Multicomponent Nanostructured Coatings Research Articles

Influence of tribological properties of Zr-ZrN-(Zr,Cr,Al)N and Zr-ZrN-(Zr,Mo,Al)N multilayer nanostructured coatings on the cutting properties of coated tools during dry turning of Inconel 718 alloy

The article studies the tribological properties of multicomponent nanostructured coatings of Zr-ZrN-(Zr,Cr,Al)N and Zr-ZrN-(Zr,Mo,Al)N, as well as the wear resistance and fracture behaviour of cutting tools with the mentioned coatings during the turning of Inconel 718 alloy. The Ti–TiN-(Ti,Cr,Al)N coating was also considered as a reference coating. While the Ti–TiN-(Ti,Cr,Al)N coating is characterized by high hardness, it also demonstrated high coefficients of friction (COF) at temperatures of 600 °C and above (i.e., at temperatures in the cutting zone). The Zr-ZrN-(Zr,Mo,Al)N coating has a balanced combination of high hardness and low COF at cutting zone temperatures. As a result, the Zr-ZrN-(Zr,Mo,Al)N-coated tool demonstrated wear resistance 2.4 times higher than that of the Ti–TiN-(Ti,Cr,Al)N-coated tool. During the process of cutting, zirconium (Zr) and chromium (Cr) oxides are formed in the Zr-ZrN-(Zr,Cr,Al)N coating, and the formation of zirconium and molybdenum (Mo) oxides is detected in the Zr-ZrN-(Zr,Mo,Al)N coating, which can have a positive effect on cutting conditions. Under the cutting conditions, the oxidizing action caused an almost complete transformation of a nitride coating structure into an oxide structure, while the nanolayer structure was partially preserved.

Effect of Surface Pre-Treatment on Adhesive Strength of Multi-Component Vacuum-Arc Coatings

The results of investigations of multi-component nanostructured coatings of (TiAlSiY)N/CrN type are presented. The influence of different variants of substrate surface pretreatment on adhesive strength and hardness of coatings was studied. Pre-treatment of samples was carried out in plasma of two-stage gas discharge according to various technological schemes. Except for ion-plasma purification, some samples were pretreated with a sublayer of chromium within 5 minutes. The coatings were formed by a vacuum-arc deposition method at simultaneous spraying of two cathode targets. The first cathode is made of chromium, and the second cathode is made of multicomponent Ti - Al - Si - Y alloy obtained by vacuum-arc remelting of powder mixture of the mentioned elements. The coatings were deposited on polished stainless-steel substrates at negative 280 V bias potential. The geometry of the unit and its elements, as well as technological characteristics of the processes of evaporation-condensation were selected so that at a speed of rotation of samples 8 revolutions per minute the formation of the coating with a total thickness of about 9.0 microns occurred in approximately 60 minutes. The analysis of the composition of the coatings shows that the content of elements in the coating differs greatly from the content of elements in the sprayed cathodes. The X-ray diffractometry has shown that all deposition modes are characterized by the formation of phases with cubic (fcc) crystal lattice in both phase layers of multilayer coatings. In the layers formed at spraying of TiAlSiY alloy, a multi-element disordered solid solution (TiAlSiY)N with a crystal lattice of NaCl type and a lattice parameter of 0.4241 nm, as well as chromium mononitride CrN with a lattice parameter of 0.4161 nm, is determined. It has been established that preliminary formation of a chromium sublayer on the substrate leads to significant changes in adhesive strength of multi-component coatings compared to coatings without a sublayer.

Specificity of Measurements of the Hardness of Thin Functional Coatings Using Sclerometry, Micro- and Nanoindentation Methods

Comparative analysis of sclerometry and micro-, and nanoindentation methods is performed for evaluation of hardness of thin multicomponent nanostructured coatings.

Specific Features of the Microstructure and Properties of Multielement Nitride Coatings Based on TiZrNbAlYCr

Multicomponent nanostructured coatings based on (TiZrNbAlYCr)N with a hardness as high as 47 GPa were obtained by cathodic arc deposition. The effect of partial nitrogen pressure PN (with constant bias potential U b =–200 V applied to the substrate) on the phase-composition variation, the size of crystallites, and their relation to the microstructure and hardness was investigated. An increase in the nitrogen pressure resulted in the formation of two phases with characteristic BCC (the lattice period is 0.342 nm) and FCC lattices with averaged nanocrystallite sizes of 15 and 2 nm. At a high pressure of 0.5 Pa, crystallites in the FCC phase with a lattice period of 0.437 nm grew in size to ~7 nm. The hardness of deposited coatings with larger (3.5 nm) FCC-phase crystallites and smaller (7 nm) BCC-phase crystallites was enhanced considerably.

Structure and properties of (Zr-Ti-Cr-Nb)N multielement superhard coatings

Structure and properties of (Zr-Ti-Cr-Nb)N multicomponent nanostructured coatings fabricated by a vacuum-arc deposition have been investigated. It has been found that the coatings thickness attained 6.2 μm, hardness and indentation load that is responsible for the stress exceeding cohesion strength of coatings were H = 43.7 GPa and L c = 62.06 N, respectively. In coatings structures have been identified that consist of three interstitial phases having cubic, hexagonal, and tetragonal lattices. The nanocrystallites sizes were from 4 to 7.3 nm. The results of the SEM, TEM, EDS, and XRD analysis have been also considered.

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.

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.

Experimental study of the structure of multicomponent nanostructured coatings on the basis of Ti-Zr-N alloys formed by ionic plasma methods

The stabilization and interpretation of properties of ion-plasma-produced multicomponent nanostructured coatings (MNCs) is a fairly complicated problem because of a great variety of factors which influence their characteristics. This work is aimed at the establishment of a correlation between the processes of the production (using vacuum-arc evaporation or a special combined method) of nanodimensional coatings on the basis of the Ti-Zr-N system and the processes proceeding in the near-surface layers of the material of the sputtered and evaporated targets. The coatings were obtained using a modernized URMZ.279.048 setup equipped with two electric-arc vaporizers and four dc magnetrons. The structure, properties, and morphological features of MNCs and the relief of the target surfaces were investigated using a Nanoskan atomic-force microscope, a CARL ZEISS LEO 1430 VP scanning electron microscope, and an Umka scanning tunneling microscope. A difference in the processes that take place on the surface of the evaporated and sputtered targets has been established and their analogy with the processes of MNC formation was revealed for the first time.

Effect of Al, Si, and Cr on the thermal stability and high-temperature oxidation resistance of coatings based on titanium boronitride

The thermal stability and resistance to high-temperature oxidation of multicomponent nanostructured coatings in the Ti-X-B-N (X = Al, Si, Cr) system have been studied using X-ray diffraction analysis, X-ray photoelectron spectroscopy, secondary-ion mass spectroscopy, and transmission electron microscopy. The hardness, elastic modulus, elastic recovery, friction coefficient, wear rate, and adhesion strength of the coatings have been determined. It has been established that Ti-B-N and Ti-Cr-B-N coatings exhibit a stable nanostructure and high stable mechanical and tribological properties up to 1000°C. The coatings with an fcc structure can be also employed as barrier layers preventing diffusion of metal atoms from the substrate. It has been shown that the high resistance to high-temperature oxidation of Ti-Cr-B-N and Ti-Al-Si-B-N coatings is connected with the fact that protective oxide layers based on (Ti,Cr)BO3 and Ti x Al y SiO z are formed on their surface.

Multifunction Nanostructural Coatings for Load-bearing Implants

Development of biomaterials that accelerate adaptation of artificial implants to living tissues and extend implant service is the field at the turn of current biology and material authority, which is now booming. The surface of implants operating under load is modified with multicomponent nanostructured coatings that ensure necessary physical, mechanical, tribological, and biological properties [1‐3]. The fundamentally new approach to designing new biocompatible thin-film materials is that some additional elements (Ca, O, P) are introduced into coatings on the basis of titanium carbide and carbonitride to improve mechanical and tribological properties of the materials and render them bioactive, biocompatible, and non-toxicity. Inorganic admixtures GAP…( Ca 10 (PO 4 ) 6 (OH) 2 ), CaO, and TiO 2 are introduced as soon as at the stage of the composite target obtaining by the method of self-propagating