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Using the method of high-frequency ion-plasma sputtering (magnetron high-frequency deposition under conditions of ion-plasma assisted using a gas (argon) plasma generator «PINK») on the surface of a high-entropy CoFeCrMnNi alloy of non-equiatomic composition. Boron-containing coatings of the elemental composition Al – Mg – B and Mg – Ti – B with a thickness of 3 μm are formed. Using transmission electron diffraction microscopy, it was found that the coatings are amorphous-crystalline, i.e. contain nanosized 1.5-2 nm islands of the crystalline phase located in an amorphous matrix. It is shown that the coating deposition is accompanied by the formation in the substrate layer (high-entropy alloy) adjacent to the coating of a nanocrystalline structure with a crystallite size of 25-40 nm. At the boundaries of the crystallites, particles of iron boride of the FeB and Fe3B compositions are revealed, which indicate the penetration of boron into the substrate. The particle size of iron boride is 5-8 nm.

Using plasma surfacing in a nitrogen environment with a PP-R18U non-current-carrying flux-cored wire, the layers up to 10 mm thick were formed on a 30HGSA steel, followed by an additional high-temperature tempering (at 580°C for 1 hour in 4 tempers). It is shown that the deposited layer has a frame-type structure formed by α-iron grains with extended layers of the Fe3W3C (M6C) carbide phase located along the boundaries. Nanosized particles of carbides of the V4C3, Cr7C3, Fe3C, Cr23C6 and WC1–x types are identified in the grain volume. It is found out that high tempering increases the microhardness of the deposited PP-R18U layer by 13% (up to 5.3 GPa) and decreases its wear resistance by 12.3% the friction coefficient by 7.7%. [ABSTRACT FROM AUTHOR]

This article reports the results of comparative studies of the composition, structure, high-temperature oxidation resistance, mechanical and tribological properties of (MoTaNbZrHf)-Si-B coatings prepared at an identical average power of 1 kW by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS). Switching from the DCMS to the HIPIMS mode is found to increase adhesion and crack resistance of the coatings and their wear resistance under friction sliding and cyclic impact conditions, as well as reduce the depth of oxidation at 1300 °C threefold. The record-breaking values of high-temperature oxidation resistance at 1500 °C are achieved due to formation of a surface film based on the borosilicate glass (a-Si:B:O) containing crystallites of the t-HfSiO 4 , o-Ta 2 O 5 , m-HfO 2 , and m-ZrO 2 phases. [Display omitted] • A multilayer target with a (MoTaNbZrHf)-Si-B working layer was produced. • DCMS and HIPIMS coatings exhibited a hardness of 13–14 GPa. • The transition from DCMS to HIPIMS improves crack- and wear resistance. • The coatings demonstrated high oxidation resistance at 1100–1500 °C. [ABSTRACT FROM AUTHOR]

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1 N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °C temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1 N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-B-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °C) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

Different approaches to formation of hard multicomponent coatings with improved tribological characteristics in a wide temperature range are considered. It is shown that deposition of a thin surface layer or introduction of additional structural components into nanocomposite coatings, which play the role of a solid lubricant, lowers substantially the friction factor and increases the wear resistance [ABSTRACT FROM AUTHOR]

Highlights: [•] TiN/TiCN multilayer film was conducted by application of an argon plasma process. [•] After argon plasma treatment, the film structure was changed significantly. [•] The mechanical properties of the treated film were enhanced accordingly. [•] The friction coefficient of TiN layer was reduced by argon plasma treatment. [ABSTRACT FROM AUTHOR]

Abstract: The effect of Zr and O incorporation on the structure and properties of TiC(N) coatings deposited by DC magnetron sputtering of composite TiC0.5 + xZrO2 (x =10 and 20wt.%) and (Ti,Zr)C0.5 +10%ZrO2 targets in an argon atmosphere or reactively in a gaseous mixture of Ar+N2 is presented. The structure, elemental and phase composition of the coatings were studied by means of X-ray diffraction, scanning electron microscopy, and glow discharge optical emission spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery using the load–depth-sensing nanoindentation method. Tribological properties were investigated using ball-on-disk tests against cemented carbide at 25°C and alumina in the temperature range of 25–500°C. To evaluate the oxidation resistance, the coatings were annealed in air at 400, 550, and 600°C for 1h. The obtained results show that the TiZrCO(N) coatings exhibit a peak hardness versus nitrogen partial pressure. The coatings with maximum hardness tested at room temperature against WC+Co and Al2O3 counterparts showed low friction coefficients below 0.25. At higher temperatures 300–500°C, the friction coefficient against an Al2O3 ball was recorded to be 0.6. The tribological tests of the coatings demonstrated their high wear resistance at moderate temperatures 25–300°C (wear rate, k ~10−6 mm3N−1 m−1). Moreover, the coatings with high Zr content were the most wear resistant. The oxidation resistance of the Zr-doped TiCON coatings was not as high as expected and restricted by 600°C. The combination of high hardness about 40GPa with low friction coefficient and superior wear resistance makes the TiZrCON coatings promising candidates for various dry tribological applications. [Copyright &y& Elsevier]

Abstract: Nanocomposite coatings of CrN–WS2 were prepared at different Cr contents (approximately 8–39at%) using an unbalanced magnetron sputtering system. Structural changes in CrN–WS2 coatings with variation in Cr content were studied using X-ray diffraction. CrN–WS2 coatings displayed a dense, compact microstructure with reduced columnar growth in the field emission scanning electron microscopy data. Nanoindentation and nanoscratch data showed that CrN–WS2 coatings exhibited improved mechanical and adhesive properties, respectively. Micro-tribometer tests at a load of 2 N indicated that CrN–WS2 coatings prepared at 31at% Cr exhibited a stable friction coefficient of 0.20–0.24 even after 8h. [Copyright &y& Elsevier]

Abstract: The aim of this work was a comparative investigation of the structure and properties of Al- and Cr-doped TiSiCN coatings deposited by magnetron sputtering of composite TiAlSiCN and TiCrSiCN targets produced by self-propagating high-temperature synthesis method. Based on X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy data, the Al- and Cr-doped TiSiCN coatings possessed nanocomposite structures (Ti,Al)(C,N)/a-(Si,C) and (Ti,Cr)(C,N)/a-SiCxNy/a-C with cubic crystallites embedded in an amorphous matrix. To evaluate the thermal stability and oxidation resistance, the coatings were annealed either in vacuum at 1000, 1100, 1200, and 1300°C or in air at 1000°C for 1h. The results obtained show that the hardness of the Al-doped TiSiCN coatings increased from 41 to 46GPa, reaching maximum at 1000°C, and then slightly decreased to 38GPa at 1300°C. The Cr-doped TiSiCN coatings demonstrated high thermal stability up to 1100°C with hardness above 34GPa. Although both Al- and Cr-doped TiSiCN coatings possessed improved oxidation resistance up to 1000°C, the TiAlSiCN coatings were more oxidation resistant than their TiCrSiCN counterparts. The TiCrSiCN coatings showed better tribological characteristics both at 25 and 700°C and superior cutting performance compared with the TiAlSiCN coatings. [Copyright &y& Elsevier]

Abstract: A comparative investigation of the structure and properties of TiAlC(N), TiCrAlC(N), and CrAlC(N) coatings deposited by sputtering of МАХ-phase Ti2− х Cr х AlC targets (where x =0, 0.5, 1.5, and 2) in an Ar atmosphere or in a gaseous mixture of Ar+N2 is presented. The coatings were characterized in terms of their structure, elemental and phase composition, hardness, elastic modulus, elastic recovery, thermal stability, friction coefficient, wear rate, corrosion, and high-temperature oxidation resistance. The structure of the coatings was studied by means of X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, glow discharge optical emission spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. To evaluate the thermal stability and oxidation resistance, the coatings were annealed either in vacuum or in air at temperatures 600–1200 °C. The results obtained show that the TiAlCN coatings possess high hardness of 32–35 GPa, low friction coefficient against WC–Co well below 0.25, high thermal stability up to 1200 °C, and superior performance in dry milling tests against high Cr steel. Meanwhile, the coatings with high Cr content demonstrated improved oxidation resistance up to 1000 °C and superior electrochemical behavior, but their mechanical and tribological properties were deteriorated. [Copyright &y& Elsevier]

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, "pin-on-disc" tribological testing and "ball-on-plate" impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1 N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °C temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating's elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1 N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-B-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °C) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate. [ABSTRACT FROM AUTHOR]

Coatings in a Zr-Mo-Si-B-N system were deposited by the magnetron sputtering of ZrB2-MoSi2 targets in argon and nitrogen. The structure of the coatings was investigated using scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and glow-discharge optical emission spectroscopy. Mechanical and tribological properties were measured using nanoindentation and pin-on-disc testing. Oxidation resistance and oxidation kinetics were estimated via annealing in air at 1000–1500 °C and precision weight measurements. We found that the coatings deposited in Ar demonstrate a superior combination of properties, including hardness of 36 GPa, elastic recovery of 84%, a friction coefficient of 0.6, and oxidation resistance at temperatures up to 1200 °C. High oxidation resistance is realized due to the formation of the protective (SiO2 + ZrO2)/SiO2 oxide layer, which inhibits the diffusion of oxygen into the coating. [ABSTRACT FROM AUTHOR]