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A set of novel (AlTiCrVTa)N x coatings are synthesized by DC magnetron sputtering to methodically investigate the effect of nitrogen content on the microstructure, mechanical and tribological properties and oxidation behavior of the coatings for the first time. As the nitrogen content increases, the coating structure transitions from amorphous to a simple fcc structure, accompanied by a change of preferred orientation from (200) to (111) and an enhancement in crystallinity. The coating morphology changes from featureless glassy to columnar crystals. The highest nanohardness of 38.1 GPa and the best wear rate of 4.9 × 10−7 mm3/Nm are achieved at 43.3 at.% nitrogen content. The friction coefficient exhibits a downward trend with rising nitrogen content, reaching the lowest value of 0.47 at 49.8 at.% nitrogen content. The oxidation tests reveal that the oxidation resistance deteriorates with increasing nitrogen content, caused by the looser structure and large-sized grain boundaries. [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 WSx/Fe/a-C/Fe multi-layer films with various Fe layer thicknesses were prepared by using magnetron sputtering and alternate deposition of WSx, Fe, and a-C layers on the silicon substrates. The morphology, micro-structure, and composition of the films were characterized by scanning electron microscope, energy dispersive spectroscopy, electron probe micro-analyzer, X-ray diffraction, and X-ray photoelectron spectroscopy. The mechanical and tribological properties of the fabricated films were evaluated by using nano-indenter, film stress tester, scratch tester, and ball-on-disk tribotester. According to the obtained results, all the multi-layer films revealed a featureless micro-structure with a smooth and dense surface. As the thickness of Fe layer increased, the S/W ratio of the films was decreased from 1.38 to 1.16, the hardness, elastic modulus, and adhesion of the films were gradually improved. Both the steady-state friction coefficient and wear rate were declined first and, then, enhanced. The film with the Fe-layer thickness of 4 nm exhibited the highest hardness (10.6 GPa) and adhesion (38.0 N); whereas, film with the Fe-layer thickness of 2 nm showed the best tribological performance with a steady-state friction coefficient of 0.218 and wear rate of 1.63 × 10−15m3 N−1 m−1. [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.

Comparative study of Ti-C-Ni-Fe, Ti-C-Ni-Al, and Ti-C-Ni-Al/Ti-C-Ni-Fe coatings obtained by electro-spark deposition (ESD) using TiCNi electrode, magnetron sputtering (MS) of TiCNiAl target, and a combination of these methods (MS-ESD) was carried out. The coating microstructures and elemental compositions were studied by means of X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and glow discharge optical emission spectroscopy. The materials were tested in terms of their hardness, elastic modulus, elastic recovery, crack resistance, friction coefficient, and wear resistance under sliding, impact and abrasive conditions, as well as corrosion- and oxidation resistance. The work demonstrated that the utilization of a combined two-step MS-ESD technology permits to obtain bilayers made of Ti-C-Ni-Al/Ti-C-Ni-Fe coatings with improved crack-, wear- and oxidation resistance compared with their single-layered Ti-C-Ni-Al counterparts deposited by MS, and with reduced friction coefficient and enhanced corrosion resistance compared with ESD Ti-C-Ni-Fe coatings. [ABSTRACT FROM AUTHOR]

Composite TiN-Ag films with various Ag content (Ag/(Ti + Ag)) were deposited using reactive magnetron sputtering and the influence of Ag content on the crystal structure, mechanical and tribological properties were investigated. The result showed that face-centered cubic (fcc) TiN and fcc-Ag co-existed in the films and TiN had a columnar-growth and the Ag nanoparticles embedded in the boundary of columnar crystal. The hardness of TiN-Ag films initially increased gradually and reached an optimum value, and then decreased with an increase in Ag content in the films. The maximum hardness value was 29 GPa at 0.8 at.% Ag. The addition of Ag into TiN film could enhance the fracture toughness ( K IC ) and critical load ( L C1 ) of the films because the nanoparticle Ag provides a large volume fraction of grain boundaries. As Ag was added into TiN film, the average friction coefficient decreased from 0.78 at 0 at.% Ag to 0.20 at 41.1 at.% Ag; however, the wear rate of TiN-Ag films initially decreased and then increased, after reaching the minimum value of about 1.3 × 10 −7 mm 3 /(mm.N), at 0.8 at.% Ag. [ABSTRACT FROM AUTHOR]

W-Si-N composite films were deposited on both stainless steel and silicon wafers using a reactive magnetron system. The silicon content of the film was varied to evaluate the effect of silicon on films' elemental composition, microstructure, oxidation resistance, mechanical and tribological properties. These series of test were conducted using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) analytical tools. The W-Si-N films showed a two-phase structure of solid solution face-centered cubic (fcc) W(Si)N x and an amorphous Si 3 N 4 . The thermal stability and the oxidation resistant temperature of W-Si-N films increased from about 380 °C at 0 at% Si to about 650 °C at 31.2 at% Si with the incorporation of Si into W 2 N matrix. The hardness of the films increased continuously from 26 GPa at 0 at% Si to 40 GPa at 23.5 at% Si which was due to solid strengthening and fine-grained strengthening. The silicon content affected the tribological properties of the film at room temperature but this was mainly influenced by the yield pressure, H/E ratio and elastic recovery, since lubricant tribo-film WO 3 was detected on all surfaces of the W-Si-N films. There was an initial gradual decrease in average coefficient of friction and wear rate until a minimum, but a further increase in silicon content resulted in increase in both friction coefficient and wear rates. The least coefficient of friction and wear rate values were 0.30 and 8.7 × 10 − 8 mm 3 /N·mm at 23.5 at% Si. [ABSTRACT FROM AUTHOR]

Hard coatings, such as nitride, carbide and diamond-like carbon (DLC), have been applied to improve the tribological resistance by forming multilayer or gradient structures. In this study, Ta/TaN/Ta(C,N)/Ta-DLC coatings in gradient content and multilayer structure with different modulation periods were prepared by high-power pulsed magnetron sputtering (HiPIMS). The effect of the modulation period on the microstructure, mechanical and tribological properties was evaluated. The average grain size of the coatings first increased from 15.2 to 17.1 nm and then decreased to 9.9 nm with decreasing modulation period from 1220 to 153 nm. Ta-DLC layer is homogeneously composed of TaC crystals and amorphous carbon. The design of the gradient structure makes the multilayer interface unclear, and the interlayer interdiffusion is obvious. The reduction of the modulation period effectively improved the adhesion strength of the multilayer coating on the substrate. The multilayer coating with a modulation period of 305 nm obtained the highest hardness of 24.5 ± 0.8 GPa and Young's modulus of 263.2 ± 16.6 GPa. Compared with single-layer TaN, Ta/TaN/Ta(C,N)/Ta-DLC multilayer gradient coating had dramatically improved tribological properties, exhibiting the lowest friction coefficient of 0.15 and the lowest wear rate of 2.47 × 10−12 m3N−1 m−1 when the modulation period is 305 nm. By combining a Ta-doped DLC layer with a low friction coefficient and a TaN layer with high hardness, the multilayer gradient coating achieved excellent mechanical and tribological properties. • Ta/TaN/Ta(C,N)/Ta-DLC multilayer gradient coating synthesized by HiPIMS • By combining TaN and DLC, a composite film with excellent mechanical and Tribological properties is obtained. • Multilayer gradient structure effectively interrupts the growth of columnar crystals and optimizes interfacial bonding. • Reducing the modulation period within a certain range improves the performance of the multilayer gradient coating. [ABSTRACT FROM AUTHOR]

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]

The present paper is focused on the development of hard tribological coatings with low friction coefficient (CoF) in different environments (humid air, distilled water) and at elevated temperatures. TiAlSiCN/MoSeC coatings were deposited by magnetron sputtering of four-segment targets consisting of quarter circle TiAlSiCN segments, obtained by self-propagating high-temperature synthesis, and one or two cold pressed segments made of MoSe 2 and C powders in a ratio 1:1 wt%. The structure and phase composition of coatings were investigated by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, and elastic recovery. The tribological properties of coatings were investigated first at room temperature against Al 2 O 3 and WC–Co balls, after which studied in distilled water and during continuous heating in air in the temperature range of 25–400 °C against Al 2 O 3 counterpart material. To evaluate their electrochemical characteristics, the coatings were tested in 1 N H 2 SO 4 solution. The obtained results show that the coating hardness depends on the amount of MoSeC additives and decreased from 40 to 28 (one MoSeC segment) and 12 GPa (two MoSeC segments). Doping with MoSeC resulted in a significant reduction of CoF values measured in humid air (RH 60 ± 5%) from 0.8–0.9 to 0.05 and an increase of wear resistance by one or two orders of magnitude depending on counterpart material. This was attributed to the presence of MoSe 2 and free carbon-based phases in the tribological contact. The TiAlSiCN/MoSeC coating with a maximal amount of MoSeC also demonstrated superior tribological characteristics in distilled water (CoF ∼ 0.1) and at moderate temperatures up to 300 °C (CoF < 0.1). The electrochemical tests showed that, in general, doping with MoSeC did not negatively affect the coating electrochemical behavior. On the contrary, the MoSeC phase demonstrated small positive effect on the anti-corrosive properties of TiAlSiCN coatings under small polarizations. [ABSTRACT FROM AUTHOR]

Ti–Mo–Si–N films with various Si content (0–17.2 at.%) were deposited by reactive magnetron sputtering and the effects of Si content on the microstructure, mechanical and tribological properties of Ti–Mo–Si–N films were investigated. The results showed that the face-centered cubic (fcc) interstitial solid solution of Ti–Mo–Si–N was formed by dissolution of Si into Ti–Mo–N lattice with the Si content in the range of 3.1–5.0 at.%. With a further increase in Si content, the films consisted of fcc-Ti-Mo-Si-N and amorphous Si 3 N 4 phases. The hardness and fracture toughness of Ti–Mo–Si–N films first increased and then decreased with the increase of Si content and the highest values were 34.5 GPa and 2.6 MP m 1/2 , respectively, at 5.0 at.% Si. The average friction coefficient and wear rate of Ti–Mo–Si–N films first decreased and then increased with the increase of Si content and the lowest values were 0.35 and 7.8 × 10 −8 mm 3 /Nmm, respectively, at 5.0 at.% Si. [ABSTRACT FROM AUTHOR]

Abstract: To improve the tribological performance of CrN coating, VN was introduced to form the CrN/VN multilayer structure via magnetron sputtering. The CrN/VN multilayer coatings with bilayer periods of 7, 13 and 27nm were investigated on the mechanical and tribological properties. The coatings were deposited on SUS420 and Si wafers (100) via in-line magnetron sputtering system. X-ray diffractometer, scanning electron microscopy, transmission electron microscopy and electron probe micro-analyzer were used to characterize the microstructures and chemical contents. Ball-on-disc wear test was used for tribological studies. The wear debris was analyzed by X-ray photoelectron spectroscopy. A hardness of 25.2GPa and coefficient of friction of 0.21 were achieved for multilayered coating in contrast to 16.7GPa in hardness and 0.4 in coefficient of friction for CrN coating. [Copyright &y& Elsevier]

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]

Abstract: Films of Ti–Ca–P–C–O–(N), Ti–Ca–C–O–(N) and Ti–Zr–C–O–(N) were deposited by DC magnetron sputtering or ion implantation-assisted magnetron sputtering of composite targets TiC0.5+10%Ca10(PO4)6(OH)2, TiC0.5+20%(CaO+TiO2) and TiC0.5+10%ZrO2 in an Ar atmosphere or reactively in a gaseous mixture of Ar+14%N2. The microstructure, elemental and phase composition of films were studied by means of X-ray diffraction, transmission electron microscopy, scanning force microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. The films were characterized in terms of their hardness, Young''s modulus, elastic recovery, adhesion strength, and friction and wear both in air and under physiological solution. Particular attention was paid to the analysis of deformation and fracture for various film/substrate systems during scratch testing. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments. In vitro studies involved the investigation of adhesion, spreading, and proliferation of MC3T3-E1 osteoblasts and IAR-2 epithelial cells, morphometric analysis, actin cytoskeleton, focal contacts staining, alkaline phosphatase activity and von Kossa staining of osteoblastic culture. Cell culture experiments demonstrated an increase of osteoblastic proliferation on Ca- and P-incorporated films. In vivo studies were fulfilled by subcutaneous implantation of Teflon plates coated with the tested films in mice and analysis of the population of adherent cells on their surfaces. The results obtained show that multicomponent nanostructured Ti–(Ca, Zr)–(C, N, O, P) films possess a combination of high hardness, wear resistance and adhesion strength, reduced Young''s modulus, low friction coefficient and high biocompatibility. [Copyright &y& Elsevier]

Abstract: A comparative investigation of Ti–B–N, Ti–Cr–B–N, Ti–Si–B–N, and Ti–Al–Si–B–N coatings deposited by DC magnetron sputtering and ion implantation assisted magnetron sputtering of composite targets TiBN, TiCrB, TiSiB, and TiAlSiB in an Ar atmosphere or reactively in a gaseous mixture of Ar+N2 is presented. The targets were manufactured by means of a self-propagating high-temperature synthesis method. The microstructure and phase composition of coatings were studied by means of X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The films were characterized in terms of their hardness, Young’s modulus, elastic recovery, adhesion (critical load), friction and wear. The lifetime of drills coated with Ti–Cr–B–N and Ti–Si–B–N coatings as well as the productivity of the drilling process were examined. [Copyright &y& Elsevier]

In the present work multicomponent thin films based on the systems Ti–Ca–C–O–N and Ti–Zr–C–O–N have been deposited and evaluated. TiC0.5+10% CaO and TiC0.5+10% ZrO2 targets were manufactured by means of the self-propagating high-temperature synthesis (SHS) method. The synthesized targets were subjected to DC magnetron sputtering in an atmosphere of argon or in a gaseous mixture of argon and nitrogen. The films were characterized in terms of their structure, surface topography, mechanical properties and tribological behavior. The films deposited on Si substrates under optimal conditions showed high hardness in the range of 36–40 GPa, low Young''s modulus 260–300 GPa and high percentage of elastic recovery 70–75%. The CaO- and ZrO2-doped Ti–C–N films showed significantly lower friction coefficient and wear rate against WC+6% Co alloy in comparison to conventional magnetron–sputtered TiC and TiN films. The biocompatibility of the films was evaluated by both in vitro and in vivo experiments (in mice). In vitro studies involved the investigation of the proliferation of fibroblasts Rat-1 and epithelial cells IAR-2 at the tested films and morphometric analysis of the cells cultivated on the films. Fibroblasts and epithelial cells were seeded on the coverslips, coated with examined films and incubated at 37 °C for 24, 48 and 72 h. We did not detect statistically significant differences in the attachment, spreading and proliferation of cultured cells on the coated and the uncoated substrata. The adhesion and proliferation of cells was good at all investigated films. We also did not observe any inflammatory reactions on the implants, inserted under the mouse skin. [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]

The spontaneously self-organizing multilayered graphite-like carbon (denoted as GLC) /TiC films with various bilayer periods in the range of 13.3–17.5 nm were deposited on silicon and 1Cr18Mn8Ni5N stainless steel substrates using closed field magnetron sputtering deposition facility. The microstructures and chemical compositions of the prepared multilayered films were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy respectively. The self-organizing multilayered structures in all of the films consisted of titanium carbide layers and sp2-rich carbon layers periodically alternate arrangement. The TiC contents and bilayer periods of the multilayered films can be controlled by means of adjusting of sputtering current of graphite target. Furthermore, the mechanical and tribological performances of the prepared films were appraised by nano-indentor, scratch measures, and ball-on-plate tribometer respectively. The results indicated that multilayer structure endowed the as-deposited TiC/GLC films outstanding mechanical and tribological properties, especially the multilayer film with 15.9 nm bilayer period deposited at 10 A sputtering current showed the excellent adhesion strength and hardness; Simultaneously it also exhibited the lowest average friction coefficient in the humid environment owing to its high content of sp2 hybrid carbon. [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]

Mo-Si-B and Mo-Hf-Si-B coatings are deposited by magnetron sputtering in two regimes (direct and pulsed current) using composite ceramic cathodes. The structure of the coatings is investigated by XRD, SEM, EDS, and GDOES. Mechanical and tribological properties are measured by nanoindentation and tribological pin-on-disc testing. The short-term oxidation resistance of the coatings in the air is evaluated at 1500 °С. Results show that pulsed current deposition decreases the coating's growth rate and the grains size of coating's main constituent h-MoSi 2 phase while promoting the formation of MoB 2. The introduction of hafnium increased the coating's density and suppressed the formation of unwanted columnar structure. The highest hardness of 28 GPa, Young modulus of 366 GPa, and elastic recovery of 64% were achieved for the Mo-Si-B coating deposited at direct current. Optimal tribological performance, including a stable friction coefficient and low wear rate of 6.9х10−6 mm3/(Nm), was determined for Mo-Hf-Si-B coating also obtained using direct current. All coatings were oxidation-resistant at 1500 °С, but the Mo-Hf-Si-B composition demonstrated oxidation resistance superior to that of Mo-Si-B coatings because of the formation of two-layered HfO 2 /SiO 2 protective film. The thickness of the oxide layer was higher for the coatings deposited using pulsed current. Unlabelled Image • Hard Mo-Si-B and Mo-Hf-Si-B coatings obtained by magnetron sputtering in d.c. and pulsed modes • Mo-Si-B exhibit maximal hardness of 28 GPa and elastic recovery of 64%. • Mo-Hf-Si-B possess higher tribological properties and oxidation resistance. • Coatings withstand short-term oxidation at 1500 °C. • Oxidation is accompanied with formation of SiO 2 and HfO 2 /SiO 2 protective layers. [ABSTRACT FROM AUTHOR]

Hf-Mo-Si-N films with a series of Si contents were prepared by magnetron sputtering in a mixed Ar/N 2 atmosphere. Microstructure and surface morphologies of films were characterized by XRD, XPS, TEM and AFM. Besides, mechanical and tribological properties were evaluated. With increasing of Si addition, the phase of films transforms from single fcc Hf-Mo-N to nanocomposite structure consisted of Hf-Mo-Si-N crystalline and amorphous Si 3 N 4 phases. The Hf-Mo-Si-N film with 5.4 at.% Si content exhibits improved hardness of 38.6 GPa and enhanced toughness of 3.6 MPa·m1/2, which is ascribed to the synergistic effect of the solid solution strengthen, fine grains and interface strengthening in nanocomposite system. The precipitated amorphous Si 3 N 4 phase could hinder the cracks propagation, which results in higher fracture toughness. The low average friction coefficient of 0.37 and wear rate of 1.8 × 10−6 mm3/N are obtained from the Hf-Mo-Si-N film with 5.4 at.% Si, which is also accompanied with high value of H/E (0.14) and H3/E*2 (0.61 GPa). • Quaternary Hf-Mo-Si-N films were synthesized by DC and RF magnetron co-sputtering. • Hard yet tough nanocomposite films with dispersed a-Si 3 N 4 phases can resist crack propagation. • The proper Si-addition greatly improves tribological properties of films. [ABSTRACT FROM AUTHOR]