and after annealing at a temperature of up to 1000 °C were studied by transmission electron microscopy, X-ray diffraction analysis, microhardness measurements and scratch tests. The study reveals a wide range of lattice bending-torsion (up to 200° μm−1) of nanosized (less than 30 nm) coherent scattering regions in the two-level coating structure and of individual (up to 15 nm) TiN nanocrystals. Annealing of the coatings causes the two-level grain structure to relax with the formation of TiN-based nanocrystals of size less than 30–40 nm and with a decrease in lattice bending-torsion down to 40°–50° μm−1. Comparative analysis of acoustic emission signals and tracks of the multicomponent and TiN coatings in scratch tests points to an increase in fracture ductility in the multicomponent coatings.

On the Concentration Unsteadiness of Chemical Vapour Deposition with a Precursor Sublimated from Packed Bed of Solid Source. Problems with Multicomponent Coatings

Abstract In some CVD processes the precursor is introduced into the reactor as vapor obtained by sublimation from particles of solid source forming packed bed in a column, where through a carrier gas passes. A typical example is the deposition of metal or metal oxide using its carbonyl compound. The study evaluates by mathematical modeling the effect of particle size reduction due to sublimation on the composition of the gas phase entering the reactor. A set of differential equations describing the convective solid to gas mass transfer process in the column is formulated. Equations for precursor equilibrium partial pressure, mass transfer coefficient, diffusivity and axial dispersion coefficient found from literature are added and the model is solved numerically by the method of finite differences. On the example of W(CO) 6 the influence of the carrier gas flow rate, temperature and CVD duration on the change of the precursor concentration is revealed. The calculated alterations are significant and may spoil the running experiments. As to prevent this problem three approaches are suggested allowing the maintenance of the reactor inlet precursor concentration in reasonable limits: (i) to use a sufficiently high initial bed for saturation of the carrier gas during the entire particular experiment; (ii) to increase step-by- step in time the bed temperature; (iii) to increase step-by-step in time the carrier gas velocity in the column on the account of its stream by-passing the column. In all three approaches the model allows to calculate the necessary factors, i.e. the sufficient bed height, the temperature and velocity increment in time. Some numerical experiments employing the suggested approaches with approximately constant precursor concentrations are illustrated. Approaches how to proceed when multicomponent coating is to be deposited are discussed. The main conclusion is that the CVD processes should be carefully prepared accounting for a possible unsteadiness and the concentration of the precursor at the reactor inlet should be monitored.

New Trends in Non-Destructive Evaluation of Surface Hardened Layers and Coatings

This article should not be considered as a full review of current methods for non-destructive testing of surface layers. Rather, it is a subjective in this area. However, the article provides some review of the challenges posed by the current state of surface layers treatment techniques on the area of Non-Destructive materials evaluation: enhancement of the sensitivity to the type of defects, increasing resolution to submicron values, the requirement to diagnose the surface layers with depth resolution of properties, diagnosis of multilayer multicomponent surface layers and coatings, treated with concentrated energy.

Influence of thermodiffusion coatings on the mechanical properties of VT14 titanium alloy

We study the influence of various functional coatings with similar morphologies (oxide, nitride, carbonitride, and carboxide) formed by thermodiffusion saturation on the mechanical properties (short-term strength, plasticity, susceptibility to delayed fracture, fatigue life under the conditions of low-cycle and rotation bending) of thermally hardened VT14 high-strength (α +β) -titanium alloy (Ti–(3.5–6.3)%, Al–(2.5–3.8)%, Мо–(0.9–1.9)% V). It is shown that, for the analyzed morphology of the modified layer, the weakest influence on the mechanical properties is exerted by the two-component oxide coating and that the influence of all coatings strongly depends on the size factor (the ratio of the area of the metal occupied by the modified layer to the working section). The multicomponent coatings based on ternary interstitial compounds (carbonitrides and carboxides) give higher strength characteristics in combination with the comparable characteristics of the fatigue resistance and plasticity.

Finite element solution of coupled-partial differential and ordinary equations in multicomponent polymeric coatings

Mass transport equations in multicomponent polymeric coatings are nonlinear coupled partial differential equations. These equations were solved using Galerkin's method of finite elements which converts them to ordinary differential equations. Residuals were made orthogonal by using quadratic basis functions. Non-uniform elements were used to capture steep concentration gradient near the top of the coating. Finite element formulation has been solved using ode15s of MATLAB. Results are in very good agreement with the earlier results using different solution techniques.

Nanostructured Arc-PVD coatings based on titanium and chromium nitrides

Multicomponent nanostructured coatings based on Ti-Cr-Al-N nitrides with a crystallite size of 10–100 nm are formed by arc physical vacuum deposition. The dependences of the structure and phase composition of the coatings on the deposition parameters, namely, the bias potential applied to a substrate and the arc current at a chromium cathode, are found. The appearance of chromium nitride phases in the coatings is accompanied by a decrease in the crystallite size. The hardness (up to 32 GPa) and the elastic modulus (up to 700 GPa) of the coatings are determined by both the crystallite size and the microstrains (up to 0.74%) induced by chemical heterogeneity in the coatings. The adhesion strength of the coatings is estimated at 90 N. Cutting hard-alloy tools with the grown coatings are characterized by a high resistance coefficient during continuous (up to 5.1) and discontinuous (up to 5.7) cutting of 38KhNMA steel.

Mechanical performance and nanoindenting deformation of (AlCrTaTiZr)NCy multi-component coatings co-sputtered with bias

This work develops (AlCrTaTiZr)NCy multi-component coatings by co-sputtering of AlCrTaTiZr alloy and graphite in an Ar/N2 mixed atmosphere with the application of different substrate biases. All the (AlCrTaTiZr)NCy coatings deposited in different conditions exhibited a simple face-centered cubic structure. As the applied substrate bias and graphite-target power increased, the (AlCrTaTiZr)NCy coatings transformed from a large columnar structure with a [111] preferred orientation to a dense, ultrafine nanocomposite structure. With increasing substrate bias and graphite-target power, the hardness, H/E ratio and H3/E2 ratio of the coatings increased from 20 to 35GPa, from 0.07 to 0.12 and from 0.10 to 0.43GPa, respectively, attributed to the densification of the coatings, the refinement of grains, the introduction of covalent-like carbide bonds, the formation of nanocomposite structure and the existence of large lattice distortions. Because of the severe distortions in the multi-component coatings caused by the addition of differently-sized atoms, the deformation mechanism was dominated by the activity of low-angle dislocations and/or stacking faults.